JPH09135537A - System-interconnection protective device of power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect and protect the individual operation of a private power generation facility at the facility side by changing the output of a power generation facility and accelerating the increase or decrease in frequency when the frequency increases or decreases and then stopping the private power generation facility or making a parallel-off of it from a system power supply, based on the result of the acceleration of the increase or decrease in frequency. SOLUTION: A function circuit 32 receives a rate of change in frequency V30 from a rate of change in frequency detector 30. Then, the function circuit 32 outputs to a reactive power controlling circuit 24 a reactive power change standard ΔQ1 * which increases lead reactive power and accelerates the increase in frequency when the rate of change in frequency V30 is increasing and which increases delay reactive power and accelerates the decrease in frequency when the rate of change in frequency V30 is decreasing. Then, a voltage standard V* is input from the reactive power controlling circuit 24 to a voltage controlling circuit 9 and the output voltage to be applied to a field circuit 8 of a generator 7 is controlled by the voltage controlling circuit 9. By this method, the individual operation of a private power generation facility during system linkage can be surely detected and protected at the facility side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid connection protection device for linking a private power generation facility such as a garbage power generation system, a cogeneration system, a fuel cell, or a solar power generation system with a system power supply.

[0002]

2. Description of the Related Art Conventionally, a grid connection system as shown in FIG. 11 has been used for general consumers to link their own power generation equipment such as cogeneration and the system power supply.
That is, the upper substation 39 lowers the voltage of the system power supply 1 via the transformer 2 and supplies power to general consumers via the circuit breaker 3. General consumers supply power to the load 5 via the circuit breaker 4.

On the other hand, in the private power generation equipment, the output of the AC generator 7 is connected to the system power supply 1 via the circuit breaker 6. The output power of the AC generator 7 is controlled by an automatic voltage regulator (AV
R) 9 by controlling the field winding 8 of the alternator 7, and the output frequency of the alternator 7
Is controlled by controlling the engine power by the governor 11 of the engine 10 that drives the engine.

As a failure detecting means, an output current of the generator 7 is detected by a current transformer 12, and an abnormal current is detected by a generator abnormality detection circuit 13 in relation to an output voltage of the generator 7.
This detection signal is given to the fault trip circuit 20 so that the circuit breaker 6
Open to the public.

In addition, a current transformer 14 is provided on the output side (substation side) of the circuit breaker 6 as protection means, and a fault trip circuit 20 is operated by an overcurrent relay (OC) 19. Further, when the system power supply 1 is abnormal, particularly when the system power supply 1 is shut off, for example, when the circuit breaker 3 is opened, the output power of the AC generator 7 is supplied to the load 5 and the frequency and voltage are abnormal. The frequency lowering relay (UF) 15, the frequency increasing relay (OF) 16, the overvoltage relay (OV) 1
7. Detected by an undervoltage relay (UV) 18, etc., and based on these detection signals, the fault trip circuit 20 gives a trip command to the circuit breaker 6 to open the circuit breaker 6, and the load 5
And the circuit breaker 3 must be able to be closed again.

[0006]

Here, for example, when an abnormality occurs in the system power supply 1 and the breaker 3 is opened, the output power of the AC generator 7 and the required power of the load 5 are effective and invalid. If the minutes are substantially equal, the frequency and the voltage hardly change, so that none of the relays 15 to 19 operate and a so-called islanding phenomenon occurs that continues the operation. An accident occurs that hinders reclosing.

For this reason, in order to prevent such an isolated operation, a method of providing a transfer cut-off device 38 connected by a dedicated line from the substation 39 to cut off the transfer to the circuit breaker 6 has conventionally been adopted. There is. The transfer cut-off device 38 sends a cut-off signal to the circuit breaker 6 to open the circuit breaker 6 when detecting a signal indicating that the circuit breaker 3 of the upper substation 39 is opened.

The transfer blocking device 38 must be provided when the upper substation is distant or when there are many customers.
For a small- and medium-capacity private power generation facility having an output of about W, the cost is extremely high, and there is little practical advantage due to grid interconnection.

Based on such a situation, the present invention is capable of reliably detecting and protecting islanding operation of a private power generation facility during grid interconnection on the private power generation facility side without providing an expensive transfer interruption device. The purpose is to provide a device.

