JP2000152507A - Accident detection for power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device detecting an accident in a power system exactly and a device detecting an accident in the power system and determining whether or not the accident exists on commercial system side. SOLUTION: This accident detection device for power system detects accident in a power system subjected to linkage operation through a separated breaker 4, in which a commercial system 1 and a distributed power source 3 for private use are inserted in a linkage bus 7, whereas it is determined as being an accident in the power system for annunciation if both of a voltage change component obtained by subtracting phase-to-phase voltage at that time from phase-to- phase voltage in the normal case and current running through the breaker 4 are above a prescribed level.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an accident in a power system and an apparatus for judging that the accident has occurred in a commercial system, and more particularly to an apparatus without erroneous detection.

2. Description of the Related Art FIG. 9 is a circuit diagram showing a configuration of a conventional power system accident detection apparatus. The commercial system 1 is connected to the three-phase interconnection bus 7 via the power receiving transformer 2, and the private power source 3 is connected. A separation circuit breaker 4 is interposed in the interconnection bus 7 to which the load 6 is connected, and
And the distributed power source 3 can be separated. Each of the phases of the interconnection bus 7 is provided with an instrument current transformer 5 for outputting a current signal of the phase, and the instrument current transformer 5
Is connected to an accident detection device 8. The figure shows U
Only the fault detector 8 connected to the phase is shown, which receives the U-phase current signal I _1U output from the current transformer 5 for the instrument. The inside of the accident detection device 8 includes a level detection circuit 9 and a notification circuit 1 as shown in a frame of a dotted line.
0. Level detection circuit 9 receives a current signal I _1U, the current signal I _1U is a circuit for outputting a signal when it exceeds a predetermined detection level. The notification circuit 10 is a circuit that determines that an accident has occurred in the power system when a signal is input, and outputs or displays a notification signal to notify the accident. Although not shown, the accident detection device 8 is similarly connected to the other phases V and W via the respective current transformers 5 for the instruments. In FIG. 9, by setting the detection level of the level detection circuit 9 higher than the level of the load current that always flows, if an accident occurs on the commercial system 1 side or the distributed power supply 3 side, an overcurrent is applied to the interconnection bus 7. Notification circuit 10 as it flows
Informs that is an accident. Thus, the power system is protected by, for example, interrupting the interconnection bus 7 with the separation circuit breaker 4.

However, the conventional apparatus as described above has a problem that the occurrence of an accident may be erroneously determined and it is not possible to determine whether the accident has occurred on the commercial system side. there were. In other words, even if an accident has not occurred, current with an abnormal waveform may enter the interconnection bus due to switching of the power system or voltage fluctuations even if an accident has not occurred. In some cases, malfunctions occurred only by detection. In order to avoid such a malfunction, conventionally, the detection level for determining an accident has been set several times higher than the level of the normal load current. Therefore, the conventional power system accident detection device has low detection sensitivity and lacks reliability. In addition, the separation circuit breaker is designed to be able to instantaneously cut off the interconnection bus because there is a possibility that the decentralized power supply may collapse together with an accident on the commercial system side. However, if the distributed power supply is a rotating machine power supply,
If the separation circuit breaker is cut off when an accident occurs on the distributed power source side load, the power system becomes unstable, and it takes a long time to return to a normal operation state. for that reason,
It is necessary to accurately detect an accident and determine that the accident has occurred on the commercial system side. Further, with the conventional power system accident detection device, it was not possible to identify the category of occurrence of the accident. An object of the present invention is to provide an apparatus for accurately detecting an accident in a power system and an apparatus for detecting an accident in a power system and determining that the accident has occurred in a commercial system.

