JP2002101563A - System interconnection protection device of power generating installation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect and protect an isolated operation of private power generation facility securely and easily in case of an outage on the system side under the condition that a reverse power flow can happen, on the private power generation facility side, without providing an expensive transfer interruption device. SOLUTION: A system interconnection protection device comprises a speed governor 14a which control a frequency of a generator 11a in private power generation facility interconnected with AC electric power system under the condition that the reverse power flow can happen, a function generating means 30a, 31a, 32a having a function property of a frequency command such as to detect a change rate of the frequency of the generator 11a and to output a big output signal as against thereto, an effective power adjustment means 36a which outputs an output signal corresponding to an effective power of the generator 11a, and a protective relay means 33a, 34a which sense anomaly of the frequency change rate of the generator 11a, wherein a signal which is a resultant of the output signals of the function generating means 30a, 31a, 32a and the output signal of the effective power adjustment means 36a is defined as a command signal of the speed governor 14a and the frequency change rate of the generator 11a is shifted to the level for which the protective relay 33a, 34a can perceive by means of the function property of the function generating means, thereby power outage of the AC electric power systems is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a generator driven by a prime mover or an inverter for converting DC power from a DC power supply for generating a DC voltage into AC power of a system power supply frequency and outputting the AC power, and shutting off the inverter. System protection system for private power generation equipment that is connected to the AC power system with reverse power flow through a switch, especially when there is a reverse power flow without installing an expensive transfer breaker. The present invention relates to a system interconnection protection device for a power generation facility, which is capable of reliably and easily detecting and protecting the isolated operation of the private power generation facility on the private power generation facility side.

[0002]

2. Description of the Related Art In general, a grid connection protection device has been proposed for a high-voltage customer to connect a power generation device for private use (hereinafter, referred to as a private power generation facility) such as a cogeneration system.

FIG. 5 is a block diagram showing an example of the configuration of a system interconnection protection device in the case where a high-voltage customer operates this type of private power generation equipment and an AC power system in interconnection.

[0004] In FIG. 5, in a distribution substation 3 which is an AC power system, the voltage of a system power supply is reduced through a transformer 4 and is sent from a circuit breaker 5 to a system bus 2 and a self-generating installation customer 1 a. Customer power receiving point breaker 16a, premises system bus 1
0, the premises load 17a through the premises load circuit breaker 18a.
Power.

The transfer circuit breaker 6 is operated by a signal from the power distribution substation 3 in the event of a system failure in the case of a reverse power flow, by a private power generation facility customer's power receiving point circuit breaker 1 of the privately installed customer 1a.
6a.

On the other hand, the self-powered installation customer 1a controls a frequency of the generator 11a by adjusting a generator (alternating current generator) 11a, a motor 13a for driving the generator 11a, and a rotation speed of the motor 13a. Governor 14a and generator 1
An automatic voltage regulator 12a for controlling the voltage of 1a, and a circuit breaker 15a for connecting the generator 11a to the local system are provided.

An undervoltage relay 21a for detecting a drop in the voltage of the generator 11a is provided as a protection device.
A frequency lowering relay 22a for detecting a decrease in the frequency (absolute value) of 1a, an overvoltage relay 23a for detecting an increase in the voltage of the generator 11a, an overcurrent relay 24a for detecting an increase in the current of the generator 11a; Direction ground fault relay 25a for detecting a ground fault accident, a reverse power relay 26a for detecting a reverse power flow, and a generator abnormality detection for detecting an abnormality of the generator 11a based on the voltage and current of the generator 11a. And a relay 27a.

[0008] Note that reference numeral 1b denotes a self-generating installation customer provided with a self-generating facility having the same configuration as that of the self-generating customer 1a, and 1c denotes a power receiving facility (not including the circuit breaker 16c) having no self-generating facility. The customer has only the premises load 17c).

By the way, when the following abnormality occurs in the system interconnection protection device for the private power generation system configured as described above, the private installation customers 1a and 1b are immediately disconnected from the power system. There is a need.

