JPH04295233A - Rotary system interconnection system - Google Patents

Abstract

PURPOSE:To provide a rotary system interconnection system which can realize high speed control between power systems and can enhance stability of the entire system by providing an exciting current controller for a wound-rotor induction machine and interconnecting some number of wound-rotor induction machines with one power system whereas interconnecting the remaining wound- rotor induction machines with the other power system. CONSTITUTION:Power is fed to a synchronous machine 1. A control section 10 controls exciting current to be fed to an AC exciting winding 11 associated with the rotor 8a of a wound-rotor induction machine 8 thus controlling voltage and power on the stator 8b side of the wound-rotor induction machine 8. Units No.1 and No.2 are disposed alternately for the synchronous machine 1 and the wound-rotor induction machine 8 so that any one wound-rotor induction machine 8 is interconnected with system A or B. Consequently, the system can be controlled at high speed and in case of a plurality of units, stability of the entire rotary system interconnection system can be enhanced.

Description

[Detailed description of the invention]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating system interconnection device for interconnecting power systems.

0002

2. Description of the Related Art A synchronous frequency converter is known as a device for mutually accommodating power between interconnected power systems. This synchronous frequency conversion device directly connects synchronous machines with different numbers of poles to perform frequency conversion and to accommodate power.

FIG. 4 is a system block diagram showing this type of synchronous frequency conversion device. Synchronous machine 1 on the A system side
The rotor 1a of the synchronous machine 1 on the B system side is connected by a direct connection shaft 2, and each stator 1b of each synchronous machine 1 is
connected to the system or B system. In addition, both synchronous machines 1
Each of the rotors 1a is provided with an excitation winding 3, and each excitation winding 3 is constantly excited with direct current via an automatic voltage control device 4 by a power source from the A system or the B system. Also, B
The synchronous machine 1 on the grid side is equipped with an armature moving device 5. The number of poles of each of the synchronous machines 1 on the A-system side and the synchronous machine 1 on the B-system side is such that the ratio of the number of poles is equal to the frequency ratio of each system.

[0004] With the above configuration, when power is transferred from system A to system B, the synchronous machine 1 that receives power from system A rotates the rotor 1a as an electric motor, converting the power to be transferred into mechanical energy. do. Then, by the direct connection shaft 2, B
The rotor 1a of the synchronous machine 1 on the system side is rotated. The synchronous machine 1 on the B system side functions as a generator and converts it into electrical energy to accommodate power to the B system. At this time, the armature moving device 5
moves the armature to adjust the load angle. Note that 6 indicates a transformer for excitation of the synchronous machine 1.

[0005] In the above conventional example, a one-unit synchronous frequency converter has been described, but a plurality of units are provided between power systems depending on the passing power capacity.

[0006]

However, the above-described synchronous frequency conversion device has the following problems. First, in the synchronous frequency converter, it is essential that one of the synchronous machines 1 is provided with an armature moving device 5 in order to adjust the load angle. Since this armature moving device 5 operates mechanically, it is difficult to adjust the load angle at high speed. Therefore, it cannot be effective in the case of emergency power interchange in interconnected power systems. Furthermore, if a system fault such as a ground fault occurs in the A system and B system shown in Figure 4, the synchronous machine 1
If only the rotary grid connection device is used alone, there is a risk of dynamic instability or, in the worst case, a step-out phenomenon, and as a result, there is a high possibility that the entire system of the rotary grid interconnection device will go down.

On the other hand, depending on the passing power capacity required of the rotary grid interconnection device, a plurality of units of the device are often required. That is, a single unit rotating machine may require constraints such as production limits or may require future expansion. Also,
Even in the case other than the above case, two or more units are inevitably required if any one unit is to maintain an operating rate of 50% or more even during maintenance. In the case of such multiple units, if a trouble such as a ground fault occurs in one system, none of the synchronous machines 1 will be able to operate due to the above-mentioned step-out phenomenon, as in the case of a single unit, resulting in the failure of the system. It becomes difficult to maintain stability.

[0008] As described above, in both the case of one unit and multiple units, in the rotating type grid interconnection device, firstly, an imbalance of supply and demand occurs in one of the interconnected power systems, which affects the system stability and When emergency accommodation from the other power system is required due to frequency fluctuation problems, high-speed control of passing power is essential. Furthermore, secondly, it is necessary to improve the stability, reliability, and availability of the entire power system system.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rotating grid interconnection device that enables high-speed control between power grids and improves the stability, reliability, and availability of the entire system. shall be.

