JP2000201434A - Voltage stability monitoring and control device - Google Patents

Abstract

(57) [Summary] To determine the stability of voltage by a simple device. SOLUTION: A plurality of load feeders 18 and a transformer 16 are provided.
In order to monitor the stability of the voltage in the substation 15 to be monitored, the voltage stability monitoring and control device 25 uses the pallet, which is information about various electric quantities in the substation 15 to be monitored and information before and after the operation of the transformer tap. Detector 26 for detecting information 21
A predetermined operation is performed using the various amounts of electricity and the pallet information 21 to determine the voltage stability of the current operating point; and, if it is determined that the current operation point is unstable, the voltage stability is ensured. A control unit 28 for performing necessary control is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage stability monitoring and control device for monitoring the voltage stability of a power system and, if unstable, performing load limitation or the like to prevent system collapse.

[0002]

2. Description of the Related Art In a conventional voltage stability monitoring and control device, a voltage stability is represented by a PV of a system showing a relationship between the active power of a load or the total demand P of the entire system and a bus voltage V of a typical electric station.
Evaluated using characteristics.

Normally, the PV characteristics of a system are represented by a PV curve in which the horizontal axis is P and the vertical axis is V, as shown in FIG. A point P is called a limit power, and a voltage at that time is called a limit voltage. The difference between the power at the current operating point and the limit power is called active power margin, and this is generally used as an index indicating voltage stability. The upper half of the PV curve is called a higher voltage solution area, and the lower half is called a lower voltage solution area.

Actually, a PV curve using the total demand P and the bus voltage V of the main substation when the demand increases at a constant rate from the current system state is obtained online by repeating the power flow calculation. And the current active power P
The difference between the current operating point and the limit power, that is, the active power margin is calculated. The voltage stability is evaluated by monitoring the obtained active power margin, and a guideline for improving the voltage stability is created according to the active power margin,
Presented to the operator. The operator drafts and executes specific stabilization measures such as operation of the phase adjustment facility based on the presented guidelines.

[0005] The conventional voltage stability monitoring and control device is
Reference "91 SM 492-9 PWRS, NEWL
Y DEVELOPED VOLTAGE SECUR
This is described in detail in "ITY MONITORING SYSTEM". Further, the PV characteristics and voltage stability of the system are described in detail in the reference document “Joint Research on Electricity, Vol. 47, No. 1, Power System Stable Operation Technology”, and thus the description is omitted here. I do.

FIG. 7 is a block diagram of a voltage stability monitoring and control device for monitoring the voltage stability of the power system.
In the figure, a power system 1 is configured such that a plurality of generators 2 and a substation 3 are connected by a transmission line 4 and each terminal is connected to each load (not shown).

[0007] A voltage detector 5 and a current detector 6 are provided at each location scattered in the power system 1, and detection signals from the voltage detector 5 and the current detector 6 are transmitted to the information communication device 7A. In each information communication device 7A, the data of the online information is input via each transmission line 8 to the information communication device 7A.
B and received by the information communication device 7B.

The data received by the information communication device 7B is sent to the voltage stability monitoring and control device 10. In the voltage stability monitoring and control device 10, first, system information input processing (10a) is performed to internally process voltages, currents, and the like measured at the plurality of substations 3, and processing data is used as input data.

Next, state estimation calculation processing (10b) is performed on the input data, and an initial state is determined. In this processing, system data set in advance such as line constants is used. When the initial state is determined, a large number of power flow calculations are repeatedly executed at high speed based on the initial state, and a PV curve creation process (10c) based on the power flow calculation is performed.

Thus, an online PV curve as shown in FIG. 6 is created. When the PV curve is created, the difference between the current active power P (current operating point) and the limit power, that is, the active power margin is calculated, and the voltage stability determination (10c) is performed. Will be

Next, a voltage stability improvement guideline for improving voltage stability according to the active power margin is prepared (10d).
Is done. Then, the PV curve and the active power margin are output-displayed (10c), transmitted as voltage stabilizing online information to the system power supply commanding station 11, and displayed on the CRT screen 12 of the operator.

The specific stabilization measures are as follows:
One operator drafts and executes based on the voltage stabilization online information.

[0013]

In the conventional voltage stability monitoring and control device 10 described above, the P
Since the −V curve is used, it is necessary to perform a large number of power flow calculations to obtain the PV curve. This power flow calculation has a problem that the calculation amount is large and a high-speed computer is required for online monitoring.

Further, in order to execute the power flow calculation, it is necessary to collect system data measured at each of the substations 3 scattered in the power system 1. For this data collection, a wide area information communication network is required. There is a problem that it is necessary and the system scale becomes large.

Therefore, the present invention has been made to solve the above-mentioned problem, and evaluates voltage stability by simple calculation using only the quantity of electricity as local information measured at a substation to be monitored. It is an object of the present invention to provide a voltage stability monitoring and control device having means and means for calculating a countermeasure amount necessary for stabilization when it is determined to be unstable.

[0016]

According to a first aspect of the present invention, there is provided a voltage stability monitoring control device for monitoring the stability of a voltage in a monitored substation comprising a plurality of load feeders and a transformer. A detection unit that detects various amounts of electricity in the substation and pallet information that is information before and after the operation of the transformer tap, and performs a predetermined calculation using the various amounts of electricity and the pallet information detected by the detection unit. And a control unit for performing control necessary to secure voltage stability when the calculation unit determines that the voltage stability is unstable. . According to this means, it is necessary to collect data over a wide range as in the conventional system, because it is possible to determine the voltage stability by simple calculation using only various electric quantities as local information measured at the monitored substation. There is no need for a wide area information communication network, so the system scale can be reduced. Further, since the voltage stability is evaluated without using the PV curve, it is not necessary to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. In addition, when voltage stability is unstable, a stabilization measure is taken.
Voltage collapse can be prevented, and power outages can be minimized. In addition, a highly reliable device having a simple device configuration can be provided.

According to a second aspect of the present invention, in the voltage stability monitoring and control apparatus according to the first aspect, the arithmetic unit is configured to calculate a high-side bus voltage and a low-side bus voltage before and after a transformer tap operation of the substation to be monitored. Thus, the voltage stability at the current operating point is determined. According to this means, the voltage stability can be determined by only the local information (various amounts of electricity) measured at the monitored substation and by a simple calculation, so that data is collected over a wide range as in the conventional system. There is no necessity and a wide area information communication network is not required, so that the system scale can be reduced. Further, since the voltage stability is determined without using the PV curve, it is not necessary to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. can do.