(A) In the event of an accident in the premises of a cogeneration customer, (b) In the event of a power system accident As a method of detecting the state of an accident at the time of these accidents, as shown in FIG. I have to.

That is, when there is no reverse power flow, an overcurrent relay 24a, a directional ground fault relay 25a, a generator abnormality detection relay 27a, a reverse power relay 26a, a frequency reduction relay 22a, etc. Detects abnormalities at the time of the accident, and uses the private power generation facility
6a is cut off and disconnected from the system.

On the other hand, when there is a reverse power flow, the system bus 2
When the private power generation equipment and the load are balanced and there is little supply and demand of electric power from the upper system, it is difficult to detect the interruption of the sending-out circuit breaker 5 when the system is abnormal, depending on each of the above-described relays and the like. .

For this reason, the transfer breaker 6 is provided, and the signal from the distribution substation 3 is used to shut off the private power generation facility customer's receiving point circuit breaker 16a of the privately-installed customer 1a to provide protection. I have to.

[0014]

However, this type of transfer circuit breaker 6 requires installation of equipment at both substations and private power generation facilities, and laying of dedicated transmission means and transmission paths (communication lines). Therefore, the device itself becomes very expensive.

SUMMARY OF THE INVENTION An object of the present invention is to reliably and easily detect the independent operation of a private power generation facility at the time of an accident on the system side in the presence of reverse power flow without providing an expensive transfer breaker. It is an object of the present invention to provide an inexpensive system interconnection protection device for a power generation facility that can be protected by a power supply.

[0016]

According to a first aspect of the present invention, there is provided a power generator driven by a prime mover, and a reverse power flow to an AC power system via a circuit breaker. In the system interconnection protection device of the private power generation equipment interconnected in, the governor that controls the frequency of the generator in response to an external command signal and the rate of change of the frequency of the generator are detected, and the frequency change Function generating means having a function characteristic of a frequency command to output a large output signal with respect to the value of the rate, and active power adjusting means for detecting active power of the generator and outputting an output signal corresponding to the detected signal And a protection relay means for detecting an abnormality in the frequency change rate of the generator and outputting a cutoff signal of the circuit breaker, and a signal obtained by combining an output signal from the function generation means and an output signal from the active power adjustment means. The above governor As a command signal, at the time of a power failure on the AC power system side, the power failure on the AC power system side is detected by shifting the frequency change rate of the generator to a level detected by the protection relay means according to the function characteristics of the function generating means. ing.

Therefore, in the system interconnection protection apparatus for a power generation facility according to the present invention, a function characteristic of a frequency command that outputs a large output signal with respect to a value of a rate of change of the frequency of the generator is provided. A signal obtained by synthesizing an output signal from the function generating means and a signal output from the active power adjusting means for outputting an output signal corresponding to the active power of the generator, and instructing the governor to control the frequency of the generator. To detect a power failure on the AC power system side by shifting the frequency change rate of the generator to a level that the protection relay means senses by using the signal as a signal and by the function characteristics of the function generating means during a power failure on the AC power system side Thereby, the minute frequency change rate is shifted to a level sensed by the protection relay means, and the cost is reduced without providing an expensive transfer cutoff device as in the conventional case described above.
It is possible to reliably and easily detect and protect the independent operation of the private power generation facility during grid connection on the private power generation facility side.

According to a second aspect of the present invention, there is provided an inverter for converting DC power from a DC power supply for generating a DC voltage into AC power having a system power supply frequency and outputting the AC power, and further comprising an AC power supply via a circuit breaker. Inverter control means for controlling the active power of the inverter in response to an external command signal and detecting the rate of change in the output frequency of the inverter in a system interconnection protection device for private power generation equipment interconnected with the system with reverse power flow A function generating means having a frequency command function characteristic for outputting a large output signal with respect to the value of the frequency change rate; detecting an active power of the inverter; and outputting an output signal corresponding to the detection signal. Active power adjusting means;
Protective relay means for sensing an abnormality in the frequency change rate of the inverter and outputting a cutoff signal of the circuit breaker, and a signal obtained by combining an output signal from the function generating means and an output signal from the active power adjusting means, The active power command signal of the inverter control device is used, and in the event of a power failure on the AC power system side, the frequency change rate of the inverter is shifted to a level sensed by the protection relay means by the function characteristics of the function generating means, so that the power failure on the AC power system side Is detected.

