JPH10215521A - System interconnection protector for power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress fluctuations of reactive power at the time of system interconnection by increasing the leading reactive power, when the frequency variation rate is positive and increasing the lagging reactive power, when the frequency variation rate is negative. SOLUTION: A function circuit 32 calculates a voltage fluctuations reference ΔV1 * from a frequency variation rate V30 , detected by a detector 30 for detecting the variation rate of output frequency of a power generation facility. When a decision is made that the frequency variation rate V30 is positive, based on a voltage fluctuation reference ΔV1 * thus operated, reactive power of the power generation facility is increased so as to accelerate increase in the frequency. When the frequency variation rate V30 is negative, power generation facility is controlled to increase the lagging reactive power thus accelerating frequency decrease. Since fluctuation of reactive power can be suppressed appropriately during a system interconnection, the power generation facility can be operated stably at a high speed, even when a large number of generators are operated.

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 60 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 of the system power supply 1 occurs and the circuit breaker 3 is opened, the output power of the AC generator 7 and the required power of the load 5 become effective components and invalid. If both are substantially equal, the frequency and voltage hardly change, so that any of the relays 15 to 19 does not operate, and the operation is continued, that is, a so-called islanding phenomenon occurs. An accident occurs that prevents reclosing.

For this reason, in order to prevent such an isolated operation, a method in which a transfer interrupting device 61 connected by a dedicated line from the substation 60 is provided to interrupt the transfer to the circuit breaker 6 has been adopted. There is. The transfer cutoff device 61 is to send a cutoff 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 60 has been opened.

[0008] The transfer cut-off device 61 must be provided when the upper substation 60 is distant or when there are many customers. However, for a small and medium-capacity private power generation facility having an output of about several hundred kW, it is very costly. And there are few practical merits of grid interconnection.

According to the present invention, based on such circumstances, it is possible to reliably detect and protect the independent operation of the private power generation facility during the grid connection without providing an expensive transfer shut-off device. It is intended to provide a device.

[0010]

According to a first aspect of the present invention, there is provided a system for interconnecting a power generation facility with a system power supply via a circuit breaker. A frequency detector for detecting a frequency, a frequency change rate detector for detecting a rate of change of the frequency detected by the frequency detector, and a voltage or reactive power fluctuation based on the rate of change of the frequency detected by the frequency change rate detector. Calculate the reference, increase the leading reactive power of the power generation equipment or decrease the output voltage of the power generation equipment when the frequency change rate is positive by this fluctuation reference, and reduce the delay reactive power when the frequency change rate is negative. While controlling the power generation equipment to increase or increase the output voltage of the power generation equipment,
Control means for setting a gain to be high in a range where the frequency change rate is extremely low, a gain to be low in a range where the frequency change rate is intermediate, and a slightly higher gain in a range where the frequency change rate is high; and Protection means for detecting frequency fluctuations promoted with voltage fluctuations of the equipment, and for disconnecting the power generation equipment from a system bus with the circuit breaker; It is.

According to the first aspect of the present invention, when the frequency change rate is positive, the leading reactive power is increased, and when the frequency change rate is negative, the delay reactive power is increased. By increasing the gain of the control means in the closed loop to be expanded in a range where the frequency change rate is small, the frequency fluctuation expansion during the isolated operation is shortened, and at the same time the gain is lowered when the frequency change rate is intermediate. Suppresses reactive power fluctuation during system

According to a second aspect of the present invention, there is provided a system for interconnecting a power generation facility with a system power supply via a circuit breaker in a system interconnection system for detecting an output frequency of the power generation facility. A device, a frequency change rate detector for detecting a change rate of the frequency detected by the frequency detector, and a voltage or reactive power fluctuation reference is calculated from the change rate of the frequency detected by the frequency change rate detector. When the frequency change rate is positive according to the fluctuation standard, the leading reactive power of the power generating equipment is increased or the output voltage of the power generating equipment is decreased, and when the frequency change rate is negative, the delayed reactive power is increased or the power of the power generating equipment is increased. Controlling the power generation equipment so as to increase the output voltage, and switching gains of a plurality of stages or switching a limit value corresponding to the fluctuation reference in accordance with the frequency change rate. And control means for detecting frequency fluctuations promoted by voltage fluctuations of the power generation equipment and disconnecting the power generation equipment from a system bus with the circuit breaker. It is a system interconnection protection device for power generation equipment.

[0013] According to the invention corresponding to claim 2, the likelihood of the single operation is detected from the magnitude of the frequency change rate, the gain or the limit value is increased, and the likelihood of the single operation is further increased (when the frequency change rate becomes large, ) And increasing the gain or the limit value to detect the isolated operation in a short time and at the same time suppress the reactive power fluctuation due to malfunction due to the malfunction.

In order to achieve the above object, the invention according to claim 3 is the control means according to claim 2, wherein the gain is reduced or the fluctuation is reduced when the frequency changes by more than a set value from a rated value. A system interconnection protection device for a power generation facility, wherein a limit value corresponding to a criterion is reduced to limit a fluctuation range of the frequency.

