JP3397608B2 - Power grid connection protection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid interconnection protection device for connecting a private power generation facility such as a garbage power generation system or a cogeneration system to a grid power source.

[0002]

2. Description of the Related Art Conventionally, a grid interconnection system as shown in FIG. 14 has been used in order for a general consumer to interconnect a power generation facility for private use such as cogeneration with a grid power source.
That is, in the upper substation 39, the voltage of the system power supply 1 is stepped down through the transformer 2 and the general customer is supplied with power through the circuit breaker 3. In the general consumer, electric power is supplied to the load 5 via the circuit breaker 4.

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

As a failure detecting means, an AC generator 7
Of the AC current is detected by the current transformer 12, the abnormal current is detected by the generator abnormality detector 13 from the relationship with the output voltage of the AC generator 7, and this detection signal is given to the fault trip circuit 20 to output the circuit breaker 6 Is open.

In addition to this, as a protection means, a current transformer 14 is provided on the output side (substation side) of the circuit breaker 6 and an overcurrent relay (OC) 19 operates a fault trip circuit 20. In addition, when the system power supply 1 is abnormal, particularly when the system power supply 1 is cut off, for example, when the circuit breaker 3 is opened, the frequency is changed from the imbalance between the output power of the AC generator 7 and the load power of the load 5. And the abnormal voltage is the frequency lowering relay (UF) 15, the frequency rising relay (OF) 16, the overvoltage relay (OV) 17, the undervoltage relay (UV) 18
And the like, and the fault trip circuit 20 gives a trip command to the circuit breaker 6 based on these detection signals to open the circuit breaker 6 to protect the load 5 or to reclose the circuit breaker 3. And need to.

[0006]

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

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

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

Based on the above circumstances, the present invention is a system of power generation equipment capable of reliably detecting and protecting an independent operation of a private power generation equipment connected to the grid on the side of the private power generation equipment without providing an expensive transfer interruption device. An object is to provide an interconnection protection device.

[0010]

In order to achieve the above object, the invention corresponding to claim 1 is a system interconnection system in which a power generation facility is connected to a system power source through a circuit breaker, and the output of the power generation facility is provided. A frequency detector for detecting a frequency, a frequency change rate detector for detecting a rate of change of the frequency detected by the frequency detector, and a voltage change reference calculated from the frequency change rate detected by the frequency change rate detector, When the frequency change rate is positive according to this voltage fluctuation reference, the advance reactive power of the power generation equipment is increased or the output voltage of the power generation equipment is decreased, and when the frequency change rate is negative, the delayed reactive power is increased or the output voltage. A function circuit for controlling the power generation equipment so as to increase the active power, an active power detector for detecting active power of the power generation equipment, and an active power detected by the active power detector is small. At any time, voltage fluctuation reference correction means for correcting the voltage fluctuation reference output from the function circuit so as to obtain sufficient fluctuations in the output frequency of the power generation equipment, and the voltage fluctuation reference correction means for increasing the voltage fluctuation of the power generation equipment. And a protection device for disconnecting the power generation equipment from the system bus at the circuit breaker by detecting the frequency fluctuation.

According to the invention according to claim 1, the function circuit increases the frequency fluctuation to detect the frequency abnormality and the excessive frequency change rate, thereby eliminating the use of the expensive transfer cutoff device which has been conventionally used. It becomes possible to detect the islanding operation. According to the invention corresponding to claim 1,
By changing the output voltage of the power generation equipment based on the detection result of the frequency change rate, it is possible to expand the frequency fluctuation and easily detect the islanding operation.

In order to achieve the above object, the invention according to claim 2 is a system interconnection system in which a power generation facility is interconnected with a system power source via a circuit breaker, and frequency detection is performed to detect the output frequency of the power generation facility. Changer, a frequency change rate detector that detects the change rate of the frequency detected by the frequency detector, a dummy load, and the dummy load according to the frequency change rate detected by the frequency change rate detector The load impedance closing / interrupting device for controlling closing or closing to the output side, and the frequency fluctuations promoted by the reactive power change caused by closing or closing the dummy load are detected, and the circuit breaker is used to generate the power from the system bus. It is a system interconnection protection device for power generation equipment, which includes a protection device that disconnects the equipment.

According to the second aspect of the invention, the frequency variation is expanded and the islanding operation is performed by turning on or off the inductive or capacitive dummy load according to the polarity of the detection result of the frequency change rate. It can be easily detected.