Therefore, in the system interconnection protection device for power generation equipment according to the present invention, the function characteristic of the frequency command that outputs a large output signal with respect to the value of the change rate of the output frequency of the inverter is provided. A signal obtained by combining an output signal from the function generating means having the function and an output signal from the active power adjusting means for outputting an output signal corresponding to the active power of the inverter is converted into an active power of the inverter control means for controlling the active power of the inverter. It is used as a command signal to detect a power failure on the AC power system side by shifting the frequency change rate of the generator to a level sensed by the protection relay means according to the function characteristics of the function generating means during a power failure on the AC power system side. As a result, the minute rate of change in frequency is shifted to a level sensed by the protection relay means, and an expensive transfer cutoff device is provided as in the conventional case described above. And cheaper without, a single operation of the private power generation equipment in system interconnection can be protected reliably and easily detected by the self-generating equipment side.

According to a third aspect of the present invention, in the grid connection protection device for a power generation facility according to the first aspect of the present invention, an abnormality in a frequency change rate of the generator is sensed, and a breaking signal of a circuit breaker is detected. In place of the protective relay means that outputs a signal, a protective relay means that detects an abnormality in the frequency fluctuation of the generator and outputs a shutoff signal of the circuit breaker is provided. By shifting to a level detected by the protection relay means, a power failure on the AC power system side is detected.

According to the third aspect of the present invention, there is provided a system interconnection protection device for a power generation facility, comprising a protection relay means for detecting an abnormality in a frequency variation of a generator and outputting a cutoff signal of a circuit breaker. At the time of a power failure on the power system side, the fluctuation of the frequency of the generator is shifted to a level that is detected by the protection relay means, and by detecting the power failure on the AC power system side, the minute frequency fluctuation of the generator is protected. The level is shifted to the level sensed by the means, and the cost is reduced without providing an expensive transfer shut-off device as in the conventional case described above, so that the independent operation of the private power generation facility during grid connection can be reliably and easily performed on the private power generation facility side. Can be detected and protected.

According to a fourth aspect of the present invention, in the system interconnection protection device for a power generation facility according to the second aspect of the present invention, an abnormality in the frequency change rate of the inverter is detected,
In place of the protection relay means for outputting a circuit breaker cutoff signal, a protection relay means for detecting an abnormal frequency fluctuation of the inverter and outputting a circuit breaker cutoff signal is provided. The power failure of the AC power system is detected by shifting the fluctuation of the power supply to a level detected by the protection relay means.

According to the fourth aspect of the present invention, there is provided a system interconnection protection device for a power generation facility, comprising a protection relay means for detecting an abnormality in frequency fluctuation of an inverter and outputting a cutoff signal of a circuit breaker. By detecting the power failure on the AC power system side by detecting the power failure on the AC power system side by shifting the frequency fluctuation of the inverter to the level detected by the protection relay means at the time of the power failure on the system side, the protection relay means can detect the slight frequency fluctuation of the inverter. To a level that is low, without providing an expensive transfer shut-off device as in the conventional case, and reducing the cost.Independent operation of the private power generation facility during grid connection is reliably and easily detected on the private power generation facility side. Can be protected.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic concept of the present invention will be described.