According to a third aspect of the present invention, in the voltage stability monitoring and control apparatus according to the first aspect, the arithmetic unit includes a high-side bus voltage before and after a transformer tap operation of the substation to be monitored, an active power passing through the transformer. Is used to determine the voltage stability at the current operating point. According to this means, local information (various amounts of electricity) measured at the monitored substation
Since the voltage stability can be determined only by the simple calculation, the data scale does not need to be collected over a wide range unlike the conventional system, and a wide area information communication network is not required, so that the system scale can be reduced. Further, since the voltage stability is determined without using the PV curve, it is not necessary to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. can do.

According to a fourth aspect of the present invention, in the voltage stability monitoring and control apparatus according to the first aspect, the operation unit includes a high-side bus voltage, a low-side bus voltage, and a transformer before and after a transformer tap operation of the substation to be monitored. The voltage stability at the current operating point is determined based on the passing active power. According to this means, the voltage stability can be determined by only the local information (various amounts of electricity) measured at the monitored substation and by a simple calculation, so that data is collected over a wide range as in the conventional system. There is no need, and there is no need for a wide area information communication network, and the system scale can be reduced. Also, P-
Since the voltage stability is determined without using the V curve, the P-V
There is no need to perform a large number of power flow calculations for finding a curve, and the amount of calculation can be reduced, so that the device can have a simple device configuration.

The invention according to claim 5 is the invention according to claims 1 to 4.
In any one of the described voltage stability monitoring and control devices, the control unit outputs a command to lock the tap operation of the transformer of the monitored substation when the voltage is determined to be unstable by the determination by the calculation unit. Things. According to this means, when it is determined that the voltage is unstable, it is possible to prevent the voltage drop due to the reverse operation of the tap only by locking the tap operation of the transformer at the substation to be monitored, thereby stabilizing measures such as load limiting. Therefore, it is possible to provide a device that increases the supply reliability of the system.

According to a sixth aspect of the present invention, there is provided the first to fourth aspects.
In any one of the voltage stability monitoring and control devices described above, the control unit performs a preset predetermined amount of load limitation when it is determined by the calculation unit that the voltage is unstable. According to this means, every time it is determined that the voltage is unstable, a predetermined amount of load limitation is performed, so that data and calculation for calculating the load limitation amount are not required. Even if the operation is performed, the load stability is performed every time it is determined that the voltage is unstable, and the voltage stability is improved. Therefore, it is possible to prevent the power outage from spreading due to the voltage collapse and to achieve a simple device configuration. .

According to a seventh aspect of the present invention, in the voltage stability monitoring and controlling apparatus according to the first aspect, the arithmetic unit executes a predetermined arithmetic operation using the various electric quantities detected by the detecting unit and the pallet information, Voltage stability determining means for determining the voltage stability of the current operating point and storing various electric quantities and pallet information in the storage means, and storing the voltage stability when the voltage stability determining means determines that the voltage is unstable. Means for obtaining the voltage stability index indicating the degree of voltage stability instability by extracting various quantities of electricity and pallet information from the means, and using the obtained voltage stability index to shift from the current operating point to the stable area. The control unit calculates the load limiting amount and determines a load feeder to be disconnected.The control unit transmits an open command to the circuit breaker determined by the control amount calculating unit and corresponding to the load feeder. It is obtained so as to provide means for force. According to this means, the load limit required for stabilization can be obtained online using the voltage stability index obtained only from various amounts of electricity as local information, so that the device configuration is simple and highly controllable. It can be a device.

According to an eighth aspect of the present invention, in the voltage stability monitoring and controlling apparatus according to the first aspect, the arithmetic unit executes a predetermined arithmetic operation using the various electric quantities detected by the detecting unit and the pallet information, Voltage stability determining means for determining the voltage stability of the current operating point and storing various electric quantities and pallet information in a storage means; and a storage means when the voltage stability determination means determines that the voltage stability is unstable. From the low-voltage bus voltage and the pallet information, and calculate the load limiting amount required to shift from the current operating point to the stable region according to the change in the low-voltage bus voltage before and after the tap operation of the transformer, The control unit includes a control amount calculation unit that determines a load feeder to be disconnected, and the control unit includes a unit that outputs an open command to a circuit breaker that is determined by the control amount calculation unit and corresponds to the load feeder. Those were. According to this means,
Since the load limiting amount required for stabilization can be obtained online using only various electric quantities as local information, an apparatus having a simple apparatus configuration and high controllability can be obtained.

[0024] The ninth aspect of the present invention provides the first to eighth aspects.
In any one of the voltage stability monitoring and control devices described above, the detection unit includes a smoothing processing unit that performs a smoothing process on various electric quantities. According to this means, the detection value is subjected to a smoothing process and used for the calculation of the determination of the voltage stability. Therefore, even if the detection value changes suddenly due to a short-period load change, etc., erroneous determination can be prevented, and Degree device.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a voltage stability monitoring and control device according to a first embodiment of the present invention. In the first embodiment, a plurality of load feeders 18 and a transformer 16 are provided. At the substation 3, the measured values of various quantities of electricity that can be measured at the monitored substation and the tap operation of the transformer are monitored, and when the tap operation of the transformer is detected, the operation before the tap operation of the transformer is performed. The voltage stability is evaluated using the later-determined values of various amounts of electricity, and when it is determined that the voltage is unstable, a stabilization measure is implemented.

In the illustrated power system 1, the transformer 16
The substation 3 composed of a circuit breaker 17, a circuit breaker 17, a plurality of load feeders 18, and the like is a specific substation 15 to be monitored. The substation 3 includes a voltage detector 5A on the primary side of the transformer 16, a voltage detector 5B on the secondary side, a power detector 19 for detecting active power passing through the transformer 16, and each load feeder 1
A power detector 20 for detecting the active power of the
A means (not shown) for outputting the pallet information 21 as the tap information is arranged.

On the other hand, the voltage stability monitoring and control device 25 comprises a detection unit 26, a calculation unit 27 and a control unit 28, and the calculation unit 27 comprises a voltage stability determination unit 29 and a storage unit 30. I have. Further, the control unit 28 of the voltage stability monitoring and control device 25 outputs a stabilization measure by displaying and outputting an alarm.
It is connected to the RT display alarm device 31 and is connected so as to output stabilization measures to the circuit breaker 17 and the transformer 16.

