JP2633150B2 - Method and device for detecting state of reverse charging from private power generation facility to power supply system side - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting the state of reverse charging from a private power generation facility installed in a power consumer to a power supply system.

[0002]

2. Description of the Related Art In recent years, consumers who consume large amounts of electric power have installed private power generators in order to save electric power in the office and to supply electric power to the office when an emergency power failure or the like occurs. Private power generation facilities for supplying inexpensive power generated by a private power generator to a private load in a facility while receiving a constant supply of power from a private power generator are being actively installed. The private power generation equipment and the power supply system side of the power company are provided with necessary measures to maintain safety in accordance with the `` Guidelines for System Interconnection Technology, '' When a failure or the like occurs, various protection devices prevent the loss of equipment on the load side, and work to recover the failure as soon as possible. In addition, when the reverse power flow phenomenon in which the surplus power of the private generator flows to the power supply system due to the fluctuation of the private load in the system interconnection between the private power generation equipment and the power supply system side, Adjustment may not be possible, which may adversely affect nearby power receiving equipment or damage the private generator itself. For this reason, devices have been developed to open the circuit breaker at the interconnection point to stop power transmission from the private generator or to reduce the output of the private generator to prevent reverse power flow. However, in recent years, laws and regulations have been revised on the power supply system side to actively purchase surplus power from distributed power sources such as new energy, and private power generation facilities have been Surplus power can be sold according to the interconnection, and it is no longer necessary to equip a reverse power flow prevention device.

[0003]

However, in a facility where reverse power flow is allowed so that the surplus power of the private power generator can be supplied to the power supply side, it is determined whether or not the power supply side has lost power. That is, it is not possible for the private power generation equipment to detect whether the circuit breaker on the power plant side is closed or open due to, for example, a ground fault accident or a disconnection accident. If the circuit breaker on the side of the private power generator is closed with the circuit breakers on the side closed, the voltage of the private generator is applied to the faulty no-load line on the power supply system side, Maintenance, inspection and restoration work are dangerous. When power is supplied by closing the circuit breaker on the power plant side after recovery from the failure on the power supply system side,
If the circuit breaker on the side of the private power generation facility is closed, there is a risk that the private generator will step out or be destroyed due to mismatches in frequency, phase, voltage, etc., and power cannot be supplied from the power supply system side. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a private power generation system connected to a power supply system side in which the current state of the power supply system is a power loss state. In other words, whether or not there is, that is, the state of reverse charging from the private power generation facility to the power supply system side can be easily detected, and the corresponding private power generation side action is taken to perform maintenance and inspection, restoration work, etc. of the electric line related to the accident etc. To provide a method and a detection device for detecting the state of reverse charging from the private power generation equipment to the power supply system side, which can safely perform the power generation and prevent step-out and destruction of the private power generator at the time of recovery from an accident or the like Is to do.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a power supply loss on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility 12 to a power supply system side 10. This is a method for detecting a state of reverse charging in a state, wherein a detection impedance load section 22 is connected from an intermediate position between a private power generation facility 12 and a power supply system side 10, and the detection impedance load section is turned on and off. Then, the load on the private power generation facility 12 side is periodically changed,
With reference to the connection point 24 of the impedance load unit 22, a change in the current or power of the private power generation facility 12 and the power supply system 10 with respect to the connection point 24 is detected,
The power loss state of the power supply system side 10 is determined based on the change amount, and the power generation system 12
And a method for detecting the state of reverse charging from the private power generation facility to the power supply system side by detecting the state of reverse charging to the power supply system. Further, a method for detecting a state of reverse charging in a power loss state on the power supply system side in a system interconnection in which reverse power flow is allowed from the private power generation facility 12 to the power supply system side 10 is provided. A detection impedance load unit 22 is connected from an intermediate position with the power supply system side 10, and the detection impedance load unit 22 is turned on and off to periodically fluctuate the load on the private power generation facility 12 side. With reference to the connection point 24 of the load unit 22, the amount of change in current or power on the private power generation facility side and the power supply system side with respect to the connection point 24, and the change amount on the detection impedance load unit side from the connection point. , And the ratio of the amount of change on the power supply system side to the amount of change in the detection impedance load section is smaller than the reference value, and the detection impedance is When the ratio of the amount of change on the private power generation equipment side to the change amount of the load unit is greater than the reference value, it is determined that the power supply system side has lost power, and the state of reverse charging from the private power generation equipment to the power supply system side is determined. It comprises a method of detecting the state of reverse charging from the detected private power generation equipment to the power supply system. Next, a device for detecting the state of reverse charging in the power supply system side in a power loss state in a system interconnection in which reverse power flow is allowed from the private power generation facility 12 to the power supply system side 10, the private power generation facility 1
2 provided at an intermediate position between the power supply system 2 and the power supply system side 10
4, the detection impedance load unit 22 connected in
A switch unit 26 for turning on and off the detection impedance load unit 22 to periodically fluctuate the load on the private power generation equipment 12 side; and a connection point 24 of the impedance load unit 22 as a reference. First detection unit 2 provided on private power generation facility 12 side with respect to connection point 24
8a, and a second detection unit 28b provided on the power supply system side 10 with respect to the connection point 24.
In response to this, the amount of change in the current or power on the private power generation facility side and the power supply system side is detected, and the power loss state on the power supply system side is determined based on the change amount, and the reverse power from the private power generation facility to the power supply system side is detected. It comprises a detecting device for detecting the state of reverse charging from the private power generation facility that detects the state of charge to the power supply system side. In addition, private power generation equipment 12
Device for detecting a state of reverse charging in a power loss state of the power supply system side in a system interconnection where reverse power flow is allowed from the power supply system side 10 to the power supply system side 10, wherein the private power generation facility 12 and the power supply system side 10 A detection impedance load unit 22 connected at a connection point 24 provided at an intermediate position between the detection impedance load unit 22 and the detection impedance load unit 22;
A switch unit 26 for periodically varying the load on the private power generation facility side and a connection point 24 of the impedance load unit 22 are used as a reference, and the connection point 24 is generated on the detection impedance load unit 22 side. A first comparing unit 30a that detects a ratio of a change amount of the current or the power generated on the private power generation equipment side to a change amount of the current or the power,
With reference to the connection point 24 of the impedance load unit 22, the amount of change in current or power generated on the detection impedance load unit 22 side with respect to the connection point 24 is
A second comparator 30b for detecting a ratio of a change in current or power generated in the power supply system, wherein a ratio of a change in the power supply system to a change in the impedance load unit 22 for detection is a reference value. When the ratio of the change amount of the private power generation equipment to the change amount of the detection impedance load unit is smaller than the reference value, it is determined that the power supply system side is in a power loss state, and the power supply system side is changed from the private power generation equipment to the power supply system side. It comprises a detection device for detecting the state of reverse charging from the private power generation facility by detecting the state of reverse charging to the power supply system.