According to the invention corresponding to claim 3, it becomes possible to prevent the frequency from changing excessively by lowering the gain when the frequency changes beyond the set width or by lowering the fluctuation reference limit value. .

In order to achieve the above object, an invention according to a fourth aspect of the present invention is to detect a change in the output frequency of the power generation equipment in a system interconnection system in which the power generation equipment is connected to a system power supply via a circuit breaker. Output frequency change detection means, and control means for outputting a control signal to the power generation equipment in order to control any of the output of the power generation equipment, the reactive power, the output set voltage, the output current and the phase of the output voltage and the output current. When,
A reactive power change rate detection means for detecting a change rate of the reactive power of the output of the power generation equipment, a voltage change rate detection means for detecting an output voltage of the power generation equipment or a reference change rate of the power generation equipment, and the reactive power A change means for changing the output of the power generation equipment when a change in the frequency is detected to be increasing or decreasing by the change rate detecting means and the voltage change rate detecting means, thereby promoting a frequency increase or a frequency decrease,
Stopping / disconnecting means for stopping the in-house power generation equipment or disconnecting from the system power supply based on the result promoted by the promoting means and a decrease in the reactive power change rate with respect to the output voltage or the reference change rate. This is a system interconnection protection device for power generation equipment.

According to the fourth aspect of the present invention, when the frequency is small during independent operation, reliable detection cannot be performed. Therefore, by detecting the change rate of the reactive power with respect to the voltage change rate, the load impedance is reduced. Indirect detection enables reliable islanding detection.

In order to achieve the above object, an invention according to a fifth aspect of the present invention is to detect a change in the output frequency of the power generation equipment in a system interconnection system in which the power generation equipment is connected to a system power supply via a circuit breaker. Output frequency change detection means, and control means for outputting a control signal to the power generation equipment in order to control any of the output of the power generation equipment, the reactive power, the output set voltage, the output current and the phase of the output voltage and the output current. When,
Detecting means for detecting the rate of change of the reactive power of the power generation equipment or the width of change of the reactive power, and when the change in the frequency detected by the output frequency change detecting means is detected as rising or falling, Facilitating means for changing the output of the power generation equipment to promote the frequency increase or decrease,
When the rate of change or the range of change of the reactive power is equal to or greater than a set value, a reduction means for reducing the function of the facilitating means is provided.

According to the fifth aspect of the present invention, when the rate of change of reactive power or the range of the change becomes equal to or larger than the set value during the interconnection of the system, the variation of the reactive power can be suppressed by acting to loosen the promoting means. it can.

To achieve the above object, an invention according to claim 6 is a system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, and detects a change in an output frequency of the power generation facility. Output frequency change detection means, and control means for outputting a control signal to the power generation equipment in order to control any of the output of the power generation equipment, the reactive power, the output set voltage, the output current and the phase of the output voltage and the output current. When,
When the change in the frequency detected by the output frequency change detecting means is detected to be increasing or decreasing, the increasing means changes the output of the power generation equipment to increase or decrease the frequency, and the increasing means After disconnecting the power generation equipment from the system based on the result promoted by
And a self-sustaining operation means for turning off the assisting means to perform an independent operation.

According to the invention corresponding to claim 6, a stable frequency can be obtained by turning off the promoting means at the time of disconnection from the system. In order to achieve the above object, an invention according to claim 7 is a system for interconnecting power generation equipment with a system power supply via a circuit breaker in an output frequency change detecting an output frequency change of the power generation equipment. Detection means, and control means for outputting a control signal to the power generation equipment to control any of the output of the power generation equipment, the reactive power, the output set voltage, the output current and the phase of the output voltage and the output current, In the vicinity of the rated frequency in front of the frequency detector for detecting the change of the output frequency detected by the output frequency change detecting means, the phase characteristic circuit means in which the voltage phase advances as the frequency increases, and the output frequency change detecting means When the detected change in the frequency is detected to be increasing or decreasing, the output of the power generation equipment is changed to promote the frequency increase or decrease. Power supply equipment, comprising: stopping means for stopping the in-house power generation equipment or disconnecting from the system power supply based on the result of the promotion by the helping means. Device.

According to the invention corresponding to claim 7, the frequency change rate is apparently amplified, so that the isolated operation detection time can be shortened. In order to achieve the above object, an invention according to claim 8 is a phase characteristic circuit unit according to claim 7, wherein the first band-pass filter having a resonance point at a frequency slightly higher than the rated frequency, This is a system interconnection protection device for power generation equipment comprising a second bandpass filter having a resonance point at a low frequency, and an addition circuit for adding the outputs of the first and second bandpass filters.

According to the invention corresponding to claim 8, the phase advances near the rated frequency as the frequency rises, and the phase is advanced as the frequency increases, and the phase is delayed as the frequency rises beyond the rated frequency. is there.

