JPH0820471B2 - Method and apparatus for measuring positive-phase component and negative-phase component of power and reactive power in three-phase system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the positive and negative phase components of active power and reactive power when determining load characteristic constants with respect to frequency and voltage in a three-phase system such as a main bus of a power system. The present invention relates to a method and apparatus for measuring a positive-phase component and a negative-phase component of power and reactive power in a three-phase method.

[0002]

2. Description of the Related Art In order to optimally perform frequency control of an interconnected system and load frequency control of the interconnected system (Load Frequency Control), or in response to a power failure or system isolation, system stabilization control (System Stabilization) is performed.
It is necessary to accurately grasp the power-frequency characteristic constant in order to set the device for performing the LiZing Control.

By the way, the power-frequency characteristic constant is
Normally, it is measured as the ratio of the power cut off from the grid during the load cut-off test of the generator or accidental loss of large-capacity power supply to the frequency dropped at that time.

However, since the power-frequency characteristic constants change every moment depending on the configuration of the load and the power supply and the operating state of the power plant, it is necessary to estimate these characteristic constants in the normal operating state.

Therefore, fluctuations in the system frequency, bus voltage, load power, and reactive power in a normal operating state of the power system are captured as irregular signals, and the spectrum analysis of the data is performed to analyze the main components of the power system. It has been proposed to measure load characteristic constants such as active power-frequency characteristic constant, reactive power-frequency characteristic constant, active power-voltage characteristic constant, and reactive power-voltage characteristic constant of a load connected to a bus.

Conventionally, in the method of measuring the load characteristic constant by performing such spectrum analysis, the active power fluctuation component and the reactive power fluctuation component are measured by collectively measuring the positive phase component and the negative phase component, and the bus voltage fluctuation component is measured. Measures only the positive phase voltage.

[0007]

However, as described above, in the method of measuring the bus voltage fluctuations by extracting only the positive phase voltage, the positive power phase fluctuations are measured in the active power fluctuations and the reactive power fluctuations. Since the measurement is performed collectively without paying attention to the extraction of the component and the anti-phase component separately, an error occurs due to neglecting the variation of the anti-phase voltage.

However, a method for measuring the fluctuation amount of the reverse phase voltage with high accuracy has not been obtained. If the positive phase component of the active power fluctuation and the reactive power fluctuation can be measured separately, the load characteristic constant for the positive phase component can be obtained with high accuracy using the positive phase component of the bus voltage fluctuation. .

Therefore, an object of the present invention is to separate the positive phase component and the negative phase component in the measurement of the active power fluctuation and reactive power fluctuation so that the measurement accuracy of the load characteristic constant data can be sufficiently obtained. It is to provide a measuring method and an apparatus therefor which can be taken out by taking out.

[0010]

In order to solve the above problems, in the present invention, each phase voltage and phase current are detected by the voltage detecting means and the current detecting means, and the detected in-phase voltage and current are detected. The active power R _e {S} and the reactive power I _m {S} of the three-phase method are obtained, and the obtained active power R _e {S} and the reactive power I _m {S} are detected by the detection means. Using the phase voltage and the phase current, the active power Re _e {S ₁ } and the reactive power I _m {S ₁ } obtained from the voltage and the current in which the phase order is shifted from the voltage are substituted into the following formula (1). and it is was subjected to measurement method for obtaining a three phase system active power positive phase component P ₁ and the negative phase component P ₂ of the positive phase component to Q ₁ reactive power reverse phase component Q _2.

[0011]

[Equation 2]

Further, at this time, each phase voltage and phase current are input, first active power measuring means for detecting active power Re {S} of the three-phase system, and first active power Im {S} for detecting reactive power Im {S}. Using one reactive power measuring means, the phase voltage and phase current,
A second active power measuring means for inputting a voltage and a current whose phase sequence is shifted from that of the voltage and detecting active power Re {S ₁ } for the input voltage and current, and reactive power Im {S.
₁ } detecting second reactive power measuring means, and the detection outputs of the first and second active power measuring means and the reactive power measuring means are input, and the input detection output is calculated according to the equation (1). a structure consisting of an arithmetic circuit that performs operation to calculate the three-phase positive sequence component P ₁ and the positive phase component to Q ₁ reverse phase component P ₂ and the reactive power of the active power type and the negative-phase component Q ₂
A measuring device using the above measuring method can be used.