[0006]

According to the method and the detecting device for detecting the state of reverse charging from the private power generation facility to the power supply system side according to the present invention, the private power generation facility installed in the power consumer is connected to the power supply system side. Then, the output of the private power generation equipment is adjusted to the same voltage, frequency, and phase as the power supply system side, and supplied to the private load. When the load capacity of the private load is larger than the output of the private power generation equipment, the power is replenished from the power supply system side, and conversely, the load capacity of the private load decreases, and surplus power is generated in the private power generation equipment. Then, the surplus power is made to flow backward to the power supply system side, and the surplus power is sold to the power supply system side. These electric powers are detected as a current flow or electric power by a detection unit connected to a private power generation facility connected to a branch line branched from the power supply system. However, it is necessary to detect whether the flow from the private power generation equipment side to the power supply system side is a healthy reverse tide state on the power supply system side or an unhealthy reverse charge state on the power supply system side. For this purpose, a detection impedance load unit is connected to an intermediate position between the private power generation facility and the power supply facility, and the detection impedance load is turned on and off to periodically fluctuate the load on the private power generation facility. Then, with reference to the connection point of the impedance load unit, the amount of change in current or power on the private power generation facility side and the power supply system side with respect to the connection point is detected, and the amount of current or power flowing through the detection impedance load unit is detected. If the amount of change on the power supply system side with respect to the amount of change is greater than the amount of change on the private power generation facility side, it is detected that the power supply system side is sound and in a reverse tide state. Conversely, the ratio of the amount of change on the power supply system side to the amount of change in the current or power flowing through the detection impedance load section is smaller than the reference value,
When the ratio of the change amount of the private power generation equipment to the change amount of the detection impedance load section is larger than the reference value, it is determined that the power supply system side has lost power, and the reverse charge from the private power generation equipment to the power supply system side is performed. It is possible to prevent the occurrence of various accidents while detecting that the operation is performed and operating the predetermined protection device.