In order to achieve the above object, the invention according to claim 3 is a system interconnection system in which a power generation facility is interconnected with a system power source through a circuit breaker, and frequency detection is performed to detect the output frequency of the power generation facility. And a frequency change rate detector that detects the rate of change of the frequency detected by the frequency detector, and a voltage change reference is calculated from the frequency change rate detected by the frequency change rate detector, and the frequency is changed by the voltage change reference. When the rate of change is positive, the advance reactive power of the power generation equipment is increased or the output voltage of the power generation equipment is decreased, and when the frequency change rate is negative, the delayed reactive power is increased or the output voltage is increased. The dummy load is output to the output side of the power generation equipment according to the number of functions for controlling the equipment, the dummy load, and the frequency change rate detected by the frequency change rate detector. A load impedance and power-off device for controlling the input or cutoff, frequency fluctuations is promoted by the voltage variation of the dummy load of the closing or reactive power change and the power plant caused by blocking is detected,
A system interconnection protection device for power generation equipment, comprising a protection device for disconnecting the power generation equipment from a system bus at the circuit breaker.

According to the invention corresponding to claim 3, the voltage fluctuation reference output from the function circuit has an effect of promoting a change in frequency, and on the other hand, the dummy load and the load impedance closing / interrupting device apply the dummy load. The cutoff also has the effect of promoting the change of the frequency f. Therefore, it is possible to easily increase the change in the frequency f by combining the above-mentioned actions, and it is not necessary to make the voltage fluctuation reference too large. Therefore, during the interconnection, there is a gap between the private power generation equipment and the grid. It is possible to suppress the amount of ineffective cross current that occurs in.

In order to achieve the above object, the invention according to claim 4 is a system interconnection system in which a power generation facility is interconnected with a system power source via a circuit breaker, and frequency detection is performed to detect an output frequency of the power generation facility. And a frequency change rate detector that detects the rate of change of the frequency detected by the frequency detector, and a voltage change reference is calculated from the frequency change rate detected by the frequency change rate detector, and the frequency is changed by the voltage change reference. When the rate of change is positive, the advance reactive power of the power generation equipment is increased or the output voltage of the power generation equipment is decreased, and when the frequency change rate is negative, the delayed reactive power is increased or the output voltage is increased. A functional circuit for controlling equipment, an active power detector for detecting active power of the power generation equipment, and the active power detector for detecting the active power even when the active power detected by the active power detector is small. A voltage variation reference correction means for adding the correction to increase the voltage variation reference a sufficient variation is output from the function circuit so as to obtain the output frequency of the equipment,
A dummy load, a load impedance closing / interrupting device that controls the dummy load to the output side of the power generation equipment according to the frequency change rate detected by the frequency change rate detector, and the load impedance closing / interrupting device. A power generation facility comprising: a protective device that detects a reactive power change caused by interruption and a frequency variation promoted by a voltage variation of the power generation facility and disconnects the power generation facility from a system bus at the circuit breaker. This is a system interconnection protection device.

According to the invention according to claim 4, by having the voltage fluctuation reference correction means, sufficient frequency fluctuation can be obtained by increasing the voltage fluctuation reference even when the effective power is small, and The effect that the frequency fluctuation can be prevented from becoming too large when the partial load is sufficiently large can be suppressed by reducing the voltage fluctuation reference.

In order to achieve the above object, the invention according to claim 5 adds load ratio setting means for setting a ratio of active power by a constant impedance load and active power by an induction motor load carried by the power generation equipment, From the active power of the power generation equipment detected by the active power detector, the active power component due to the constant impedance load of the ratio set by the load ratio setting means is detected, and the active power due to the detected constant impedance load is used. The system interconnection protection device for power generation equipment according to claim 1 or 4, wherein the voltage variation reference is corrected by the voltage variation reference correction means.

According to the invention corresponding to claim 5, since the load ratio setting means is provided, the frequency can be sufficiently varied in consideration of the difference in the degree of contribution to the frequency variation due to the load.

In order to achieve the above object, the invention according to claim 6 is characterized in that the voltage fluctuation reference correcting means increases the active power of the power generation equipment detected by the active power detector, or the constant power. The system interconnection protection device for a power generation facility according to any one of claims 1, 4, and 5, wherein the voltage fluctuation reference is reduced as the active power due to the impedance load increases.

According to the invention corresponding to claim 6, since the voltage fluctuation reference correcting means is provided, the islanding operation is detected by expanding the frequency fluctuation during the islanding operation and detecting the frequency or frequency change rate abnormality. Easy to do.

In order to achieve the above object, the invention according to claim 7 is characterized in that, in the dummy load and the load impedance closing / interrupting device, the dummy load is composed of an inductive load and a capacitive load. A load is cut off from the private power generation equipment, and when the frequency change rate detected by the frequency change rate detector is positive, only the inductive load is input to the private power generation equipment to detect the frequency change rate. The system interconnection protection device for power generation equipment according to any one of claims 2 to 6, wherein only the capacitive load is input to the private power generation equipment when the frequency change rate detected by the generator is negative.