[0010]

In order to achieve the above object, the present invention is directed to a first aspect of the present invention, wherein in a system in which a private power generation facility is connected to a grid power source, a change in output frequency of the power generation facility is controlled. Detection means for detecting, and reactive means which is the output of the power generation equipment, output setting voltage, control means for outputting a control signal to the power generation equipment to control any one of the phases of the output current and the output voltage and output current, , When the change in the frequency is detected by the detecting means as rising or falling, the output of the power generation equipment is changed to promote the frequency rising or the frequency lowering, and the facilitating means. A system interconnection protection device for power generation equipment, comprising: a stop / disconnection means for stopping or disconnecting the private power generation equipment based on the result.

According to the invention of claim 1, it is possible to reliably detect and protect the islanding operation of the power generation equipment connected to the grid on the private power generation equipment side without providing an expensive transfer interruption device.
In order to achieve the above-mentioned object, the present invention relates to a second aspect of the present invention, in which a private power generation facility using a rotary generator is connected to a grid power source and a breaker is provided between the grid power source and the private power generation facility. In a system configured to detect and trip an output abnormality of the private power generation equipment by a protection device, and a frequency detector that detects the output frequency of the power generation equipment, A frequency change rate detector that detects the rate of change of the frequency detected by the frequency detector, and detects the reactive power of the power generation equipment, and outputs a voltage reference for controlling this reactive power detection value to the reactive power reference. And a frequency change rate detector that changes the reactive power in a forward direction when the frequency change rate detector detects that the frequency change rate is positive, and detects the frequency change rate. A function circuit for adding a reactive power fluctuation reference for changing the reactive power in the delay direction to the reactive power reference of the reactive power control circuit when it is detected that the frequency change rate is negative by the reactive power control circuit. From the reactive power control circuit, and the voltage fluctuation signal obtained by inputting the output of the function circuit is input to the field circuit of the rotary generator. And a voltage control circuit for controlling an output voltage given to the power generation equipment.

In order to achieve the above-mentioned object, the present invention relates to a third aspect of the invention, in which a private power generation facility using a rotary generator is connected to a grid power source, and a disconnection is made between the grid power source and the private power generation facility. In a system in which a protective device is provided and a trip is made by detecting that an abnormality in the output of the private power generation equipment has occurred by a frequency detector that detects the output frequency of the power generation equipment. And a frequency change rate detector that detects the rate of change of the frequency detected by the frequency detector, and the power generation equipment when the frequency change rate detector detects that the rate of change of the frequency is positive. A voltage fluctuation group for decreasing the output voltage and increasing the output voltage of the power generation equipment when the frequency change rate detector detects that the frequency change rate is negative. And a voltage control circuit that controls the output voltage applied to the field circuit of the rotary generator by the voltage fluctuation signal obtained by inputting the output of the function circuit. This is a system interconnection protection device for power generation equipment.

According to the invention according to claim 2 or 3, when the frequency change rate is positive, the reactive power is changed in the forward direction, or the output voltage of the power generation equipment is lowered,
And when the frequency change rate is negative, by changing the reactive power in the delay direction or increasing the output voltage of the power generation equipment, the output frequency of the rotary generator, the output frequency change rate,
Since the abnormal value of the output voltage is generated, and this is detected by the protection device to disconnect the generator, it is possible to operate the generator independently during grid connection without installing an expensive transfer interruption device. The power generation equipment can reliably detect and protect. In addition, it detects the frequency change rate and expands in synchronization with the frequency fluctuation so as to promote the direction in which the frequency is changing. It is possible to provide a system interconnection protection device for power generation equipment, which can also detect islanding operation without deterioration of characteristics.

In order to achieve the above-mentioned object, the present invention relates to a fourth aspect of the invention, in which the frequency detector has a frequency when a detection frequency which is an input of the frequency change rate detector rises near a rated frequency. When the reactive power advances in the forward direction or decreases in the output voltage of the power generation equipment as the frequency rises, and the detection frequency that is the input of the frequency change rate detector decreases near the rated frequency, the reactive power decreases in the delay direction or as the frequency decreases. The system interconnection protection device for power generation equipment according to claim 2 or 3, wherein the output voltage of the power generation equipment is changed in a direction of increasing the output voltage.

According to the invention corresponding to claim 4, in addition to the effects of claims 2 and 3, an unstable point is created near the rated frequency and the frequency is shifted during the islanding operation. Independent operation can be detected.

