JP2002281673A - System interconnection protecting device for power generating facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly easily detect and protect independent operations of non-utility power generating facilities in the course of system interconnection on the side of the non-utility power generating facilities, without providing expensive transfer interrupting device. SOLUTION: The output frequency and its change rate of the non-utility power generating facilities 8 to be linked with a system power source via a circuit-breaker are detected, and a voltage variation reference for increasing the leading reactive power of the generating facilities 8, when the change rate of the frequency is positive, or increasing the lagging reactive power when the change rate is negative, is outputted. Also a frequency variation which is fostered by voltage variation of the generating facilities 8 produced by adding a compensated voltage variation reference obtained by compensating the voltage variation reference, in order to compensate for the influence given to rotational speed variation by an inertia constant in the rotational speed control system of the generating facilities 8, to a voltage reference of an automatic voltage regulator 12 of the generating facilities 8, is detected, circuit-breaker is opened, and parallel off of the generating facilities 8 from system bus-bars is made to be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system interconnection protection device for a private power generation system such as a garbage power generation system or a cogeneration system, which is connected to a system power supply via a circuit breaker, and particularly an expensive transfer interruption device. The present invention relates to a system interconnection protection device for a power generation facility capable of reliably and easily detecting and protecting the independent operation of the private power generation facility during the system interconnection on the side of the private power generation facility without providing the system.

[0002]

2. Description of the Related Art Conventionally, a system interconnection protection device as shown in a block diagram of FIG. 13 has been used for a general customer to interconnect a private power generation facility such as a garbage power generation system or a cogeneration system with a system power supply. Used.

[0003] That is, in FIG.
In this example, the voltage of the system power supply 2 is stepped down through the transformer 3, and power is supplied to the general consumer 5 through the circuit breaker 4. The general customer 5 supplies power to the load 7 via the circuit breaker 6.

On the other hand, in the private power generation facility 8, the output of the AC generator 11 is supplied to a load 45 via a circuit breaker 44 in order to supply power to a load 43 in the premises.

In the private power generation facility 8, the output of the AC generator 11 is supplied to the system power supply 2 via circuit breakers 9 and 10.
It is interconnected with.

On the other hand, the output voltage of the AC generator 11 is controlled by controlling the voltage of a field winding 13 of the AC generator 11 by an automatic voltage regulator (AVR) 12.

The output frequency of the alternator 11 is controlled by controlling the governor 1 of the engine 14 that drives the alternator 11.
5 by controlling the engine speed.

As a failure detecting means, an output current of the generator 11 is detected by a current transformer 16, and an abnormal current is detected by a generator abnormality detecting circuit 17 based on a relationship with an output voltage of the generator 11. A signal is supplied to the fault trip circuit 18 to open the circuit breaker 9.

[0009] In addition, as a system interconnection protection device 19,
A current transformer 20 is provided on the output side (substation side) of the circuit breaker 9, and a fault trip circuit 22 is operated by an overcurrent relay (OC) 21.

When the system power supply 2 is abnormal, particularly when the system power supply 2 is cut off, for example, when the circuit breaker 4 is opened, the output power of the AC generator 11 and the load 7 and the load 45
That the frequency and voltage become abnormal due to the imbalance with the load power of the load, the frequency lowering relay (UF) 23, the frequency raising relay (OF) 24, the overvoltage relay (OV) 25,
Detection is performed by a protection relay such as an undervoltage relay (UV) 26.

Then, based on these detection signals, the fault trip circuit 22 gives a trip command to the circuit breaker 10 to open the circuit breaker 10 so that the circuit breaker 4 can be closed again.

[0012]

By the way, in such a system interconnection protection device for a power generation facility, for example, when an abnormality occurs in the system power supply 2 and the circuit breaker 4 is opened, the AC generator 11 is turned off. When the output power and the required power of the load 7 and the load 45 are substantially equal for both the active component and the reactive component, the frequency and the voltage hardly change, so that none of the protection relays 23 to 26 operate and the operation is continued. I do.

So-called islanding (islanding)
A phenomenon occurs, which prevents the circuit breaker 4 from being closed again.

Therefore, conventionally, in order to prevent such an isolated operation, a method of providing a transfer blocking device 27 connected by a dedicated line from the upper substation 1 and blocking the transfer to the circuit breaker 10 is adopted. There are things that are.

That is, when the transfer cutoff device 27 detects a signal indicating that the circuit breaker 4 of the upper substation 1 has been opened,
A break signal is sent to the breaker 10 to open the breaker 10.

However, this type of transfer blocking device 27
Is very expensive for the small and medium-capacity private power generation equipment 8 having an output of about several hundreds of kW, and there is little practical advantage due to grid interconnection.

An object of the present invention is to make it possible to reliably and easily detect and protect the independent operation of a private power generation facility connected to a power system without providing an expensive transfer cutoff device. An object of the present invention is to provide a system interconnection protection device for a power generation facility.

[0018]

In order to achieve the above object, a system interconnection protection device for a power generation facility according to the first aspect of the present invention is a private power generation system interconnected to a system power supply via a circuit breaker. Frequency detection means for detecting the frequency from the output of the equipment, frequency change rate detection means for detecting the rate of change of the frequency detected by the frequency detection means, based on the frequency change rate detected by the frequency change rate detection means, If the rate of change in frequency is positive, the leading reactive power of the private power generation facility is increased (output voltage is reduced), and if the rate of frequency change is negative, the delayed reactive power of the private power generation facility is increased (output voltage). And a voltage fluctuation reference determining means for defining the relationship between the frequency change rate and the voltage fluctuation reference as a function so as to output the voltage fluctuation references respectively. A rotational speed fluctuation compensating means for compensating for a voltage fluctuation standard so as to compensate for the influence on the rotational speed fluctuation due to an inertia constant in a rotational speed control system of a private power generation facility, and a rotational speed fluctuation compensating means. Detects the frequency fluctuations that are fostered by the voltage fluctuations of the private power generation equipment caused by adding the obtained voltage fluctuation reference to the voltage reference of the automatic voltage regulator of the private power generation equipment, and opens the circuit breaker. Protection means for disconnecting the private power generation equipment from the system bus.