[0007]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a single-line diagram of a first embodiment for implementing a method for detecting a state of reverse charging from a private power generation facility to a power supply system according to the present invention. A private power generation facility 12 is connected to the grid side 10. In the method of the present invention, the state of reverse charging in the power supply system side power loss state in the system interconnection in which reverse power flow is allowed from the private power generation facility 12 to the power supply system side 10 is detected. Here, the reverse charging refers to a state in which a voltage is applied from the private power generation equipment 12 to the power supply system side 10 in a power supply loss state on the power supply system side. In the figure, a power supply system side 10 is provided with a generator 14 for supplying electric power.
4, an electric line 16 is connected and extended, and a general load, a power load, and the like (not shown) are connected to the electric line 16.

[0008] A private power generation facility (generator) 12, for example, as one power consumer, is connected to the electric line 16 via a branch line 18. Various private loads 20 to which electric power is supplied from the private power generation facility 12 are connected to the private power generation facility 12.

A feature of the present invention is that a detection impedance load section 22 is connected to an intermediate position between the private power generation facility 12 and the power supply system side 10, and the detection impedance load section 22 is turned on and off. In this case, the load on the private power generation facility 12 side is periodically fluctuated. At this time, a connection point 24 to the branch line 18 of the detection impedance load unit 22 is used as a reference, and the private power generation facility 12 and the power supply system are connected to the connection point 24. Detecting the amount of change in current or power on the side 10, judging the power loss state of the power supply system 10 based on the amount of change, and detecting the state of reverse charging from the private power generation facility 12 to the power supply system 10 It is.

[0010] Now, from the private power generation equipment 12 side to the connection point 24
Self-generated current flowing to the power supply system side 10 from the connection point 24 = IJ, the power system side current flowing from the connection point 24 to the power supply system side 10, the detection impedance load section 22 is only the resistor R, and the load current flowing therethrough = IR. I do. Therefore, the power supply system side 1
In order to detect whether 0 is a reverse tide state in a healthy state or a reverse charge state in an unhealthy state, the detection impedance load unit 22 is changed to an ON state connected to a connection point 24. At this time, the change in the current IR flowing through the impedance load is equal to the sum of the change in the power system side current IK and the self-generation side current IJ, and if the power supply system side 10 is healthy, the short-circuit current is Since it is extremely large with respect to the emission-side current, a change in the power system-side current IK and a change in the spontaneous-generation side current IJ are established.

For example, it is detected that IK = IJ = 10A,
It is assumed that a current is flowing from the private power generation facility 12 to the power supply system 10. Therefore, in order to detect whether the power supply system side 10 is in a reverse tide state in a healthy state or in a reverse charging state in an unhealthy state, the impedance load unit 22 for detection is connected to the connection point 24. Change to ON state.
At this time, the resistance R of the impedance load is set to 10Ω,
When load current IR = 10A is detected and at the same time IJ = 10A and there is no change or the change width of IJ is small, the state becomes closer to IK = 0A according to Kirchhoff's law, and the current flowing to the impedance load side is Therefore, the power supply system side 10 is in a healthy state, and the surplus power of the private power generation equipment 12 is transferred to the power supply system side 10.
Is detected to be in the reverse tide state supplied to

Basically, as described above, based on Kirchhoff's law, the connection point 24 is considered as a reference, and when the detection impedance load section 22 is turned on, the current or the amount of change in power on the power supply system side is changed. Can be determined to be sound when it is larger than that of the private power generation facility side, but if an extremely large number of private power generation facilities are arranged recently, it is not possible to exceed the short-circuit capacity of the power supply system side However, such a situation is generally considered impossible. However, when the short-circuit capacity due to the self-generated power becomes large, when the detection impedance load section is turned on as described above, the IR side The current to the load eventually becomes a problem of load sharing. Then, at this time, when the short-circuit capacity on the power supply system side and the total short-circuit capacity on the in-house power generation side have been approximated, the comparison of the above-mentioned change amount is more specifically performed with the short-circuit capacity on the power supply system side. Then, the ratio to the total short-circuit capacity of the private power generation side is set, and the determination is made based on the ratio of the amount of change on the IK side and IJ side to the set ratio.