[Configuration of the invention]

[Means for Solving the Problems] The present invention provides a system in which a rotating machine connected to one power system and a rotating machine connected to the other power system are connected by a direct shaft to form one unit. (2
In a rotating system interconnection device consisting of the above natural number) units, the rotating machine constituting one unit is a synchronous machine and a wound induction machine, and the excitation current of the AC excitation winding provided in this wound induction machine is controlled. m (a natural number greater than or equal to 1, m<n) wound induction machines are connected to one power system, while the remaining The nm winding induction machines are connected to the other power system.

[0011]

According to the above structure, the excitation current of the AC excitation winding provided in at least one wound induction machine is controlled by the frequency conversion device and the control device. Therefore, high-speed control between power systems is possible, and the stability and reliability of the entire system of the rotary grid interconnection device is improved, and the operating rate is increased.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system block diagram of a rotary grid interconnection device showing one embodiment of the present invention. The difference from Fig. 4 is that one rotating machine in one unit is a wound induction motor 8.
Moreover, it is composed of two units. In this embodiment, unit No. 1 and unit no. The synchronous machine 1 and the wound induction machine 8 of No. 2 are arranged oppositely. That is, unit no. In No. 1, the stator 1b of the synchronous machine 1 is connected to the A system side for interconnection, while the stator 8b of the wound induction machine 8 is connected to the B system side for interconnection. Further, the rotor 1a of the synchronous machine 1 and the rotor 8a of the wound induction machine 8 are connected through a directly coupled shaft 2, so that both rotate at the same time. On the other hand, unit no. In 2, unit N
o. 1, on the contrary, the stator 8b of the wound induction machine 8 is connected to the A system side for interconnection, and the stator 1b of the synchronous machine 1 is connected to the B system side for interconnection. The rotor 8b of the wound induction machine 8 and the rotor 1a of the synchronous machine 1 are connected by a connecting shaft 2.

[0014] Here, unit No. 1 and unit number
．． The synchronous machine 1 and the wound induction machine 8 disposed in 2 and the control system for controlling them also have the same configuration. Unit No. 1, the control system of the synchronous machine 1 is synchronized with the A system because the terminals of the stator 1b of the synchronous machine 1 have the same voltage and frequency as the A system. Further, a constant excitation voltage is applied to the field winding 3 provided on the rotor 1a by the automatic voltage control device 4 via the excitation transformer 6.

On the other hand, the control system of the wound induction machine 8 is as follows:
The AC excitation winding 1 provided on the rotor 8a by the control unit 10
The magnitude, phase, and frequency of the alternating current excitation current flowing through the motor 1 are controlled. The control unit 10 includes a power detector 12, a voltage detector 13, a voltage control device 14, a power control device 15, a frequency conversion device 16, and a resolver 17. Here, the power detector 12 receives detection signals from the current detector 18 and the voltage detector 13, detects the power on the stator 8b side, and outputs this as a power detection signal 19 to the power control device 15. do. The voltage detector 13 detects the voltage on the stator 8b side and outputs it as a voltage detection signal 20 to the voltage control device 14 and the frequency conversion device 16. The voltage control device 14 inputs the voltage detection signal (V) 20 and the target voltage signal 21 and outputs it as a voltage control signal 22 to the frequency conversion device 16. The power control device 15 performs arithmetic processing based on the target power signal (P) 23 and the power detection signal 19, and outputs the result to the frequency conversion device 16 as a power control signal 24. The frequency conversion device 16 is composed of a cycloconverter, and controls the power and terminal voltage on the stator 8b side of the wound induction machine 8 based on the voltage control signal 22 and the power control signal 24. The resolver 17 detects the rotation speed of the rotor 8a of the wound induction machine 8 and outputs the rotation speed detection signal to the frequency conversion device 16. Note that the power required by the frequency converter 16 is supplied from the stator 8b side of the wound induction machine 8 via the transformer 25.

With the above configuration, the stator 1b of the synchronous machine 1 has A
Electric power is supplied from the grid, and the rotor 1a of the synchronous machine 1 rotates at a synchronous speed. On the other hand, the control unit 10 controls the magnitude, phase, and frequency of the AC excitation current flowing in the AC excitation winding 11 provided in the rotor 8a of the wound induction machine 8, and voltage and power control.