Therefore, the system interconnection protection device for power generation equipment according to the first aspect of the present invention detects the rate of change of the frequency of the private power generation equipment and obtains a voltage drop command if the frequency change rate is positive. When the rate of change in frequency is negative, a voltage increase command is obtained, and a voltage fluctuation reference is further compensated to compensate for the effect of the inertia constant on the rotation speed fluctuation in the rotation speed control system of the private power generation equipment. By applying the voltage fluctuation reference to the automatic voltage regulator, the output voltage of the private power generation equipment is changed, thereby expanding the frequency fluctuation, and without providing the expensive transfer shut-off device as in the above-described conventional system. It is possible to reliably and easily detect and protect the isolated operation of the private power generation facility during interconnection on the private power generation facility side.

[0020] Further, a system interconnection protection device for a power generation facility according to the invention according to claim 2 comprises frequency detection means for detecting a frequency from an output of a private power generation facility connected to a system power supply via a circuit breaker; Frequency change rate detection means for detecting a change rate of the frequency detected by the frequency detection means; and private power generation based on the frequency change rate detected by the frequency change rate detection means when the frequency change rate is positive. To increase the leading reactive power of the equipment (lower the output voltage), and to output the voltage fluctuation reference to increase the delay reactive power of the private power generation equipment (increase the output voltage) when the frequency change rate is negative. , The relationship between the frequency change rate and the voltage fluctuation reference is defined by a function, and the gain of the function can be switched in multiple stages or the shape of the function can be switched in multiple stages. A plurality of thresholds are set for the frequency change rate detected by the determination means and the frequency change rate detection means, and the gain of the function is switched or A voltage fluctuation reference switching means for outputting a switching command for function shape switching and a voltage fluctuation reference output from the voltage fluctuation reference determining means are input and given to a rotational speed fluctuation due to an inertia constant in a rotational speed control system of a private power generation facility. A rotational speed fluctuation compensating means for compensating the voltage fluctuation standard so as to compensate for the influence, and adding the voltage fluctuation standard obtained by the compensation by the rotational speed fluctuation compensating device to a voltage standard of the automatic voltage regulator of the private power generation equipment. Detects frequency fluctuations that are promoted by the voltage fluctuations of the private power generation facilities that occur in And a protection means for Kairetsu.

Therefore, in the system interconnection protection device for power generation equipment according to the second aspect of the invention, the influence on the system is reduced during system interconnection by the multi-stage detection method, and the frequency fluctuation during the isolated operation is reduced. In addition to the action of expanding
In the initial stage of multi-stage detection, the voltage fluctuation standard is compensated to compensate for the effect on the rotational speed fluctuation due to the inertia constant in the rotational speed control system of the private power generation equipment, and the frequency fluctuation during isolated operation is expanded, By detecting the frequency change rate abnormality, the frequency fluctuation is expanded, and the independent operation of the private power generation equipment during grid interconnection is performed on the private power generation equipment side without providing an expensive transfer cutoff device as in the conventional case described above. Detection and protection can be performed more reliably and easily.

On the other hand, the system interconnection protection device for a power generation facility according to the third aspect of the present invention is the system interconnection protection device according to the first or second aspect of the present invention, wherein the system interconnection compensation device compensates for the rotation speed fluctuation by the rotation speed variation compensating means. The excitation system transfer function compensating means for compensating the voltage fluctuation standard so as to compensate for the response characteristic (transfer function) related to the voltage control of the private power generation equipment is added to the obtained voltage fluctuation standard as an input. The voltage fluctuation reference obtained by compensation by the compensating means is added to the voltage reference of the automatic voltage regulator of the power generation equipment as a final compensation signal for the voltage fluctuation reference.

Therefore, in the system interconnection protection device for power generation equipment according to the third aspect of the present invention, the rate of change of the frequency of the private power generation equipment is detected, and when the frequency change rate is positive, a voltage drop command is obtained. In the case where the frequency change rate is negative, a voltage increase command is obtained, the influence on the rotation speed fluctuation due to the inertia constant in the rotation speed control system of the private power generation equipment is compensated, and the voltage control of the private power generation equipment is performed. By applying the voltage fluctuation reference obtained by compensating the voltage fluctuation reference to compensate the response characteristic (transfer function) to the automatic voltage regulator, the output voltage of the private power generation equipment is changed, thereby expanding the frequency fluctuation. Therefore, the independent operation of the private power generation facility during grid connection can be reliably and easily detected and easily detected and protected on the private power generation facility side without providing an expensive transfer cutoff device as in the conventional case described above. It is possible.

According to a fourth aspect of the present invention, there is provided the system interconnection protection device for a power generation facility according to the third aspect, wherein the system interconnection protection device is connected to a system power supply via a circuit breaker. When a plurality of private power generation facilities to be interconnected exist in the same distribution system, and each of the private power generation facilities includes the grid interconnection protection device of the invention corresponding to claim 3, the respective private power generation facilities are connected to each other. The compensation value of the rotation speed fluctuation compensation means of each private power generation equipment is set so that the rotation speed (frequency) fluctuation due to the load fluctuation based on the voltage fluctuation becomes the same, and the response concerning the voltage control of each private power generation equipment is set. The compensation value of the excitation system transfer function compensating means of each private power generation facility is set so that the characteristics (transfer functions) are the same.