In order to achieve the above-mentioned object, the present invention according to claim 5 provides the frequency detector, wherein the detection frequency which is an input of the frequency change rate detector is higher than a rated frequency by a set value or more. In this case, the reactive power is characteristically inverted from the forward direction to the delayed direction or the output voltage of the power generation equipment from the downward direction to the upward direction according to the frequency increase, and the detection frequency that is the input of the frequency change rate detector is set from the rated frequency 4. When the voltage falls below the predetermined value, the reactive power is characteristically inverted from the delay direction to the advance direction or the output voltage of the power generation equipment is changed from the rising direction to the falling direction in accordance with the decrease of the frequency. It is a system interconnection protection device for the power generation equipment described.

According to the invention corresponding to claim 5, in addition to the effect of claim 2 or claim 3, when the frequency changes by a set value or more by reversing the characteristics, it acts in a direction to prevent the divergence of the frequency. However, the change width of the frequency can be limited.

In order to achieve the above object, the present invention provides a function circuit according to claim 6, wherein the function circuit changes a reactive power fluctuation reference or a voltage fluctuation that changes according to the frequency change rate detected by the frequency change rate detector. The system interconnection protection device for power generation equipment according to claim 2 or 3, which outputs a reference.

According to the invention corresponding to claim 6, in addition to the effect of claim 2 or claim 3, the reactive power fluctuation or voltage fluctuation is increased as the frequency change rate increases, and the positive feedback effect is increased. Also, in order to compensate for the delay of the reactive power control, a stepwise reactive power reference is output when the polarity of the frequency change rate changes.

In order to achieve the above-mentioned object, the present invention according to claim 7 is such that when the frequency change rate detected by the frequency change rate detector is zero or less than a set value, reactive power of a constant cycle is obtained. 4. A circuit for adding a fluctuation or voltage fluctuation signal is newly provided, and the circuit according to claim 2 or 3.
It is a system interconnection protection device for the power generation equipment described.

According to the invention corresponding to claim 7, in addition to the effect of claim 2 or claim 3, when the reactive power and the active power are balanced, the islanding operation is performed by the reactive power change due to the constant period fluctuation. Frequency fluctuations can be produced therein.

In order to achieve the above-mentioned object, the present invention according to claim 8 is such that, when the frequency change rate detected by the frequency change rate detector becomes equal to or more than a set value, a constant cycle is set so as to match a desired polarity. 4. The system interconnection protection device for power generation equipment according to claim 2 or 3, wherein the phase of the reactive power fluctuation or voltage fluctuation signal is changed.

According to the invention corresponding to claim 8, in addition to the operation of claim 2 or claim 3, when the polarity of the frequency change rate changes by the delay of the reactive power control loop, the phase of the reactive power reference of a constant cycle. By changing the setting of, the frequency variation effect can be increased.

In order to achieve the above object, the present invention relates to a ninth aspect of the invention, in which an in-house power generation facility including a static DC power source and a power converter is connected to a system power source, and
In a system in which a circuit breaker is arranged between the system power supply and the private power generation facility, and a protection device detects that an abnormal output of the private power generation facility has occurred and trips the circuit breaker. A frequency detector that detects the output frequency of the power generation equipment, a frequency change rate detector that detects the rate of change of the frequency detected by the frequency detector, an active power reference, and a frequency change rate detector that detects the frequency change rate detector. A system interconnection protection device for power generation equipment, characterized in that active power and reactive power are controlled based on a reactive power standard determined based on the frequency change rate.

According to the invention corresponding to claim 9, even in static power generation equipment, frequency fluctuation is caused by controlling the reactive power according to the value of the frequency change rate, and the power generation equipment operates independently. Can detect and protect.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a system interconnection protection device for power generation equipment according to the present invention will be described below with reference to the drawings. The differences from the conventional example of FIG. 11 will be mainly described. <First Embodiment> (Structure) FIG. 1 is a block diagram showing a first embodiment of the present invention. The difference from the conventional system interconnection protection system of FIG. 11 is that the conventional example is expensive. Instead of providing the special transfer blocking device 38, it is configured as follows.

That is, as shown in FIG.
Frequency is detected by the frequency detector (f) 21 from the output voltage of the frequency change rate (df / d).
t) by the detector 30 detects a frequency change rate V _30.

Frequency change rate (df / dt) excess detector 3
1 detects whether the frequency change rate V ₃₀ is equal to or greater than a set value, and outputs an abnormal output signal V ₃₁ when the frequency change rate V ₃₀ is equal to or greater than the set value. The fault trip circuit 20 gives a trip to the circuit breaker 6 to open the electric circuit.