When the power supply system side 10 is unhealthy, the resistance R = 1 of the impedance load as in the normal state.
A load current IR corresponding to 0Ω flows ,
If only such a constant-current power supply is used for private power generation,
In this case, the ratio DVJR = DIJ / DIR of the change DIJ of the spontaneous-side current IJ to the change DIR of the load current IR, and the change D of the load current IR
Ratio D of change DIK of power system side current IK to IR
VKR = DIK / DIR, IJ / IR, IK
/ IR change ratio is calculated, and depending on whether the ratio is larger or smaller than the reference value derived from the set ratio, soundness or unhealth on the power supply system side, in other words, reverse power flow
State or reverse charge state is detected. That is, when the detection impedance load unit 22 is turned on and off, a ratio of a change amount of the power supply system side 10 to a change amount of the detection impedance load 22 with respect to the connection point 24 is smaller than a reference value, and It determines that the power supply system side 10 is a power loss state when the change amount of the private power generation equipment 1 2 side with respect to the change amount of the detection impedance load section 22 is larger than the reference value. At this time, it is detected that the private power generation facility 12 is in the reverse charging state to the power supply system side 10.

For example, the reference value DDS = 50%, and IJ
= 20A, IK = 20A, IR = 0A, the impedance load side is turned on, and IJ = 20A, IK = 13
A, if IR = 7A is detected, in this case, DVKR = 7/7 = 100%> 50% DVJR = 0/7 = 0% <50% DVKR> DDS and DVJR <DDS The power supply system side 10 is in a healthy state, that is, the private power generation facility 1
It is determined that the surplus power on the second side is flowing backward to the power supply system 10. Also, IJ = 20A, IK = 20
A, IR = 0A, when IJ = 25A, IK = 17A and IR = 8A are detected by turning on the impedance load side, DVKR = 3/8 = 37% <50% DVJR = 5/8 = 63 %> 50% DVKR <DDS and DVJR> DDS, the change in load current is shared by the private power generation equipment 12, and it is determined that the power supply system side 10 is in an unhealthy state or a reverse charge state.

Next, as shown in FIG. 1, a device for detecting the state of reverse charging from the private power generation facility to the power supply system side is connected to the private power generation facility 12 through the electric wire line 16 on the power supply system side 10. A detection impedance load unit 22 connected to a connection point 24 provided at an intermediate position of the extended branch line 18, and the detection impedance load unit 22 is turned on and off to cycle the load on the private power generation facility 12 side. A switch section 26 for changing the impedance, a first detection section 28a provided on the private power generation equipment side with respect to a connection point 24 of the detection impedance load section 22, and the connection point 24.
Detection unit 2 provided on the power supply system side 10
8b.

The detection impedance load section 22 includes:
For example, an impedance load such as a resistor R is provided, and the resistor R, the switch unit 26, and the third detection unit 28c on the impedance load side are connected in series to the connection point 24,
The end of the resistor R is grounded. The impedance load section 22 is not necessarily limited to the resistor R, but may be a combination of a reactance L, a capacitance C and the like. Further, the first, second, and third detection units 28
Reference numerals a, 28b, and 28c each include a current transformer, a wattmeter, and the like, and detect a change in current or power.

Further, the apparatus for detecting the state of reverse charging from the private power generation equipment to the power supply system side comprises turning on and off the detection impedance load section 22 to generate a current or power generated on the impedance load side. And a first comparing unit 30a for detecting a ratio of a change in current or power generated on the private power generation facility 12 side with respect to a change in the power supply system. A second comparing unit 30b for detecting a ratio of a change amount of the current or the electric power. The first comparison unit 30a
The first detection unit 28a and the third detection unit 2
8c is connected to the input side of the second comparing section 30b. The second detecting section 28b and the third detecting section 28c are connected to the input side of the second comparing section 30b, and the output sides of the first and second comparing sections 30a and 30b are connected. Is connected to an interconnection breaker 32 connected to the branch line 18 at a position closer to the power supply system side 10. The first,
The second comparing sections 30a and 30b are composed of comparison detectors such as comparators, and the switching section 26 is composed of switching elements such as thyristors.