In order to achieve the above-mentioned object, the invention according to claim 8 is characterized in that the dummy load and the load impedance closing / interrupting device comprise the dummy load consisting of an inductive load and a capacitive load, and usually the dummy load. A load is applied to the private power generation equipment, and when the frequency change rate detected by the frequency change rate detector is positive, only the capacitive load is cut off from the private power generation equipment to detect the frequency change rate. The system interconnection of the power generation equipment according to any one of claims 2 to 6, wherein only the inductive load is cut off from the private power generation equipment when the frequency change rate detected by the power generator is negative. It is a protective device.

According to the invention according to claim 7 or claim 8, the frequency variation is expanded by turning on or off an inductive or capacitive dummy load according to the polarity of the detection result of the frequency change rate. However, islanding can be easily detected.

In order to achieve the above object, in the invention according to claim 9, the dummy load is composed of a plurality of inductive loads and a plurality of capacitive loads, the frequency change rate is large or small, or the active power is large. Control of turning on and off of the plurality of dummy loads by the load impedance making and breaking device, so that the output of the detector or the output of the active power detector is calculated by the load ratio setting means as the effective power obtained by the ratio set by the load ratio setting means. 9. The system interconnection protection device for power generation equipment according to claim 7 or claim 8, which determines which of the plurality of inductive loads and the plurality of capacitive loads is to be turned on or off. .

According to the invention corresponding to claim 9, the frequency can be sufficiently varied. In order to achieve the above object, the invention according to claim 10 is characterized in that the power generation equipment is a static DC power supply and a power converter or a reactive power compensator. It is a system interconnection protection device for the power generation equipment described in Crab. According to the invention corresponding to claim 10, the same effect as the invention according to any one of claims 1 to 9 can be obtained.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a system interconnection protection device for power generation equipment of the present invention will be described below with reference to the drawings. Here, the points different from the conventional example of FIG. 14 will be mainly described. <First Embodiment> (Corresponding to Claim 1 or Claim 6) (Structure) FIG. 1 is a structural diagram showing a first embodiment of the present invention.
14 is different from the conventional system interconnection protection device shown in FIG. 14 in that it is configured as follows instead of the conventional expensive transfer interruption device 38.

That is, as shown in FIG.
The frequency (f) detector 21 detects the frequency from the output voltage of the
t) The detector 30 detects the frequency change rate V30.

Frequency change rate (df / dt) excess detector 3
1 detects whether or not the frequency change rate V30 exceeds a set value, and when it exceeds the set value, outputs an abnormal output signal V31 and gives it to the fault trip circuit 20. The fault trip circuit 20 gives a trip signal to the circuit breaker 6 to open the electric circuit.

The reactive power detector 23 inputs the output current of the generator 7 detected by the current transformer 12 and the output voltage of the generator 7 to detect the reactive power. The active power detector 26 inputs the output current of the generator 7 detected by the current transformer 12 and the output voltage of the generator 7 to detect active power.

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

The first function circuit 32 inputs the frequency change rate V30 from the frequency change rate detector 30 and outputs the voltage variation reference ΔV ^* , and the frequency change rate is positive (the frequency is rising). Is a voltage that lowers the output voltage of the generator 7 to promote the frequency increase, and increases the output voltage of the generator 7 to promote the frequency decrease when the frequency change rate is negative (frequency is decreasing). The fluctuation reference ΔV ^* is output. Further, the voltage fluctuation reference ΔV ^* is the voltage fluctuation reference correction means 3
3, the correction is applied according to the active power P from the active power detector 26, and the corrected voltage fluctuation reference ΔV ^* ′ is output.

The voltage fluctuation reference correction means 33 is, for example, as shown in FIG.
As shown in, a configuration is possible in which the gain K is defined as a function with respect to the detected active power P and the voltage fluctuation reference ΔV ^* is multiplied by the gain K to obtain the corrected voltage fluctuation reference ΔV ^* ′. Of course, another configuration may be used as long as the voltage variation reference ΔV ^* can be corrected, and a configuration that acts on the function itself of the function circuit 32 and changes or corrects the function may be used.

The reactive power control circuit (AQR) 24 has a reactive power reference Q ^* from a reactive power reference (Q ^* ) setter 28 ^.
And a voltage reference ΔVQ ^* for matching the reactive power detected by the reactive power detector 23.

The automatic voltage adjusting circuit (AVR) 9 has a voltage reference V ^{* from} a voltage reference (V ^* ) setter (90R) 29 ^.
And the voltage reference ΔVQ ^* from the reactive power control circuit 24,
The corrected voltage fluctuation reference ΔV ^* ′ from the voltage fluctuation reference correction means 33 is used to adjust the field of the field winding 8 in order to control the output voltage of the generator 7.

The active power reference setter 25, the active power control circuit 27, the speed governor 11, and the engine 10 form a speed control loop. Reactive power reference setter 2
8, the reactive power detector 23, and the reactive power control circuit 24 constitute a reactive power control loop.

The voltage reference setter (90R) 29, the voltage reference ΔVQ ^* which is the output of the reactive power control circuit 24, and the corrected voltage variation reference Δ from the voltage variation reference correction means 33.
V ^* 'and the automatic voltage adjustment circuit 9 constitute a voltage control loop.