According to the present invention, in order to attain the above object, according to the present invention, a commercial power system and a private distributed power source are connected to each other via a separation circuit breaker inserted in a connection bus. This is a device that detects an accident in the power system in which the voltage change from the normal value of the inter-phase voltage of the interconnection bus and the current flowing through the separation circuit breaker both exceed a predetermined level. It may be determined that an accident has occurred in the system. Thus, an accident is determined by adding the inter-phase voltage change, so that an accident in the power system can be accurately detected. Further, the present invention is a device for detecting an accident in a power system in which a commercial system and a private distributed power supply are connected to each other via a disconnecting circuit breaker inserted in a connection bus, and which detects a normal voltage between phases of the connection bus. When the voltage change from the time value and the current flowing through the separation circuit breaker both become equal to or higher than a predetermined level and the voltage change continues for a predetermined time or more while maintaining the predetermined level or higher, an accident occurs in the power system. May be determined to have occurred. As a result, the continuation of the voltage change is also added to the condition for judging the accident, so that an accident in the power system can be detected more accurately. Further, in such a power system accident detection device, when a power system accident is detected, the current of the interconnection bus when the direction in which the interconnection bus flows from the distributed power source side to the commercial system side is positive polarity, It may be determined that an accident has occurred on the commercial power system side when the polarity of the current of the distributed power source is the same as the polarity of the current of the distributed power source when the direction flowing from the distributed power source to the interconnection bus is positive. Thus, if an accident occurs on the commercial system side, the current of the interconnection bus and the current of the distributed power supply have the same polarity, and it can be determined that the accident has occurred on the commercial system side. Further, in such a power system accident detection device, when a power system accident is detected, the current of the commercial system when the direction flowing from the commercial system to the interconnection bus is set to positive polarity, When the polarity of the current flowing into the distributed power supply is different from the polarity of the current flowing into the distributed power source when the flow direction is positive, it may be determined that an accident has occurred on the commercial system side. Accordingly, if an accident occurs on the commercial system side, the current of the commercial system and the current of the distributed power source have different polarities, so that it can be determined that the accident has occurred on the commercial system side. Further, in such a power system fault detection device, when a power system fault is detected, the polarity of the voltage change obtained by subtracting the interphase voltage at that time from the normal interphase voltage of the interconnection bus, and the interconnection bus, When the direction of the current flowing from the distributed power source side to the commercial system side is a positive polarity and the polarities of the currents of the interconnection buses are the same, it may be determined that an accident has occurred on the commercial system side. As a result, if an accident occurs on the commercial grid side, the change in the inter-phase voltage of the interconnecting bus and the current on the interconnecting bus have the same polarity, so it is necessary to determine that the accident has occurred on the commercial grid side. Can be. Further, in such a power system fault detection device, when a power system fault is detected, the polarity of the normal interphase voltage of the interconnection bus and the direction in which the power flows from the distributed power source side to the commercial power system side are positive. In this case, when the polarity of the current difference change obtained by subtracting the normal value from the current difference between the phases of the interconnection bus is the same, it may be determined that an accident has occurred on the commercial system side. As a result, if an accident occurs on the commercial system side, the polarity of the inter-phase voltage during normal operation of the interconnection bus and the polarity of the current difference change become the same, so that the accident has occurred on the commercial system side. Can be determined.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments.
Will be explained. FIG. 1 shows a power system according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a configuration of a conventional accident detection device. Three-phase ream
The system breaker 4 is interposed in the system bus 7,
Is connected to the commercial system 1 and the private power source 3
You. The configuration of the interconnection bus 7 to which the load 6 is connected is as follows.
It is the same as FIG. Between each phase of the interconnection bus 7
When the instrument transformer 15 that outputs the interphase voltage is interposed
The current of each phase is output to each phase of the interconnection bus 7
An instrument current transformer 5 is provided. Accident detection device 1
4 is a device for detecting an accident in the power system,
On the output side of the power transformer 15 and the output side of the instrument current transformer 5
It is connected. That is, the accident detection device 14
Signal between U-phase and V-phase output from transformer 15 for use
V_UV, V signal between the V and W phases_VWBetween the W and U phases
Voltage signal V_WU, And instrument current
U-phase current signal I output from the heater 5_1U, V-phase current signal
Issue I_1V, W-phase current signal I_1WIs receiving. The figure shows
Pressure signal V_UVAnd the current signal I_1UOnly shown. Accident detection
The inside of the delivery device 14 is shown in a dotted frame. sand
That is, the voltage change detection circuit 16 outputs the voltage signal V_UVReceiving
Voltage signal V when interconnection bus 7 is normal_UVFrom that time
Voltage signal V_UVThen, the voltage change is subtracted. Lebe
The circuit 17 detects the output signal of the voltage change detecting circuit 16.