First, in the frequency converter 16, the speed of the rotating magnetic field as viewed from the stator 8b side of the wound induction machine 8, that is, the synchronous speed N1 is determined from the voltage detection signal 20 of the voltage detector 13. On the other hand, the rotor 8 of the wound induction machine 8
The mechanical rotational speed Nr of a is determined by the resolver 17. Then, the frequency converter 16 calculates the difference between the synchronous speed N1 and the rotational speed Nr, and calculates the difference between the synchronous speed N1 and the rotational speed Nr.
The AC excitation winding 11 is excited with a low slip frequency fe corresponding to Nr=N2. In this way, the synchronous speed N1 on the stator 8b side of the wound induction machine 8 and the wound induction machine 8
Match the magnetic field speed Nr+N2 on the rotor 8a side,
Always follow and synchronize with the B system. That is, the rotational speed Nr of the rotor 8a is determined from the synchronous speed N1 of the stator 8b.
is slow, when the AC excitation winding 11 is excited with a slip frequency fe corresponding to N2 = N1 - Nr, the rotating magnetic field speed on the rotor 8a side becomes N2 +Nr, which matches the synchronous speed N1, and AC power with the same frequency as the B system. can occur. Conversely, even when the rotational speed Nr is faster than the synchronous speed N1, the magnetic field speed and direction are changed by the slip frequency fe applied to the AC excitation winding 11, so that the synchronous speed N1 and the rotor 8a
B by matching the speed of the rotating magnetic field N2 +Nr of
Synchronize with the grid.

The voltage control device 14 also outputs a voltage detection signal 20 detected by the voltage detector 13 and a target voltage signal (V
) 21 and output to the frequency converter 16 as a voltage control signal 22. The frequency converter 16 changes the magnitude of the excitation current having the slip frequency fe described above based on the voltage control signal 22 and applies the same to the AC excitation winding 11 .

As a result, the voltage of the B system becomes equal to the target voltage signal (
V) Control is performed to match 21.

On the other hand, the power passing to the B system is detected by the power detector 12 and output as a power detection signal 19 to the power control device 15. The power control device 15 performs arithmetic processing based on the target power signal (P) 23 and the power detection signal 19, and outputs the resultant signal to the frequency conversion device 16 as a power control signal 24. In the frequency converter 16, the phase of the terminal voltage of the stator 8b is detected using the voltage detection signal 20, and in addition to the slip frequency fe and the magnitude of the excitation current, the phase of the terminal voltage of the stator 8b is controlled. As a result, the power passing from the stator 8b to the B system is the target power signal (P).
23.

As described above, the magnitude and phase of the internal induced voltage created by the magnetic flux of the AC excitation winding 11 are controlled,
Thereby, the voltage is controlled by the stator 8b by the change in the magnitude. Furthermore, the power is controlled by changing the phase. Therefore, even if the rotational speed Nr of the rotor 8a of the wound induction machine 8 changes, the frequency of the AC excitation current from the frequency converter 16 is always followed as the slip frequency fe, and the AC excitation current can be increased as necessary. and phase can be controlled at high speed. Further, the magnitude of the magnetic flux of the AC excitation winding 11 and the phase angle with respect to the stator 8b side can be adjusted at high speed. As a result,
Power between each power grid can be controlled instantly.

By the way, a system comprising a wound induction machine having such functions, a frequency conversion device such as a cycloconverter, and a control device thereof is generally called an AC variable speed machine. In this embodiment, the AC variable speed machine realizes the same function as the armature moving device of a conventional synchronous frequency converter.

Next, a change in the power on the stator 8b side of the wound induction machine 8 is transmitted to the synchronous machine 1 via the direct connection shaft 2, and is transmitted to the A system as a power change of the synchronous machine. When the target power signal (P) 23 is maintained at a constant value, the power is controlled as described above, and the power passing through the wound induction machine 8 is kept constant. In this case, the interchangeable power between the A system and the B system does not change. However, if the target power signal (P)2
3, the power of the wound induction machine 8 is changed to the control unit 10.
The control operation changes so as to pursue the target power signal (P) 23. Unit No. mentioned above. The operation of unit no. The same applies to 2. Unit N
o. In case 2, the wound induction machine 8 installed in the B system
The control unit 10 performs power control and voltage control. That is, in a steady state where passing power is applied from system A to system B, unit No. The wound induction machine 8 of No. 2 supplies mechanical energy to the synchronous machine 1 as an electric motor. The synchronous machine 1 supplies power to the B system as a generator. And unit no. 1, the AC excitation winding 11 of the wound induction machine 8 is excited at the slip frequency fe to synchronize with the A system.