[0013]

In the method of measuring the positive phase component and the negative phase component of the power and reactive power in such a three-phase system, for example, the three-phase voltage V _a detected by the voltage detection means and the current detection means,
The complex power S obtained from V _b , V _c and the phase currents I _a , I _b , I _c is

[0014]

(Equation 3)

Here, in the non-grounded system,

[0016]

[Equation 4]

The symmetrical component of the three-phase voltage and current is

[0018]

(Equation 5)

When the formula (3) is expressed by a conjugate complex number,

[0020]

(Equation 6)

[0021]

Therefore, the complex power S is

[0023]

(Equation 7)

Since the complex power S is composed of active power P ₁ and reactive power Q _{1 for} the positive phase and active power P ₂ and reactive power Q ₂ for the negative phase, respectively, S = (P ₁ + jQ ₁ ) + (P ₂ + jQ ₂ ), and = (P ₁ + P ₂ ) + j (Q ₁ + Q ₂ ).

Therefore, the active power R _e {S} and the reactive power I _m {S} are calculated as R _e {S} = (P ₁ + P ₂ ) …………………… (4) I _m {S} } = (Q ₁ + Q ₂ ).

Further, using the phase voltage and the phase current, the complex power S ₁ obtained from the voltage and the current in which the phase order is shifted from the voltage is

[0027]

(Equation 8)

The complex power S ₁ the positive-phase component active power P ₁ and the reactive power Q _1, is represented by a reverse-phase effective power P ₂ and the reactive power Q _2,

[0029]

[Equation 9]

Therefore, P ₁ , P ₂ , Q ₁ , and Q ₂ are calculated by the following equations (4) and (5).

[0031]

[Equation 10]

It becomes

Further, the measuring device is such that the active power R _{e is}
{S} and reactive power I _m {S} are measured by active power measuring means or reactive power measuring means such as a power meter and reactive power meter, while the active power Re _e {S ₁ } and reactive power are measured. I
_m {S ₁ } is measured by the active power measuring means and the reactive power measuring means in which the phase sequence of the voltage input and the current input is shifted, and the output of the measuring means is calculated by the mathematical expression (1). The measurement can be performed by calculating with a calculation device such as a circuit or a computer, and separating the positive phase component and the negative phase component of the active power and the reactive power.

[0034]

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

FIG. 1 shows a block diagram of a measuring apparatus according to the method for measuring the positive phase component and the negative phase component of the power and reactive power in the three-phase system of the present invention.

This measuring device comprises electric power measuring means 1 to 4 and an arithmetic circuit 5.

The power measuring means 1 to 4 are composed of active power measuring devices 1 and 3 and reactive power measuring devices 2 and 4, respectively, and the active power measuring devices 1 and 3 and the reactive power measuring devices 2 and 4, respectively. , First and second three-phase AC power transducer 1,
3 and reactive power transducers 2 and 4. Here, as shown in FIG. 2, the power transducer has voltage input terminals a, b, c and current input terminals a, c, and the voltage input terminals a, b, c are three-phase via PT. When the voltage of the circuit is input and the currents of the a and c phases are input to the current input terminals a and c via CT, the active power of the three-phase circuit is output.

In the above first power transducer 1,
The voltage outputs of the ab and cb phases of PT are input to the voltage input terminals a, b and c, and the a of CT is input to the current input terminals a and c.
The current outputs of the phase and the c-phase are input, and the active power R _e {S} of the three-phase circuit is output.

[0039]

[Equation 11]

The voltage input terminals a, b and c of the second power transducer 3 are supplied with the voltage outputs of the ab and cb phases of PT, and the current input terminals a and c are supplied with the first case. The phase-shifted b and a-phase currents are input from the CT and output active power R _e {S ₁ }.

[0041]

(Equation 12)

On the other hand, the reactive power transducers 2, 4
Has voltage input terminals a, b, c and current input terminals a, b, c as shown in FIG. 3, and voltage input terminals a, b, c
When the voltage of the three-phase circuit is input to PT and the currents of the a and c phases are input to the current input terminals a, b, and c via CT, the reactive power of the three-phase circuit is output.

The first reactive power transducer 2
, Voltage input terminals a, b, and c are connected to the ab phase from PT,
The voltage of the cb phase is input, the phase currents of the a, b, and c phases are input to the current input terminals a, b, c, and the reactive power I
Output _m {S}.

[0044]

(Equation 13)

In addition, the second reactive power transducer 4
To the voltage input terminals a, b and c, the ab phase from PT,
cb phase voltage is input, a current input terminal a, b, the c, b of shifting the first case and phase sequence, c, by the current of a phase is input from the CT, reactive power I _m {S ₁ }
Is output.