Received when the output signal exceeds a predetermined level.
Output a signal. On the other hand, the level detection circuit 9 outputs the current signal I
_1UReceiving the current signal I_1UExceeds a certain level
Output a signal. The AND circuit 18 detects the level
OR circuit when receiving output signals of both paths 17 and 9
19 to output a signal. This accident detection device 14
Only one configuration up to the AND circuit 18 is shown in FIG.
Although the same configuration is not distributed in all three phases,
And the configuration of the remaining phases is the voltage signal V_VWAnd current signal
I_1V, Voltage signal V_WUAnd the current signal I_1WIs receiving. Or
The circuit 19 outputs the output signal W of the AND circuit 18 from each phase. ₁
When an output signal is received from any one of the phases.
A signal is output to the knowledge circuit 10. Information
The road 10 is notified when a signal from the OR circuit 19 is received.
Signal an accident by outputting or displaying a signal
I do. FIG. 7 is a time chart illustrating a voltage change.
is there. The upper time chart shows the waveform of the interphase voltage,
The lower timing chart shows the waveform of the voltage change. Waveform
11 is an example of a normal case, and the waveform 12 is a time t.₀In things
This is an example of the case where a fault occurs and the voltage becomes zero. Voltage change
The minute is the value obtained by subtracting the waveform 12 from the waveform 11,
It looks like shape 13. Returning to FIG. 1, the voltage change detection circuit
Numeral 16 has an internal storage circuit, and reserves a normal voltage waveform.
From the normal phase voltage of the interconnection bus 7
Outputs the amount of voltage change obtained by subtracting the interphase voltage.
ing. In the event of an accident, the voltage change of the interconnection bus 7 always increases
As the current increases, the current flowing through the separation circuit breaker 4 increases.
You. The accident detection device 14 is connected to the interconnection bus 7 as described above.
Voltage change and the current of the separation circuit breaker 4 are both predetermined.
Accident occurred in the power system when the
The conventional device shown in FIG.
With only the simple condition of only detecting the overcurrent value like
To prevent the alarm circuit 10 from operating and malfunctioning
Can be. FIG. 2 is a circuit diagram of a power supply according to another embodiment of the present invention.
It is a circuit diagram showing the composition of the accident detection device of a power system. accident
The detection device 20 is connected to each other similarly to the accident detection device 14 of FIG.
Voltage signal V_UVAnd the current signal I_1UIs receiving. Dotted line
The configuration up to the upper OR circuit 19 in the frame is the same as in FIG.
The same. In the lower stage, another set of voltage change detection circuits 16 and
Level detection circuits 17 and 9 are provided, and a voltage signal V_UVWhen
Current signal I_1UHas been received. This voltage change detection circuit
16 and the functions of the level detection circuits 17 and 9 are as shown in FIG.
Is the same as Output signal of lower level detection circuit 17
Is input to the time setting circuit 21, and the time setting circuit 21
If the output signal of the level detection circuit 17 is longer than a predetermined time,
For example, a signal is output when the time is continued for 1 ms or more. further,
The output signal of the time setting circuit 21 is obtained by converting the input signal to a predetermined time.
AND circuit 23 via voltage holding circuit 22 for maintaining the width
Is input to The AND circuit 23 includes a voltage holding circuit 22
When both output signals from the level detection circuit 9 are input
The signal is output to the OR circuit 24. This accident detection device 20
, The configuration up to the AND circuit 23 is only one in the figure.