The reactive power detector 23 inputs the output current of the generator 7 detected by the current transformer 14 and the output voltage of the generator 7 to detect the reactive power. The active power detector 26 inputs the output current of the generator 7 detected by the current transformer 14 and the output voltage of the generator 7 to detect active power.

On the other hand, the active power control circuit (APR) 27
Compares the active power reference P ^* from the active power reference (P ^* ) setting unit 25 with the active power P from the active power detector 26 and gives the deviation to the governor 11 to control the speed of the engine 10. I do.

The function circuit 32 includes a frequency change rate detector 30.
Enter the frequency change rate V ₃₀ from the reactive power variation reference Δ
Q ₁ ^* is output. Specifically, as shown in FIG. 4, when the frequency change rate is increasing, the reactive power is increased to promote the frequency increase, and when the frequency is decreasing, it is delayed. The reactive power fluctuation reference ΔQ ₁ ^* which increases the reactive power and promotes the frequency decrease is output.

The reactive power control circuit (AQR) 24 receives the reactive power reference Q ^* from the reactive power reference (Q ^* ) setting unit 28 ^.
And a new reactive power reference obtained by adding the reactive power variation reference ΔQ ₁ ^* of the function circuit 32 and the reactive power Q detected by the reactive power detector 23 are output as a voltage reference V ^* .

The voltage control circuit (AVR) 9 gives a field command for controlling the output voltage of the generator 7 to the field winding 8 based on the voltage reference V ^* from the reactive power control circuit 24.
The active power reference (P ^* ) setter 25, the active power control circuit 27, the speed governor 11, and the engine 10 form a speed control loop. Reactive power reference setter 28
The reactive power detector 23 and the reactive power control circuit 24 constitute a reactive power control loop. The voltage reference V ^* output from the reactive power control circuit 24 and the constant voltage control circuit 9 constitute a voltage control loop.

(Operation) Next, the operation of the above-described first embodiment will be described with reference to FIGS. now,
2, the active power output of the generator 7 P, reactive power Q, the active power P _L which is the load 5 requires, reactive power and Q _L, and active power ΔP flowing into the system power source 1 Reactive power ΔQ is expressed as follows.

ΔP = P−P _L ΔQ = Q−Q _L Here, the inductance between the generator 7 and the system is l, the voltage of the load 5 is V, and the frequency is f.

Then, normally, ΔP≈0, ΔQ
Even if the circuit breaker 3 is opened in a state close to ≒ 0, the voltage V and the frequency f of the load 5 hardly change.
To 19 cannot be detected, and the islanding operation is continued.

However, since the phases of the system power supply 1 and the load 5 are gradually deviated, the circuit breaker 3 cannot be re-closed because it leads to the expansion of the accident and is dangerous, thus degrading the stability of the distribution system. It will be.

The voltage during the independent operation is determined by P = V ² / (ωL). On the other hand, the frequency f during islanding is Q = (V ² ωC)
It is determined by − (V ² / ωL). In particular, paying attention to the frequency f, when the load 5 is the generator 7 from the reactive power Q _L to request is shifted to reactive power leading direction to supply increases the current i _C of the capacitor C frequency f is increased , The inductance current i _L decreases and the frequency f changes in a balance direction.

When the reactive power supplied by the generator 7 is deviated from the reactive power Q _L required by the load 5 in the delay direction, the frequency f decreases, the inductance current i _L increases, and the capacitor current i _C increases. Decreases, and the frequency f changes in the balance direction.

Next, as shown in FIG. 3, the frequency fluctuation in the case of independent operation in the condition of ΔQ≈0 and ΔQ ≠ 0 shows a stable point f ₁ while the frequency f fluctuates after the system is cut off (t ₀ ). , F
It has been confirmed by simulation that the approach to ₂ is approached.

In FIG. 3, f ₁ is the case where ΔQ is slightly advanced, and f ₂ is the case where ΔQ is slightly delayed. + Δf and −Δf shown in FIG. 3 are protective relays 15 to 19
Is a level at which islanding can be detected.

FIG. 4 is a diagram for explaining the function and effect of the embodiment shown in FIG. 1, f is the frequency f detected by the frequency detector 21, and df / dt is the frequency change rate detector 30. Is the frequency change rate detected by ΔQ ₁ ^*
Indicates the output of the function circuit 32.