[0046]

[Equation 14]

The arithmetic circuit 5 is an analog arithmetic circuit using an operational amplifier, and as shown in FIG. 1, buffer amplifiers a ₁ , a ₂ , non-inverting amplifiers b ₁ , b ₂ , inverting amplifiers c ₁ , c ₂ , Inverters d ₁ and d ₂ and inverting adders e _{1 to} e
_4, and an arithmetic circuit corresponding to the equation (1) is formed.

That is, the arithmetic circuit 5 outputs the output R _e {S} of the first power transducer 1, the output I _m {S} of the first reactive power transducer 2, and the output R _{e of} the second power transducer 3. {S ₁ } and the output I _m {S ₁ } of the second reactive power transducer 4 are respectively provided, and the output Re _e {S} of the first power transducer 1 is connected to the buffer amplifier a ₁ and the gain √3. It is inputted to the inverting adder e ₁ having a gain of 1 through the inverting amplifier c ₁ and the inverter d ₁ having a gain of 1, and further the output I _m {S} of the first reactive power transducer 2 is input to the adder e ₁ . And the output I _m {S ₁ } of the second reactive power transducer 4 are input via a buffer amplifier a ₂ having a gain of 1 and a non-inverting amplifier b ₂ of a gain of 2, respectively, and added to obtain a positive phase. power -2√3P ₁ = - [√3 _{e {S} + (I m} {S} +2
I _m {S ₁ })] is output.

Similarly, the output R _e {S} of the first power transducer ₁ is amplified by an inverting amplifier c ₁ having a gain of √3 and the output I of the first reactive power transducer 2.
A value obtained by amplifying _m {S} through the buffer amplifier a ₂ and a value obtained by amplifying the output I _m {S ₁ } of the second reactive power transducer 4 by the non-inverting amplifier b ₂ having a gain of 2 are inverted adders e ₂
By adding with, the negative phase power 2√3P ₂ = − [− √3R _e {S} + (I _m {S} +2
I _m {S ₁ })] is output.

Similarly, the positive-phase reactive power 2√3Q ₁ = − [− √3I _m {S} + (R _e {S} +2)
R _e {S ₁ })] and anti-phase reactive power −2√3Q ₂ = − [√3I _m {S} + (R _e {S} +2
R _e {S ₁ })] is output.

This embodiment is constructed as described above. Next, the operation of this measuring apparatus will be described to explain the measuring method according to the present invention.

In this measuring device, for example, as shown in FIG. 4, a CT is attached to a three-phase circuit between a transformer and a secondary bus,
Its output is the first and second power transducers 1, 3
And to the first and second reactive power transducers 2, 4.

Further, a PT is attached to the secondary bus bar, and its output is connected to the first and second power transducers 1 and 3,
To the first and second reactive power transducers 2, 4.

At this time, the first power transducer 1
The current inputs of the a-phase and the c-phase are input to the current input terminals a and c. Further, the current input terminals a, b, and c of the first reactive power transducer 2 are input with current inputs of the a, b, and c phases.

Therefore, both transducer outputs output the complex power S of the three-phase circuit.

[0056]

(Equation 15)

Here, the symmetrical component of the three-phase voltage and current is

[0058]

[Equation 16]

Substituting and expressing by positive phase voltage and positive phase current and negative phase voltage and negative phase current,

[0060]

[Equation 17]

It becomes

This output is composed of active power and reactive power by the positive phase component and the negative phase component, respectively, and S = (P ₁ + jQ ₁ ) + (P ₂ + jQ ₂ ) = (P ₁ + P ₂ ). + J (Q ₁ + Q ₂ ).

Furthermore, since this output is a value measured by the first power transducer 1 and the reactive power transducer 2, R _e {S} = P ₁ + P ₂ ............ (4) I _m {S} = Q ₁ + Q ₂ .

Further, the current input terminals a of the second power transducer 3 and the second reactive power transducer 4,
b, c are different from the first case in b, c, a, respectively.
Phase current input is input.

Therefore, the outputs of both transducers 3 and 4 are

[0066]

(Equation 18)

[Mathematical formula-see original document] In the same way as the above, equation (2),
Substituting (3) and expressing by positive phase voltage and positive phase current and negative phase voltage and negative phase current,

[0068]

[Formula 19]

Then,

[0070]

(Equation 20)

It becomes

Therefore,

[0073]

[Equation 21]

It becomes These are the values measured by the second power transducer 3 and the reactive power transducer 4.

These outputs are input to the arithmetic circuit 5.