Although not shown, the same configuration is distributed in all three phases.
And the configuration of each of the remaining phases is a voltage signal V_VWAnd electricity
Flow signal I_1V, Voltage signal V_WUAnd the current signal I_1WReceiving
You. The OR circuit 24 outputs the output of the AND circuit 23 from each phase.
Signal W_TwoAnd receive an output signal from any phase
Output a signal to the AND circuit 25 when
I have. The AND circuit 25 outputs the output signals of the OR circuits 19 and 24.
Output a signal to the notification circuit 10 when both signals are input.
You. Notification circuit 10 receives a signal from AND circuit 25.
Output or display a notification signal when
To report the accident. In FIG. 7, a predetermined voltage change
Level △ V_mThen, the waveform 13 becomes the time t₀To t
_mIt will be continued until. Voltage change is instantaneously determined
Level △ V_mCan cause noise in the power system.
This can happen when they are superimposed. But the accident
If this occurs, make sure that the voltage
However, for example, it continues for 1 ms or more. Therefore, given
A voltage change equal to or higher than the level is equal to or longer than a predetermined time, for example, 1
ms or more as an accident judgment condition.
Thus, the accident can be accurately detected. Return to FIG.
The voltage holding circuit 22 outputs the output signal of the time setting circuit 21.
Is converted to a waveform that lasts, for example, about ten ms, and is output.
Things. This is because the AND circuit 23 is a level detection circuit.
9 and the output signal from the voltage holding circuit 22
Are made to make it easier to compare. In FIG.
Either the voltage change of the system bus 7 or the current of the
Also exceeds a predetermined level, and the voltage of the interconnection bus 7
For more than a predetermined time while the change is at or above a predetermined level, for example
If it lasts more than 1ms, it will be judged as an accident
So that malfunction can be further prevented.
Was. FIG. 3 is a circuit diagram of a further embodiment of the present invention.
It is a circuit diagram showing the composition of the accident classification detection device of a power system.
The configuration of the power system different from that of FIG.
The current transformer 27 for the instrument is interposed in the phase.
7, a U-phase current signal I_2U, V-phase current signal
I_2V, W-phase current signal I_2WIs input to the accident detection device 26.
The only thing that has changed. In the figure, the voltage signal V_UVAnd current signal
Issue I_1U, I_2UOnly shown. Accident detection device 26
Is the configuration up to the upper OR circuit 19 in the frame of the dotted line.
Is the same as FIG. The lower polarity determination circuit 28
Signal I_1UAnd the current signal I_2UThe polarity of the
A signal indicating polarity is output. Classification determination circuit 29
Is a signal indicating that the output signal from the polarity discrimination circuit 28 indicates the same polarity.
If it is a signal, a signal is output to the OR circuit 30. This accident detection
In the output device 26, the configuration up to the OR circuit 30 is shown in FIG.
Although only one is shown, three of the same configuration
The phases are distributed, and the configuration of each of the remaining phases is a voltage signal.
V_VWAnd the current signal I_1V, I_2V, Voltage signal V_WUAnd the current signal I
_1W, I_2WIs receiving. The OR circuit 30 is provided for each phase.
Output signal W of minute determination circuit 29_ThreeWhich phase or one phase
Signal to the AND circuit 31 when receiving the output signal.
Output. AND circuit 31
Notification when both output signals of roads 19 and 30 are input
A signal is output to the path 32. The notification circuit 32 includes an AND circuit
Output an annunciation signal when it receives a signal from
Or an accident occurred on the commercial system 1 side
Notify that you are. In FIG. 3, the current signal I_1U,
I_1V, I_1WAnd the current signal I_2U, I_2V, I_2WMeans
From the winding terminals K and L of the secondary winding of the current transformers 5 and 27
The currents that are extracted and flow through the primary conductor
Current signal I in the direction of arrow B _1U, I_1V, I_1W
And the current signal I_2U, I_2V, I_2WHave the same polarity as each other
It is connected like this. An accident occurred on the commercial system 1 side,
When an accident current flows in the system bus 7 in the direction of arrow A, the distributed power
The current on the third side flows in the direction of arrow B. Therefore, on the spot
The current signal I_1U, I_1V, I_1WAnd the current signal I_2U, I
_2V, I_2WHave the same polarity, so that the notification circuit 32
And that the accident has occurred on the commercial system 1 side
Be informed. The configuration up to the OR circuit 19 in FIG.