Here, the detection unit 26 detects various electric quantities including the bus voltage in the substation to be monitored, the active power passing through the transformer, and the active power of each load feeder, and the pallet information as the tap information of the transformer. I do. The calculation unit 27 includes the detection unit 2
A predetermined calculation is executed using the various amounts of electricity detected by step 6 and the pallet information to determine the voltage stability of the current operating point. The control unit 28 performs control necessary for ensuring voltage stability when the arithmetic unit 27 determines that the voltage is unstable.

Here, the conventional voltage stability monitoring and control device 10 described with reference to FIGS. 6 and 7 raises the voltage on the PV curve and increases the difference from the current operating point in the solution region to the limit power,
That is, the voltage stability is evaluated by looking at the active power margin, and the operation and monitoring in the lower voltage solution region are not considered. However, in practice, the operation can be continued even if the operating point shifts to the lower half of the PV curve, that is, the lower voltage solution region. When the operating point on the PV curve exceeds the limit power and enters the solution area where the voltage is low and the solution becomes lower due to the increase in demand, the voltage becomes unstable and the operation cannot be continued because the voltage characteristics of the system load are all constant power characteristics. Only when the load on the real grid is
Many loads with constant current characteristics and constant impedance characteristics are included, and it is possible to continue the operation of the system to some extent even in the lower voltage solution region. Since the voltage characteristics and the voltage stability of the load are described in detail in the reference document "Electric Cooperative Research, Vol. 47, No. 1, Power System Stable Operation Technology", the description is omitted here.

Therefore, the present invention focuses on the above-mentioned point, and it is determined whether the operating point of the current system has shifted to a lower voltage solution area on the PV curve, that is, an area where the voltage stability is unstable. If it is determined that the voltage is in the lower voltage solution area (voltage instability), implement stabilization measures, raise the operating point of the system to a higher voltage, shift to the lower limit or limit power, and improve the voltage stability. It is to secure.

Next, the determination of the voltage stability (low voltage solution region) will be described with reference to FIG.

In general, the taps of the transformer 16 of the substation 3 for the load supply system operate for the purpose of controlling the voltage on the secondary side. When the tap operation is performed in the direction in which the voltage on the secondary side of the transformer increases (the tap ratio n increases),
Transformer voltage V ₁ of the primary side decreases, voltage V ₂ of the transformer secondary is increased. Along with the increase in the voltage V ₂ of the secondary side, since the power consumption of the load increases, passing the active power of the transformer is increased. At this time, the PV curve is
As shown in FIG. 2, the PV curve changes (shown from a dashed line to a shown solid line) with an increase in the tap ratio n (arrow C in the figure),
Assuming that the operating point before the tap operation is A, the operating point is A → A ′
Move to

However, in the lower voltage solution region, if there is a tap operation in the direction of increasing the voltage on the secondary side of the transformer (increase in tap ratio n), the secondary side voltage V ₁ on the secondary side decreases with respect to the decrease in the primary side voltage V ₁ . there are cases where the voltage V ₂ decreases. If this phenomenon is represented by a PV curve, it changes as shown by BB 'in FIG. In the case of an on-load tap changer (LTC) such as a distribution substation that is automatically operated so as to maintain the voltage on the transformer secondary side, at point B, the tap operates further in response to this voltage drop due to the operation of the tap. (Tap ratio n → increase) and the voltage drop progresses.

The above phenomenon is known as a reverse operation phenomenon of a tap of a transformer, and is referred to in the reference document “Joint Research on Electricity, No. 47”.
Vol. 1, Power System Stable Operation Technology ".

The voltage stability monitoring and control device 25 according to the first embodiment of the present invention captures an actual reverse operation phenomenon of the tap using various amounts of electricity measurable at the substation 15 to be monitored. Is used to determine whether the voltage is stable or unstable.

Next, the processing flow of the voltage stability monitoring and control device 25 will be described with reference to FIG.

First, in the detection unit 26, the bus of the substation 15 to be monitored, each load feeder 18 or the transformer 16
Bus voltage V _{1 of} substation 3 installed in substation equipment such as
There is by bus voltage V ₂ detected by the voltage detector 5A is detected by the voltage detector 5B, it passes through the active power P _TR of the transformer 16 is detected by the power detector 19. Furthermore, detected by the effective power P _L is the power detector 20 of the load feeder 18, together with various electrical quantity is measured at all times, in order to monitor the operation existence of transformer taps 16 monitored substation 15 always The pallet information 21 of the tap of the transformer is input, and these data are passed to the arithmetic unit 27.

When the tapping operation of the transformer 16 is detected by using the pallet information 21 of the tap of the transformer 16, the arithmetic unit 27 performs the operation before and after the tap operation by using various amounts of electricity measured every moment. Based on the subsequent changes in the amounts of electricity, the current voltage stability of the system is determined to be stable (higher voltage solution area) or unstable (lower voltage solution area), and the determination result is sent to the control unit 28
Pass to

The processing of each means of the arithmetic section 27 will be described below.

The voltage stability determination means 29 determines whether the voltage stability at the current operating point of the system is stable.

First, the bus voltages V ₁ , V _{2 of} the substation measured instantaneously by the detection unit 26 and the active power P passing through the transformer 16
_TR, and temporarily stores various electric quantity in the memory means 30 comprising an effective power P _L of the load feeder 18. In parallel with this process, using the pallet information 21 of the taps of the transformer 16 obtained by the detection unit 26, whether the taps of the transformer 16 have operated in the direction of increasing the voltage on the secondary side of the transformer 16 Monitor whether. When there is no tap operation of the transformer 16, these processes are continuously performed.

The fact that the bus voltage V ₂ of the substation 3 decreases due to the influence of the load fluctuation and the tap of the transformer 16 operated in the direction of increasing the secondary voltage by the load tap changer (LTC) or the like. If detected using pallet information 21,
The bus voltage V _1bf or the bus voltage V _2bf of the substation 3 before the tap operation and the active power P _TRbf passing through the transformer 16 stored in the storage means 30 are called, and after the tap position is completely switched, the detecting unit Using the bus voltage V _1af or the bus voltage V _{2af of} the substation 3 measured at 26 and the passing active power P _TRaf of the transformer 16, the values after the tap operation and before the tap operation are calculated according to the equations (1.1) and (1.2). The values ΔV _B and ΔP _TR are obtained by subtracting the values.

ΔV _B = V _Baf −V _Bbf (1.1) ΔP _TR = P _TRaf −P _TRbf (1.2)

Here, the voltage V _B is the magnitude of the voltage,
Used bus voltages V ₁ or bus voltage V _2. The subscript af in the expression indicates a value after the tap operation, and bf indicates a value before the tap operation.