[0025] The system interconnection protection device of the power generation equipment of the present invention comprises:
The frequency of the generator or the output frequency of the inverter that constitutes the private power generation equipment is governed by the system frequency during interconnection with the AC power system, but during isolated operation, the prime mover connected to the generator Of the governor, or the fact that it is dominated by the load connected to the inverter, when the private operation of the private power generation equipment, when the function of the frequency command of the function generating means, the generator or It works so as to increase the frequency change rate or frequency fluctuation of the inverter, and shifts to a level that is detected by the protection relay means, so that a power failure of the system can be detected.

Hereinafter, embodiments of the present invention based on the above concept will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a configuration example of a system interconnection protection device for a private power generation facility according to the present embodiment, and the same parts as those in FIG. The description thereof is omitted, and only different portions will be described here.

That is, as shown in FIG. 1, the system interconnection protection device for the private power generation equipment according to the present embodiment is configured as shown in FIG.
, The transfer circuit breaker 6 and the reverse power relay 26a are omitted, and a frequency detector 30a, a function generator 31a, a differentiator 32a, an active power adjuster 36a, and a frequency increasing relay 28a, a frequency change rate decreasing relay 33a, and a frequency change rate increasing relay 34a.

The frequency detector 30a detects the frequency of the generator from the terminal voltage of the generator 11a.

The differentiator 32aa includes a frequency detector 30a
And outputs a time differential value (frequency change rate) of the frequency detection value based on.

The function generator 31a generates a special function for the frequency-time differential plant by the differentiator 32a.

That is, the function generator 31a has a frequency command function characteristic that outputs a large output signal with respect to the frequency-time differential plant by the differentiator 32a.

The active power adjusting device 36a includes a generator 11a
And outputs an output signal corresponding to the detection signal.

The frequency increasing relay 28a is connected to the generator 11a
Of the frequency (absolute value) of the private power generation equipment and outputs a cutoff signal of the customer power receiving point circuit breaker 16a.

The frequency change rate reduction relay 33a detects an abnormal decrease in the frequency change rate of the generator 11a, and outputs a cutoff signal of the private power generation equipment customer receiving point circuit breaker 16a.

The frequency change rate increasing relay 34a senses an abnormal increase in the frequency change rate of the generator 11a and outputs a cutoff signal of the private power generation facility customer power receiving point circuit breaker 16a.

For the governor 14a, instead of the frequency (rotation speed) command signal which is a fixed value for adjusting the speed of the generator 11a to a constant speed, a function generator 31a outputs a signal from the function generator 31a. Output signal and active power adjusting device 36a
The signal obtained by combining (adding) the output signal from the
4a, the frequency change rate of the generator 11a is reduced by a function characteristic of the function generator 31a during a power failure on the system side. Relay 34
By shifting to a level that a senses, a power outage on the grid side is detected.

Next, the operation of the system interconnection protection device for the private power generation facility according to the present embodiment configured as described above will be described with reference to FIG.

FIG. 2 is a diagram showing an example of the function characteristics of the function generator 31a.

In FIG. 2, curve a (frequency command function)
Is an example of a function of the function generator 31a, and shows a relationship between the detection frequency time differential value and the frequency command.

Now, it is assumed that the rated operation is performed at the point where the frequency change rate is 0, and there is almost no transmission and reception of electric power with the system.

Even if the system is disconnected in such a state, the frequency fluctuation is minute, and the conventional frequency lowering relay 22a
Or, it cannot be detected by the frequency increasing relay 28a.

On the other hand, if a function generator 31a for generating a special function with respect to the frequency change rate is provided, if the frequency change rate becomes slightly larger than 0, the function a functions to rotate the generator 11a. By issuing a command signal to the governor 14a to increase the speed, the frequency change rate is further increased.

By repeating this operation, the level of the frequency change rate increasing relay 34a becomes a level that can be sensed, and a power failure on the system side can be detected.

As a result, the private power generation facility customer power receiving point circuit breaker 16a can be disconnected.

Conversely, if the rate of change in frequency is slightly less than 0, a command signal is issued to the governor 14a to reduce the rotation speed of the generator 11a by the function of the function a. Decrease rate.