Is a circuit for detecting the presence or absence of an accident.
It may be replaced with a configuration of up to two AND circuits 25. Figure
4 is a power system according to still another embodiment of the present invention.
FIG. 2 is a circuit diagram showing a configuration of an accident classification detection device of FIG. Figure 3 and
In a different configuration, the current transformer for instrument 34 is also provided on the commercial system 1 side.
U-phase power output from the current transformer for instrument 34.
Flow signal I_3U, V-phase current signal I_3V, W-phase current signal I_3W
Is input to the accident detection device 33 only. Figure
Has a voltage signal V_UVAnd the current signal I_1U, I_2U, I_3UOnly
It is shown. Within the dotted frame of the accident classification detector 33
The configuration up to the upper OR circuit 19 in FIG.
You. The lower polarity determination circuit 28 outputs the current signal I_2UAnd current signal
Issue I_3UDetermine the polarity and indicate the same polarity or different polarity
Output a signal. The classification determination circuit 35 is a polarity determination circuit 2
OR circuit if the output signal from 8 is a signal showing different polarity
The signal is output to 36. In this accident detection device 33
Only one configuration up to the OR circuit 36 is shown in FIG.
No, but the same configuration is distributed in all three phases.
And the configuration of the remaining phases is the voltage signal V_VWAnd current signal
I_1V, I_2V, I_3V, Voltage signal V_WUAnd the current signal I_1W,
I_2W, I_3WIs receiving. The OR circuit 36 is provided for each phase.
Output signal W of decision circuit 35_FourAnd from which phase or one phase
However, when an output signal is received, a signal is output to the AND circuit 37.
It is designed to help. AND circuit 37 is an OR circuit
Notification circuit when both 19 and 36 output signals are input
32 to output a signal. The notification circuit 32 includes the AND circuit 3
7 outputs a notification signal when receiving a signal from
Or an accident has occurred on the commercial system 1 side
Notify that In FIG. 4, the current signal I_2U,
I_2V, I_2WAnd the current signal I_3U, I_3V, I_3WMeans
Whether the winding terminals K and L of the secondary winding of the current transformers 27 and 34 are
And the current flowing through the primary conductor
Current signal I in the direction of arrow C_2U, I_2V, I
_2WAnd I_3U, I_3V, I_3WAre connected so that they have the same polarity.
Have been. An accident occurred on the commercial system 1 side,
When the fault current in the direction of arrow B flows to the
The current flows in the direction of arrow D. Therefore, in that case
Is the current signal I_2U, I_2V, I_2WAnd I_3U, I_3V, I_3WAnd
Since the polarity is different, the notification circuit 32 outputs a notification signal,
It is notified that the accident has occurred on the commercial system 1 side.
The configuration up to the OR circuit 19 in FIG.
Since it is a circuit for detecting the presence or absence,
The configuration up to the road 25 may be replaced. FIG.
Of power system accident classification according to another embodiment
It is a circuit diagram which shows the structure of an output device. Configuration different from Fig. 2
Is provided with an accident detection device 38 instead of the accident detection device 20.
That is the point. Within the dotted line frame of the accident detection device 38
The configuration up to the upper OR circuit 19 in FIG.
You. The polarity discrimination circuit 40 at the lower stage of the accident classification detector 38 is
Voltage signal V between phases_UVThrough the voltage change detection circuit 39
And the current signal I_1UAnd determine their polarity.