[0024] In order to achieve the above object, an invention according to claim 9 is to interconnect a power generation facility by a rotary generator with a system power supply, and arrange a circuit breaker between the system power supply and the power generation facility. And a system configured to detect the occurrence of an abnormality in the output of the power generation equipment by the protection means and to trip the circuit breaker, wherein a frequency detector for detecting an output frequency of the power generation equipment, and the frequency detector A frequency change rate detector for detecting a rate of change of the frequency detected in the step (a), and a reactive voltage reference for detecting the reactive power of the power generation equipment and controlling the reactive power detected value to a reactive power reference. Low-speed response reactive power control means, and when the frequency change rate detector detects that the rate of change of the frequency is positive, the reactive power is changed in the forward direction, and the frequency change is performed. When a detector detects that the frequency change rate is negative, a reactive power fluctuation reference for changing the reactive power in a delay direction is compared with a value obtained by detecting a reactive power fluctuation from the reactive power. The high-speed reactive power control means controlled by the voltage reference of the following, and the voltage reference obtained based on the first and second voltage references of the output of the low-speed and high-speed reactive power control means, to the field circuit of the rotary generator Voltage control means for controlling the output voltage, and a protection means for disconnecting the power generation equipment from a system bus at the circuit breaker from the second voltage reference and the fluctuation value of the reactive power from the high-speed reactive power control means. And a system interconnection protection device for power generation equipment.

According to the ninth aspect of the present invention, the low-speed response reactive power control unit controls the steady-state reactive power of the generator, and the high-speed response reactive power fluctuation control unit controls the reactive power according to the frequency change rate. The fact that the reactive power fluctuation is small relative to the output of the reactive power fluctuation control means during operation makes it possible to detect the separation from the system.

According to a tenth aspect of the present invention, the output of the reactive power fluctuation control circuit and the frequency change rate are controlled based on a voltage reference for controlling the voltage of the rotary generator. A system interconnection protection device for a power generation facility, wherein a generator voltage fluctuation criterion based on the reference value is added.

According to the tenth aspect of the present invention, by adding the reactive power fluctuation loop output and the voltage fluctuation reference, the reactive power control output is small when the power system is interconnected, but when the power supply is separated from the power system, the motor is particularly driven. In the case of a load, the detection can be performed by utilizing the fact that the impedance with respect to the reactive power increases and the reactive power fluctuation with respect to the voltage fluctuation decreases.

In order to achieve the above object, the invention according to claim 11 is characterized in that when the power generation equipment is constituted by a static power converter or a reactive power control device, the power generation equipment is delayed by a reactive power fluctuation control or a voltage fluctuation control circuit. The system interconnection protection device for a power generation facility according to any one of claims 1 to 10, wherein a circuit is added. According to the invention corresponding to claim 11, it is possible to generate a delay equivalent to the delay of the field of the synchronous generator and to match the operation phases of the stationary machine and the synchronous generator.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below. Here, the points different from the conventional example of FIG. 11 will be mainly described. <First Embodiment> (Configuration) FIG. 1 is a configuration diagram showing a first embodiment of the present invention, which is different from the conventional system interconnection protection system of FIG. Instead of providing the shut-off device 38, the configuration is as follows.

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

Frequency change rate (df / dt) excessive 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 receives the output current of the generator 7 detected by the current transformer 12 and the output voltage of the generator 7 and detects reactive power. The active power detector 26 receives the output current of the generator 7 detected by the current transformer 12 and the output voltage of the generator 7 and detects active power.

On the other hand, an 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 detected by the active power detector 26, and gives this deviation to the governor 11, Perform speed control.

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, while the frequency change rate df / dt is increasing, the reactive power is increased to promote the frequency increase, and the frequency change rate df is increased. While / dt is falling, the reactive power fluctuation criterion ΔQ ₁ ^* that increases the delay reactive power and promotes the frequency drop ^.
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 voltage reference V ^* for matching the reactive power Q detected by the reactive power detector 23 with the new reactive power reference obtained by adding the reactive power fluctuation reference ΔQ ₁ ^* from the function circuit 32.

The automatic voltage adjusting 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 setter 25, the active power control circuit 27, the governor 11, and the engine 10 form a speed control loop. The reactive power reference setting unit 28, the reactive power detector 23, and the reactive power control circuit 24 form a reactive power control loop. Reactive power control circuit 24
A voltage control loop is constituted by the voltage reference V ^*, which is the output of the circuit, and the automatic voltage adjustment circuit 9.

On the other hand, the frequency change rate V ₃₀ is determined by the level detector 3.
4, a plurality of levels are detected, and the function of the function circuit 32 is switched by the switching circuit 36 only for the set time after the level detection by the timer 35.