Therefore, the system interconnection protection device for a power generation facility according to the present invention detects the rate of change of the frequency of a plurality of private power generation facilities, and issues a voltage drop command when the frequency change rate is positive. When the frequency change rate is negative, a voltage increase command is obtained, and the influence on the rotational speed fluctuation due to the inertia constant in the rotational speed control system of the private power generation equipment is compensated for. A voltage fluctuation reference obtained by compensating the voltage fluctuation reference so as to compensate for the response characteristic (transfer function) according to the present invention is given to the automatic voltage regulator, so that the output voltage of the private power generation equipment is changed, and thus a plurality of private Even in the case where the power generation equipment is connected to the same distribution system, the frequency fluctuation is expanded, and without providing an expensive transfer shut-off device as in the conventional case described above, the self-connection during the system connection is performed. Islanding of use power generation equipment can be protected reliably and easily detected by the private power generation equipment side.

[0026]

Embodiments of the present invention will be described below 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 power generation facility according to the present embodiment, and the same parts as those in FIG. The description thereof will be omitted, and only different portions will be described here.

As shown in FIG. 1, the system interconnection protection device of the power generation equipment according to the present embodiment is different from the conventional system interconnection protection device of the power generation equipment shown in FIG. The transfer blocking device 8 is omitted, and the following configuration is used instead.

That is, as shown in FIG. 1, a frequency (f) detector 28 detects a frequency from the output voltage of the AC generator 11, and a frequency change rate (df / dt) detector 29 is obtained from the detected frequency. detecting a frequency change rate V ₃₀ by.

Frequency change rate (df / dt) excessive detector 3
0 detects whether or not the frequency change rate V ₃₀ is equal to or greater than a set value. If the frequency change rate V ₃₀ is equal to or greater than the set value, the abnormal output signal V ₃₁ is output to the fault trip circuit 22.

The fault trip circuit 22 outputs the abnormal output signal V
_{When 31} is given, a trip signal is given to the circuit breaker 10 to open the electric circuit.

The reactive power (Q) detector 31 is connected to the current transformer 16
, The output current of the AC generator 11 and the output voltage of the AC generator 11 are input, and the reactive power Q is detected based on these.

The active power (P) detector 32 is connected to the current transformer 16.
, The output current of the AC generator 11 and the output voltage of the AC generator 11 are input, and the active power P is detected based on these.

On the other hand, an active power control circuit (APR) 33
Compares the active power reference P ^* from the active power reference (P ^* ) setting unit 34 with the active power P from the active power detector 32, and gives these deviations to the governor 15 to give the engine 14
Of the prime mover.

The voltage fluctuation criterion determining means 35 detects the frequency change
Frequency change rate V from rate detector 29 ₃₀As input
Pressure fluctuation reference ΔV^*And the frequency change rate.
V₃₀Is positive (the frequency is rising), the alternator 1
1 lowers the output voltage to promote the frequency rise, and
Frequency change rate V₃₀Is negative (frequency is falling), AC
The output voltage of the electric machine 11 is increased to promote the frequency decrease.
Voltage fluctuation reference ΔV^*Output each,
Number change rate V₃₀And voltage fluctuation reference ΔV^*The relationship with, for example,
It is defined by a function as shown in FIG.

FIG. 2 shows functions (a) and (b) of two examples. Rotation speed fluctuation compensation means 36
Receives the voltage fluctuation reference ΔV ^* output from the voltage fluctuation reference determining means 35 and compensates for the influence on the rotational speed fluctuation due to the inertia constant of the rotating body of the private power generation facility 8 when the load torque fluctuates. The voltage fluctuation reference ΔV ^* is compensated, and the compensated voltage fluctuation reference ΔV ^* is input to the automatic voltage regulator (AVR) 12.

The reactive power control circuit (AQR) 37 receives the reactive power reference Q from the reactive power reference (Q ^* ) setting unit 38.
^*, And outputs a voltage reference [Delta] V _Q ^* for matching the reactive power detected by reactive power detector 31.

The automatic voltage regulator (AVR) 12 receives the voltage reference V ^{* from} the voltage reference (V ^* ) setter (90R) 39 ^.
And the voltage reference ΔV _Q ^* from the reactive power control circuit 37;
The field of the field winding 13 is adjusted so as to control the output voltage of the AC generator 11 based on the voltage fluctuation reference ΔV ^* from the voltage fluctuation reference determining means 35 compensated by the rotation speed fluctuation compensating means 36. I do.

In the above description, the active power reference (P ^* ) setting unit 34, the active power control circuit 33, the governor 15, and the engine 14 constitute an active power control loop.

The reactive power reference (Q ^* ) setting unit 38
, The reactive power detector 31 and the reactive power control circuit 37 constitute a reactive power control loop.

Further, a voltage reference (V ^* ) setting device (90)
R) 39, the voltage reference ΔV _Q ^* output from the reactive power control circuit 37, the voltage fluctuation reference ΔV ^* from the voltage fluctuation reference determining means 35, the rotation speed fluctuation compensating means 36, and the automatic voltage regulator 12. Form a voltage control loop.

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

In FIG. 3, the active power of the output of the AC generator 11 is P, the reactive power is Q, the load 7 and the load 45
The active power required by the combined load 46 obtained by combining the P _L,
When the reactive power and Q _L, active power ΔP and reactive power ΔQ flowing into the system power source 2 are respectively expressed as follows.

ΔP = P−P _L ΔQ = Q−Q _L Here, the inductance between the AC generator 11 and the system is 1, the voltage of the combined load 46 is V, and the frequency is f.

Then, in the normal case, ΔP ≒ 0,
Even if the circuit breaker 4 is opened in a state close to ΔQ ≒ 0, the voltage V and the frequency f of the combined load 46 hardly change.
It cannot be detected by the protection relays 23 to 26, and the isolated operation is continued.