FIG. 2 shows a procedure (flowchart) of a detection process for detecting a state of reverse charging from the private power generation facility to the power supply system. As is clear from the figure, first of all, from the first step 34, in the next step 36, the switch 2
6 is counted on and off, and the number of times is added T
I do. This addition T is set to about three times. In the next step 38, the first, second, and third detection units 28a, 28b,
At 28c, the autonomous side current IJ and the power system side current I
K, Measure the load current IR. In the next step 40, it is determined whether the electric power system side current IK is larger or smaller than the contract value IH with the private power generation facility 12 side. If IK> IH in step 40 is YES, the overcurrent protection relay 42 causes the interconnection breaker 32 to open 44.

If NO in step 40, it is determined in next step 46 whether the power system side current IK is larger or smaller than a current starting value established value IS for operating the protection overcurrent relay. In this step 46, IK> I
If YES to S, the current value of IK is integrated over time in step 48, and the integrated value TI of IK is compared with the integral set value TS of the overcurrent relay in the next step 50 to determine TI.
If YES for TS, return to step 38
If O, the overcurrent relay 42 operates and the circuit breaker 3
2 is opened 44. In step 46, IK> IS
Is NO, that is, if IK <IS, the next step 5
Then, in step 52, it is determined whether or not the thyristor SCR of the switch section 26 is OFF. YE
If the state is S, that is, if the switch unit 26 is OFF, the pre-current, the power system-side pre-current IKP, the load-side pre-current IRP, and the self-generating-side pre-current IJP before the detection impedance load unit 22 is connected in step 54 are calculated. The measurement is performed, and the process returns to step 36. When step 52 is NO, that is, when the switch 26 is ON, the next step 5
6 and go to step 58 to detect whether the voltage or frequency of each power system side, self-propelled side, load side, etc. is normal or abnormal state in which the voltage or frequency rises or falls below a specified value. The open circuit breaker 32 is opened 44 while the symbol is displayed. Steps 40 and 46 described above,
The determination of the power system side current IK, the self-generation side current IJ, the load current IR, and the like in Steps 56 and 58 and the like are made by the first and second comparison units 30a and 30b, and the interconnection breaker 32 is turned on by a protection relay or the like. To make it work.

If the above voltages and frequencies are normal, DIK = IK−IKP, DIR = IR−
IRP and DIJ = IJ-IJP are calculated by the first and second comparison units 30a and 30b, respectively. That is, the amount of change in each of the power system side current IK, the spontaneous side current IJ, and the load current IR of the impedance load in the ON / OFF state of the switch unit 26 is calculated. Then, it is determined whether or not DIR = 0 in step 64. If DIR = 0 in step 64, the display lamp 66 turns on the thyristor SC.
It is determined that the impedance load section 22 including R is defective or the power supply is completely disconnected 68. If step 64 is NO, in the next step 70 NRI = (DIK + DIJ) /
Calculate DIR.

At the next step 72, it is determined whether or not the NRI is not substantially 1. If step 72 is YES, that is, if the NRI is not 1, the first, second and third lamps are indicated by the display lamps 66. The inconvenience of setting the sensors of the detection units 28a, 28b, 28c, etc., or the failure 74 of the electric circuit including the current transformer
Judge. If NO in step 72, that is, if it is determined that the NRI is approximately 1, in the next step 76, DVKR = D
The percentage ratio of IK / DIR, DVJR = DIJ / DIR is calculated, and in the next step 78, for example, the change in the power system side current and the change in the autonomous side current with respect to the change in the load current of the impedance load section 22 are calculated. Reference value DD of change
Assuming S = 50%, DVKR> DDS, and DVJR
<DDS is determined. This step 78 is YE
In the case of S, most of the change in the load current is shared by the power system side current, and the power supply system side 10 is in a healthy state and is determined to be in the reverse tide state in step 36.
Go back.

If step 78 is NO, ie, if DV
As KR <DDS and DVJR> DDS, most of the change DIR in the load current is shared by the private power generation equipment 12, and the power supply system side 10 is determined to be unhealthy and in a reverse charge state. Is done. Therefore, the next step 80
Enter the counter K = K + 1, and in the next step 82, K <
If YES under 3, the process returns to step 38 and repeats the measurement.
, Ie, DVKR <DDS and DVJR> DDS
, The power supply system side 10 is detected as unhealthy and in the reverse charging state as before, and the dangerous state of the reverse charging is indicated by the display lamp 84 in order to protect the private power generation side equipment 12. Is displayed, the interconnection breaker 32 is opened 44.