By repeating this operation, the level of the frequency change rate lowering relay 33a becomes a level that can be detected, and a power failure on the system side can be detected.

As a result, the private power generation facility customer power receiving point circuit breaker 16a can be disconnected.

By the way, the function a
If the frequency change rate of the system has a value for some reason, the frequency of the generator 11a is tried to be changed by the governor 14a. Since the frequency of 11a is dominant, the frequency of generator 11a remains the system frequency.

Then, the rate of change of the frequency is determined by the frequency change rate decreasing relay 33a and the frequency change rate increasing relay 34a.
The operation is continued without exceeding the detection level.

At this time, since active power may flow more than necessary from the generator 11a to the system or vice versa, as shown in FIG. 1, an active power regulator (APR) 36a is combined. Then, the value obtained by adding the output signal from the active power adjusting device 36a and the output signal from the function generator 31a by the adder 35a is added to the governor 14
It is used as the command signal of a.

By using the command signal of the governor 14a obtained in this way, the frequency command function a shown in FIG. 2 is corrected to prevent unnecessary power flow of the active power with the system. be able to.

Also in this case, the active power adjusting device 3
If the response of 6a is set to be slow, it is sufficiently possible to detect the independent operation of the private power generation facility.

As described above, in the system interconnection protection device for private power generation equipment according to the present embodiment, the privately-installed customer 1
a In the premises, the generated power of the private power generation equipment and the load power are almost balanced, and even when the system is disconnected when there is little supply and demand of the system and the power, the minute frequency change rate is reduced by the frequency change rate reducing relay 33a and the frequency. Since the shift is increased to the level sensed by the rate-of-change relay 34a, an expensive transfer circuit breaker 6 as in the prior art is provided between the sending circuit breaker 5 and the private power generation equipment customer receiving point remote circuit breaker 16a. Without installation, the private power generation equipment customer power receiving point remoter 16a
Can be separated.

Thus, without providing the expensive transfer circuit breaker 6, the independent operation of the private power generation equipment in the event of an accident on the system side in the case of reverse power flow is reliably and easily detected and protected on the private power generation equipment side. It is possible to obtain an inexpensive system interconnection protection device for private power generation equipment.

(Second Embodiment) FIG. 3 is a block diagram showing an example of the configuration of a system interconnection protection device for private power generation equipment according to the present embodiment, and the same parts as those in FIG. The description thereof is omitted, and only different portions will be described here.

That is, as shown in FIG. 3, the system interconnection protection device for the private power generation equipment according to the present embodiment is the same as that shown in FIG.
, The generator 11a and the prime mover 13a are omitted, and a direct-current power supply 39a and an inverter 38a are newly added instead of these.

Further, the governor 14a for adjusting the rotation speed of the prime mover 13a in FIG. 1 is omitted, and a new inverter control device 37a is added instead.

The DC power supply 39a generates a DC voltage.

The inverter 38a includes a DC power supply 39a
Is converted into AC power of the system power supply frequency and output.

The inverter control device 37a controls the active power of the inverter 38a.

A signal obtained by combining (adding) the output signal from the function generator 31a and the output signal from the active power adjusting device 36a is provided as an active power command signal of the inverter control device 37a. In the event of a power failure, the output frequency change rate of the inverter 38a is reduced by the function characteristics of the function generator 31a, and the frequency change rate lowering relay 33a, which is the protection relay means, and the frequency change rate increasing relay 3
By shifting to a level detected by 4a, a power failure on the system side is detected.

Next, the operation of the system interconnection protection device for the private power generation facility according to the present embodiment configured as described above will be described with reference to FIG.

FIG. 2 is a diagram showing an example of the function characteristics of the function generator 31a.

In FIG. 2, a curve c (active power command function) is an example of a function of the function generator 31a.
The relation between the detection frequency time differential value and the active power command is shown.

Now, it is assumed that the rated operation is performed at the point where the frequency change rate is 0, and there is almost no transmission and reception of electric power to and from the system.