However, since the phases of the system power supply 2 and the combined load 46 are slowly shifted, the re-input of the circuit breaker 4 leads to an increase in accidents, which is 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 determined by Q = (V ² ωC) − (V ² / ωL).

In particular, focusing on the frequency f, the combined load 4
Than reactive power Q _L of 6 requests, when the alternator 11 is shifted in the advance direction is the reactive power supply, the current i _C of the capacitor C increases the frequency f is increased, the inductance current i _L is It decreases and changes in the direction in which the reactive power balances.

[0050] Further, when the reactive power alternator 11 supplies are shifted to a request direction lags reactive power Q _L to the combined load 46, the inductance current i _L increases in the frequency f is lowered, the capacitor The current i _C decreases and changes in a direction in which the reactive power balances.

Accordingly, in the case of the islanding operation in the state of ΔP ≠ 0 and ΔQ ≠ 0, the frequency fluctuation when only the above load balance is considered, as shown in FIG.
After 0), the frequency f approaches the stable points f ₁ and f ₂ while fluctuating.

In FIG. 4, f ₁ indicates a case where ΔQ is slightly advanced, and f ₂ indicates a case where ΔQ is slightly delayed.

+ Δf and −Δf shown in FIG. 4 are levels at which the protection relays 23 and 24 can detect the isolated operation.

FIG. 5 is a diagram for explaining the operation and effect of the embodiment shown in FIG.

In FIG. 5, f is the frequency f detected by the frequency detector 28, df / dt is the frequency change rate detected by the frequency change rate detector 29, and the voltage fluctuation reference ΔV ^* is the voltage fluctuation reference ΔV ^*. The output of the reference determination means 35 is shown.

Now, when the frequency f changes as shown in FIG. 5, df / dt becomes a waveform advanced by 90 ° from this.

FIG. 6 is a waveform diagram showing how the frequency f changes when the influence of the voltage fluctuation voltage reference ΔV ^* is considered.

In FIG. 6, when df / dt> 0, the frequency f is increasing, and during this period, the voltage fluctuation reference determining means 35 supplies a voltage drop command (leading reactive power command).
Is output, and the frequency f acts to further increase (FIG. 6A).

When df / dt <0, since the frequency f is decreasing, a voltage increase command (delayed reactive power command) is output from the voltage fluctuation reference determining means 35 during this time, and the frequency f is further reduced. Acts to descend (Fig. 6
(B)).

Next, this point will be described with reference to FIGS.
This will be described in more detail using (c).

As shown in FIG. 7A, a general rotation speed control system used in the private power generation equipment 8 includes a transfer function 47 representing a governor, a transfer function 48 representing a droop characteristic, an actuator, It can be represented by a transfer function 49 representing an engine output characteristic composed of a fuel injection amount control device and the like, and a transfer function 50 representing an influence of an inertia constant of a rotating body of a power generator component.

The effect of the inertia constant of the rotating body of the private power generation facility 8 is greatly affected by the size and type of the engine. It is very large compared to

Therefore, even if the same voltage fluctuation criterion is given to the automatic voltage regulator 12 by the islanding operation detecting device 42, the fluctuation of the rotation speed (frequency) due to the load fluctuation based on the voltage fluctuation constitutes the private power generation equipment 8. Depending on the size and type of the prime mover, there may be cases where sufficient frequency fluctuation for detecting islanding operation cannot be obtained.

For this reason, the rotational speed fluctuation compensating means 36 compensates for the difference in the rotational speed (frequency) fluctuation based on the load fluctuation due to the difference in the inertia constant of the rotating body of the private power generation facility 8.

FIG. 7B is a block diagram showing a rotation speed control system of the private power generation equipment 8 to which the isolated operation detection device 42 is applied.

In FIG. 7B, G _E (S) 51 is
This is a transfer function obtained by synthesizing a transfer function 47 representing the governor 15, a transfer function 48 representing the droop characteristic, and a transfer function 49 representing the output characteristic of the engine 14 including an actuator, a fuel injection amount control device, etc., and G ₁ (S ) 52 is a transfer function (consisting of 28, 29, 35 in FIG. 1) from the frequency (rotation speed) to the determination of the voltage fluctuation reference, and G ₂ (S) 53 represents the response of the excitation system. Transfer function (consisting of 11, 12, 13 in FIG. 1)
₃ (S) 54 is a transfer function representing load fluctuation (torque fluctuation) based on terminal voltage fluctuation of the alternator 11,
M _A is the inertia constant of the rotating part, and G _C (S) 55
Indicates a transfer function representing the rotational speed fluctuation compensating means 36.

FIG. 7C shows a portion (FIG. 7) related to the inertia constant of FIG.
It is a block diagram which extracts and shows (b) the part within the dashed-dotted line.

[0068] That is, when synthesizing the transfer _{function, 1 / [M A · S} + G 1 (S) · G 2 (S) · G 3 (S)
G _C (S)].

In the above description, M _A is the inertia constant of the private power generation facility 8 using the steam turbine as the prime mover 14.

Next, a gas engine or a diesel engine
The inertia constant of the private power generation facility 8 with the_O
And the compensation by the rotational speed variation compensating means 36 is not performed.
7 (c) is 1 / [M_O・ S + G₁(S) · G_Two(S) · G
_Three(S)], and a rotational speed fluctuation compensating means such that both become equal.
Transfer function G representing 36 _C(S) I'll decide 55
And [(M_O-M_A) · S] / [G₁(S) · G_Two(S) ・
G_Three(S)] + 1.