Accordingly, whether the current state of the power supply system 10 on the private power generation facility 12 side is a power loss state, that is, the state of reverse charging from the private power generation facility 12 to the power supply system side 10 Can be easily detected, and the corresponding private power generation equipment 12 can be treated to safely perform maintenance and inspection of the electric line related to the accident, restoration work, etc., and damage to the private generator at the time of restoration from the accident etc. Can be prevented.

Next, FIG. 3 shows a single-line connection diagram of a second embodiment of the present invention, in which
0 is connected to the private power generation facility 12. As is clear from the figure, on the power supply system side 10, a circuit breaker CB1 is connected to a generator 14 for supplying power, and an electric line 16 is extended from the circuit breaker CB1. A load or another power load is connected. The private power generation facility 12 is a branch line 1 branched from the electric wire path 16.
8 and a detection unit 28d connected to the interconnection circuit breaker CB2. A circuit breaker CB3 is connected to the branch line 18 extended from the detection unit 28d. A private power generation facility (private generator) 12 is connected to the circuit breaker CB3. Further, a connection point 24 is provided at an intermediate position between the circuit breaker CB3 and the detector 28d, and a detection unit 28e for detecting current, power, and the like on the private load side is connected to the connection point 24. A private load 86 and a detection impedance load section 88 are connected in parallel to 28e, and a switch section 90 is connected in series to the detection impedance load section 88. In order to open the circuit breaker CB2 on the side of the private power generation facility 12 and protect the private power facility 12 side, the same circuit breaker CB2
Is connected to a switch unit 90, detectors 28d and 28e, and the like.

In the above embodiment, the private power generation facility 1
The electric power required by the private load 86 in 2 is supplied by the private power generation equipment 12. When the electric power of the private load 86 is required to be equal to or more than the output of the private power generation equipment 12, the insufficient electric power is supplied to the private load 86 via the interconnection breaker CB2, and the flow of this current is detected by the detection unit 28d. Is detected. Further, when the load capacity of the private load 86 decreases and surplus power is generated in the output of the private power generation equipment 12, the surplus power is automatically transmitted from the interconnection breaker CB2 to the power supply system side 1.
The power is returned to 0 and sold to the power supply system side 10. While these current flows are constantly detected by the detection unit 28d, when the display of the detection unit 28d becomes zero, whether the power balance between the output of the private power generation facility 12 and the load capacity of the private load 86 is equal. , The failure has occurred in the power supply system side 10 and the circuit breaker CB1 has been opened. Then, a failure occurs in the power supply system side 10 and the circuit breaker CB1
Is open, it is necessary to open the circuit breaker CB2 for preventing reverse charging from the private power generation facility 12 side.

Therefore, when the control unit 92 detects that the current display of the detection unit 28d is zero, the switch unit 90 of the detection impedance load unit 88 connected to the connection point 24 at the same time.
Is closed, and the load capacity of the detecting impedance load unit 88 connected in parallel with the private load 86 is periodically changed at least once. At this time, if the detection unit 28d detects a change in the current and power between the power supply system side 10 and the private power generation facility 12 side, it is determined that the power supply system side 10 has no failure and is sound. Conversely, when the display of the detection unit 28d still shows zero, and when no current flows from the power supply system side 10 to the private power generation facility 12 side, a failure state in which the circuit breaker CB1 and the like of the power supply system side 10 are opened, That is, it can be immediately determined that the sound is unhealthy. At this time, the controller 92
Issues an open command to the interconnecting circuit breaker CB2 to immediately open the interconnecting circuit breaker CB2 to protect the private power generation equipment 12 side.

As a result, the private power generation facility 12 can supply power to the private load 86 in the facility while operating continuously, and the breaker CB1 and other circuit breakers are opened due to a failure, and the power is supplied to the unloaded electric power line 16. The failure inspection and recovery work can be performed safely without transmitting power from the private power generation equipment 12 or the like. In addition, even if the circuit breaker CB1 on the power supply system side 10 is closed immediately after the restoration of the failure of the power line 16, even if the interconnecting circuit breaker CB2 is opened, the equipment on the private power generation facility 12 side is not damaged, and the private power generation system 12 is not damaged. After synchronizing the voltage, frequency, phase, etc. with the power supply system side 10 with a synchronization verifier, the machine closes the interconnection breaker CB2 and connects the private power generation equipment 12 to the power supply system side 10 while connecting the system. It is linked to return to the normal state.

[0028]

As described above, according to the method for detecting the state of reverse charging from the private power generation facility to the power supply system according to the first aspect, the grid connection in which reverse power flow is allowed to the supply system side. A method for detecting a state of reverse charging in a power supply system side of a power supply system in a power loss state, comprising: connecting a detection impedance load section from an intermediate position between a private power generation facility and a power supply facility; On, off, periodically fluctuate the load on the private power generation equipment side, based on the connection point of the impedance load unit,
The amount of change in the current or power on the private power generation facility side and the power supply system side with respect to the connection point is detected, and the power loss state on the power supply system side is determined based on the change amount. By detecting the state of reverse charging to the power supply system, it is possible to easily detect whether the power supply system side is in a power loss state, that is, the state of reverse charging from the private power generation facility to the power supply system side, It is possible to safely perform maintenance and inspection, restoration work, and the like of electric lines related to an accident and the like by performing a measure on the side of the private power generation, and also prevent loss of synchronism and destruction of the private generator at the time of restoration from an accident and the like.

According to a second aspect of the present invention, there is provided a method for detecting a state of reverse charging in a power supply loss state on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility to a power supply system side. There, connecting a detection impedance load portion from an intermediate position between the private power generation equipment and the power supply equipment, turning on and off the detection impedance load, periodically fluctuating the load on the private power generation equipment side, With reference to the connection point of the impedance load unit, the amount of change in current or power on the private power generation facility side and the power supply system side with respect to the connection point, and the amount of change on the detection impedance load unit side from the connection point. The ratio of the amount of change in the power supply system to the amount of change in the impedance load for detection is smaller than the reference value, and the change in the impedance load for detection is compared. If the ratio of the amount of change on the side of the private power generation facility to the amount of power is greater than the reference value, it is determined that the power supply system side has lost power and the state of reverse charging from the private power generation facility to the power supply system side is detected. By comparing and detecting the amount of change on the power supply system side and the private power generation equipment side with respect to the change amount when the detection impedance load unit is turned on, the power supply system side power loss state, Can be accurately determined.

Next, according to the third aspect, an apparatus for detecting a state of reverse charging in a power loss state on the power supply system side in a system interconnection in which reverse power flow is allowed from the private power generation equipment to the power supply system side. And a detection impedance load unit connected at a connection point provided at an intermediate position between the private power generation facility and the power supply facility, and turning on and off the detection impedance load to reduce the load on the private power generation facility side. A first detecting unit provided on the side of the private power generation facility with respect to a connection point between the switch unit and the impedance load unit based on a connection point for periodically changing the connection point; A second detection unit provided on the supply system side,
Having a change in current or power on the private power generation facility side and the power supply system side with respect to the connection point, and determining a power loss state on the power supply system side based on the change amount;
By detecting the state of reverse charging from the private power generation facility to the power supply system side, the first and second detectors detect the amount of change in current or power on the private power generation facility side and the power supply system side. However, whether or not the power supply system is in a power loss state, that is, the state of reverse charging from the private power generation facility to the power supply system side can be easily detected, and the corresponding private power generation side measures are taken to prevent an accident, etc. It is possible to safely perform maintenance and inspection, restoration work, and the like of the electric line, and to prevent loss of synchronism and destruction of the private generator at the time of restoration from an accident or the like.

According to a fourth aspect of the present invention, there is provided an apparatus for detecting a state of reverse charging in a power supply loss state on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility to a power supply system side. There is a detection impedance load section connected at a connection point provided at an intermediate position between the private power generation facility and the power supply facility, and the detection impedance load is turned on and off to periodically cycle the load on the private power generation facility side. The switch unit and the connection point of the impedance load unit are used as a reference, and the amount of change in the current or power generated on the detection impedance load unit side with respect to the connection point with respect to the connection point. A first comparing unit for detecting a ratio of a change amount of a current or a power generated in the impedance load unit, and detecting the connection point based on the connection point of the impedance load unit. A second comparator for detecting the ratio of the amount of change in the current or power generated in the power supply system to the amount of change in the current or power generated in the impedance load unit, and a detection impedance load unit. If the ratio of the amount of change on the power supply system side to the amount of change is smaller than the reference value, and the ratio of the amount of change on the private power generation facility side to the amount of change in the detection impedance load is greater than the reference value, It is preferable to determine the state of power loss and to detect the state of reverse charging from the private power generation facility to the power supply system side. The data detected by the first and second detection units is used by the first and second comparison units. While comparing, the amount of change on the power supply system side or the private power generation equipment side with respect to the change amount of the detection impedance load section is accurately determined, whereby the power supply system side power loss state, private power generation The ability to determine accurately the inverse state of charge from the facility side.

[Brief description of the drawings]

FIG. 1 is a single-line diagram showing a method and an apparatus for detecting a state of reverse charging from a private power generation facility to a power supply system according to an embodiment of the present invention.

FIG. 2 is a flowchart of a procedure for detecting a state of reverse charging from a private power generation facility to a power supply system.

FIG. 3 is a single-line diagram showing a method and apparatus for detecting a state of reverse charging from a private power generation facility to a power supply system according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Power supply system side 12 Private power generation equipment 20 Private load 22 Detecting impedance load part 24 Connection part 28 Detecting part 30 Comparison part 86 Private load 88 Detecting impedance load part

Claims (4)

(57) [Claims] 1. A method for detecting a state of reverse charging in a power supply loss state on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation system to a power supply system side, the method comprising: A detection impedance load section is connected from an intermediate position with the power supply system side, and the detection impedance load section is turned on and off to periodically fluctuate the load on the private power generation facility side. With respect to the connection point, the amount of change in the current or power on the private power generation system side and the power supply system side with respect to the connection point is detected, and the power loss state on the power supply system side is determined based on the change amount. A method for detecting the state of reverse charging from the private power generation facility to the power supply system by detecting the state of reverse charging from the power supply system to the power supply system. 2. A method for detecting a state of reverse charging in a power loss state on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility to a power supply system side, the method comprising: A detection impedance load section is connected from an intermediate position with the power supply system side, and the detection impedance load section is turned on and off to periodically fluctuate the load on the private power generation facility side. With respect to the connection point, the amount of change in current or power on the private power generation facility side and the power supply system side with respect to the connection point is compared with the change amount on the detection impedance load side from the connection point, and detection is performed. The ratio of the amount of change on the power supply system side to the amount of change in the impedance load unit is smaller than the reference value, and the ratio of the amount of change in the detection impedance load unit is If the rate of change on the electrical equipment side is greater than the reference value, it is determined that the power supply system has lost power, and the private power generation equipment is configured to detect the state of reverse charging from the private power generation equipment to the power supply system. A method of detecting the state of reverse charging on the power supply system side. 3. An apparatus for detecting a state of reverse charging in a power-loss state of a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility to a power supply system side, comprising: A detection impedance load unit connected at a connection point provided at an intermediate position with the power supply system side, and a detection load unit for turning on and off the detection impedance load to periodically fluctuate the load on the private power generation facility side. A switch unit, a first detection unit provided on the private power generation equipment side with respect to the connection point with respect to the connection point of the impedance load unit, and a first detection unit provided on the power supply system side with respect to the connection point. A second detection unit, which detects a change in current or power on the side of the private power generation facility and the power supply system with respect to the connection point, and detects a power loss on the power supply system based on the change. It determines the state detection device for detecting a reverse state of charge from the detection to private power generation equipment comprising the power supply system side opposite state of charge from the private power generation equipment to the power supply mains. 4. An apparatus for detecting a state of reverse charging in a power supply loss state on a power supply system side in a system interconnection in which reverse power flow is allowed from a private power generation facility to a power supply system side, comprising: A detection impedance load unit connected at a connection point provided at an intermediate position with the power supply system side, and a detection load unit for turning on and off the detection impedance load to periodically fluctuate the load on the private power generation facility side. With respect to the connection point of the impedance load unit, the switch unit and the current or the change amount of the current or power generated on the detection impedance load unit side with respect to the connection point, the current generated on the private power generation facility side or A first comparing unit that detects a ratio of a power change amount, and a detection impedance negative with respect to a connection point of the impedance load unit with respect to the connection point. With respect to the amount of change in current or power is caused to part side, the detecting the ratio of the current or power of the variation is caused in the power supply system side 2
A ratio of a change amount of the power supply system to a change amount of the detection impedance load portion is smaller than a reference value, and a change amount of the private power generation equipment side to a change amount of the detection impedance load portion. When the ratio is larger than the reference value, it is determined that the power supply system side has lost power, and the state of reverse charging from the private power generation system to the power supply system side is detected. A detection device that detects the state of charge.