Separately, a signal indicating whether the polarity is the same or different is output. Ward
The minute determination circuit 29 outputs the signal from the polarity determination circuit 40
If the signals have the same polarity, a signal is output to the OR circuit 41.
You. In this accident detection device 38, up to the OR circuit 41
Although only one configuration is shown in the figure,
Are divided into three phases, and the composition of the remaining phases is
Each voltage signal V_VWAnd the current signal I_1V, Voltage signal V_WUAnd electricity
Flow signal I_1WIs receiving. The OR circuit 41 is divided into phases.
Output signal W of decision circuit 29_FiveAnd from which phase or one phase
However, when an output signal is received, a signal is output to the AND circuit 42.
Power. The AND circuit 42 outputs the outputs of the OR circuits 19 and 41.
Outputs a signal to the notification circuit 32 when both signals are input
I do. The notification circuit 32 receives a signal from the AND circuit 42.
Outputs or displays a notification signal when a signal is emitted
To notify that an accident has occurred on the commercial system 1 side
You. In FIG. 5, a voltage change detecting circuit 39 detects a voltage signal.
Issue V_UV, V_VW, V_WUFrom the normal value of
Outputs the subtracted voltage change. The current signal I_1U, I
_1V, I_1WAre the winding terminals K, of the secondary winding of the current transformer 5 for the instrument.
The current drawn from L and flowing through the primary conductor is in the direction of arrow A
Is connected so as to have a positive polarity when. Commercial
If an accident occurs on the system 1 side, the voltage
When the minute has a positive polarity, the current signal I_1U, I_1V, I_1WIs positive
become. On the other hand, when the voltage change has a negative polarity, the current signal I
_1U, I_1V, I_1WBecomes negative polarity. Therefore, the voltage signal
V_UV, V_VW, V_WUVoltage change and current signal I_1U, I_1V,
I_1WIf an accident occurs on the commercial system 1 side, be sure to
Become the same polarity, so that the notification circuit 32
Is output, reporting that an accident has occurred on the commercial system 1 side.
Be informed. The configuration up to the OR circuit 19 in FIG.
Is a circuit for detecting the presence or absence of an accident.
May be replaced with the configuration up to the AND circuit 25. FIG.
Is a power system according to still another embodiment of the present invention.
It is a circuit diagram which shows the structure of an accident division detection apparatus. Different from Fig. 2
Configuration is to detect the accident classification instead of the accident detection device 20
The point is that the device 50 is provided. Accident classification detector 5
Configuration up to the upper OR circuit 19 within the frame of the dotted line 0
Is the same as FIG. Note at the bottom of the accident classification detector 50
The storage circuit 56 is configured to output a voltage signal between the U-phase and the V-phase of the interconnection bus 7.
Issue V _UVAnd receive the normal waveform temporarily
Even if there is an accident, it is as if the grid is normal.
Output voltage waveform signal. On the other hand, the current conversion circuit 57
Is the current signal I of the U-phase and V-phase of the interconnection bus 7_1U, I_1VTo
Receiving the current signal I_1UFrom the current signal I_1VOf the value after subtracting
Outputs a current signal. The current difference change detection circuit 55
Receiving the output signal of the
The output signal of the current conversion circuit 57 in the normal state is temporarily recorded.
Remember that the output signal of the current conversion circuit 57 at the time of the accident
The output signal of the current conversion circuit 57 when the system is normal is
Output the subtracted signal. The polarity determination circuit 54 stores
Output signal from the circuit 56 and the current difference change detecting circuit 55
Signal and determine the polarity of both signals,
A signal indicating whether the polarity is the same or different is output. Classification judgment
The circuit 53 has the same polarity as the output signal from the polarity determination circuit 54.
A signal is output to the OR circuit 52 only in the case of This thing
In the late detection device 50, the configuration up to the AND circuit 52 is as follows.
Although only one is shown in FIG.