Therefore, in the case of the private power generation facility 8 having the inertia constant M _A , the transfer function of the rotation speed fluctuation compensating means 36 is defined as [(M _O · M _A ) · S] / [G ₁ (S) · G ₂ (S) ・
By setting G ₃ (S)] + 1, if the same voltage fluctuation reference ΔV ^* is given, a rotation speed (frequency) fluctuation based on the same load fluctuation as the private power generation facility 8 having the inertia constant M _O can be given. .

By adding such means, the frequency fluctuation is increased by the positive feedback effect accompanying the voltage fluctuation, and the frequency fluctuation during the isolated operation is reduced from the characteristic shown in FIG. 4 as shown in FIG. By detecting an abnormal frequency or an excessive frequency change rate with the excessive frequency change rate detector 30, the isolated operation can be detected without using an expensive transfer cut-off device conventionally used. Can be.

As described above, in the system interconnection protection device for power generation equipment according to the present embodiment, the frequency change rate df / dt of the AC generator 12 is detected, and the frequency change rate is df / dt.
If> 0, a voltage drop command is obtained, and the frequency change rate becomes d.
If f / dt <0, a voltage increase command is obtained, and the rotation speed fluctuation compensating means 36 further compensates for the influence of the inertia constant of the rotating body of the private power generation equipment 8 on the rotation speed fluctuation so as to compensate for the influence on the rotation speed fluctuation. The output voltage of the alternator 11 is changed by giving the voltage fluctuation reference obtained by compensating the above to the automatic voltage regulator 12, so that the frequency fluctuation is enlarged and the cost is increased 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 8 during system interconnection without providing the transfer interruption device 27.

(Second Embodiment) FIG. 8 is a block diagram showing a configuration example of a system interconnection protection device for a power generation facility according to the present embodiment, and the same parts as those in FIG. The description thereof will be omitted, and only different portions will be described here.

As shown in FIG. 8, the system interconnection protection device of the power generation equipment according to the present embodiment is different from the system interconnection protection device of the power generation equipment shown in FIG. 1 in the following configuration. It is that you are.

That is, as shown in FIG. 8, the following function is added to the voltage fluctuation reference determining means 35 in FIG. 1, and a voltage fluctuation reference switching means 40 is further added.

As described above, the voltage fluctuation reference determination means 35 defines the relationship between the frequency change rate V ₃₀ and the voltage fluctuation reference ΔV ^* by a function, and can switch the gain of the function in a plurality of stages or Can be switched in a plurality of stages.

The voltage change reference switching means 40 sets a plurality of threshold values for the frequency change rate detected by the frequency change rate detector 29. An instruction to switch the gain of the function or to switch the shape of the function is output to the determination unit 35.

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

In FIG. 8, the voltage fluctuation reference determining means 35
Receives the frequency change rate V ₃₀ from the frequency change rate detector 29, and outputs a voltage variation reference [Delta] V ^*.

Here, similarly to the first embodiment, when the frequency change rate is positive (the frequency is increasing),
The output voltage of the alternator 11 is reduced to promote the frequency increase, and when the frequency change rate is negative (the frequency is decreasing), the output voltage of the alternator 11 is increased to promote the frequency decrease. Such a voltage fluctuation reference ΔV ^* is output.

The frequency fluctuation based on the voltage fluctuation increases as the voltage fluctuation increases. Private power generation equipment 8
However, it is preferable to apply a voltage change that causes a sufficient frequency change when the isolated operation is performed in order to distinguish whether the operation is the isolated operation or the grid connection. There is a concern that providing the may cause disturbance in the system.

Therefore, initially, a small voltage fluctuation reference ΔV ^* which does not adversely affect the system is set.

[0084] In the first voltage variation reference [Delta] V ^* of work, exceeds a threshold frequency change rate was set initially, so as to provide increased voltage variation reference [Delta] V ^*.

When the frequency change rate further exceeds the following threshold value due to this effect, the voltage fluctuation reference ΔV ^* is further increased.

The above-described repetition is repeated several times to realize a multi-step detection method in which the action based on the voltage fluctuation reference ΔV ^* is increased stepwise while confirming the possibility of islanding.

This multi-step detection method is realized by voltage fluctuation reference switching means 40 having a plurality of frequency change rate thresholds and outputting a voltage fluctuation reference switching command to voltage fluctuation reference determining means 35.

Further, the voltage fluctuation criterion determining means 35 can switch the gain of the function for determining the voltage fluctuation criterion from the frequency change rate or switch the shape of the function.
Switching is performed according to a command from the voltage fluctuation reference switching means 40.

FIG. 9 is an image diagram showing an example of a function for determining a voltage fluctuation reference. A plurality of functions may be prepared and a limit level may be provided.

The rotation speed fluctuation compensating means 36 operates in the same manner as in the first embodiment, and improves the voltage fluctuation state by compensating the voltage fluctuation reference ΔV ^* in a multi-stage detection method.

As described above, by the multi-stage detection method, the influence on the system is reduced during system interconnection, and in addition to the operation of rapidly expanding the frequency fluctuation during the single operation, the initial stage of the multi-stage detection is improved. The voltage fluctuation criterion is compensated so as to compensate for the influence of the inertia constant on the rotation speed fluctuation in the rotation speed control system of the private power generation facility 8, and the frequency fluctuation at the time of the single operation of the private power generation facility 8 is shown in FIG. By expanding from the characteristic to the characteristic as shown in FIG.
It is easy to reliably detect the islanding operation of the private power generation facility 8 side.