Further, the frequency f from the frequency detector 21 is detected by the level detector 37 to detect that the frequency has changed from the rated value to a value other than the set level, and the gain of the function circuit 32 is reduced via the switching circuit 38. Switch to

(Operation) Next, the basic operation of the above-described first embodiment will be described with reference to FIGS.
Now, in FIG. 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, active power flowing into the system power source 1 S
P and reactive power SQ are respectively expressed as follows.

SP = P−P _L SQ = Q−Q _L Here, the inductance between the generator 7 and the system is 1, the voltage of the load 5 is V, and the frequency is f.

Then, in a normal case, SP ≒ 0, SQ
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 slowly shifted, the re-input of the circuit breaker 3 leads to an accident and may be dangerous and may not be performed, thereby deteriorating the stability of the power distribution system. Will be.

The voltage during single operation is determined by P = V ² / R. On the other hand, the frequency f during the isolated operation is Q = (V ² ωC) −
(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 feed increases the frequency f is the current i _c of elevated capacitor C , The inductance current i _L decreases and the reactive power changes in a direction to balance.

[0044] When the reactive power generator 7 is supplied is shifted in the reactive power Q _L from the delay direction demanded by the load 5, the inductance current i _L frequency f is lowered is increased, the capacitor current i _c And the reactive power changes in a direction to balance.

Next, as shown in FIG. 3, after the system is shut down (t ₀ ), the frequency fluctuates when the isolated operation is performed in the state of SQ ≠ 0 at SP ≒ 0, and the frequency f fluctuates and the stable point f ₁ ,
The approach to f ₂ has been measured and confirmed by simulation.

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

FIG. 4 is a diagram for explaining the operation and effect of the embodiment shown in FIG. 1, where f is the frequency f detected by the frequency detector 21 and df / dt is obtained by the frequency change rate detector 30. This is the detected frequency change rate, and 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 increasing, and during this time, the leading ΔQ ₁ ^* is output from the function circuit 32, and the frequency f acts to further increase. Also, df / dt <0
In the case of, since the frequency f is falling, the function circuit 3
2, a delay ΔQ ₁ ^* is output, and the frequency f acts to further decrease. As described above, the frequency fluctuation is increased by the positive feedback action as shown in FIG. 5, and the abnormal frequency or the excessive frequency change rate is detected by the excessive frequency change rate detector 31, whereby the expensive transfer interrupting device (conventionally used) is used. Even without using 61) in FIG. 11, it is possible to detect and protect the isolated operation.

The basic operation has been described above.
When the islanding operation is performed in the state of 0 and SQ = 0, it takes time until the frequency fluctuation is expanded by the positive feedback, and it may be difficult to detect the islanding operation within 3 seconds or less within the re-closing time.

Thus, in the present invention, this time can be shortened by increasing the gain of the function circuit 32 to increase the amount of positive feedback. However, with this method alone, the normal df / d
The risk that reactive power fluctuation becomes excessive due to t fluctuation increases.

The above problem is solved by making the function circuit 32 of FIG. 1 a special function as shown in, for example, A of FIG. In other words, if the operation becomes the islanding operation in the state of SQ = 0, df / dt is initially df / dt (1) to df / d
Since df / dt in the range of t (3) is extremely small, the voltage fluctuation reference ΔV ₁ with the gain increased in this range.
^{* Is} output to increase the amount of positive feedback to increase the frequency fluctuations quickly. This acts as a kind of trigger signal.

Df /
df / dt (2) is set near the maximum value of dt, and df / dt is set.
In the range of dt (1) to df / dt (2), the characteristic is to reduce the gain (or to limit ΔV ₁ ^* to the characteristic of B) to prevent excessive fluctuation of reactive power (voltage excessive fluctuation). When df / dt (2) and df / dt (4) are exceeded, the characteristic is such that the gain is increased again so that the frequency fluctuation during single operation is rapidly enlarged.

Minor characteristics such as the characteristic A and the characteristic B may be changed depending on the state of the system. (Effects) As described above, according to the first embodiment of the present invention, the islanding detection time is shortened by the substantially constant amount of the trigger signal of ΔV ₁ ^* , and at the same time, the voltage fluctuation during interconnection is suppressed, Moreover, it is possible to provide a high-speed and stable system interconnection protection device for power generation equipment.

<Second Embodiment> When the df / dt output detected by the level detector 34 shown in FIG. 1 is small, the likelihood of an isolated operation is detected. The state of the function circuit 32 is increased by increasing the gain of the function circuit 32 via the circuit 36. For example, FIG.
When the level detector 34 to look at how the in G ₁ characteristic by increasing the gain G ₂ characteristic reaches a second level, a predetermined time by the timer 35 increases the further gain G ₃ of G ₂ in FIG. By performing such an operation, the isolated operation is detected early, and even when the frequency fluctuation of the system becomes excessive due to an accident or the like, the gain is not excessively increased and the system is not unstable. When the frequency variation of the system is still of gain by the timer 35 is restored to G _1.