The arithmetic circuit 5 calculates the outputs of the respective transducers 1 to 4 by the arithmetic circuit,
By solving the equations (4) and (5), −2√3P ₁ = − [√3R _e {S} + (I _m {S} + 2I _m {S ₁ })] 2√3P ₂ = -[-√3R _e {S} + (I _m {S} + 2I _m {S ₁ })] 2√3Q ₁ =-[-√3I _m {S} + (R _e {S} + 2R _e {S ₁ })] − 2√3Q ₂ = − [√3I _m {S} + (R _e {S} + 2R _e {S ₁ })] Power positive phase component P ₁ and antiphase component P ₂ and reactive power positive The phase component Q ₁ and the anti-phase component Q ₂ are output.

Therefore, at this time, for example, as shown in FIG. 4, even if there is power fluctuation on the secondary side, it can be immediately detected.

This output is, for example, as shown in FIG.
It can be input to the computer 7 using the A / D converter 6 and used for calculation of load characteristics.

As described above, this measuring apparatus can separate the positive-phase component and the negative-phase component of the power and the reactive power of the three-phase circuit and obtain the values in real time.

The measuring method and apparatus are not limited to the three-phase method and can be used in a multi-phase method such as six-phase or twelve-phase based on the three-phase method.

Further, the phase sequence of shifting between the first power transducer and the second power transducer and between the first reactive power transducer and the second reactive power transducer is not limited to that of the embodiment.

Furthermore, in the embodiment, an arithmetic circuit using an analog circuit is shown, but the arithmetic circuit is not limited to this and may be performed by digital arithmetic using a microcomputer or the like.

[0083]

According to the present invention, the positive phase component and the negative phase component of the power and the reactive power can be separated and measured by the above measuring method.

Therefore, the accuracy of measurement of the load characteristic constant can be improved, and the frequency of the interconnection system controlled by using the characteristic constant and the interconnection power flow control and system stabilization control can be optimized.

Further, in the measuring apparatus using this measuring method, it is possible to easily separate and measure the positive phase component and the negative phase component of the reactive power by using the power measuring device and the reactive power measuring device. .

[Brief description of drawings]

FIG. 1 is a block diagram of a measuring device according to an embodiment.

FIG. 2 is a connection diagram of the power transducer of the embodiment.

FIG. 3 is a connection diagram of the reactive power transducer of the embodiment.

FIG. 4 is a connection diagram at the time of measurement of the measuring apparatus of the embodiment.

[Explanation of symbols]

1 Power Transducer 2 Reactive Power Transducer 3 Power Transducer 4 Reactive Power Transducer a ₁ Buffer Amplifier a ₂ Buffer Amplifier b ₁ Non-Inverting Amplifier b ₂ Non-Inverting Amplifier c ₁ Inverting Amplifier c ₂ Inverting Amplifier d ₁ Inverter d ₂ Inverter e ₁ ~ E ₄ Inverting adder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-187466 (JP, A) JP-A-1-162163 (JP, A)

Claims (2)

[Claims] 1. Each phase voltage and phase current are detected by a voltage detection means and a current detection means, and based on the detected in-phase voltage and current, three-phase active power R _e {S} and reactive power I.
_m {S} is obtained, the obtained active power _Re {S} and reactive power I _m {S}, and the phase voltage and phase current detected by the detection means are used,
The active power Re _e {S ₁ } and the reactive power I _m {S ₁ } obtained from the voltage and the current whose phase sequence is shifted from the voltage are expressed by the following mathematical formulas.
(1) substituted, positive phase component to Q ₁ three phase system of the positive-phase component P ₁ and the negative-phase component P ₂ and the reactive power of the active power and the negative-phase component Q ₂
A method for measuring the positive-phase component and the negative-phase component of the power and reactive power in the three-phase method for obtaining and. [Equation 1] 2. A first active power measuring means 1 for inputting each phase voltage and phase current and detecting active power Re {S} of the three-phase system, and a first active power measuring means 1 for detecting reactive power Im {S}. A reactive power measuring means 2 ; a voltage that uses the phase voltage and the phase current; a voltage and a current that is out of phase with the voltage are input, and active power Re {S ₁ } for the input voltage and current is detected; Second active power measuring means 3 , second reactive power measuring means 4 for detecting reactive power Im {S ₁ }, and first and second active power measuring means
1 , 3 and the detection output of the reactive power measuring means 2 , 4 are input, and the input detection output is calculated by the above equation (1) to obtain a positive phase component P _{1 of the} three-phase active power and a reverse phase. reverse-phase component and the positive phase component of the power and the reactive power in a three phase system according to claim 1 comprising a positive phase component Q _1, reversed-phase component Q ₂ and calculates the arithmetic circuit 5 which component P ₂ and the reactive power Measurement of
Measuring device using a fixed method .