Even if the system is disconnected in such a state, the frequency fluctuation is minute, and the conventional frequency lowering relay 22a
Or, it cannot be detected by the frequency increasing relay 28a.

On the other hand, when the function generator 31a for generating a special function for the frequency change rate is provided, if the frequency change rate becomes slightly larger than 0, the function c causes the active power of the inverter 38a to be increased. By issuing an active power command signal to the inverter control device 37a so as to increase the output, the rotation speed of the electric motor included in the private load 17a increases, so that the system frequency is increased and the frequency change rate is further increased.

On the other hand, when the frequency change rate is slightly smaller than 0, the function c causes the inverter control device 37a to output the active power command signal to the inverter control device 37a so as to reduce the active power output of the inverter 38a. As a result, the rotation speed of the electric motor included in the private load 17a decreases, so that the system frequency is reduced and the frequency change rate is further reduced.

By repeating this operation, the level of the frequency change rate lowering relay 33a or the frequency change rate increasing relay 34a becomes a detectable level, and a power failure on the system side can be detected.

As a result, the private power generation facility customer power receiving point circuit breaker 16a can be disconnected.

By the way, the above function c during system interconnection
Considering the effect of the above, if the frequency change rate of the system has a value for some reason, the inverter control device 37a attempts to change the output frequency of the inverter 38a.
Since the output frequency of the inverter 38a is dominated by the system frequency during system interconnection, the output frequency of the inverter 38a remains at the system frequency.

Then, the rate of change of the frequency is reduced by the frequency change rate decreasing relay 33a and the frequency change rate increasing relay 34a.
The operation is continued without exceeding the detection level.

At this time, since there is a possibility that the active power may flow from the generator 11a side to the system side or in the opposite direction more than necessary, as shown in FIG. Then, the value obtained by adding the output signal from the active power adjusting device 36a and the output signal from the function generator 31a by the adder 35a is added to the governor 14
It is used as the command signal of a.

By using the command signal of the governor 14a obtained in this way, the frequency command function c shown in FIG. 2 is corrected to prevent unnecessary power flow of the active power with the grid. be able to.

Also in this case, the active power adjusting device 3
If the response of 6a is set to be slow, it is sufficiently possible to detect the independent operation of the private power generation facility.

As described above, in the system interconnection protection device of the private power generation equipment according to the present embodiment, the private installation customer 1
a In the premises, the generated power of the private power generation equipment and the load power are almost balanced, and even when the system is disconnected when there is little supply and demand of the system and the power, the minute frequency change rate is reduced by the frequency change rate reducing relay 33a and the frequency. Since the shift is increased to the level sensed by the rate-of-change relay 34a, an expensive transfer circuit breaker 6 as in the prior art is provided between the sending circuit breaker 5 and the private power generation equipment customer receiving point remote circuit breaker 16a. Without installation, the private power generation equipment customer power receiving point remoter 16a
Can be separated.

Thus, without providing the expensive transfer circuit breaker 6, the independent operation of the private power generation equipment in the event of a reverse power flow on the system side is reliably and easily detected and protected by the private power generation equipment side. It is possible to obtain an inexpensive system interconnection protection device for private power generation equipment.

(Third Embodiment) FIG. 4 is a block diagram showing a configuration example of a system interconnection protection device for a private power generation facility according to the present embodiment, and the same parts as those in FIG. The description thereof is omitted, and only different portions will be described here.

That is, as shown in FIG. 1, the system interconnection protection device for private power generation equipment according to the present embodiment
, The frequency change rate decreasing relay 33a and the frequency change rate increasing relay 34a are omitted.

At the time of a power failure on the system side, the frequency fluctuation of the generator 11a is protected by the frequency reduction relay 22a, which is a protection relay means, by the function characteristics of the function generator 31a.
By shifting to a level detected by the frequency increasing relay 28a, a power failure on the system side is detected.