As described above, in the system interconnection protection device for power generation equipment according to the present embodiment, the frequency change rate df / dt of the AC generator 11 is detected, and the frequency change rate is df / dt.
If> 0, a voltage drop command is obtained, and the frequency change rate becomes d.
When f / dt <0, a voltage increase command is obtained, and at this time, the magnitude of the voltage command is switched by switching the gain in multiple stages. In the initial stage of the multi-stage detection, the voltage control of the private power generation equipment 8 is performed. The voltage fluctuation criterion is compensated so as to compensate for such response characteristics (transfer function), and the frequency fluctuation at the time of isolated operation is expanded to detect the frequency and the frequency change rate abnormality. Therefore, without providing the expensive transfer blocking device 27 as in the related art described above,
It is possible to more reliably and easily detect and protect the isolated operation of the private power generation facility 8 during system interconnection on the private power generation facility 8 side.

(Third Embodiment) FIG. 10 is a block diagram showing an example of a main configuration of a system interconnection protection device for a power generation facility according to the present embodiment. The illustration and description thereof are omitted, and only different portions will be described here.

As shown in FIG. 10, the system interconnection protection device of the power generation equipment according to the present embodiment is different from the system interconnection protection device of the power generation equipment shown in FIG. 8 in the following configuration. It is that you are.

That is, as shown in FIG.
In this configuration, an excitation system transfer function compensating means 41 is added between the rotational speed fluctuation compensating means 36 and the automatic voltage regulator 12 of the private power generation facility 8.

The excitation system transfer function compensating means 41 receives the voltage fluctuation reference obtained by the compensation by the rotational speed fluctuation compensating means 36 as input and compensates the response characteristic (transfer function) related to the voltage control of the private power generation equipment 8. To compensate for the voltage fluctuation criteria.

The excitation system transfer function compensating means 41
Is added to the voltage reference of the automatic voltage regulator 12 of the private power generation facility 8 as a final compensation signal for the voltage fluctuation reference.

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

In FIG. 10, the voltage fluctuation reference determining means 3
5 is the frequency change rate V ₃₀ from the frequency change rate detector 29.
And outputs the voltage fluctuation reference ΔV ^* .

Here, similarly to the above-described second embodiment, when the frequency change rate is positive (the frequency is increasing),
The output voltage of the alternator 11 is reduced to promote the frequency increase, and when the frequency change rate is negative (the frequency is decreasing), the output voltage of the alternator 11 is increased to promote the frequency decrease. Such a voltage fluctuation reference ΔV ^* is output.

At this time, the rotational speed fluctuation compensating means 36 compensates for the voltage fluctuation reference so as to compensate for the influence on the rotational speed fluctuation due to the inertia constant of the rotating body of the private power generation facility 8.

At this time, if the response to the command value in the voltage control loop is slow, it will take a long time to reach the level of the voltage fluctuation reference ΔV ^* , and it is difficult for sufficient voltage fluctuation to occur, or if the overshoot is large, the voltage fluctuation It is conceivable that a voltage fluctuation occurs above the level of the reference ΔV ^* , which has an adverse effect on connected devices (FIG. 11).

Therefore, the excitation system transfer function compensating means 41 supplies the voltage fluctuation reference ΔV from the rotational speed fluctuation compensating means 36.
By compensating for ^* , the voltage fluctuation state is improved.

As described above, in the system interconnection protection device for power generation equipment according to the present embodiment, the frequency change rate df / dt of the alternator 11 is detected, and the frequency change rate is df / dt.
> 0, a voltage drop command is obtained, and if the frequency change rate is df / dt <0, a voltage increase command is obtained. Further, the rotation speed fluctuation compensating means 36 controls the rotation of the rotating body of the private power generation facility 8. The voltage fluctuation criterion is compensated so as to compensate for the influence of the inertia constant on the rotation speed fluctuation, and the voltage fluctuation criterion is compensated by the excitation system transfer function compensating means 41 so as to compensate the response to the command value in the voltage control loop. By giving the obtained voltage fluctuation reference to the automatic voltage regulator 12, the output voltage of the AC generator 11 is changed. Without providing the 27, it is possible to reliably and easily detect and protect the independent operation of the private power generation facility 8 during system interconnection on the private power generation facility 8 side.

(Fourth Embodiment) FIG. 12 is a block diagram showing an example of a configuration of a main part of a system interconnection protection device for a power generation facility according to the present embodiment. The illustration and description thereof are omitted, and only different portions will be described here.

As shown in FIG. 12, the system interconnection protection device of the power generation equipment according to the present embodiment is different from the system interconnection protection device of the power generation equipment shown in FIG. 10 in the following configuration. It is that you are.

That is, as shown in FIG.
At 0, a plurality (two in this example) of private power generation facilities 8 exist in the same power distribution system, and each of the private power generation facilities 8 includes the grid interconnection protection device described in the third embodiment. It has a configuration.

In FIG. 12, the private power generation equipment 901 and the private power generation equipment 902 are connected to the in-plant load 43, the grid connection protection device 19,
Each has a facility corresponding to the private power generation facility 8 and the islanding operation detection device 42, and the loads 801 to 803 are:
This corresponds to the general customer 5 shown in the range on the grid side in FIG.

Private power generation equipment 901 and private power generation equipment 9
02 has different characteristics.
No. 1 uses a gas engine as a prime mover and has a small inertia constant.

The private power generation facility 902 uses a steam turbine as a prime mover and has a large inertia constant.

Further, the capacity and the response of the excitation system are different between the private power generation facility 901 and the private power generation facility 902.

Here, each private power generation facility 90
The compensation values of the rotational speed fluctuation compensating means 36 of each of the private power generation facilities 901 and 902 are set so that the rotational speed (frequency) fluctuation due to the load fluctuation based on the voltage fluctuations of the power generation units 1 and 902 becomes the same.

Further, each of the private power generation facilities 901,
Each of the private power generation facilities 901 and 90 so that the response characteristics (transfer function) related to the voltage control of 902 become the same.
2, the compensation value of the excitation system transfer function compensating means 41 is set.