ΔV _B and ΔP _TR obtained by the above equations are negative values, that is, the voltage V _Baf and the active power P _TRaf after the tap operation are compared with the voltage V _Bbf and the active power P _TRbf before the tap operation. If the value is lower (decreased), it is determined that the current operating point of the system is in an unstable voltage (low voltage solution region). In the case of other conditions, it is determined to be stable (high voltage solution region).

The control unit 28 includes a voltage stability determination unit 29
When it is determined that the current operating point of the system is unstable, the control necessary to improve the voltage stability is performed to avoid the unstable voltage.

As described above, according to the first embodiment, the voltage stability can be determined only by local information (various amounts of electricity) measured at the substation to be monitored and by a simple calculation. As described above, there is no need to collect data over a wide area and a wide area information communication network is not required, so that the system scale can be reduced. Further, since the voltage stability is evaluated without using the PV curve, it is not necessary to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. Further, since a stabilization measure is taken when the voltage stability is unstable, voltage collapse can be prevented and the time between power outages can be minimized. Therefore, a highly reliable device having a simple device configuration can be provided.

Next, a second embodiment of the present invention will be described with reference to FIGS.

According to the second embodiment of the present invention, the voltage stability of the current operating point is determined based on the high-side bus voltage and the low-side bus voltage before and after the tap operation of the transformer of the substation 15 to be monitored. An arithmetic unit 27 is provided. Note that the detection unit 26 and the control unit 28 are the same as those in the first embodiment.

First, the voltage stability determination means 29 determines whether the voltage stability at the current operating point of the system is stable or unstable.

More specifically, the high-voltage bus voltage V ₁ and the low-voltage bus voltage V ₂ of the substation 3 measured at _every moment by the detection unit 26 are temporarily stored in the storage unit 30. In parallel with this, the tap of the transformer 16 is changed to the transformer 16 using the pallet information 21 of the tap of the transformer obtained by the detecting unit 26.
It monitors whether the secondary side has operated in the direction of increasing the voltage. When there is no tap operation of the transformer 16, these processes are continuously performed.

The fact that the bus voltage V ₂ of the substation 3 decreases due to the influence of load fluctuation and the like, and the tap of the transformer 16 operated by the load tap changer (LTC) in the direction of increasing the secondary side voltage, If detected using pallet information 21,
The high-voltage bus voltage V _1bf and the low-voltage bus voltage V _2bf of the substation 3 before the tap operation stored in the storage means 30 are called. Next, the bus voltage V on the high voltage side of the substation 3 measured by the detection unit 26 after the tap position is completely switched.
_1af and the low-voltage side of the bus voltage V _2af the bus voltage V _1BF the high pressure side of the tap operation before the substation 3 calling from the memory means 30
(1.3) to (1.4) using the low-voltage side bus voltage V _2bf
As shown in the equation, the values ΔV ₁ and ΔV ₂ of the electric quantities are obtained by subtracting the value before the tap operation from the value after the tap operation.

ΔV ₁ = V _1af −V _1bf (1.3) ΔV ₂ = V _2af −V _2bf (1.4)

ΔV ₁ and ΔV ₂ obtained by the above equations are negative values, that is, the bus V on the high voltage side before the tap operation.
_{When 1bf} and the bus voltage V _2af on the low voltage side decrease (decrease), it is determined that the current operating point of the system is unstable. In other conditions, it is determined that the condition is stable. The above determination result of the voltage stability is passed to the control unit 28.

As described above, according to the second embodiment, the voltage stability can be determined by only the local information (various amounts of electricity) measured at the monitoring substation and by a simple calculation.
Unlike a conventional system, there is no need to collect data over a wide area, and there is no need for a wide-area information communication network, so that the system scale can be reduced. Further, since the voltage stability is determined without using the PV curve, there is no need to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. Therefore, a device having a simple device configuration can be provided.

Next, a third embodiment of the present invention will be described with reference to FIGS.

In the third embodiment, the voltage stability at the current operating point is determined based on the high-side bus voltage before and after the tap operation of the transformer of the substation 15 to be monitored and the active power passing through the transformer. An arithmetic unit 27 is provided. Note that the detection unit 26 and the control unit 28 are the same as those in the first embodiment.

First, the voltage stability determining means 29 determines whether the voltage stability at the current operating point of the system is stable or unstable. The high voltage side bus voltage V _{1 of} the substation 3 and the active power _PTR passing through the transformer 16 measured momentarily by the detection unit 26 are temporarily stored in the storage unit 30. In parallel with this, the pallet information 21 of the tap of the transformer 16 obtained by the detection unit 26 is displayed.
Is used to monitor whether the tap of the transformer 16 has operated in a direction to increase the voltage on the secondary side of the transformer 16. When there is no tap operation of the transformer 16, these processes are continuously performed.

The fact that the bus voltage V ₂ of the substation 3 decreases due to the influence of the load fluctuation and the like, and the tap of the transformer 16 operated in the direction of increasing the secondary side voltage by the load tap changer (LTC) or the like, If detected using pallet information 21,
Before the tap operation, the high-side bus voltage V _1bf of the substation 3 and the active power P _T passing through the transformer 16 stored in the storage means 30 are stored.
_{Call Rbf} . Then, the tap operation before substations that called from the storage unit 30 and passing through the active power P _{TRa f} of the high-pressure side bus voltage V _1af a transformer 16 of the substation 3, as measured by the detector 26 after the tap position switches to complete 3 pass active power P _TRbf the high side bus voltage V _1BF a transformer 16
As shown in the equations (1.5) to (1.6), the values after the tap operation are subtracted to obtain the change amounts ΔV ₁ and ΔP _{TR of the} respective electric quantities.
Ask for.

ΔV ₁ = V _1af −V _1bf (1.5) ΔP _TR = P _TRaf −P _TRbf (1.6)

ΔV ₁ , ΔP obtained by the above equations
_TR, respectively negative value, that is, the high pressure side bus voltage V _1BF before tapping operation, active power P _TRbf high side bus voltage V _1af after operation compared to found the active power P _TRAF decrease (reduction)
In this case, it is determined that the current operating point of the system is unstable. In other conditions, it is determined that the condition is stable.

As described above, according to the third embodiment, the voltage stability can be determined by only the local information (various amounts of electricity) measured at the monitoring substation and by a simple calculation. Further, unlike the conventional system, there is no need to collect data over a wide area, and there is no need for a wide-area information communication network, so that the system scale can be reduced. Further, since the voltage stability is determined without using the PV curve, a large number of power flow calculations for obtaining the PV curve can be reduced, so that the apparatus can have a simple configuration.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.