Are divided into three phases, and the configuration of the remaining phases is
Pressure signal V_VWAnd the current signal I_1V, I_1W, Voltage signal V_WUAnd current
Signal I_1W, I_1UIs receiving. The OR circuit 52
Output signal W of classification determination circuit 53₆Which phase or one phase
When receiving an output signal from the
Is output. The AND circuit 51 is connected to the OR circuits 19 and 52.
When both output signals are input, a signal is sent to the notification circuit 32.
Output. The notification circuit 32 receives a signal from the AND circuit 51.
Output or display a notification signal when received
Notify that an accident has occurred on the commercial system 1 side
I do. FIG. 8 is a time chart for explaining a change in current difference.
It is. The upper time chart shows the waveform of the current difference between the phases.
The lower time chart shows the waveform of the current difference change.
You. Waveform 61 is the current difference between the normal phases, and waveform 62 is
Time t₀Accident occurs and the current difference between the phases rises sharply
This is an example of the case. The current difference change is calculated from the waveform 62 to the waveform 61
Is subtracted, and a waveform 63 at the lower stage is obtained.
Returning to Fig. 6, if an accident occurs on the commercial grid side,
7 and the current difference change increases.
The polarity of the minute must always be the same as the polarity of the
Matches. Therefore, by determining its polarity,
To determine that an accident has occurred on the commercial grid side.
it can. This keeps the power system stable.
I came to be able to. Note that the OR circuit 19 shown in FIG.
Is a circuit for detecting the presence or absence of an accident.
Thus, the configuration up to the AND circuit 25 in FIG.
No.

As described above, according to the present invention, when the amount of change in the inter-phase voltage of the interconnection bus from the normal value and the current flowing through the separation circuit breaker both exceed a predetermined level, an accident occurs in the power system. As a result, it was possible to accurately detect an accident in the electric power system and eliminate malfunction. In addition, the amount of change from the normal value of the inter-phase voltage of the interconnection bus and the current flowing through the separation circuit breaker are all equal to or higher than a predetermined level, and the amount of change from the normal value of the inter-phase voltage of the interconnection bus is a predetermined amount. When it is determined that an accident has occurred in the power system when the electric power system has continued for a predetermined time or more while maintaining the level or more, the accident in the power system can be more accurately detected, and the malfunction can be further eliminated. . Further, in such an accident detection device for a power system, the current flowing through the interconnection bus from the private distributed power source side to the commercial system side having a positive polarity, and the direction flowing from the private distributed power source into the interconnection bus, being positive. It is determined that an accident has occurred on the commercial system side by determining that an accident has occurred on the commercial system side when the polarities with the current of the private distributed power supply are the same. And the power system can be kept stable. Further, in such an accident detection device for a power system,
The polarities of the current of the commercial system with the positive direction flowing from the commercial system to the interconnection bus and the current of the private distributed power system with the positive direction flowing from the private distributed power supply to the interconnection bus were different from each other. Sometimes, by determining that an accident has occurred on the commercial system side, it can be determined that the accident has occurred on the commercial system side, and the power system can be kept stable. Further, in such an accident detection device for a power system, the polarity of the voltage change obtained by subtracting the inter-phase voltage at that time from the normal inter-phase voltage of the interconnection bus, and the direction in which the interconnection bus flows from the private distributed power source side to the commercial system side It is determined that an accident has occurred on the commercial system side by determining that an accident has occurred on the commercial system side when the polarity of the current of the interconnection bus with Power system can be kept stable. Further, in such an accident detection device for a power system, the polarity of the inter-phase voltage of the interconnection bus at normal time and the current difference between the phases of the interconnection bus when the direction flowing from the distributed power supply side to the commercial system side is set to positive polarity. By judging that an accident has occurred in the commercial system when the polarity of the current difference change obtained by subtracting the normal value is the same, it is possible to determine that the accident has occurred in the commercial system. The power system can be kept stable.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a power system accident detection apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a power system accident detection apparatus according to another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of a power system accident detection apparatus according to still another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a power system accident detection apparatus according to still another embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of an apparatus for detecting an accident in a power system according to still another embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a power system accident detection device according to still another embodiment of the present invention.