Such a gain adjustment is performed based on the voltage fluctuation reference ΔV
_The same effect can be obtained by changing the limit value of ₁ ^* . <Third Embodiment> In FIG. 1, if the frequency fluctuation during the isolated operation becomes excessive, it causes a failure such as a motor connected to the load, so that the level detector 37 detects an excessive or excessive frequency f and switches. The function and the output limit value of the function circuit 32 are reduced via the circuit 38, and the positive feedback function is weakened to suppress the frequency variation. By doing so, reliability and safety are improved.

<Fourth Embodiment> In the load 5 shown in FIG. 1, the fluctuation of the active power fluctuation ΔP and the fluctuation of the reactive power ΔQ with respect to the generator output voltage fluctuation ΔV are reduced during the isolated operation when the motor ratio is high, The rate of change of frequency df / dt tends not to increase.

In such a case, the configuration shown in FIG. 7 may be used. That is, in FIG. 1, a voltage fluctuation reference (ΔV ₁ ^* ) detection circuit 40, a reactive power fluctuation (ΔQ) detection circuit 41, a ΔQ / ΔV ₁ ^* detection circuit 42, a level detector 43, an OR circuit (OR circuit) are newly added. 44 may be added as shown.

In FIG. 7, the level detector 34,
Although FIG. 37 does not show the timer 35 and the switching circuits 36 and 38, the level detectors 34 and 37, the timer 35, and the switching circuits 36 and 38 are often necessary.

[0059] That is, to detect the [Delta] V ₁ ^* by the voltage variation reference detection circuit 40 detects a Delta] Q by reactive power fluctuation detection circuit 41, and inputs them to the Delta] Q / [Delta] V ₁ ^* detection circuit 42, where [Delta] V ₁ ^* Is detected. ΔQ / ΔV ₁ ^* ΔQ detected by the detection circuit 42
/ ΔV ₁ ^* is input to the level detector 43 and ΔQ / ΔV ₁ ^*
, That is, the islanding is detected,
This is supplied to the fault trip circuit 20 via the OR circuit 44 to be disconnected from the system, or the frequency change rate excess detector 31
Output from OR through the OR circuit 44 to the fault trip circuit 2
It is configured to be disconnected from the system by giving it to 0.

In such a configuration, ΔQ / ΔV ₁ ^* has a large value because the power source impedance is low during interconnection with the system, but during independent operation, particularly when the motor load is large, ΔQ / ΔV ₁ ^This is based on the fact that ^* is small.

Note that the voltage fluctuation reference setter ΔV ₁ ^* shown in FIG.
It is needless to say that the operation is exactly the same even if the generator output voltage fluctuation ΔV is used instead of. <Fifth Embodiment> As shown in FIG. 7, an extra-variable-width detection circuit 45 and a gain adjustment (or limit) circuit 46 are newly added to the fourth embodiment. That is, when ΔQ becomes equal to or larger than the set width from the output of the aforementioned reactive power fluctuation detection circuit 41 by the excessive change width detection circuit 45,
The gain adjustment (or limit) circuit 46 allows the function circuit 3
The fluctuation of ΔV ₁ ^* is suppressed by lowering the gain of _No. 2 or limiting the output, thereby limiting the reactive power fluctuation width.

It is to be noted that substantially the same operation can be obtained by detecting ΔQ / Δt instead of the reactive power fluctuation detecting circuit 41. <Sixth Embodiment> As shown in FIG. 7, an OFF circuit 47 and a switching circuit 48 are newly added to the fourth and fifth embodiments, and the auxiliary contact 3a is newly added to the circuit breaker 3. It has been added. The isolated operation is detected and the opening of the circuit breaker 3 is detected by the auxiliary contact 3a, and the output side of the voltage fluctuation reference setting device 33 and the automatic voltage regulator 9 are detected by the OFF circuit 47.
The open / close circuit 48 inserted in series on the input side is opened to open the positive feedback circuit. The circuit breaker 3 is opened to disconnect from the system, and at the same time, the positive feedback loop is opened to form a stable voltage control loop, which can be used as an independent power supply.

<Seventh Embodiment> A phase characteristic circuit 39 is newly added to the fourth to sixth embodiments as shown in FIG.
Is added. Specifically, the frequency detector 21
And a phase characteristic circuit 39 is inserted between the input side of the circuit breaker 6 and one end of the circuit breaker 6. The phase characteristic circuit 39 has a characteristic in which the phase advances as the frequency increases near the rated frequency, with the horizontal axis representing the frequency and the vertical axis representing the phase.

For this reason, the change in frequency can be detected in an enlarged manner, the positive feedback from the df / dt signal can be strengthened near the rated frequency, and the detection time for isolated operation can be shortened. When the frequency fluctuates further, the phase characteristic is inverted and the positive feedback action is automatically weakened, so that excessive frequency fluctuation can be prevented. It goes without saying that such a phase characteristic circuit 39 can perform software processing after detecting the frequency f.