In the fourth embodiment, the voltage stability of the current operating point is determined based on the high-side bus voltage, the low-side bus voltage, and the active power passing through the transformer before and after the transformer tap operation of the substation 15 to be monitored. Is provided with an arithmetic unit 27 that determines Note that the detection unit 26 and the control unit 28 are the same as in the first embodiment.

First, the voltage stability determining means 29 determines whether the voltage stability at the current operating point of the system is stable or unstable.

More specifically, the high-voltage bus voltage V ₁ and the low-voltage bus voltage V _{2 of} the substation 3 and the active power _PTR passing through the transformer 16, which are momentarily measured by the detection unit 26, are temporarily stored in the storage unit 30. store. In parallel with this, it is monitored whether or not the tap of the transformer 16 has operated in the direction of increasing the voltage on the secondary side of the transformer, using the pallet information 21 of the tap of the transformer 16 obtained by the detection unit 26. I do. When there is no tap operation of the transformer 16, these processes are continuously performed.

The fact that the bus voltage V ₂ of the substation 3 decreases due to the influence of load fluctuation and the like, and the tap of the transformer 16 operated by the load tap changer (LTC) in the direction of increasing the secondary side voltage, When detecting using the pallet information 21,
The high-side bus voltage V _1bf and the low-voltage measurement bus voltage V _2bf of the substation 3 before the tap operation and the active power P _TRbf passing through the transformer 16 stored in the storage means 30 are called. Then, calling the pass active power P _TRAF storage means 30 of the high-pressure measuring bus voltage V _1af and the low-bus voltage V _2af a transformer 16 of the substation 3, as measured by the detector 26 after the tap position switches to complete Using the high-side bus voltage V _1bf and low-side bus voltage V _2bf of the substation 3 before the tap operation and the active power P _TRbf passing through the transformer 16, the tap operation is performed as shown in equations (1.7) to (1.9). The values ΔV ₁ , ΔV ₂ , ΔP _TR of the respective electric quantities are obtained by subtracting the value before the tap operation from the value after the tap operation.

ΔV ₁ = V _1af −V _1bf (1.7) ΔV ₂ = V _2af −V _2bf (1.8) ΔP _TR = P _TRaf −P _TRbf (1.9)

The ΔV ₁ , ΔV ₂ , ΔV obtained by the above equations
P _TR is a negative value, that is, the high-side bus voltage V _1bf , the low-side bus voltage V _2bf , and the active power P before the tap operation.
_If the high-side bus voltage V _1af , the low-side bus voltage V _2af , and the active power P _TRaf after operation are lower (decreased) than _TRbf , it is determined that the current operating point of the system is unstable. . In other conditions, it is determined that the condition is stable. The above determination result of the voltage stability is passed to the control unit 28.

As described above, according to the fourth embodiment, the voltage stability can be determined only by local information (various amounts of electricity) measured at the monitoring substation and by a simple calculation. Unlike a conventional system, there is no need to collect data over a wide area, and there is no need for a wide-area information communication network, so that the system scale can be reduced. Further, since the voltage stability is determined without using the PV curve, there is no need to perform a large number of power flow calculations for obtaining the PV curve, and the amount of calculation can be reduced. Therefore, a device having a simple device configuration can be provided.

Next, a fifth embodiment of the present invention will be described with reference to FIG.

In the fifth embodiment, the control unit 2 outputs a command for locking the tap operation of the transformer of the substation 15 to be monitored when the voltage is determined to be unstable by the calculation unit 27.
8 is provided. Note that the detection unit 26 and the calculation unit 27 are the same as in the first embodiment.

In the control unit 28, when the voltage stability determination means 29 of the calculation unit 27 determines that the current operating point of the system is unstable, the transformer 16 of the monitored substation 15
And outputs a command to lock the tap operation of the transformer 16 to prevent the voltage drop due to the reverse operation phenomenon of the tap of the transformer 16 from progressing.

As described above, according to the fifth embodiment, when it is determined that the voltage is unstable, only the tap operation of the transformer of the monitored substation is locked to prevent the progress of the voltage drop due to the reverse operation phenomenon of the tap. Since it is not necessary to take a stabilizing measure such as load limitation, it is possible to provide a device that increases the supply reliability of the system.

Next, a sixth embodiment of the present invention will be described with reference to FIG.

In the sixth embodiment, a control unit 28 is provided to limit the load by a predetermined amount when it is determined by the calculation unit 27 that the voltage is unstable. Note that the detection unit 26 and the calculation unit 27 are the same as in the first embodiment.

First, in the control unit 28, every time the voltage stability determination means 29 of the calculation unit 27 determines that the current operating point of the system is unstable, the load is limited by a predetermined amount. I do. For example, if the number of load feeders 18 is connected to the monitored substation 15 summarizes some of the load feeder 18, so that the total value of the active power P _L is approximately the same size, the substation 3 The load feeders 18 in the group are divided into groups, and priorities for disconnecting in groups are determined and set in advance. Based on this setting, the load is limited each time the voltage stability determination unit 29 of the calculation unit 27 determines that the voltage is unstable. The target of the load limitation is to select the group having the highest priority among the groups that are not disconnected from the system as the disconnection target, and issue an open command to the circuit breaker 17 to which the target load feeder 18 is connected. Is output, and the voltage stability of the substation 15 to be monitored is improved by performing the negative limit.

As described above, according to the sixth embodiment, a predetermined amount of load limitation is performed each time it is determined that the voltage is unstable, so that data and calculation for calculating the load limitation amount are required. Because there is no, the device configuration can be simplified,
Even if the power is always operated near the limit power, the load is limited and the voltage stability is improved each time it is determined that the voltage is unstable, so that the power failure can be prevented from expanding due to voltage collapse and the device configuration can be simplified. Can be realized.

Next, a seventh embodiment of the present invention will be described with reference to FIG.

In the seventh embodiment, a predetermined calculation is executed using the various electric quantities detected by the detecting section 26 and the pallet information to determine the voltage stability of the current operating point, and to determine the various electric quantities. And pallet information are stored in the storage means 30. If the voltage stability determination means 29 determines that the voltage is unstable, the storage means 3
From 0, various electric quantities and pallet information are taken out to obtain a voltage stability index representing the degree of voltage stability instability, and from the obtained voltage stability index, it is necessary to shift from the current operating point to the stable region. A load limiting amount is calculated, and an operation unit 27 including a control amount calculating unit 32 for determining the load feeder 18 to be disconnected and an open command to the circuit breaker 17 determined by the control amount calculating unit 32 and corresponding to the load feeder 18 are output. This is provided with a control unit 28 having means for performing the operation. The detecting unit 26 is the same as in the first embodiment.