Next, in the system interconnection protection device for the private power generation equipment according to the present embodiment configured as described above, the abnormality of the frequency fluctuation of the generator 11a is detected, and the private power generation equipment customer power receiving point circuit breaker is detected. A frequency lowering relay 22a and a frequency increasing relay 28a, which are protection relay means for outputting a cutoff signal of the generator 16a, are provided.
By shifting the fluctuation of the frequency a to the level sensed by the frequency lowering relay 22a and the frequency raising relay 28a, the power failure on the system side is detected, so that the minute frequency fluctuation of the generator 11a is reduced. Shifting to a level sensed by the lowering relay 22a and the frequency increasing relay 28a, and providing a conventional expensive transfer breaker 6 between the sending-out circuit breaker 5 and the private power generation facility customer receiving point disconnector 16a. In addition, it is possible to quickly disconnect the in-house power generation facility customer power receiving point remote interrupter 16a.

In this way, the independent operation of the private power generation equipment in the event of an accident on the system side in the case of reverse power flow can be reliably and easily detected and easily protected by the private power generation equipment without providing the expensive transfer circuit breaker 6. It is possible to obtain an inexpensive system interconnection protection device for private power generation equipment.

(Other Embodiments) The frequency change rate decreasing relay 33a and the frequency change rate increasing relay 34a in FIG. 3 are omitted, and when a power failure occurs on the system side, the function characteristics of the function generator 31a are used. Frequency-reducing relay 2 which is a protection relay means for protecting against frequency fluctuation of inverter 38a.
2a, a power failure on the grid side may be detected by shifting to a level detected by the frequency increasing relay 28a.

In the system interconnection protection device for the private power generation facility having the above-described configuration, the minute frequency fluctuation of the inverter 38a can be reduced by the frequency lowering relay 22a and the frequency increasing relay similarly to the third embodiment described above. The level is shifted to the level detected by 28a, and the private power generation equipment is quickly provided without providing the expensive transfer breaker 6 as in the prior art between the sending out circuit breaker 5 and the customer power receiving point remote circuit breaker 16a. The customer receiving point disconnector 16a can be disconnected.

As a result, the independent operation of the private power generation equipment in the event of an accident on the system side when there is a reverse power flow can be reliably and easily detected and easily protected by the private power generation equipment without providing the expensive transfer circuit breaker 6. It is possible to obtain an inexpensive system interconnection protection device for private power generation equipment.

[0087]

As described above, according to the present invention, when the private power generation equipment is operated alone, the frequency change rate or the frequency fluctuation of the generator or the inverter is reduced by the characteristic of the frequency command function of the function generating means. Since it is increased to shift to the level sensed by the protective relay means, the independent operation of the private power generation equipment in the event of a reverse power flow on the grid side without using an expensive transfer breaker It is possible to provide an inexpensive system interconnection protection device for a power generation facility that can be reliably and easily detected and protected on the power generation facility side.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an example of a function characteristic of a function generator in the system interconnection protection device of the private power generation facility according to the first embodiment.

FIG. 3 is a block diagram showing a second embodiment of a system interconnection protection device for private power generation equipment according to the present invention.

FIG. 4 is a block diagram showing a third embodiment of a system interconnection protection device for private power generation equipment according to the present invention.

FIG. 5 is a block diagram showing a configuration example of a conventional system interconnection protection device for private power generation equipment.

[Explanation of symbols]

 1a, 1b: self-powered installation customer, 2: system bus, 3: power distribution substation, 4: transformer, 5: feed-out circuit breaker, 6: transfer circuit breaker, 10: premises system bus, 11a (AC) Generator, 12a: automatic voltage regulator, 13a: prime mover, 14a: governor, 15a, 16c, 18a: circuit breaker, 16a: private power generation equipment customer receiving point circuit breaker, 17a, 17c: premises load, 21a ... Undervoltage relay, 22a: frequency reduction relay, 23a: overvoltage relay, 24a: overcurrent relay, 25a: directional ground fault relay, 26a: reverse power relay, 27a: relay for abnormality detection of generator, 28a: frequency rise relay, 30a ... frequency detector, 31a ... function generator, 32a ... differentiator, 33a ... frequency change rate decreasing relay, 34a ... frequency change rate increasing relay, 35a ... adder, 6a ... active power regulator, 37a ... inverter control device, 38a ... inverter, 39a ... DC power supply.