<Eighth Embodiment> Phase characteristic circuit 3 in FIG.
Reference numeral 9 denotes a bandpass filter 391 having a resonance point slightly higher than the rated frequency as shown in FIG. 8, and a bandpass filter 392 having a resonance point slightly lower than the rated frequency.
And an addition circuit 393 for adding the outputs of the band-pass filters 391 and 392. With such a configuration, the gain characteristics can be as shown in the upper diagram and the phase characteristics can be as shown in the lower diagram.

The phase characteristic circuit 39 is connected to the frequency detector 2
It is possible to provide a software at the exit of the first. <Ninth Embodiment> As shown in FIG. 9, a low-speed response reactive power control circuit 50, a voltage reference ( _VA ^* ) setter 51, a .DELTA.Q detection circuit are newly provided instead of the reactive power control circuit 24 in FIG. 52, high-speed response reactive power control circuit 53, voltage fluctuation reference (ΔV _B ^* ) setting device 54, addition circuit 55, ΔQ / Δ
With the addition of a V _B ^* detector 56. In FIG. 9, the level detectors 34 and 37, the timer 35, the switching circuit 3
Although 6 and 38 are omitted, these are often required in practice.

That is, the output of the reactive power reference setting unit 28 and the output of the reactive power detector 23 are compared and input to the low-speed response reactive power control circuit 50. Then, since the low-speed response reactive power control circuit 50 has a high gain only when the frequency is in a low range, an output is generated only at this time, and the reactive power is controlled by the voltage reference ( _VA ^* ) setting unit 51 in about several tens of seconds. The voltage reference V _A ^* is output as much as possible, and is input to one input terminal of the addition circuit 55.

On the other hand, the detection output of the reactive power detector 23 is input to the reactive power fluctuation detecting circuit 52, where the reactive power fluctuation is detected, and the reactive power fluctuation is compared with the output of the function circuit 32. Is input to the fast response reactive power control circuit 53.

Since the high-speed response reactive power control circuit 53 has a high gain only when the frequency is in a high frequency range, an output is generated only at this time, and the voltage fluctuation reference (ΔV _B ^* ) setting unit 54 sets the voltage fluctuation reference ΔV _B ^* to 0. It is input to the other input terminal of the adder circuit 55 in order to control the reactive power in about .5 seconds.

The voltage fluctuation reference ΔV ₁ obtained by adding the voltage fluctuation reference ΔV _B ^* and the voltage reference V _A ^* in the adding circuit 55.
^* And the generator fluctuation voltage V are compared, and this is input to the automatic voltage regulator 9.

On the other hand, the reactive power fluctuation value output from the reactive power fluctuation detecting circuit 52 and the voltage fluctuation reference ΔV _B ^* of the voltage fluctuation reference setting unit 54 are input to a ΔQ / ΔV _B ^* detector 56, where they are detected. Ratio of ΔV _B ^* and ΔQ (ΔQ / ΔV
_B ^* ) is input to the level detector 43, and when ΔQ / ΔV _B ^* is reduced, that is, when the isolated operation is detected, the output, that is, V _{31, a} command for outputting a trip command to the fault trip circuit 20. Is given.

With this configuration, it is possible to control ΔQ at a high speed according to ΔQ ₁ ^* during system interconnection. However, since the change in ΔQ is extremely small especially in an isolated operation when the motor load is large, Even if ΔV _B ^* swings greatly, Δ
By detecting a decrease in ΔQ / ΔV _B ^* with little change in Q, islanding can be detected.

<Tenth Embodiment> The ninth embodiment described above is a case where the voltage fluctuation reference (ΔV ₁ ^* ) setting unit 33 is not provided on the output side of the function circuit 32. A setter 33 is provided and a voltage fluctuation reference ΔV ₁
^{The *} is newly added to the input terminal of the adder circuit 55.

In this case, during the interconnection, ΔV ₁ ^* acts in a feed-forward manner, and ΔV _B ^* operates as a feedback loop for controlling the reactive power fluctuation. If ΔQ ≒ 0 during single operation mainly with a motor load, ΔV _B ^* and ΔV ₁ ^*
Is added to control to increase ΔQ, so that ΔQ / Δ
V _B ^* decreases.

<Eleventh Embodiment> As the power generation equipment described in the above embodiment, a rotating machine such as an AC generator and a stationary type such as an inverter or SVC (stationary reactive power device) are used. In some cases, these are mixed in actual use. In the case of a rotating machine, 0.3 to 0.
Although a control delay of about 5 sec occurs, in the case of the stationary type, the response of the control is so short that it can be ignored. Therefore, when these are mixed, it is necessary to substantially adjust the delay in order to operate in a cooperative manner. Therefore, as shown in FIG. 10, ΔV ₁ ^* is set as a voltage fluctuation reference via a delay circuit 57 and ΔQ ₁ ^*
In addition, by using the reactive power fluctuation reference via the delay circuit 58 and the reactive power control circuit 24, the application to the static converter becomes effective.