(Operation) Next, the operation of the above-described first embodiment will be described with reference to FIGS. now,
In FIG. 3, the output active power of the AC generator 7 is P, the output reactive power of the AC generator 7 is Q, the load active power required by the load 5 is PL, and the load reactive power required by the load 5 is Q.
Letting L be the outflow active power ΔP and the outflow reactive power ΔQ that flow out to the system power supply 1, respectively.

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

Then, normally, ΔP≈0, ΔQ
Even if the circuit breaker 3 opens in a state close to ≈ 0, the voltage V and the frequency f of the load 5 hardly change, so the relay 15
It cannot be detected at ~ 19 and the islanding operation is continued.

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

The voltage during islanding is determined by P = V ² / R. On the other hand, the frequency f during islanding is Q = (V ² ωC) −
It is determined by (V ² / ωL). In particular, focusing on the frequency f, when the reactive power supplied by the generator 7 is deviated from the reactive power QL required by the load 5 in the forward direction, the frequency f rises, the current iC of the capacitor C increases, and the inductance The current iL decreases and the reactive power changes in the direction of balance.

Further, the output reactive power Q supplied by the generator 7
Is shifted in the delay direction from the load reactive power QL,
The frequency f decreases, the inductance current iL increases, the capacitor current iC decreases, and the reactive power balances.

Next, delta P ≒ 0 frequency variation when it becomes isolated operation in Delta] Q ≠ 0 state after system shut off (t0) as shown in FIG. 4, a stable point while the frequency f varies f1, f
Approach 2 In FIG. 4, f1 is a case where .DELTA.Q is slightly advanced, and f2 is a case where .DELTA.Q is slightly delayed. + Δf and −Δf shown in FIG. 4 are protection relays 15 to 19
This is the level at which islanding can be detected.

FIG. 5 is a diagram for explaining the function and effect of the embodiment shown in FIG. 1, where f is the frequency f detected by the frequency detector 21, and df / dt is the frequency change rate detector 30. Is the frequency change rate detected by the voltage fluctuation reference ΔV ^*, which indicates the output of the function circuit 32.

Now, if f changes as shown in FIG. 5, df
/ Dt is a waveform with a 90 ° phase advance from this. df
If / dt> 0, the frequency is rising, so during this time the function circuit 32 issues a voltage drop command (lead reactive power command).
Is output and the frequency f acts so as to further increase.
When df / dt <0, the frequency is falling, so
During this time, the function circuit 32 outputs a voltage increase command (delayed reactive power command), and the frequency f acts so as to further decrease. As described above, by increasing the frequency fluctuation by the positive feedback action and detecting the frequency abnormality or the excessive frequency change rate by the excessive frequency change rate detector 31, without using the expensive transfer cutoff device 38 used conventionally, It becomes possible to detect islanding.

The effect of increasing the frequency fluctuation is caused not only by the relationship between the reactive power and the reactance load, but also by
It also occurs in active power fluctuations due to voltage fluctuations and in the governor system. The active power fluctuation is determined by the relationship between the voltage fluctuation and the active load. Under the same voltage fluctuation, the active power fluctuation is small when the active load is small, and the active power fluctuation is large when the active load is large. . When the active power fluctuates, the load torque applied to the engine 10 changes, so that it appears as a speed fluctuation, that is, a frequency fluctuation. When the active power fluctuation is small, the frequency fluctuation is also small.
When the active power fluctuation is large, the frequency fluctuation is also large.

That is, under the same voltage fluctuation, the frequency fluctuation is small when the effective load is small, and the frequency fluctuation is large when the effective load is large. Since the protection is performed based on the frequency fluctuation, the voltage fluctuation reference correction means 33 is provided in consideration of the influence of the load amount that the frequency fluctuation becomes small when the effective load is small. Even if the active load is small, the active power fluctuation can be increased by increasing the voltage fluctuation reference and the voltage fluctuation by the correction, so that the frequency fluctuation can be improved.

In the voltage fluctuation reference correction means 33 configured as shown in FIG. 2, the gain K corrects the difference in the influence on the frequency fluctuation due to the size of the active load based on the detected active power. As sufficient frequency variation even when the active component power is low can be obtained, to obtain a voltage variation reference [Delta] V ^* 'which is significantly corrected from the voltage variation reference [Delta] V ^*, to vary the voltage.

It is also conceivable that the frequency fluctuation becomes too large when the effective component load is sufficiently large. Voltage variation reference was corrected reduced from the voltage variation reference ΔV ^* ΔV ^* '
As a result, the voltage fluctuation does not increase so much, so that the frequency fluctuation can be prevented from becoming too large. In FIG. 2, the above-described correction effect is obtained by defining the relationship between P and K such that the gain K is large when the active power P is small and the gain K is small when the active power P is large.