Next, the operation of the above-configured system interconnection protection device for power generation equipment according to the present embodiment will be described.

In FIG. 12, the characteristics of the private power plant 901 and the private power plant 902 are different (the private power plant 901 uses a gas engine as a motor, has a small inertia constant, and the private power plant 902 has a steam turbine. Is used as a prime mover and the inertia constant is large), and the capacity and the response of the excitation system are also different.

[0116] In this case, based on the voltage variation reference [Delta] V ^* in private power generation facility 1, and the rotational speed (frequency) fluctuation and voltage fluctuation during a load torque fluctuation based on the voltage variation reference [Delta] V ^* in private power plant 2, If the rotation speed (frequency) fluctuation and the voltage fluctuation at the time of load torque fluctuation are different from each other, there is a possibility that a mutual fluctuation is canceled out and a sufficient fluctuation cannot be obtained.

Therefore, by adjusting the respective compensation values of the rotational speed fluctuation compensating means 36 and the excitation system transfer function compensating means 41 of the private power generation equipment 901 and the private power generation equipment 902, the load torque fluctuation with respect to the voltage fluctuation reference ΔV ^{* is obtained.} , The rotational speed (frequency) fluctuation and the voltage response can be made equal.

Thus, even in the same power distribution system in which a plurality of private power generation facilities 901 and 902 exist, sufficient frequency fluctuation and voltage fluctuation based on the voltage fluctuation reference ΔV ^* can be obtained.

As described above, in the system interconnection protection device for a power generation facility according to the present embodiment, a plurality of private power generation facilities 9 are provided.
01,902 Frequency change rate df / d of the alternator 11
t, a voltage drop command is obtained when the frequency change rate is df / dt> 0, and a voltage rise command is obtained when the frequency change rate is df / dt <0. A voltage fluctuation criterion obtained by compensating the voltage fluctuation criterion so as to compensate for the fluctuation of the rotation speed (frequency) based on the load torque fluctuation and the response characteristic to the command value in the voltage control loop in the equipments 901 and 902 is the same. By giving the voltage to the automatic voltage regulator 12, the private power generation equipment 90
Since the output voltage of the power generation equipment 902 is changed, even when a plurality of private power generation facilities 901 and 902 are connected to the same power distribution system, the frequency fluctuation is expanded and Power generation equipment 901 and 901,
It is possible to reliably and easily detect and protect the isolated operation of the 902 on the private power generation facilities 901 and 902 side.

(Other Embodiments) The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention in the implementation stage. It is. In addition, the embodiments may be implemented in combination as appropriate as much as possible, in which case the combined operation and effect can be obtained. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some components are deleted from all the components shown in the embodiment, at least one of the problems described in the section of the problem to be solved by the invention can be solved, and the effects of the invention can be solved. In the case where (at least one of) the effects described in the section is obtained, a configuration from which this component is deleted can be extracted as an invention.

[0121]

As described above, according to the system interconnection protection device for a power generation system of the present invention, the independent operation of the private power generation system during the system interconnection can be performed without providing an expensive transfer interruption device. It is possible to reliably and easily detect and protect on the equipment side.

Further, according to the system interconnection protection device for a power generation facility of the present invention, even when a plurality of private power generation facilities are interconnected to the same distribution system, only the private power generation facility in the system interconnection is used. The operation can be reliably and easily detected and protected on the private power generation equipment side.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an example of a shape of a function for determining a voltage fluctuation criterion in the system interconnection protection device for power generation equipment according to the first embodiment.

FIG. 3 is a diagram for explaining the operation of the system interconnection protection device of the power generation equipment according to the first embodiment.

FIG. 4 is a diagram for explaining the operation of the power grid connection protection device of the power generation equipment according to the first embodiment.

FIG. 5 is a diagram for explaining the operation of the system interconnection protection device of the power generation equipment according to the first embodiment.

FIG. 6 is a diagram for explaining the operation of the system interconnection protection device of the power generation equipment according to the first embodiment.

FIG. 7 is a block diagram for explaining the operation of the system interconnection protection device of the power generation equipment according to the first embodiment.

FIG. 8 is a block diagram showing a second embodiment of a system interconnection protection device for power generation equipment according to the present invention.

FIG. 9 is a diagram showing an example of the shape of a function for determining a voltage fluctuation criterion in a multi-stage detection method in the system interconnection protection device for power generation equipment according to the second embodiment.

FIG. 10 is a block diagram showing a third embodiment of a system interconnection protection device for power generation equipment according to the present invention.

FIG. 11 is a diagram showing an example of a command value response of a voltage control loop in the system interconnection protection device of the power generation equipment according to the third embodiment.

FIG. 12 is a block diagram showing a fourth embodiment of a system interconnection protection device for power generation equipment according to the present invention.

FIG. 13 is a block diagram showing a configuration example of a conventional system interconnection protection device for power generation equipment.