[0076]

As described above, according to the present invention, even when the active power and the reactive power flowing out to the system are both zero and it is most difficult to detect the islanding operation, the islanding operation can be detected in a short time by devising the function circuit. It is possible to suppress reactive power fluctuations (voltage fluctuations) during connection to an appropriate value, and it is fast, stable and reliable even when multiple generators are running or when both rotary and stationary types are mixed. A system interconnection protection device for a power generation facility can be provided.

[Brief description of the drawings]

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

FIG. 2 is a diagram supplementing a part of the blocks of the embodiment of FIG. 1;

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

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

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

FIG. 6 is a characteristic diagram for explaining functions of the function circuit of FIG. 1;

FIG. 7 is a block diagram showing a seventh or eighth embodiment of the system interconnection protection device for power generation equipment according to the present invention.

FIG. 8 is a diagram for explaining the phase circuit of FIG. 7;

FIG. 9 is a block diagram showing a ninth or tenth embodiment of the system interconnection protection device for power generation equipment according to the present invention.

FIG. 10 is a block diagram showing only a part of an eleventh embodiment of a system interconnection protection device for power generation equipment 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 (automatic voltage regulation circuit), 10 engine, 11 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, 23: reactive power detector, 24: AQR (reactive power control circuit), 25:
Active power reference setting device, 26 ... Active power detector, 27 ... A
PR (active power control circuit), 28: reactive power reference setter, 30: frequency change rate detector, 31: excessive frequency change rate detector, 32: function circuit, 33: voltage fluctuation reference, 3
4, 37: Level detector, 35: Timer, 36, 38
... Switching circuit, 39 ... Phase characteristic circuit, 40 ... Voltage reference fluctuation detecting circuit, 41 ... Reactive power fluctuation detecting circuit, 42 ... ΔQ /
ΔV ₁ ^* detection circuit, 43: level detector, 44: OR circuit, 45: excessive change width detection circuit, 46: gain adjustment circuit (limit circuit), 47: off circuit, 48: open / close circuit,
50: low-speed control circuit, 51: voltage reference generator, 52: reactive power fluctuation detection circuit, 53: high-speed control circuit, 54: voltage reference generator, 55: addition circuit, 56: ΔQ / ΔV _B ^* detector, 57 , 58 ... delay circuit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chihiro Okado 2-24-24 Harumi-cho, Fuchu-shi, Tokyo TOSHIBA FA System Engineering Co., Ltd. Address Nishiba Electric Machinery Co., Ltd. (72) Inventor Shigeo Nomiya 1-1-1, Shibaura, Minato-ku, Tokyo Inside the Toshiba head office

Claims (11)