Now, when f changes as shown in FIG. 4, df
/ Dt is a waveform advanced by 90 ° from this. df
When / dt> 0, the frequency is rising, and during this time, the leading ΔQ ₁ ^* is output from the function circuit 32, and the frequency f acts so as to further increase. Also, df / dt <0
In the case of, since the frequency f is falling, the function circuit 3
A delayed ΔQ ₁ ^* is output from 2, and the frequency f acts to further decrease. In this way, the frequency fluctuation is increased by the positive feedback action, and the frequency abnormality or the excessive frequency change rate is detected by the excessive frequency change rate detector 31,
It becomes possible to detect and protect the islanding operation without using the expensive transfer interruption device used conventionally.

Although the positive feedback effect is generated by setting -df / dt directly to ΔQ ₁ ^* , the frequency detection delay is 1
Control delay of cycle, ΔQ or ΔV is 0.2-0.3s
Since ec is generated, df / dt is used to compensate for this delay.
It is desirable to advance the pattern of ΔQ ₁ ^* .

In the case of a fixed period, advance control can be performed by adding a component obtained by further differentiating df / dt. However, since the period changes, the function circuit 32, as shown in FIG.
As in ΔQ ₁ ^{* in} FIG. 4, a delay component may be compensated by a component depending on the magnitude of df / dt and a fixed component depending on the polarity of df / dt. As the function circuit 32, df / d
The simplest structure can be obtained by outputting a square wave based only on the polarity of t.

By adding such a circuit, it is possible to detect the isolated operation by expanding the frequency fluctuation during the isolated operation as shown in FIGS. 3 to 5 and detecting the frequency or the frequency change rate abnormality. It will be easy.

By the function circuit 32, the output can be increased when df / dt exceeds a certain level, whereby the frequency fluctuation can be expanded quickly. (Effect) According to the first embodiment described above, df /
If dt is detected and df / dt> 0, then proceed reactive power,
Further, when df / dt <0, the delayed reactive power is additionally output from the generator 7, whereby the frequency fluctuation can be expanded and the islanding operation can be easily detected.

Further, according to the first embodiment, df /
Since the system can be synchronized with the polarity of dt, even in the case of a plurality of private power generation facilities, it is possible to expand the frequency fluctuation and detect the islanding operation like one private power generation facility. On the other hand, in the reactive power fluctuation method and the voltage fluctuation method different from those of the embodiment of the present invention, the fluctuation directions of a plurality of units do not match, so that the effect is reduced.

Moreover, the excessive frequency change rate detector 31 can detect and protect the isolated operation early before the change of ± Δf is reached. <Second Embodiment> In FIG. 1, when the response of the reactive power control circuit 24 is slow, the reactive power fluctuation reference ΔQ ₁ ^* which is the output of the function circuit 32 is simply input to the reactive power control circuit 24. Instead, as shown by the broken line, the voltage fluctuation signal ΔV ₁ ^* obtained by branching the reactive power fluctuation reference ΔQ ₁ ^* which is the output of the function circuit 32 and inputting it to the inverting amplifier 33 is input to the constant voltage control circuit 9. The voltage reference V ^* is applied in a feedforward manner.

In this case, df / dt> 0 and ΔQ ₁ ^*
Progresses, ΔV ₁ ^* decreases, and output power decreases →
The frequency fluctuates even in the loop of frequency increase (due to the response delay and regulation of the governor 11).

Further, the amplifier of the reactive power control circuit 24 is generally composed of an I (integral) controller, but it is composed of a PI (proportional integral) controller. With this configuration, the proportional amount P becomes the voltage fluctuation amount ΔV ₁ ^* .

<Third Embodiment> The function circuit 32 of FIG.
The reactive power fluctuation reference ΔQ ₁ ^* which is the output of the inverting amplifier 3 shown by the broken line in FIG. 1 is not input to the reactive power control circuit 24.
3, the voltage fluctuation reference ΔV ₁ ^* is changed and added to the voltage reference V ^* of the constant voltage control circuit 9.
Also in this case, the same effect as that of the embodiment of FIG. 1 can be obtained.

This embodiment is particularly effective for a system having no loop of the reactive power control circuit 24 in a small capacity generator. <Fourth Embodiment> In FIG. 2, ΔP = 0, ΔQ =
In the case of 0, both the active power and the reactive power are perfectly balanced, so that the voltage and the frequency do not change even in the isolated operation. Such a case is extremely rare, but theoretically exists. Even in such a case, to detect the islanding operation,
It is configured as shown in FIG.