FIG. 7 is a time chart illustrating a voltage change;

FIG. 8 is a time chart illustrating a current difference change amount.

FIG. 9 is a circuit diagram showing the configuration of a conventional power system accident detection device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Commercial system 2 Power receiving transformer 3 Distributed power supply 4 Separation circuit breaker 5,27,34 Instrument current transformer 6 Load 7 Interconnection bus 8,14,20,26,33,38,50 Accident detection device 9,17 Level detection circuit 10, 32 Notification circuit 11, 12 Voltage waveform 13 Voltage change waveform 15 Instrument transformer 16, 39 Voltage change detection circuit 18, 23, 25, 31, 37, 42, 51 AND circuit 19, 24 , 30,36,41,52 OR circuit 21 hours setting circuit 22 voltage holding circuit 28,40,54 polarity determination circuit 29, 35 category determination circuit 57 current conversion circuit 55 current difference variation detecting circuit 56 storage circuit V _UV, V _VW , V _WU voltage signals I _1U , I _1V , I _1W , I _2U , I _2V , I _2W , I _3U , I _3V , I
_3W current signals _{W 1, W 2, W 3} , W 4, W 5, W 6 signals from other phases

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuo Shibata 1-1-1 Tanabeshinda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Fuji Electric Co., Ltd. 2G033 AA01 AB04 AD13 AD16 AD18 AG12 5G066 HA11 HA13 HB02

Claims (6)

[Claims] An apparatus for detecting an accident in a power system in which a commercial system and a private distributed power supply are connected to each other via a separation circuit breaker inserted in a connection bus, comprising: The power system is characterized in that it is determined that an accident has occurred in the power system when both the voltage change from the normal value of the voltage and the current flowing through the separation circuit breaker have exceeded a predetermined level. Accident detection device. 2. An apparatus for detecting an accident in a power system in which a commercial power system and a private distributed power supply are connected to each other via a separation circuit breaker inserted in a connection bus, comprising: When both the voltage change from the normal value of the voltage and the current flowing through the separation circuit breaker are equal to or higher than a predetermined level and the voltage change is equal to or higher than a predetermined level and continues for a predetermined time or longer, An accident detection device for an electric power system, which determines that an accident has occurred in a system. 3. An apparatus for detecting a fault in a power system according to claim 1, wherein when a fault in the power system is detected, the direction in which the interconnection bus flows from the distributed power source side to the commercial system side is determined. An accident occurs on the commercial system side when the polarity of the current of the interconnection bus when the polarity is positive and the direction of the current of the distribution power source when the direction flowing from the distributed power source to the interconnection bus is the same are the same. An accident detection device for an electric power system, which determines that an accident has occurred. 4. An apparatus for detecting an accident in a power system according to claim 1, wherein, when an accident in the power system is detected, the direction of flow from the commercial system to the interconnection bus is positive. It is determined that an accident occurred on the commercial power system side when the polarity of the current of the commercial power system and the current of the distributed power source were different from each other when the direction of the current flowing from the distributed power source to the interconnection bus was positive. An accident detection device for an electric power system. 5. The power system fault detecting device according to claim 1, wherein when a power system fault is detected, the phase voltage at that time is calculated from the normal phase voltage of the interconnection bus. When the polarity of the subtracted voltage change and the polarity of the current of the interconnection bus when the direction in which the interconnection bus flows from the distributed power supply side to the commercial system side is positive are the same, An accident detection device for a power system, wherein the accident is determined to have occurred in the system. 6. The power system fault detecting device according to claim 1, wherein when a fault in the power system is detected, the polarity of the inter-phase voltage in the normal state of the interconnection bus and the distributed power source are detected. When the polarity of the current difference change obtained by subtracting the normal value from the current difference between the interconnection bus phases when the direction of flow from the side to the commercial system side is positive is the same as the commercial system side An accident detection device for a power system, wherein the accident is determined to have occurred in the system.