[Explanation of Signs] 1 ... Upper substation, 2 ... System power supply, 3 ... Transformer, 4 ... Circuit breaker, 5 ... General customer, 6, 62, 63, 64 ... Circuit breaker, 7, 72, 73, 74 ... Load, 8: Private power generation equipment, 9: Circuit breaker (52G), 10: Circuit breaker (52R), 11: AC generator, 12: Automatic voltage regulator (AVR), 13: Field winding, 14 ... Engine 15 Governor 16 Current transformer 17 Generator abnormality detection circuit 18 Fault trip circuit 19 System interconnection protection device 20 Current transformer 21 Overcurrent relay (OC) 22, a fault trip circuit, 23, a frequency lowering relay (UF), 24, a frequency increasing relay (OF), 25, an overvoltage relay (OV), 26, an undervoltage relay (UV), 27, a transfer interruption device, 28 ... Frequency detecting means, 29: Frequency change rate detection Stage, 30 ... frequency change rate excessive detector, 31 ... reactive power detector, 32 ... active power detector, 33 ... active power control circuit (APR), 34 ... active power reference (P ^*) setter 35 ... Voltage Fluctuation reference determining means, 36: rotational speed fluctuation compensation means, 37: reactive power control circuit (AQR), 38: reactive power reference (Q ^* ) setting device, 39: voltage reference setting device (90R), 40: voltage fluctuation reference Switching means, 41: Excitation system transfer function compensating means, 42: Single operation detection device, 43: Local load, 44: Circuit breaker, 45: Load, 46: Composite load (Load 7 and general load 4 for general customers)
5), 47 ... an example of a transfer function representing a governor, 48 ... an example of a transfer function representing a droop, 49 ... an example of a transfer function representing an engine output characteristic, 50 ... a transfer function representing an influence by an inertia constant, 51 ... A transfer function obtained by synthesizing a transfer function 49 representing the output characteristics of the engine 14, 52: a transfer function representing from the frequency (rotation speed) to the determination of the voltage fluctuation reference, 53 ... an excitation including the automatic voltage regulator (AVR) 12 A transfer function representing the response of the system; 54 a transfer function representing a load variation based on a terminal voltage variation of the AC generator 11; 55 a transfer function representing the rotational speed variation compensating means 36; 801, 802, 803 ... a general consumer Loads corresponding to 5, 901 and 902: Private power generation equipment.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toyokuni Kato 1000 Hamada, Aboshi-ku, Himeji-shi, Hyogo Nishiba Electric Machinery Co., Ltd. F-term (reference) 5G066 HA11 HA19 HB02

Claims (4)

[Claims] 1. A system interconnection protection device for a private power generation facility connected to a system power supply via a circuit breaker, wherein the frequency detection means detects a frequency from an output of the private power generation equipment; Frequency change rate detection means for detecting the change rate of the frequency, based on the frequency change rate detected by the frequency change rate detection means, if the frequency change rate is positive, the advance of the private power generation equipment The reactive power is increased (output voltage is reduced), and when the frequency change rate is negative, the delayed reactive power of the private power generation equipment is increased (output voltage is increased).
Voltage fluctuation criterion determining means for defining the relationship between the frequency change rate and the voltage fluctuation criterion as a function so as to output the respective voltage fluctuation criterion to be output, A rotational speed fluctuation compensating means for compensating the voltage fluctuation standard so as to compensate for an influence on a rotational speed fluctuation due to an inertia constant in a rotational speed control system of the private power generation equipment; Detecting frequency fluctuations that are facilitated by the voltage fluctuations of the private power generation facility caused by adding the obtained voltage fluctuation reference to the voltage reference of the automatic voltage regulator of the private power generation facility,
Protection means for opening the circuit breaker and disconnecting the private power generation equipment from a system bus. 2. A system interconnection protection device for a private power generation facility interconnected to a system power supply via a circuit breaker, wherein the frequency detection means detects a frequency from an output of the private power generation equipment; Frequency change rate detection means for detecting the change rate of the frequency, based on the frequency change rate detected by the frequency change rate detection means, if the frequency change rate is positive, the advance of the private power generation equipment The reactive power is increased (output voltage is reduced), and when the frequency change rate is negative, the delayed reactive power of the private power generation equipment is increased (output voltage is increased).
The relationship between the frequency change rate and the voltage fluctuation reference is defined by a function so that each of the voltage fluctuation references to be output is output, and the gain of the function can be switched in a plurality of stages or the shape of the function can be switched in a plurality of stages. And a plurality of threshold values are set for the frequency change rate detected by the frequency change rate detection means, and each time the threshold value is exceeded, the voltage change reference determination means A voltage fluctuation reference switching unit that outputs a switching command for gain switching of the function or shape switching of the function, and a voltage fluctuation reference output from the voltage fluctuation reference determining unit as input, and a rotation speed of the private power generation equipment. A rotational speed fluctuation compensating means for compensating the voltage fluctuation reference so as to compensate for the effect of the inertia constant on the rotational speed fluctuation in the control system. The voltage fluctuation reference obtained by compensating by the rotational speed fluctuation compensation means is added to the voltage reference of the automatic voltage regulator of the private power generation equipment, and the voltage fluctuation of the private power generation equipment is caused by the voltage fluctuation reference. Detected frequency fluctuations,
Protection means for opening the circuit breaker and disconnecting the private power generation equipment from a system bus. 3. The private power generation system according to claim 1, wherein the voltage fluctuation reference obtained by compensating the rotation speed fluctuation compensating means is input to the private power generation system. Exciting system transfer function compensating means for compensating the voltage fluctuation reference so as to compensate for response characteristics (transfer function) related to voltage control of equipment is added, and the voltage obtained by compensating by the exciting system transfer function compensating means is added. A system interconnection protection device for a power generation facility, wherein a fluctuation reference is added to a voltage reference of an automatic voltage regulator of the power generation equipment as a final compensation signal for the voltage fluctuation reference. 4. The system interconnection protection device for a power generation facility according to claim 3, wherein a plurality of private power generation facilities connected to a system power supply via the circuit breaker exist in the same power distribution system. When the private power generation equipment is provided with the grid interconnection protection device according to claim 3, the rotation speed (frequency) fluctuation due to the load fluctuation based on the voltage fluctuation of each of the private power generation equipment is the same. Setting a compensation value of the rotational speed fluctuation compensating means of each of the private power generating facilities; and setting each of the private power generating facilities so that response characteristics (transfer functions) concerning voltage control of the private power generating facilities are the same. A system interconnection protection device for a power generation facility, wherein a compensation value of the excitation system transfer function compensating means of the power generation facility is set.