Specifically, a pattern generation circuit 36 is added to the configuration shown in FIG. 1, and a constantly small reactive power fluctuation signal ΔQ ₂ ^* obtained from this is input to the reactive power control circuit 24, and the reactive power fluctuation is also received. The configuration is such that the minute voltage fluctuation signal ΔV ₁ ^* obtained by inputting the signal ΔQ ₂ ^* to the inverting amplifier 33 is input to the constant voltage control circuit 9 as shown by the broken line. In this way, the frequency fluctuation starting source is configured.

In this case, when the output df / dt of the frequency change rate detector 30 reaches a set level, the output of the pattern generating circuit 36 can be adjusted. <Fifth Embodiment> As shown in FIG. 7, a polarity discriminating circuit 34 for discriminating only the polarity of the output of the frequency change rate detector 30 of FIG. 1 is provided, and the output of the polarity discriminating circuit 34 is set to a phase setting circuit 35. It is input to the pattern generating circuit 36 which is always connected via. Then, the output ΔQ ₁ of the pattern generation circuit 36
Input ^* to the reactive power control circuit 24 and add
The voltage fluctuation signal ΔV ₁ ^* obtained by inputting ΔQ ₁ ^* to the inverting amplifier 33 is input to the constant voltage control circuit 9.

With such a configuration, the phase of the pattern generating circuit 36 is set to the polarity for advancing the power when the frequency increases and the polarity for outputting the delayed power when the frequency decreases according to the polarity change of the frequency change rate. Since the circuits are matched so that they substantially match, the same effect as that of the above-described first embodiment can be obtained.

<Sixth Embodiment> As shown in FIG.
The output of the frequency detector 21 in the circuit of FIG. 7 is branched from the frequency change rate detector 30 and input to the reactive power function generator 22, and the reactive power fluctuation reference ΔQ ₂ ^* obtained by this is input ^.
To the reactive power control circuit 24. Alternatively, the voltage fluctuation reference ΔV ₂ ^* obtained by inputting the reactive power fluctuation reference ΔQ ₂ ^* to the inverting amplifier 37 is added to the input of the constant voltage control circuit 9. In this way, the frequency fluctuation starting source is configured.

The principle of this operation will be described with reference to FIG. That is, the reactive power fluctuation reference Δ with respect to the frequency f
When the characteristics of Q ^* (reactive power ΔQ flowing to a system power supply), the load is in a resonance state at the rated frequency f _0, the reactive power of the load is the characteristic shown in Q _L.

Between the frequencies f ₀ and f ₁ , the reactive power output from the generator is ahead of the reactive power required by the load, so the frequency rises, and similarly between f ₀ and f ₂ the load demands. The frequency drops because the reactive power output by the generator lags the reactive power. For the same reason, the frequency falls below f _{1 and} rises below f ₂ .

Therefore, the point f ₀ becomes an unstable point and f ₁ , f
₂ Shift to either one. Since the f ₁ and f ₂ points are stable points, they have a function of shifting to the f ₁ or f ₂ points. In addition, ΔQ ^*
The curve of is a condition that requires an upper right characteristic near the load near the f ₀ (rated frequency), and other curves are not directly related to the frequency shift action, so various curves can be selected. Only the slope of the curve of ΔQ ^* is important, and when the reactive power Q ^* is constantly output at the point f ₀ , the movement is the same as that indicated by the broken line, and the shift point is the same.

<Seventh Embodiment> In the above-described embodiment, the system interconnection protection device for the power generation equipment by the AC generator 7 has been described, but FIG. 10 shows the system interconnection protection device for the stationary type power generation equipment. Here is an example. In this case, in the circuit of FIG. 1, the AC generator 7, the field winding 8, the constant voltage control circuit 9, the engine 10, the speed governor 11, the reactive power detector 23, the reactive power reference setter 28, the reactive power. What is newly provided with a current reference circuit 40, a current control circuit 41, a power converter such as an inverter 42, and a DC power supply 43 without providing the control circuit 24, the active power detector 26, and the active power reference setter 25. Is.

The current reference circuit 40 inputs the active power reference P ^* , and also inputs the reactive power fluctuation reference ΔQ ₁ ^* and the reactive power reference Q ^* , which are the outputs of the function circuit 32, adds them and adds them. Active power standard P ^* and reactive power standard (Q ^* +
The current reference of the inverter 42 is output from ΔQ ₁ ^* ).
The current control circuit 41 inputs the current reference from the current reference circuit 40 and the output current of the inverter 42 detected by the current transformer 12, and gives a phase signal to the inverter 42 such that the output current becomes the current reference.