The voltage stability determination unit 29 determines whether the voltage stability is stable or unstable, and then determines the determination result and the detection unit 26.
In passing bus voltage V ₁ of the substation and the measured momentarily, V ₂ and passing effective power P _TR, various electrical quantity including active power P _L of the load feeder 18 to the control amount calculating section 32.

The control amount calculating means 32 obtains a voltage stability index indicating the degree of instability of the voltage stability, and determines a load limiting amount necessary for shifting the current operating point to a higher voltage solution range from the index. calculate.

Specifically, when the voltage stability determining means 29 determines that the voltage is unstable, the voltage stability determining means 29 stores the bus voltage of the substation 3 before the tap operation stored in the storage means 30. V _1bf or the bus voltage V _2bf and the passing active power P _TRbf of the transformer 16 are called, and after the tap position is completely switched, the bus voltage V _1af or the bus voltage V _{2af of} the substation 3 measured by the detection unit 26 and the transformer 16
As shown in equations (1.10) to (1.11), the values before tap operation are subtracted from the values after tap operation to obtain the change amounts ΔV _B and ΔP _TR of the respective electric quantities using the passing active power P _TRaf of .

ΔV _B = V _Baf −V _Bbf (1.10) ΔP _TR = P _TRaf −P _TRbf (1.11) Here, V _B is the magnitude of the voltage, and the bus voltage V ₁ or V ₂ is used.

Next, the ratio between ΔP _TR and ΔV _B is used as a voltage stability index indicating the degree of voltage stability instability, and the load limiting amount P _LCUT is calculated from the magnitude of the ratio ΔP _TR / ΔV _B. .

As can be seen from the PV curve, this index indicates a change in the voltage as the voltage drop progresses in the lower half of the PV curve, that is, in the lower voltage solution region. Since the degree of change in power becomes large, the ratio ΔP _TR / ΔV _B can be used to determine the degree of instability of voltage stability. ΔP _TR / ΔV _B obtained using the measured various quantities of electricity is used as an online voltage stability index.

Next, the relationship between the voltage stability index and the load limit in the lower voltage solution region obtained by the offline simulation is set in advance, and the load limit _PLCUT is calculated using the online index.

FIG. 4 shows an example of the relationship between the voltage stability index and the load limiting amount obtained by off-line simulation, which can be represented by a proportional characteristic. If this is set in advance, the load limit amount _PLCUT required for stabilization can be _obtained as shown in equation (1.12) using the online voltage stability index ΔP _TRon / ΔV _Bon .

P _LCUT = K · ΔP _TRon / ΔV _Bon (1.12) where K is a preset coefficient.

Finally, based on the load limiting amount P _LCUT , a load feeder 18 that is actually _disconnected from the system is selected.

[0092] Specifically, by using the active power P _L of the load feeders 18 as measured with time by the detection unit 26 selects the sequentially disconnecting target from the large load feeder 18 of active power P _L, is selected It was to compare the load limit amount P _LCUT the sum P _LT of active power P _L of the load feeder 18,
Or equal to the total value P _LT load limit amount P _LCUT, when you grow, stop selection of disconnection subject determines the load feeder 18 selected so far as the disconnecting target.

The control unit 28 outputs an open command to the circuit breaker 17 to which the load feeder 18 to be disconnected is connected, based on the selection result of the control amount calculation means 32 of the calculation unit 27, and By performing the restriction, the voltage stability of the monitoring target substation 15 is improved.

A method for obtaining the relationship between the voltage stability index and the load limiting amount shown in FIG. 4 by off-line simulation will be described below.

First, data is prepared so that the power flow of the monitored system can be calculated off-line, and a simulation simulating the tap operation and load limitation of the transformer 16 is performed based on the power flow calculation. If you increase a certain amount of load of all load feeders connecting, seeking a transformer 16 being monitored substation 15 pass active power P _TR and bus voltage V _B, to create a P-V curve.

Next, a voltage stability index and a load limiting amount necessary for stabilization are obtained at several operating points in the lower voltage solution region of the obtained PV curve, and the voltage stability index and the load limiting amount are obtained. Figure out the relationship.

Specifically, the transformer 16 in the lower voltage solution region
The voltage stability index is obtained by using the quantity of electricity before and after the tapping operation, and the load limiting amount at which the operating point is set to a voltage higher solution area is obtained by simulation.

[0098] First, the voltage stability index is seeking passing active power P _TR and bus voltage V _B of the transformer 16 of the front and rear tap operation point in the voltage lower solution area, in (1.13) - (1.14) below As shown, the change amounts ΔV _Bof and ΔP _TRof of the respective electric quantities obtained by subtracting the value before the tap operation from the value after the tap operation are obtained, and the ratio is determined by the offline voltage stability index ΔP _TRof /
_Let ΔV _Bof .

ΔV _Bof = V _Baf −V _Bbf (1.13) ΔP _TRof = P _TRaf −P _TRbf (1.14)

Next, a simulation is performed in the case where load limitation is performed immediately after the tap operation, and a load limitation amount for shifting the operating point to a solution region with a higher voltage is obtained.

More specifically, a certain load limiting amount is set as a parameter, and a simulation is performed when load limiting is performed immediately after the tap operation.
Find the curve. Then, from the obtained PV curve, it is determined whether or not the operating point after the load limitation is in the high voltage solution region,
In the case of a voltage higher solution area, the set load limiting amount is determined as a load limiting amount necessary for stabilization. If the voltage is not in the high voltage solution region, the parameter load limit is changed (increased), the simulation is performed again, and the evaluation is performed using the PV curve in the same manner as described above. Once, if it is not found, the necessary load limiting amount can be determined by repeating this operation.

According to the above procedure, the relationship between the off-line voltage stability index and the load limiting amount can be grasped. Therefore, this relationship is formulated and set in advance.

As described above, according to the seventh embodiment, the load limiting amount required for stabilization can be obtained online using the voltage stability index obtained only with local information (various electric quantities). In addition, it is possible to provide a device having a simple device configuration and high controllability.

Next, an eighth embodiment of the present invention will be described with reference to FIG.

In the eighth embodiment, a predetermined calculation is executed using the various electric quantities detected by the detecting section 26 and the pallet information to determine the voltage stability of the current operating point, and to determine the various electric quantities. And a pallet information are stored in the storage means 30. If the voltage stability determination means 29 determines that the voltage is unstable, the low-voltage bus voltage and the pallet information are extracted from the storage means 30. Control amount calculating means for calculating a load limiting amount necessary for shifting from the current operating point to the stable region in accordance with a change in the low-voltage bus voltage before and after the tap operation of the transformer, and determining a load feeder to be disconnected. And a control unit 28 having means for outputting an open command to the circuit breaker 17 corresponding to the load feeder 18 determined by the control amount calculation means 32.
Are provided. The detecting unit 26
Is the same as in the first embodiment.

The voltage stability determination means 29 determines whether the voltage stability is stable or unstable, and then determines the determination result and the detection unit 2
6 pass the bus voltage V _1, V ₂ of the substations 3 and the measured momentarily and the various electrical quantity including active power P _L of the load feeder 18 to the control amount calculating section 32.

The control amount calculating means 32 calculates a load limiting amount necessary for shifting to a higher voltage solution region which is a region for stabilizing voltage stability.

First, when the voltage stability determination means 29 determines that the voltage is unstable, the voltage stability determination means 29 stores the bus voltage V _2bf of the substation 3 before tap operation stored in the storage means 30. Using the bus voltage V _2af of the substation 3 measured by the detection unit 26 after the call and the tap position are completely switched, the value before the tap operation is subtracted from the value after the tap operation as shown in Expression (1.15). To obtain a change ΔV ₂ in the bus voltage.

ΔV ₂ = V _2af −V _2bf (1.15)

Using this ΔV ₂ , a load limiting amount P _LCUT is calculated according to the magnitude of ΔV ₂ as shown in equation (1.16).

P _LCUT = K · | ΔV ₂ | (1.16)

Here, K is a coefficient set in advance, and is obtained by an off-line simulation as in the case of the seventh embodiment.

As described above, according to the eighth embodiment, the load limit required for stabilization can be obtained online using only local information (various quantities of electricity). High equipment can be provided.

Next, a ninth embodiment of the present invention will be described with reference to FIG.

In the ninth embodiment, a detector 26 having a smoothing means 33 for smoothing various electric quantities is provided. The operation unit 27 and the control unit 28 are the same as in the first embodiment.

The detecting section 26 measures various electric quantities, performs a smoothing process on the measured values in the smoothing processing means 33, and obtains tap pallet information 21 for monitoring the tap operation of the transformer 16. . Specifically, via a measuring device installed in a substation facility such as a bus or each load feeder 18 of the substation 15 to be monitored or a transformer 16,
The bus voltage V ₁ , the bus voltage V _{2 of the} substation 3 and the active power P _TR passing through the transformer 16, and the active power P _L of each load feeder 18
Is constantly measured, and the smoothing processing means 33
Removes high-frequency noise components associated with short-period load fluctuations contained in the measured values.

For example, if a first-order low-pass filter is used for the smoothing processing means 33, it is possible to cut a component in a band higher than an arbitrary frequency (cutoff frequency) and pass only a low frequency component. And the measured values can be smoothed. When the characteristics of the first-order low-pass filter are represented by the transfer function G (S), the following equation (1.17) is obtained.

G (S) = ω ₀ / (s + ω ₀ ) (1.17) Here, ω ₀ represents a cutoff frequency, and s represents a Laplace operator.

At the same time, the pallet information 21 of the tap is obtained in order to constantly monitor the presence / absence of the tap operation of the transformer 16 of the substation 15 to be monitored. The measured data of the various electric quantities and the pallet information 21 of the tap, which have been subjected to the above-described smoothing processing, are passed to the arithmetic unit 27.

Here, the effect of a sudden change in various electric quantities due to a short-period load fluctuation or the like on the determination of the voltage stability will be described.

For example, a load (flicker load) having a characteristic in which the active power demand and the reactive power demand fluctuate sharply at the time of starting and during operation, such as an arc furnace for iron making, a rolling mill, a welding machine, and an electric railway. When the system to which is connected is a monitoring target, in order to determine the voltage stability of the system, for example, as shown in the equations (1.1) and (1.2) of the first embodiment, the monitoring target substation 15 Using the measured various amounts of electricity, the amount of change in each amount of electricity is determined, and the voltage stability is determined from the tendency of the difference. In this case, if there is the flicker as described above, the measured various electric quantities greatly change in a short time. Therefore, if the change is obtained from the equations (1.1) to (1.2) without performing the smoothing process, the obtained amount is obtained. The change due to the load fluctuation becomes dominant, and the change in various electric quantities due to the original tap operation cannot be obtained, and there is a possibility that an erroneous determination is made.

As described above, according to the ninth embodiment, the measured value is subjected to the smoothing process and used for the calculation of the determination of the voltage stability. This can also prevent erroneous determination and provide a highly reliable voltage stability monitoring and control device.

[0123]

As described above, according to the voltage stability monitoring and control device of the first aspect, the voltage stability can be calculated by a simple calculation using only various amounts of electricity as local information measured at the monitored substation. It is not necessary to collect data over a wide area unlike the conventional system, and a wide area information communication network is not required, so that the system scale can be reduced and the voltage stability can be evaluated without using a PV curve. Therefore, it is not necessary to perform a large number of power flow calculations for obtaining the PV curve, the amount of calculation can be reduced, and a stabilization measure is performed when the voltage stability is unstable. Since the power failure section can be minimized, the device configuration can be simplified and the device can be highly reliable.

Further, according to the voltage stability monitoring and control device of the second aspect, the voltage stability can be determined only by local information measured at the substation to be monitored and by a simple calculation. Moreover, since the voltage stability is determined without using the PV curve, it is not necessary to perform a large number of power flow calculations, the amount of calculation can be reduced, and the device can have a simple configuration.

Further, according to the voltage stability monitoring and control device of the third aspect, the voltage stability can be determined by a simple calculation using only local information measured at the substation to be monitored, so that the system scale can be reduced. Since the voltage stability is determined without using the PV curve, it is not necessary to perform a large number of power flow calculations, the amount of calculation can be reduced, and the device can have a simple device configuration.

Further, according to the voltage stability monitoring and control device of the fourth aspect, the voltage stability can be determined by a simple calculation using only local information measured at the substation to be monitored, so that the system scale can be reduced. Since the voltage stability is determined without using the PV curve, it is not necessary to perform a large number of power flow calculations, the amount of calculation can be reduced, and the device can have a simple device configuration.