By adding such a circuit, it is possible to detect the isolated operation by expanding the frequency fluctuation during the isolated operation as shown in FIGS. 4 to 6 and detecting the frequency or the frequency change rate abnormality. It will be easier.

(Effect) According to the first embodiment described above, df / dt is detected, and if df / dt> 0, the voltage drop command is issued, and if df / dt <0, the voltage increase command is issued. By giving the voltage to the automatic voltage adjusting circuit 9 and changing the output voltage of the generator 7, it is possible to expand the frequency fluctuation and easily detect the islanding operation.

<Second Embodiment> (Claims 2, 7, and 8)
(Structure) FIG. 7 is a block diagram showing a second embodiment of the present invention, and is different from the drawing showing the first embodiment of FIG. 1 in that it is a function circuit for outputting a voltage fluctuation reference. 32 and the voltage fluctuation reference correction means 33 are not provided, and the dummy load 41
And a load impedance closing device 42.

The dummy load 41 is connected to the bus bar via a load impedance closing / breaking device 42. The dummy load 41 is an inductive load and a capacitive load, and is composed of one inductive load and one capacitive load, or a plurality of inductive loads and a plurality of capacitive loads.

The load impedance input / cutoff device 42 is
For example, as shown in FIG. 8, the capacitive load 411 and the inductive load 412 in the dummy load 41, the switches 421 and 422 provided for them, and the frequency change rate (df
/ Dt) signal and a controller 423 that controls opening and closing of the switches 421 and 422.

(Operation) As described with reference to FIG. 2 in the description of the first embodiment, when the islanding operation is performed, the load 5
When the reactive power supplied from the generator 7 deviates in the forward direction from the reactive power QL required by the frequency f, the frequency f increases, the current iC of the capacitor C increases, and the inductance current iL
When the reactive power supplied by the generator 7 is deviated in the delay direction from the reactive power QL required by the load 5, the frequency f decreases and the inductance current iL decreases. Is increased, the capacitor current iC is decreased, and the reactive power is changed to balance.

In other words, if the balance between the reactive power supplied by the generator 7 and the reactive power required by the load is largely lost, the frequency f changes greatly so that the reactive power is balanced. Therefore, when the frequency f changes from the balance of the reactive power by shifting to the islanding operation, the dummy load 4 is used to break the balance of the reactive power so as to promote the change of the frequency f.
1 may be turned on or off.

On the other hand, the dummy load 41 of the second embodiment is normally cut off from the bus, and df / dt
In the case of> 0, the frequency is increasing, and during this period, the frequency f acts so as to further increase by applying only the inductive load. Further, when df / dt <0, the frequency is decreasing, and during this period, only the capacitive load is turned on so that the frequency f further decreases. By increasing the frequency variation and detecting the frequency abnormality and the frequency change rate excessive by the frequency change rate excessive detector, it is possible to use the expensive transfer cutoff device 38 which has been used conventionally.
It becomes possible to detect islanding.

Also, the dummy load 41 is normally applied to the bus bar, and if df / dt> 0, the frequency is rising, so during this period only the capacitive load is cut off and df / dt
When dt <0, the frequency is decreasing, so that the same action can be achieved by interrupting only the inductive load during this period. However, since the dummy load 41 is constantly turned on, it is necessary to make the reactance of the inductive load and the reactance of the capacitive load substantially the same.

By adding such a circuit, it is possible to detect the islanding operation by expanding the frequency fluctuation during the islanding operation as shown in FIGS. 4 to 6 and detecting the frequency and the frequency change rate abnormality. It will be easier.

(Effect) According to the second embodiment described above, df / dt is detected, and according to the polarity of df / dt,
By turning on or off the inductive or capacitive dummy load, it is possible to expand the frequency fluctuation and easily detect the islanding operation.

<Third Embodiment> (Corresponding to Claim 3) (Structure) FIG. 9 is a structural diagram showing a third embodiment of the present invention, which corresponds to the second embodiment of FIG. Voltage fluctuation standard ΔV ^*
A function circuit 32 for outputting is added.

(Operation and Effect) As described in the description of the first embodiment and the description of the second embodiment, the voltage fluctuation reference ΔV ^* output from the function circuit 32 is the change in the frequency f. On the other hand, the closing and closing of the dummy load 41 by the dummy load 41 and the load impedance closing and breaking device 42 also has the effect of promoting the change of the frequency f. Of course, it is possible to easily increase the change in the frequency f by combining both actions, but it is not necessary to increase the voltage fluctuation reference ΔV ^* so much, so that the generator 7 and the grid are connected during the interconnection. It is possible to suppress the amount of invalid cross current that occurs during the period.