With this configuration, it is possible to detect the isolated operation by controlling the reactive power with the value of df / dt to cause the frequency fluctuation, exactly as in the above-described embodiment.

In the case of the inverter 42, since there is almost no control delay, the function circuit 32 may be omitted. When the function circuit 32 is omitted, the reactive power reference is corrected as follows by directly inputting the frequency change rate detected by the frequency change rate detector 30 to the current reference circuit 40.
That is, the reactive power reference is corrected such that the reactive power is changed in the forward direction when the frequency change rate is positive, and the reactive power is changed in the delay direction when it is detected that the frequency change rate is negative.

Even if the circuit shown in FIG.
Similarly, an active power control loop and a reactive power control loop can be provided. <Modifications> Modifications of the embodiment of FIG. 1 include the following.

(1) As a simplified form of the embodiment of FIGS. 1, 6, 7, and 8, the active power control circuit 27 and the active power reference setter 25 provided on the input side of the speed governor 11 are shown.
Even if it is omitted, the same operational effect as the first embodiment can be obtained.

(2) Even if a frequency change amount detector for detecting the frequency change amount for each furnace cycle is provided instead of the frequency change rate detector 30 of FIG. 1, the same operation as that of the embodiment of FIG. 1 is performed. The effect is obtained.

(3) As a function of the function circuit 32 shown in FIG.
By using the one to which the function of increasing the output when df / dt exceeds a certain level is added, the frequency variation can be expanded faster than in the first embodiment.

[0069]

As described above, according to the present invention, it is possible to reliably detect and protect the isolated operation of the private power generation equipment during grid interconnection on the private power generation equipment side without providing an expensive transfer interruption device. A system protection device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a system interconnection protection device according to the present invention.

FIG. 2 is an operation explanatory view of the embodiment of FIG. 1;

FIG. 3 is an operation explanatory diagram of the embodiment in FIG. 1;

FIG. 4 is an operation explanatory diagram of the embodiment in FIG. 1;

FIG. 5 is an operation explanatory view of the embodiment of FIG. 1;

FIG. 6 is a block diagram showing a fourth embodiment of a grid interconnection protection device according to the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of a grid interconnection protection device according to the present invention.

FIG. 8 is a block diagram showing a sixth embodiment of a grid interconnection protection device according to the present invention.

9 is an explanatory diagram of the operation of the embodiment of FIG.

FIG. 10 is a block diagram showing a seventh embodiment of a grid interconnection protection device according to the present invention.

FIG. 11 is a block diagram showing an example of a conventional system interconnection protection device for power generation equipment.

[Explanation of symbols]

1: System power supply, 2: Transformer, 3, 4, 6 ... Circuit breaker, 5 ...
Load, 7 ... AC generator, 8 ... field winding, 9 ... AVR (constant voltage control circuit), 10 ... engine, 11 ... speed governor, 1
2, 14 ... current transformer, 13 ... generator abnormality detection circuit, 15 ...
UF (frequency lowering relay), 16 ... OF (frequency raising relay), 17 ... OV (overvoltage relay), 18 ... UV (undervoltage relay), 19 ... OC (overcurrent relay), 20 ...
Fault trip circuit, 21 ... Frequency detector, 22 ... Reactive power function generator, 23 ... Reactive power detector, 24 ... AQR
(Reactive power control circuit), 25 ... Active power reference setter, 2
6 ... Active power detector, 27 ... APR (active power control circuit), 28 ... Reactive power reference setter, 30 ... Frequency change rate detector, 31 ... Frequency change rate excessive detector, 32 ... Function circuit, 33 ... Inversion Amplifier, 34 ... Polarity discrimination circuit, 35 ... Phase setting circuit, 36 ... Pattern generating circuit, 37 ... Inversion amplifier.