[Claims] 1. A system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, a frequency detector detecting an output frequency of the power generation facility, and a rate of change of the frequency detected by the frequency detector. A frequency change rate detector for detecting the change rate of the voltage or the reactive power from the change rate of the frequency detected by the frequency change rate detector, and when the change rate of the frequency is positive by the change criterion, the power generation equipment Increase the reactive power or decrease the output voltage of the power generation equipment, and control the power generation equipment to increase the delay reactive power or increase the output voltage of the power generation equipment when the frequency change rate is negative, The gain is high when the frequency change rate is extremely low, the gain is low when the frequency change rate is intermediate, and the gain is high when the frequency change rate is high. Control means for setting the power in so as to be slightly higher, and protection means for detecting frequency fluctuations promoted by voltage fluctuations of the power generation equipment and disconnecting the power generation equipment from a system bus with the circuit breaker. A system interconnection protection device for a power generation facility, characterized in that: 2. A system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, a frequency detector detecting an output frequency of the power generation facility, and a rate of change of the frequency detected by the frequency detector. A frequency change rate detector for detecting the change rate of the voltage or the reactive power from the change rate of the frequency detected by the frequency change rate detector, and when the change rate of the frequency is positive by the change criterion, the power generation equipment Increase the reactive power or decrease the output voltage of the power generation equipment, and control the power generation equipment to increase the delay reactive power or increase the output voltage of the power generation equipment when the frequency change rate is negative, Control means for switching a gain of a plurality of stages or a limit value corresponding to the fluctuation criterion according to the frequency change rate; and There conducive to the detected frequency variation, the breaker the power plant system interconnection protection device of the power generation facility which is characterized by comprising a protection means for Kairetsu, a from the system bus at. 3. The control means limits the fluctuation range of the frequency by lowering the gain or lowering a limit value corresponding to the fluctuation criterion when the frequency changes by more than a set value from a rated value. 3. The system interconnection protection device for a power generation facility according to claim 2, wherein: 4. In a system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, an output frequency change detection means for detecting a change in an output frequency of the power generation facility, and an output of the power generation facility. Reactive power, output set voltage, control means for outputting a control signal to the power generation equipment to control any of the output current and the phase of the output voltage and output current, the rate of change of the reactive power of the output of the power generation equipment Reactive power change rate detecting means for detecting, output voltage of the power generation equipment or voltage change rate detection means for detecting a reference change rate of the power generation equipment, the reactive power change rate detection means and the voltage change rate detection means When the change in the frequency is detected to be increasing or decreasing, the increasing means changes the output of the power generation equipment to increase or decrease the frequency, and the increasing means Stopping / disconnecting means for stopping the in-house power generation equipment or disconnecting from the system power supply based on the result of the increase in the reactive power change rate with respect to the output voltage or the reference change rate. A power grid connection protection device for power generation equipment. 5. In a system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, an output frequency change detection means for detecting a change in an output frequency of the power generation facility, and an output of the power generation facility. Control means for outputting a control signal to the power generation equipment for controlling any of the reactive power, the output set voltage, the output current and the phase of the output voltage and the output current, and the rate of change of the reactive power of the power generation equipment or the reactive power Detecting means for detecting the width of change in power, and when the change in the frequency detected by the output frequency change detecting means is detected to be increasing or decreasing, the output of the power generation equipment is changed to increase the frequency or increase the frequency. A promoting means for promoting the descent, and a reducing means for reducing the function of the promoting means when a change rate or a change width of the reactive power is equal to or more than a set value. System protection device for power generation equipment. 6. A system interconnection system that interconnects a power generation facility with a system power supply via a circuit breaker, wherein: an output frequency change detection unit that detects a change in an output frequency of the power generation facility; and an output of the power generation facility. Reactive power, output set voltage, control means for outputting a control signal to the power generation equipment to control any of the output current and the phase of the output voltage and output current, and the frequency of the frequency detected by the output frequency change detection means An encouraging means for changing the output of the power generation equipment when the change is detected to be rising or falling, thereby encouraging a frequency increase or a frequency decrease, and a system of the power generation equipment based on the result of the encouraging by the encouraging means. And a self-sustaining operating means for turning off the facilitating means and operating independently after further disconnection. 7. A system interconnection system for interconnecting a power generation facility with a system power supply via a circuit breaker, wherein an output frequency change detection means for detecting a change in an output frequency of the power generation facility, and an output of the power generation facility. Control means for outputting a control signal to the power generation equipment to control any of reactive power, output set voltage, output current and the phase of the output voltage and output current, and an output frequency detected by the output frequency change detection means In the vicinity of the rated frequency in front of the frequency detector for detecting the change in frequency, a phase characteristic circuit means in which the voltage phase advances as the frequency increases, and the change in the frequency detected by the output frequency change detecting means is increasing or decreasing. When it is detected that it is during the change, the output of the power generation equipment is changed to promote the frequency increase or the frequency decrease, and the promoting means, The length has been based on the results the private power generation equipment to stop or the system interconnection protection device of the power generation facility for a stop-disconnection means for disconnection from the mains power supply, characterized by comprising a. 8. The phase characteristic circuit means includes: a first band-pass filter having a resonance point at a frequency slightly higher than a rated frequency; a second band-pass filter having a resonance point at a frequency slightly lower than the rated frequency; This first and second
The system interconnection protection device for a power generation facility according to claim 7, comprising an addition circuit that adds the output of the band pass filter. 9. A power generation facility using a rotary generator is connected to a system power supply, a circuit breaker is disposed between the system power supply and the power generation facility, and the circuit breaker causes an abnormality in the output of the power generation facility. In a system configured to detect the occurrence of a fault and to trip by a protection means, a frequency detector for detecting an output frequency of the power generation equipment, and a frequency change rate for detecting a change rate of the frequency detected by the frequency detector. A detector; a low-speed responsive reactive power control means controlled by a first voltage reference to detect reactive power of the power generation equipment and control the reactive power detection value based on the reactive power reference; When the detector detects that the rate of change of the frequency is positive, the reactive power is changed in the leading direction, and that the rate of change of the frequency is negative by the frequency change rate detector. A high-speed reactive power control means controlled by a second voltage reference by comparing a reactive power fluctuation reference for changing the reactive power in the delay direction with a value obtained by detecting a reactive power fluctuation from the reactive power. A voltage control means for applying to a field circuit of the rotary generator and controlling an output voltage based on a voltage reference obtained based on first and second voltage references of outputs of the low-speed and high-speed reactive power control means; Protection means for disconnecting the power generation equipment from the system bus at the circuit breaker from the second voltage reference from the high-speed reactive power control means and the fluctuation value of the reactive power; Grid connection protection device. 10. The system according to claim 9, wherein an output of a reactive power fluctuation control circuit and a generator voltage fluctuation reference based on the frequency change rate are added to a voltage reference for controlling the voltage of the rotary generator. Grid protection equipment for power generation equipment. 11. When the power generation equipment comprises a static power converter or a reactive power control device, a delay circuit is added to a reactive power fluctuation control or voltage fluctuation control circuit. A system interconnection protection device for a power generation facility according to any one of the above.