The rise or fall of the output voltage of the generator 7 due to the voltage fluctuation reference ΔV ^* delays the action on the fluctuation of the frequency f due to the delay of the voltage control loop, but the dummy load 41 is turned on or off by the control loop. Since there is no delay, there is no delay in the action on the fluctuation of the frequency f.
The action of turning on or off the current as an assist until the action based on the voltage fluctuation reference ΔV ^* rises can be considered.

<Fourth Embodiment> (Corresponding to Claim 4) (Structure) FIG. 10 is a structural diagram showing a fourth embodiment of the present invention, which corresponds to the first embodiment of FIG. The dummy load 41 and the load impedance closing / breaking device 42 are added, which can be said to be a configuration in which the voltage fluctuation reference correction means 33 is added to the third embodiment.

(Operation and Effect) As described in the description of the first embodiment due to the provision of the voltage fluctuation reference correction means 33 in the effect of the third embodiment, the voltage is reduced even when the effective power is small. There is an effect that a sufficient frequency fluctuation can be obtained by increasing the fluctuation reference ΔV ^* and that the frequency fluctuation becomes too large when the effective load is sufficiently large by reducing the voltage fluctuation reference ΔV ^*. Join.

<Fifth Embodiment> (Corresponding to Claim 5) (Constitution) If the load 5 has a constant impedance load,
There is also an induction motor load. In consideration of the characteristics of the load, in FIGS. 1 and 10, the active power P signal is not input to the voltage fluctuation reference correction means 33 as in FIG. 11, but is input to the load ratio setting means 43, and the load ratio setting means is input. Only the active power due to the constant impedance load is detected by 43, and the signal of the active power P ′ due to the constant impedance load is used as the input signal of the voltage fluctuation reference correction means 33.

The load ratio setting means 43 has a setter 431 as shown in FIG. 12, for example, and is configured to multiply the set value of the setter 431 by the signal of the active power P. (Operation, effect) In the case of induction motor load, voltage fluctuation standard Δ
Even if the output voltage of the generator 7 is changed by V ^*, active power fluctuation does not occur much. Therefore, the active power fluctuation and the frequency fluctuation in the speed governor system which are described in the description of the first embodiment cannot be expected.

Therefore, it is detected how much of the detected active power P is the active power due to the constant impedance load,
Voltage fluctuation reference ΔV due to active power contributing to frequency fluctuation
^* Is to be corrected.

Since the load ratio setting means 43 is for setting the ratio of the constant impedance load, the setter 431
As an example, the set value of can be determined as follows. a) Anyway, considering the total load on the customer premises, it is determined by the ratio of the constant impedance load and the load that is not.

B) Considering only the load that is always used or often used among the loads on the customer premises, the load is determined by the ratio of the constant impedance load and the load that is not. c) Considering the ratio of the constant impedance load that differs depending on the time zone and the load that does not, such as the operation pattern of the consumer plant, the setting is switched depending on the time zone.

In order to switch, an element for storing the pattern is required. d) When performing a fixed amount of reverse power flow operation, the amount of reverse power flow is not regarded as a constant impedance load, but it is considered that the constant impedance load exists only in the customer premises.

By doing so, the frequency can be sufficiently varied in consideration of the difference in the degree of contribution to the frequency variation due to the load. <Sixth Embodiment> (Corresponding to Claim 9) (Structure) As shown in FIG. 13, a dummy load 41 is composed of a plurality of inductive loads and a plurality of capacitive loads. The active power P or P ′ is used to determine how many (or which) loads of these dummy loads 41 should be turned on or off.

(Operation, Effect) As described above, in the fluctuation of active power due to fluctuation of voltage and the fluctuation of frequency by speed governor system, the magnitude of active power of the load is a factor for determining the frequency fluctuation amount. On the other hand, the frequency fluctuation caused by turning on or off the dummy load is a factor that determines the amount of frequency fluctuation by the magnitude of the reactance of the dummy load. When the active power fluctuation due to the voltage fluctuation and the frequency fluctuation due to the speed governor system cannot be sufficiently obtained because the active power of the load is not so large, the reactance of appropriate size is turned on or off to compensate the frequency fluctuation.

In FIG. 13, the dummy load 41 is normally used.
(411a, 411b, 411c, ..., 412a, 41
2b, 412c, ...) are all cut off from the bus bar, when the frequency change rate V30 detected by the frequency change rate detector 30 is positive, only the inductive load of the dummy load is turned on, When the frequency change rate V30 is negative, the frequency variation can be promoted by turning on only the dummy capacitive internal capacitive load. Regarding the number of dummy loads to be input, the number is increased when the active power P or P ′ is small, and the number is decreased when the active power P or P ′ is large. The relationship between the number of dummy loads applied to the active power P or P ′ can be seen in the same manner as the relationship between P and K when K in FIG. 2 is regarded as the number of dummy loads applied.