By the way, in this embodiment, as shown in the figure,
Unit No. 1 and unit no. 2 has a configuration in which the synchronous machines 1 and the wound induction machines 8 are arranged alternately, and any one of the wound induction machines 8 is connected to the A system or the B system for interconnection. Figure 2 (A) shows the effect of such a configuration.
, (B) and FIGS. 3(A) and (B). For example, if there is a system fault such as a ground fault on the B system side, after the B system fault is removed, if the B system side is configured with only synchronous machine 1, as shown in Figure 3 (A), As shown, unit No. 1 and unit no. In both cases, the active power fluctuates greatly, resulting in dynamic instability or, in the worst case, loss of synchronization. However, as shown in Figure 2(A),
It has been confirmed through simulation analysis that stability is maintained by alternately arranging the wound induction machines 8. That is, as shown in FIG. 2(B), unit No. Although the active power of 2 fluctuates greatly, it has been confirmed that the system of wound induction machine 8 not only does not have any step-out phenomenon itself, but also contributes to improving the stability of synchronous machines connected to the same system. has been done. This is due to the succession effect of the wound induction machine 8 and the effect of power transfer between the wound induction machine 8 and the synchronous machine 1. The above is also applied to the A system side shown in FIG. 2(A), and system down of the entire rotary grid interconnection device is avoided. However, in a rotating grid-connected system in which the B system includes only the synchronous machine 1 as shown in FIG. 3A, stability in the event of a grid fault is difficult to maintain. This means that there is a possibility that the entire rotating grid interconnection device will go down.

As described above, in this embodiment, one of the units is provided with an AC exciter consisting of a wound induction machine, a frequency converter, and the like. Therefore, power control and voltage control of the system can be controlled at high speed. In particular, in the case of multiple units, the stability of the entire system of the rotary grid interconnection device can be improved by alternately arranging the synchronous machine and the wound induction machine.

[0026] Therefore, the reliability of the entire system is improved and the operating rate of the entire system is increased. Note that the configuration shown in FIG. 3(A) cannot achieve the effects of this embodiment, but when the next expansion is performed, that is, when unit No. When adding Unit No. 3, connect it to the B system side and connect it to the B system side. Similar effects can be obtained by arranging No. 3 wound induction machines.

[0027]

As described above, according to the present invention, a rotary grid interconnection device capable of high-speed control of a power grid can be realized. Furthermore, since at least one wound induction machine is connected to each power system, the stability and reliability of the entire system, as well as the operating rate, can be improved.

[Brief explanation of drawings]

FIG. 1 is a system block configuration diagram of a rotating grid interconnection device showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the effects of the configuration of the device and an explanatory diagram showing the stability of the device.

FIG. 3 is an explanatory diagram showing the effect of another configuration of the rotary grid interconnection device and an explanatory diagram showing the stability of the device.

FIG. 4 is a system block configuration diagram of a rotary grid interconnection device showing a conventional example.

[Explanation of symbols]

1 Synchronous machine 1a Rotor of synchronous machine 1b Stator of synchronous machine 2 Directly connected shaft 3 Excitation winding 8 Wound induction machine 8a Rotor of wound induction machine 8b Stator of wound induction machine 10 Control section 11 AC excitation winding 12 Power detector 13 Voltage detector 14 Voltage control device 15 Power control device 16 Frequency conversion device 17 Resolver 18 Current detector

Claims (1)

[Claims] Claim 1: A rotary machine connected to one power system and a rotary machine connected to the other power system connected by a direct shaft to form one unit, consisting of n (a natural number of 2 or more) units. In the rotary grid interconnection device, the rotating machine constituting the one unit is a synchronous machine and a wound-type induction machine, and a frequency conversion device for controlling the excitation current of an AC excitation winding provided in the wound-type induction machine. and a control device thereof, and
m among the above n units (a natural number of 1 or more, m<n)
A rotary system characterized in that a number of the wound induction machines are interconnected to the one power system, and the remaining nm number of the wound induction machines are interconnected to the other power system. Grid connection device.