According to the voltage stability monitoring control device of the fifth aspect, when it is determined that the voltage is unstable, the voltage drop due to the reverse operation phenomenon of the tap is performed only by locking the tap operation of the transformer of the substation to be monitored. Can be prevented, and it is not necessary to take a stabilization measure such as load limitation, so that it is possible to provide a device that increases the supply reliability of the system.

According to the voltage stability monitoring control device of the present invention, a predetermined amount of load limitation is performed every time it is determined that the voltage is unstable, so that the data for calculating the load limitation amount is used. And operation can be unnecessary, and even if the power supply is always operated near the limit power, the load is determined to be unstable and the voltage stability is improved to improve the voltage stability. A device having a simple configuration can be provided.

Further, according to the voltage stability monitoring and control device of the seventh aspect, the load limit required for stabilization can be obtained online using the voltage stability index obtained only from local information. A device having a simple configuration and high controllability can be obtained.

Further, according to the voltage stability monitoring and control device of the eighth aspect, the load limit required for stabilization can be obtained online only by local information, so that the device configuration is simple and the controllability is high. It can be.

According to the ninth aspect of the present invention, since the measured value is subjected to a smoothing process and used for the calculation of the determination of the voltage stability, the measured value is affected by a short-period load change or the like. Can be prevented from being erroneously determined even if abruptly changes, and a highly reliable device can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a voltage stability monitoring and control device applied to a first embodiment to a sixth embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a tap reverse operation phenomenon of a transformer represented by a PV curve.

FIG. 3 is a configuration diagram of a voltage stability monitoring and control device applied to a seventh embodiment and an eighth embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a relationship between a voltage stability index and a load limiting amount according to a seventh embodiment of the present invention.

FIG. 5 is a configuration diagram of a voltage stability monitoring and control device applied to a ninth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a PV curve.

FIG. 7 is a configuration diagram illustrating a conventional voltage stability monitoring and control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power system 2 Generator 3 Substation 4 Transmission line 5 Voltage detector 6 Current detector 7 Information communication device 8 Transmission line 10, 25 Voltage stability monitoring and control device 11 System power supply command center 12 CRT screen 15 Substation to be monitored 16 Transformer 17 Circuit breaker 18 Load feeder 19, 20 Power detector 21 Pallet information 26 Detection unit 27 Operation unit 28 Control unit 29 Voltage stability determination unit 30 Storage unit 31 CRT display / alarm device 32 Control amount calculation unit 33 Smoothing processing unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuu Yoshida 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Kansai Electric Power Company (72) Inventor Hidetoshi Nishigakiuchi 3-3 Nakanoshima, Kita-ku, Osaka-shi, Osaka −22 Kansai Electric Power Co., Inc. (72) Inventor Kazuya Omata 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Plant (72) Inventor Takeshi Kaneko 1-Toshiba-cho, Fuchu City, Tokyo Toshiba Fuchu Plant F term (reference) 5G066 AA09 AD20 AE07 AE09 DA01 DA10 5H223 AA19 BB08 EE13 FF05

Claims (9)

[Claims] 1. A voltage stability monitoring and control device for monitoring voltage stability in a substation to be monitored comprising a plurality of load feeders and a transformer, wherein various amounts of electricity in the substation to be monitored and transformer taps are provided. A detection unit that detects pallet information that is information before and after the operation; and a predetermined calculation is performed using the various amounts of electricity detected by the detection unit and the pallet information to determine the voltage stability of the current operating point. A voltage stability monitoring and control device, comprising: a calculation unit that performs control necessary to secure voltage stability when the calculation unit determines that the voltage stability is unstable. 2. The method according to claim 1, wherein the calculating unit determines the voltage stability of a current operating point based on a high-side bus voltage and a low-side bus voltage before and after a transformer tap operation of the substation to be monitored. The voltage stability monitoring and control device according to claim 1. 3. The operation unit determines voltage stability of a current operating point based on a high-side bus voltage before and after a transformer tap operation of the substation to be monitored and an active power passing through the transformer. The voltage stability monitoring and control device according to claim 1, wherein: 4. The operation unit determines a voltage stability of a current operating point based on a high-side bus voltage, a low-side bus voltage, and a transformer passing active power before and after a transformer tap operation of the monitored substation. The voltage stability monitoring and control device according to claim 1, wherein the determination is performed. 5. The control unit according to claim 1, wherein the control unit outputs a command to lock a tap operation of a transformer of the substation to be monitored when the voltage is determined to be unstable by the calculation unit. Item 5. The voltage stability monitoring control device according to any one of Items 4. 6. The control unit according to claim 1, wherein, when it is determined by the calculation unit that the voltage is unstable, the control unit performs a load limitation of a predetermined amount set in advance. Any one of the voltage stability monitoring and control devices. 7. The arithmetic unit executes a predetermined arithmetic operation using the various electric quantities detected by the detecting unit and the pallet information to determine the voltage stability of the current operating point, and to execute the various arithmetic operations. A voltage stability determination unit that stores the electric quantity and the pallet information in the storage unit; and when the voltage stability determination unit determines that the voltage is unstable, the storage unit stores the various electric quantities and the pallet information. Take out the voltage stability index that indicates the degree of voltage stability instability, calculate the load limit required to shift from the current operating point to the stable area from the obtained voltage stability index, and disconnect it. A control amount calculating unit that determines a load feeder; and the control unit includes a unit that outputs an open command to a circuit breaker corresponding to the load feeder determined by the control amount calculating unit. G Voltage Stability monitor control apparatus according to claim 1, wherein. 8. The arithmetic unit executes a predetermined arithmetic operation using the various electric quantities detected by the detection unit and the pallet information to determine the voltage stability of a current operating point and to execute the various arithmetic operations. A voltage stability determination unit that stores the electric quantity and the pallet information in a storage unit, and when it is determined that the voltage is unstable by the voltage stability determination unit, the low voltage side bus voltage and the pallet information are stored in the storage unit. Control to calculate the load limit required to shift from the current operating point to the stable region according to the change in the low-side bus voltage before and after the transformer tap operation, and determine the load feeder to be disconnected And a controller that outputs an open command to a circuit breaker corresponding to the load feeder determined by the control amount calculator. Voltage stability monitoring and control device according. 9. The voltage stability monitoring control according to claim 1, wherein the detection unit includes a smoothing processing unit that performs a smoothing process on the various electric quantities. apparatus.