Each load of the dummy load 41 (411a, 41a
1b, 411c, ..., 412a, 412b, 412c,
When the capacities are the same, the number is determined and the charging is controlled as described above. However, when the loads are provided as different capacities and the effective power P or P ′ is small, a dummy load having a large capacity is charged to enable the effective charging. A configuration in which a dummy load having a small capacity is input when the electric power P or P ′ is large can be considered.

By doing so, the frequency can be changed sufficiently. <Seventh Embodiment> (Corresponding to Claim 10) In the first to sixth embodiments, the rotary power generation facility mainly including the AC generator 7 and the engine 10 has been described. Even in the case of a DC power supply and an inverter, or in the case of reactive power generation equipment, it is configured to control to increase the forward reactive power when the frequency change rate is positive and to increase the delayed reactive power when the frequency change rate is negative. You may. With this configuration, the above-mentioned first
~ The same effect as any of the sixth embodiments can be obtained.

[0078]

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

[Brief description of drawings]

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

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

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

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

5 is an operation explanatory diagram of the embodiment of FIG. 1. FIG.

FIG. 6 is an operation explanatory diagram of the embodiment of FIG. 1.

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

FIG. 8 is a diagram supplementing a part of a block according to the second embodiment.

FIG. 9 is a block diagram showing a third embodiment of a system interconnection protection device according to the present invention.

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

FIG. 11 is a diagram supplementing a part of a block according to a fifth embodiment.

FIG. 12 is a diagram supplementing a part of the blocks of the fifth embodiment.

FIG. 13 is a diagram supplementing a part of the blocks of the sixth embodiment.

FIG. 14 is a block diagram showing an example of a conventional system interconnection protection device for power generation equipment.

[Explanation of symbols]

1 ... System power supply, 2 ... Transformer, 3, 4, 6 ... Circuit breaker, 5 ...
Load, 7 ... Alternator, 8 ... Field winding, 9 ... Automatic voltage adjusting circuit (AVR), 10 ... Engine, 11 ... Governor, 1
2, 14 ... Current transformer, 13 ... Generator abnormality detector, 15 ... Frequency lowering relay (UF), 16 ... Frequency rising relay (O
F), 17 ... Overvoltage relay (OV), 18 ... Undervoltage relay (UV), 19 ... Overcurrent relay (OC), 20 ... Fault trip circuit, 21 ... Frequency detector, 23 ... Reactive power detector, 24 ... Reactive power control circuit (AQR), 25 ... Active power reference setter, 26 ... Active power detector, 27 ... Active power control circuit (APR), 28 ... Reactive power reference setter,
29 ... Voltage reference setting device (90R), 30 ... Frequency change rate detector, 31 ... Frequency change rate excessive detector, 32 ... Function circuit, 33 ... Voltage change reference correction means, 39 ... Upper substation,
41 ... Dummy load, 42 ... Load impedance input / interruption device, 411, 411a, 411b, 411c ... Capacitive load, 412, 412a, 412b, 412c ... Inductive load, 421, 421a, 421b, 421c, 42
2, 422a, 422b, 422c ... Switch, 423
... controller, 43 ... load ratio setting means, 431 ... setting device, 44 ... frequency deviation setting device.

Front page continuation (72) Inventor Chihiro Okado 1-24-2 Harumi-cho, Fuchu-shi, Tokyo Inside Toshiba FA System Engineering Co., Ltd. (72) Inventor Shigeo Nomiya 1-1-1 Shibaura, Minato-ku, Tokyo (56) References JP-A-8-223809 (JP, A) JP-A-8-331765 (JP, A) JP-A-56-153935 (JP, A) JP-A-10- 191570 (JP, A) Actual development Sho 48-88933 (JP, U) Actual development Sho 53-75743 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J 3/00-5 / 00 H02H 3/44-3/46

Claims (10)