Claims (9)

[Claims] 1. A system for interconnecting a private power generation facility with a grid power source, and detecting means for detecting a change in an output frequency of the power generation facility, reactive power output from the power generation facility, an output set voltage, and an output current. Control means for outputting a control signal to the power generation equipment to control either of the output voltage and the phase of the output current; and when the change in the frequency is detected by the detection means as rising or falling. A facilitating means for changing the output of the power generation equipment to promote a frequency increase or a frequency fall, and a stop / disconnect means for stopping or disconnecting the private power generation equipment based on the result promoted by the facilitating means. A system interconnection protection device for a power generation facility, comprising: 2. A private power generation facility using a rotary generator is connected to a system power supply, a circuit breaker is provided between the system power supply and the private power generation facility, and the circuit breaker outputs the power of the private power generation facility. In a system configured to detect that an abnormality has occurred by a protective device and cause a trip, a frequency detector that detects the output frequency of the power generation facility, and a rate of change of the frequency detected by the frequency detector are detected. A frequency change rate detector to detect the reactive power of the power generation equipment, a reactive power control circuit that outputs a voltage reference for controlling the reactive power detection value to the reactive power reference, by the frequency change rate detector When it is detected that the frequency change rate is positive, the reactive power is changed in the forward direction, and the frequency change rate detector detects that the frequency change rate is negative. When a function circuit for adding a reactive power fluctuation reference for changing the reactive power in the delay direction to the reactive power reference of the reactive power control circuit, and directly input the voltage reference from the reactive power control circuit, or A voltage control circuit that adds a voltage fluctuation signal obtained by inputting the output of the function circuit to the voltage reference from the reactive power control circuit and inputs the voltage fluctuation signal, and controls the output voltage applied to the field circuit of the rotary generator. A system interconnection protection device for power generation equipment, comprising: 3. A private power generation facility using a rotary generator is connected to a grid power source, a circuit breaker is disposed between the grid power source and the private power generation facility, and the breaker outputs the private power generation facility. In a system configured to detect that an abnormality has occurred by a protective device and cause a trip, a frequency detector that detects the output frequency of the power generation facility, and a rate of change of the frequency detected by the frequency detector are detected. And a frequency change rate detector that reduces the output voltage of the power generation equipment when the frequency change rate detector detects that the frequency change rate is positive, and the frequency change rate detector detects the frequency change. A function circuit that outputs a voltage fluctuation reference for increasing the output voltage of the power generation equipment when it is detected that the rate is negative, and an output of the function circuit are input and obtained. Voltage variation signal, the rotating power generator system interconnection protection device of the power generation facility which is characterized by comprising a voltage control circuit for controlling the output voltage to be supplied to the field circuit, the being. 4. The frequency detector, when the detection frequency which is an input of the frequency change rate detector rises in the vicinity of the rated frequency, decreases the reactive power or the output voltage of the power generation facility as the frequency rises. In addition, when the detection frequency which is the input of the frequency change rate detector falls near the rated frequency, the reactive power is changed in the delay direction or in the direction of increasing the output voltage of the power generation equipment as the frequency falls. The grid interconnection protection device for power generation equipment according to claim 2 or claim 3. 5. The frequency detector, when the detection frequency, which is an input to the frequency change rate detector, rises above a rated frequency by a preset value or more, the reactive power increases from the forward direction to the lag direction or the power generation. When the output voltage of the equipment is inverted from the descending direction to the ascending direction, and the detected frequency that is the input of the frequency change rate detector falls below the rated frequency value below the set value, the reactive power is delayed according to the decreasing frequency. 4. The system interconnection protection device for power generation equipment according to claim 2 or 3, wherein characteristic is inverted from the forward direction to the forward direction or the output voltage of the power generation equipment from the rising direction to the falling direction. 6. The function circuit according to claim 2, wherein the function circuit outputs a reactive power fluctuation reference or a voltage fluctuation reference that changes according to the frequency change rate detected by the frequency change rate detector. System protection device for power generation equipment. 7. When the frequency change rate detected by the frequency change rate detector is zero or less than a set value, a circuit for adding a reactive power fluctuation or voltage fluctuation signal of a constant cycle is newly provided. The grid interconnection protection device for power generation equipment according to claim 2 or claim 3. 8. When the frequency change rate detected by the frequency change rate detector exceeds a set value, the phase of the reactive power fluctuation or voltage fluctuation signal of a constant cycle is changed so as to match a desired polarity. The system interconnection protection device for power generation equipment according to claim 2 or 3. 9. A private power generation facility comprising a static DC power source and a power converter is connected to a system power source, and a breaker is provided between the system power source and the private power generation facility, and the breaker is provided. In a system configured to trip by detecting an abnormality in the output of the private power generation equipment by a protection device, a frequency detector that detects the output frequency of the power generation equipment, and is detected by the frequency detector. The active power and reactive power are controlled by the frequency change rate detector for detecting the frequency change rate, the active power reference, and the reactive power reference determined based on the frequency change rate detected by the frequency change rate detector. A system interconnection protection device for power generation equipment, which is characterized by: