JP2002252928A - Distributed power supply system, and control/protection device for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distributed power supply system and a control/protection device for the same capable of minimizing the occurrence of power failures and effectively using a power supply output to the maximum. SOLUTION: The distribution power supply system is provided with circuit breakers 11-13 connected to a distributed power supply 50, a system 81 and a load 85 respectively, current transformers 21-23 which detect respective currents n the system 81, the power supply 50 and the load 85, voltage transformers 31 and 32 which detect voltages in the system 81 and the power supply 50 respectively, and a control/protection device 40 which controls the circuit breakers 11-13, the distributed power supply 50 and the load 85 based on detected outputs by the voltage transformers 31 and 32 and the current transformers 21-23. In addition, a control and protection device 40 for the distributed power supply system 1 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed power system which operates in cooperation with a distribution power system and a control / protection device therefor. The present invention relates to a distributed power supply system that can be freely switched to an operation state and a control / protection device therefor.

[0002] As a technical guideline for linking a distributed power source with a power distribution system, "Guidelines for Technical Requirements for Linking Power Systems" (hereinafter referred to as "linkage guidelines") was revised in 1998 and issued by the Agency for Natural Resources and Energy. . The second section of the above-mentioned coordination guidelines sets out the technical guidelines for coordinating low-voltage distribution lines and distributed power sources. According to the technical guidelines on disconnection specified in paragraph 4, a method using "two mechanical switching points" is specified as an example of a main disconnection method. For example, a power receiving cut-off device and an output terminal cut-off device of a power generation facility are defined as mechanically disconnected parts.

Conventionally, as a distributed power supply system conforming to the above-mentioned coordination guidelines, as shown in FIG. 6, a distributed power supply 50 and a load 85 are connected to a low-voltage distribution system 81 via two circuit breakers 11 and 16. The load 85 can be supplied with power from the distributed power supply 50 and the low-voltage distribution system 81 through the switch 17.

Therefore, in the conventional distributed power supply system 9,
If the distributed power supply 50 fails, this effect is
Circuit breakers 11 and 16 are opened in order not to spread to 1, and power is not supplied to load 85 from distributed power supply 50 nor from power distribution system 81, resulting in a power failure state. Further, even when the load 85 is in a failure state, this influence is also reflected on the system 81.
The circuit breakers 11 and 16 are opened in order to prevent the power from spreading to the reverse side, and the output of the distributed power supply 50 cannot be reversely flown to the system 81 side, so that the distributed power supply 50 cannot be effectively used to the maximum extent. For this reason, for example, valuable power that does not require cost, such as solar power generation or wind power generation, cannot be effectively used, and even in the case of other types of distributed power sources, at least the usage efficiency is reduced.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present invention minimizes the power outage time of a load so as to operate the load as much as possible, and maximizes the output of a distributed power supply to maximize the utilization efficiency. The aim is to provide a distributed power system that maximizes and its control and protection devices.

[0006]

According to the first aspect of the present invention, there is provided a distributed power supply system for operating a distributed power supply in association with a power system and a load, wherein the distributed power supply is separately connected to each of the distributed power supply, the power system, and the load. A current transformer for separately detecting the current of each of the distributed power supply, the power system and the load, a voltage transformer for separately detecting each voltage of the distributed power supply and the power system, A distributed power supply system, comprising: a breaker, a distributed power supply, and a control / protection device that controls a load based on a detection output of the voltage transformer and the current transformer.

A first point of particular interest in the distributed power supply system according to the present invention is that a separate circuit breaker is provided for each of the distributed power supply, the power system, and the load. By adopting such a configuration, the condition regarding the disconnection point in the link requirement between the distributed power source and the low-voltage distribution system in the link guideline is satisfied. In other words, there are two mechanical switching points between the distributed power supply and the system, that is, the distributed power circuit breaker and the system circuit breaker. The condition of the fourth term will be satisfied.

In addition, by adopting such a configuration,
If the distributed power supply fails, the circuit breaker for the distributed power supply is opened to prevent the effects of the failure from spreading to the system, and at the same time, the load can be continuously supplied from the distribution system. A power failure does not cause a power outage. On the other hand, if the load becomes faulty, opening the circuit breaker for the load will not spread this effect to the system, and both the circuit breaker for the distributed power supply and the circuit breaker for the system will work together. By closing the circuit, the output of the distributed power supply can be reverse-flowed to the system side, and the output of the distributed power supply can be used effectively to the maximum without wasting.

Further, in the event of a system failure, the load can be fed from the distributed power supply by opening the circuit breaker. The operation can be performed.

A second point of particular interest in the distributed power supply system according to the present invention is that the distributed power supply, the current transformer for separately detecting the currents of the power system and the load, the distributed power supply and the power A voltage transformer for separately detecting each voltage of the system. In this way, by separately grasping the current of each of the distributed power supply, the power system, and the load and the voltage of each of the distributed power supply and the power system, a failure can occur in any of the distributed power supply, the power system, and the load. When it occurs, it can be easily determined which of the failures it is.

In the case where either the distributed power supply or the power system fails and the connection between the two is disconnected, and the failure is recovered, the detected voltages of the distributed power supply and the power system are compared. By detecting the difference in the voltage value, the difference in the frequency, and the difference in the phase, the distributed power supply can be synchronized with the system. As described above, according to the distributed power supply system of the present invention, the power failure of the load can be minimized so that the load can be operated to the maximum, and the output of the distributed power supply can be effectively used to the maximum.

[0012] Such a distributed power supply system includes:
For example, as described in claim 5, claim 2 described below
This can be realized by using the control / protection device according to the fourth aspect.

According to a second aspect of the present invention, there is provided a control / protection device used in the distributed power supply system, wherein when a failure occurs on the power system side, a circuit breaker for the power system is opened to open the output and load of the distributed power supply. Independent operation is performed by adjusting the distributed power supply or the load so that the power consumption of the distributed power supply becomes equal to that of the power supply. The distributed power supply system is characterized in that the power is supplied from the power system, and in the case of a failure on the load side, the circuit breaker for the load is opened and the output of the distributed power source is controlled to flow backward to the power system. In the protective device.

Thus, as described above, when the distributed power supply is stopped due to a failure or repair, power supply from the distribution system is continued, and when the load fails, only the load circuit breaker is opened to disperse. The output of the type power supply can be reversely flowed to the system side, and in the case of a system failure, the load can be supplied from the distributed type power supply by opening only the circuit breaker for the system.

Next, the invention of claim 3 of the present application more specifically shows the control / protection device according to claim 2, wherein a failure on the power system side is recovered during the self-sustaining operation. In this case, the voltage value, frequency, and phase of the distributed power supply are adjusted so as to match the voltage value, frequency, and phase of the power system, and the difference between the voltage value, frequency, and phase is zero or slightly different. The control / protection device is characterized in that the power circuit breaker is turned on when the power supply is turned off.

This control / protection device is a control / protection system for the distributed power supply system which realizes synchronization control and synchronization of the distributed power supply to the system when the failure of the power system is recovered during the independent operation. Device. That is, based on the voltage on the secondary side of the voltage transformer, the voltage value, frequency and phase of the distributed power source are adjusted so that the voltage value, frequency and phase of the distributed power source coincide with the voltage value, frequency and phase on the power system side, and the voltages of both are adjusted. When the difference between the value, the frequency and the phase becomes zero or a small difference, the circuit breaker for the power system is turned on. Thus, when the failure on the power system side is restored, the distributed power supply can automatically restore the link.

Next, the invention of claim 4 of the present application is a more specific example of the control / protection device according to the above-mentioned claim 2, wherein the distributed power supply is stopped due to a failure or repair and the like. When power is supplied to the load only by the grid, when the failure of the distributed power supply is restored, the voltage, frequency, and phase of the distributed power supply are adjusted to match the voltage, frequency, and phase of the power grid. The control / protection device is characterized in that the device is adjusted and the circuit breaker for the distributed power supply is turned on when the difference between the voltage, frequency and phase of the two becomes zero or a slight difference.

This control / protection device realizes synchronization control and synchronization of the distributed power supply to the system when the distributed power supply is stopped due to a failure or repair and power is supplied to the load only by the power system. A control and protection device for the distributed power supply system described above. That is, when the failure of the distributed power supply or the like is restored, the voltage value, frequency and phase of the distributed power supply are based on the voltage on the secondary side of the voltage transformer, and the voltage value on the power system side,
Adjust to match the frequency and phase, the voltage of both,
When the difference in frequency and phase becomes zero or a slight difference, the circuit breaker for the distributed power supply is turned on. This makes it possible to automatically restore the link with the system when the failure or repair of the distributed power supply is restored. The control and protection device according to claim 3 and the control and protection device according to claim 4 have the function of the control and protection device, so that the control and protection device can be further improved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment As shown in FIG. 1, this embodiment is a distributed power supply system in which a distributed power supply 50 as a photovoltaic power generator is operated in conjunction with a low-voltage distribution system 81 and a load 85. And the distributed power source 50
, The circuit breakers 11 to 13 connected to the receiving point of the low-voltage distribution system 81 and the feeding point of the load 85, respectively, and the currents of the low-voltage distribution system 81, the distributed power supply 50, and the load 85 are separately detected. Current transformers 21 to 23, voltage transformers 31 and 32 for separately detecting respective voltages of the low-voltage distribution system 81 and the distributed power supply 50, and a voltage transformer 3
The control and protection device 40 controls the circuit breakers 11 to 13, the distributed power supply 50 and the load 85 based on the detection outputs of the current transformers 1 and 32 and the current transformers 21 to 23.

As described above, in the present system 1, the circuit breaker 1
When the distributed power supply 50 fails, the circuit breaker 11 for the distributed power supply 50 is opened so that the influence of the failure is not spread to the system 81 and the load 85 Can continue power supply from the low-voltage distribution system 81, so that even if the distributed power supply 50 fails, no power failure occurs. On the other hand, when the load 85 is in a failure state, if the circuit breaker 13 for the load 85 is opened, this effect is not spread to the system 81, and both the circuit breaker 11 and the circuit breaker 12 are closed. The distributed power supply 50
Can be made to flow backward to the system side, and the output of the distributed power supply 50 can be effectively used to the maximum without wasting.

As shown in FIG. 2, the distributed power supply 50 includes a solar panel 51 and an inverse converter 52 for converting a DC output of the solar panel 51 into an alternating current. Then, in the event of a failure on the low-voltage distribution system 81 side, the control / protection device 40 opens the circuit breaker 11 for the low-voltage distribution system 81 so that the output of the distributed power supply 50 and the consumption of the load 85 become equal. The self-sustaining operation is performed by adjusting the type power supply 50 or the load 85, and in the case of a failure on the side of the distributed type power supply 50, the circuit breaker 12 for the distributed type power supply 50 is opened to supply power to the load 85 from the low-voltage distribution system 81. Then, in the case of a failure on the load 85 side, the circuit breaker 13 for the load 85 is opened to control the output of the distributed power supply 50 to flow backward to the low-voltage distribution system 81.

That is, the low-voltage distribution system 81 and the distributed power source 5
0 detects the inter-phase voltages Vs and Vd and the phase currents Is and Id of each phase, and the load 85 detects the current IL of each phase. ) Vs2, Vd2, Is2, Id2, IL2 are controlled.
The data is input to the protection device 40 and is controlled as follows. First, the following fault signal and control signal can be detected based on the input signal group (secondary value). Current value: detection of overcurrent (OCR) (see FIGS. 3 to 5 described later)
Voltage values: detection of overvoltage (OV) and undervoltage (UV) (see reference numerals 461 and 462 in FIGS. 3 to 5 described later) Frequency value: frequency abnormality (over OF, under UF) Detection (see FIG. 2 described later) Direction: Determination of current (power) direction (see reference numerals 471 and 472 in FIGS. 3 and 4 described later) Difference: Detection of voltage difference, frequency difference, and phase difference (FIG. 2 described later)
Reference numeral 41)

Then, for example, by the logic circuit of FIG.
The failure of the low-voltage distribution system 81 can be detected, and the control / protection device 40 transmits a break signal of the circuit breaker 11 to the circuit breaker 11. That is, when an overcurrent and an undervoltage occur in either the system 81 or the distributed power supply 50 and the current (power) direction is toward the system 81, it is determined that the system 81 has failed and the circuit breaker 11 Is transmitted to the circuit breaker 11.