(57) [Claims] 1. In a grid interconnection system in which power generation equipment is connected to a grid power source via a circuit breaker, a frequency detector for detecting an output frequency of the power generation equipment, and a rate of change in frequency detected by the frequency detector. And a frequency change rate detector for detecting the frequency change rate detector, and calculates a voltage fluctuation reference from the frequency change rate detected by the frequency change rate detector. To increase or decrease the output voltage of the power generation equipment, when the frequency change rate is negative, to increase the delay reactive power or to increase the output voltage function circuit for controlling the power generation equipment, active power of the power generation equipment An active power detector for detecting the active power detector, so that when the active power detected by the active power detector is small, sufficient variation is obtained in the output frequency of the power generation equipment. Voltage fluctuation reference correction means for correcting the voltage fluctuation reference output from several circuits, and frequency fluctuations that are promoted due to voltage fluctuations of the power generation equipment, and the circuit breaker detects the power generation equipment from the system bus. And a protection device for disconnecting the power generation system. 2. In a grid interconnection system in which power generation equipment is connected to a grid power source via a circuit breaker, a frequency detector for detecting an output frequency of the power generation equipment, and a rate of change in frequency detected by the frequency detector. A frequency change rate detector for detecting a load, a dummy load, and a load impedance input for controlling the dummy load to the output side of the power generation equipment according to the frequency change rate detected by the frequency change rate detector. A circuit breaker; and a protection device that detects a frequency fluctuation promoted by a reactive power change caused by turning on or breaking the dummy load and disconnects the power generation equipment from a system bus at the circuit breaker. System protection device for power generation equipment. 3. In a grid interconnection system in which power generation equipment is connected to a grid power source via a circuit breaker, a frequency detector for detecting an output frequency of the power generation equipment, and a rate of change of frequency detected by the frequency detector. And a frequency change rate detector for detecting the frequency change rate detector, and calculates a voltage fluctuation reference from the frequency change rate detected by the frequency change rate detector. Or decrease the output voltage of the power generation equipment, when the frequency change rate is negative, the number of functions to control the power generation equipment to increase the delay reactive power or increase the output voltage, a dummy load, the frequency A load impedance that controls turning on or off of the dummy load to the output side of the power generation equipment according to the frequency change rate detected by the change rate detector. An on / off device, and a protection that detects a reactive power change caused by turning on or off of the dummy load and a frequency fluctuation promoted by a voltage fluctuation of the power generation equipment, and disconnects the power generation equipment from a system bus at the circuit breaker. A system interconnection protection device for power generation equipment, characterized in that it comprises a device. 4. In a grid interconnection system in which power generation equipment is connected to a grid power source via a circuit breaker, a frequency detector for detecting an output frequency of the power generation equipment, and a rate of change in frequency detected by the frequency detector. And a frequency change rate detector for detecting the frequency change rate detector, and calculates a voltage fluctuation reference from the frequency change rate detected by the frequency change rate detector. To increase or decrease the output voltage of the power generation equipment, when the frequency change rate is negative, to increase the delay reactive power or to increase the output voltage function circuit for controlling the power generation equipment, active power of the power generation equipment An active power detector for detecting the active power detector, so that when the active power detected by the active power detector is small, sufficient variation is obtained in the output frequency of the power generation equipment. Voltage fluctuation reference correction means for correcting the voltage fluctuation reference output from several circuits, a dummy load, and the dummy load according to the frequency change rate detected by the frequency change rate detector And a load impedance closing and breaking device for controlling closing and closing of the dummy load, and a change in reactive power caused by turning on or breaking of the dummy load and a frequency change facilitated by a voltage change of the power generation equipment are detected, and the circuit breaker is used. A protection device for disconnecting the power generation equipment from a power generation bus, and a system interconnection protection device for the power generation equipment. 5. Effectiveness of the power generation equipment detected by the active power detector is added by adding load ratio setting means for setting a ratio of active power due to a constant impedance load carried by the power generation equipment and active power due to an induction motor load. The active power component due to the constant impedance load of the ratio set by the load ratio setting means is detected from the electric power, and the voltage fluctuation reference correction means corrects the voltage fluctuation reference using the active power due to the detected constant impedance load. The system interconnection protection device for power generation equipment according to claim 1 or 4. 6. The voltage fluctuation reference correction unit is configured to correct the voltage fluctuation reference as the active power of the power generation equipment detected by the active power detector increases or as the active power of the constant impedance load increases. 6. The system interconnection protection device for power generation equipment according to claim 1, characterized in that 7. The dummy load and the load impedance closing / interrupting device are configured such that the dummy load is composed of an inductive load and a capacitive load, and the dummy load is normally cut off from the private power generation facility. When the frequency change rate detected by the frequency change rate detector is positive, only the inductive load is put into the private power generation equipment, and when the frequency change rate detected by the frequency change rate detector is negative, The system interconnection protection device for power generation equipment according to any one of claims 2 to 6, wherein only a capacitive load is input to the private power generation equipment. 8. The dummy load and the load impedance closing / interrupting device are configured such that the dummy load is composed of an inductive load and a capacitive load, and the dummy load is normally input to the private power generation facility. When the frequency change rate detected by the frequency change rate detector is positive, only the capacitive load is cut off from the private power generation facility, and when the frequency change rate detected by the frequency change rate detector is negative, 7. The system interconnection protection device for power generation equipment according to claim 2, wherein only an inductive load is cut off from the private power generation equipment. 9. The dummy load is composed of a plurality of inductive loads and a plurality of capacitive loads, and has a frequency change rate, an output of the active power detector, or an output of the active power detector. The active power determined by the ratio set by the load ratio setting means is used for controlling the making and breaking of the plurality of dummy loads by the load impedance making and breaking device, and the plurality of inductive loads and the plurality of inductive loads are used. 9. The system interconnection protection device for power generation equipment according to claim 7, wherein which of the capacitive loads is to be turned on or off is determined. 10. The system interconnection protection of the power generation facility according to claim 1, wherein the power generation facility is a static DC power source and a power converter or a reactive power compensator. apparatus.