Continuing on the front page (72) Inventor Ken Taniguchi 1000 Hamada, Aboshi-ku, Himeji-shi, Hyogo Nishishiba Electric Machinery Co., Ltd. (72) Inventor Shigeo Nomiya 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Corporation On-site F term (reference) 5G066 HA11 HB02 5H007 AA00 BB00 CC01 DA03 DA04 DB02 DB05 DC03 DC04 DC05 FA02 FA12 FA19 5H590 AA04 AB20 CA07 CA21 CC01 CE02 DD23 DD77 EB02 EB14 FA01 FA06 GA02 GA06 HA01 HA02 HA06 HA09 HB02 HB

Claims (4)

[Claims] A generator driven by a prime mover,
And in a system interconnection protection device of a private power generation facility interconnected with an AC power system and a reverse power flow via a circuit breaker, a speed governor that receives a command signal from the outside and controls the frequency of the generator, A function generation unit having a function characteristic of a frequency command that detects a rate of change of the frequency of the generator and outputs a large output signal with respect to the value of the rate of frequency change, and detects active power of the generator. Active power adjusting means for outputting an output signal corresponding to the detection signal, and protection relay means for detecting an abnormality in the frequency change rate of the generator and outputting a cutoff signal of the circuit breaker, wherein the function generation is performed. A signal obtained by combining the output signal from the means and the output signal from the active power adjusting means is used as the command signal of the governor. Machine By shifting the frequency change rate to a level where the protective relay unit senses, the AC power generating plant system interconnection protection device, wherein a power failure of the power system side so as to detect. 2. An inverter for converting DC power from a DC power supply for generating a DC voltage into AC power at a system power supply frequency and outputting the AC power, and connected to the AC power system via a circuit breaker with a reverse power flow. An inverter control means for controlling the active power of the inverter in response to an external command signal, detecting a change rate of an output frequency of the inverter, and detecting the change rate of the frequency change rate. Function generating means having a function characteristic of a frequency command to output a large output signal with respect to a value, active power adjusting means for detecting active power of the inverter and outputting an output signal according to the detected signal, Protective relay means for detecting an abnormality of the frequency change rate of the inverter and outputting a cutoff signal of the circuit breaker, wherein an output signal from the function generation means and A signal obtained by synthesizing the output signal from the active power adjusting means is used as an active power command signal of the inverter control device. A system interconnection protection device for a power generation facility, wherein a power outage on the AC power system side is detected by shifting to a level detected by the protection relay means. 3. The system interconnection protection device for a power generation facility according to claim 1, wherein an abnormality in the rate of change in frequency of the generator is detected, and a protection relay unit that outputs a cutoff signal of the circuit breaker is provided. A protection relay unit that senses an abnormality in the frequency fluctuation of the generator and outputs a cut-off signal of the circuit breaker.When the power failure occurs on the AC power system side, the protection relay unit detects the frequency fluctuation of the generator. A system interconnection protection device for a power generation facility, wherein a power outage on the AC power system side is detected by shifting to a level to be sensed. 4. The system interconnection protection device for a power generation facility according to claim 2, wherein, instead of the protection relay unit that detects an abnormality in a frequency change rate of the inverter and outputs a cutoff signal of the circuit breaker,
A protection relay unit for detecting an abnormality in the frequency fluctuation of the inverter and outputting a cutoff signal of the circuit breaker; and a level at which the protection relay unit detects a fluctuation in the frequency of the inverter during a power failure on the AC power system side. , Thereby detecting a power outage on the AC power system side.