Further, for example, the failure of the distributed power supply 50 can be detected by the logic circuit shown in FIG. 4, and the control / protection device 40 transmits a cutoff signal of the circuit breaker 12 to the circuit breaker 12. That is, the distributed power source 50 has an overcurrent and the system 8
1 or the distributed power supply 50, if the current (power) direction is toward the distributed power supply 50, it is determined that the distributed power supply 50 has failed and the circuit breaker 1
2 is transmitted.

The failure of the load 85 can be detected by the logic circuit shown in FIG. 5, for example, and the control / protection device 40 transmits a cutoff signal of the breaker 13 to the breaker 13.
That is, when the load current IL is an overcurrent and an undervoltage occurs in either the system 81 or the distributed power supply 50, it is determined that the load 85 has failed, and a cutoff signal of the circuit breaker 13 is transmitted.

Further, the control / protection device 40 adjusts the load 85 so that the output of the distributed power supply 50 and the consumption of the load 85 are equalized by opening the circuit breaker 11 in the event of a fault on the low-voltage distribution system 81 side. To perform independent operation, and
In the case of a failure on the side of the load, the circuit breaker 12 is opened to supply power to the load 85 from the low-voltage distribution system 81. In the case of a failure on the load 85 side, the circuit breaker 13 is opened and the output of the distributed power supply 50 is controlled. Control so that reverse power flows to the power system.

For example, the control / protection device 40 includes the circuit breaker 1
For example, if it is determined that the voltage value of the system has recovered and the fault on the low-voltage distribution system 81 has been recovered during the self-sustaining operation with the circuit 1 open, the voltage value, frequency and phase of the distributed power supply 50 Adjust so as to match the voltage value, frequency and phase on the side. That is, as shown in FIG. 2, the comparator 41 compares the secondary-side voltages Vs2 and Vd2 of the voltage transformers 31 and 32, and compares the difference DV (δv, δ).
f, δθ) to the inverse converter 52 of the distributed power supply 50. The inverter 52 is controlled by a controller (not shown) so that the value of the difference DV (δv, δf, δθ) decreases.

The input command device 42 outputs the difference DV.
When the voltage deviation value δv, the frequency deviation value δf, and the phase deviation value δθ of (δv, δf, δθ) become small differences equal to or smaller than the predetermined values Sv, Sf, So, the circuit breaker 11 is activated via the circuit breaker control circuit 43. throw into. As described above, in the distributed power supply system 1 of the present example, when the failure on the low-voltage distribution system 81 side is restored, the link between the distributed power supply 50 and the system 81 can be automatically restored.

The control / protection device 40 recovers from the failure of the distributed power supply 50 when the distributed power supply 50 is stopped due to a failure or inspection and the load 85 is supplied only by the low-voltage distribution system 81. Time is controlled as follows.
That is, as shown in FIG. 2, the comparator 41 compares the voltages Vs2 and Vd2 on the secondary side of the voltage transformers 31 and 32, and compares the difference DV (δv, δf, δθ) with the inverse conversion of the distributed power supply 50. The result is transmitted to the device 52, and the inverse converter 52 adjusts the output so that the value of the difference DV (δv, δf, δθ) decreases.

The input command device 42 outputs the difference DV.
When the voltage deviation value δv, the frequency deviation value δf, and the phase deviation value δθ of (δv, δf, δθ) become small differences smaller than or equal to predetermined values Sv, Sf, So, the distributed power supply 50 via the circuit breaker control circuit 43. The circuit breaker 12 for use. As described above, in the distributed power supply system 1 of this example, when the failure or repair of the distributed power supply 50 is restored, the link with the system 81 can be automatically restored.

On the other hand, when a failure such as a short circuit or a short circuit occurs in the load 85, opening the circuit breaker 13 for the load 85 does not spread the influence to the system 81 and the distributed power supply 50. By closing both the circuit breaker 12 for the system 81 and the circuit breaker 11 for the system 81, the output of the distributed power supply 50 can be reversely flown to the system 81 side. Therefore, the output of the distributed power supply 50 can be effectively used to the maximum without wasting.

As described above, the distributed power supply system 1 of the present embodiment
According to this configuration, the power failure of the load 85 can be minimized so that the load 85 can be operated to the maximum, and the output of the distributed power supply 50 can be effectively used to the maximum.

[0033]

As described above, according to the present invention, a distributed power supply system capable of maximizing the operation while minimizing the power failure of the load and maximizing the effective use of the output of the distributed power supply. The control and protection device can be obtained.

[Brief description of the drawings]

FIG. 1 is a skeleton of a distributed power supply system according to an embodiment.

FIG. 2 is a block diagram of a control / protection device and a distributed power supply according to the embodiment.

FIG. 3 is a system failure determination circuit in the control / protection device of the embodiment.

FIG. 4 is a failure determination circuit of a distributed power supply in the control / protection device of the embodiment.

FIG. 5 is a load failure determination circuit in the control / protection device of the embodiment.

FIG. 6 is a skeleton of a conventional distributed power system.

[Explanation of symbols]

 1, 9: Distributed power supply system 11, 12, 13, 16: Circuit breaker 17: Switch 21, 22, 23: Current transformer 40: Control / protection device 41: Comparator 42: Closing command device 43: Circuit breaker control circuit 50: Distributed power supply 51: Solar panel 52: Inverter 31, 32: Voltage transformer 81: Low voltage distribution system

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[Procedure amendment]

[Submission date] March 12, 2001 (2001.3.1.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014] Thus, as described above, when the distributed power supply is stopped due to a failure or repair, power supply from the power system is continued, and when the load fails, only the load circuit breaker is opened and the distributed power supply is opened. The output of the type power supply can be reversely flowed to the system side, and in the case of a system failure, the load can be supplied from the distributed type power supply by opening only the circuit breaker for the system.

Claims (5)

[Claims] 1. A distributed power supply system for operating a distributed power supply in association with a power system and a load, the distributed power supply comprising:
A circuit breaker separately connected to each of the power system and the load, a current transformer for separately detecting the current of each of the distributed power source, the power system and the load, and a voltage of each of the distributed power source and the power system. Dispersion comprising: a voltage transformer for separately detecting; and a control / protection device for controlling the circuit breaker, the distributed power supply, and the load based on detection outputs of the voltage transformer and the current transformer. Power system. 2. In the event of a fault on the power system side, the distributed power source or load is adjusted by opening the circuit breaker for the power system so that the output of the distributed power source and the load consumption are equal. Independent operation is performed, and in the case of a failure on the distributed power supply side, the circuit breaker for the distributed power supply is opened to supply power to the load from the power system. 2. The control and protection device for a distributed power system according to claim 1, wherein the circuit breaker is opened to control the output of the distributed power source to flow backward to the power system. 3. When the failure on the power system side is recovered during the self-sustaining operation, the voltage value, frequency and phase of the distributed power supply are adjusted so as to match the voltage values, frequency and phase on the power system side. The control and control device according to claim 2, wherein the circuit breaker for the power system is turned on when a difference between the voltage value, the frequency and the phase of the two becomes zero or a slight difference.
Protective equipment. 4. When the distributed power supply is stopped due to a failure or the like and supplies power to the load only by a power system, the voltage value, frequency, and phase of the distributed power supply are restored when the failure of the distributed power supply is restored. Is adjusted to match the voltage value, frequency and phase on the power system side, and when the difference between the voltage, frequency and phase of both becomes zero or a slight difference, the circuit breaker for the distributed power supply is turned on. The control / protection device according to claim 2 or 3, wherein 5. The distributed power system according to claim 1, comprising the control / protection device according to claim 2. Description: