JP2005045859A - Anomaly detector for current transformer in distributed power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detector of a current transformer in a distributed power supply system in which disconnection and short circuit of the current transformer in a power generation unit can be detected utilizing apparatus in the detector without requiring any extra element additionally. <P>SOLUTION: The abnormality detector for detecting abnormality of a current transformer installed at the power receiving inlet from a commercial power supply in a distributed power generation unit interconnected with a power system comprises a detection means CI receiving a current from the secondary circuit of the current transformer and producing a detection signal when such a state as the power received from the commercial power supply is not higher than a specified level sustains for a specified time or longer, an operation control means CE performing test run of auxiliary machines in the distributed power generation unit when a detection signal is produced from the detection means, and a means W for determining the state of the current transformer by monitoring the detection signal from the detection means when the operation control means performs test run. The detection means may detect a receiving current in place of the receiving power. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a distributed power supply system, and more particularly to an apparatus for detecting an abnormality of a current transformer in a power generation unit constituting the system.
[0002]
[Prior art]
In recent years, distributed power systems that operate in conjunction with the power system of commercial power sources have become widespread. This type of distributed power system uses a current transformer installed in the connection line between the power system and the load to detect the current exchanged with the power system, to prevent reverse power flow and to control the received power to be constant. Yes.
[0003]
When the secondary circuit of the current transformer is disconnected or short-circuited and no current can be detected, it is necessary to stop the operation of the power generation unit.
[0004]
Therefore, conventionally, abnormal voltage at the time of disconnection is detected as shown in Patent Document 1, or abnormality is determined by comparing secondary currents of a plurality of current transformers as shown in Patent Document 2. Has been done.
[0005]
Also, as control of the distributed power supply system, Patent Document 3 detects the current and voltage of the power system and each distributed power generation unit, and controls the circuit breaker, the distributed power generation unit and the load based on the detection result. Shown to do.
[0006]
In a small-scale distributed power supply system, when it is difficult to provide a detection device due to cost and space constraints, 2 is used when the secondary output of the current transformer is zero or very small for a certain time or more. In some cases, it is determined that the next circuit is disconnected, and the distributed power source is urgently stopped to notify the abnormality.
[0007]
[Patent Document 1]
JP-A-10-144540 [Patent Document 2]
JP-A-11-205998 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-252928
[Problems to be solved by the invention]
In order to detect a current transformer abnormality in this way, the voltage on the secondary side of the current transformer is constantly monitored, or a plurality of current transformers are provided to detect an abnormality from the difference in secondary current. The method requires separate components, adds complexity to the circuit, increases manufacturing costs, and may increase the possibility of malfunction.
[0009]
On the other hand, without attaching these detection devices, if it is determined that a failure has occurred simply under the condition that the secondary current is zero for a certain period of time, if a situation occurs in which a minute load continues for a long time, a sudden alarm will be issued even though it is not a failure. Can cause problems for customers.
[0010]
The present invention has been made in consideration of the above-mentioned points, and it is possible to accurately detect the disconnection and short circuit of the current transformer of the distributed power generation unit using the equipment in the apparatus without adding a special element. An object of the present invention is to provide an abnormality detection device for a current transformer in a distributed power supply system.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
In an apparatus for detecting an abnormality of a current transformer installed at a power receiving inlet from a commercial power source of a distributed power generation unit operated in connection with an electric power system, the current of the current transformer secondary circuit is obtained and A detecting means for generating a detection signal when detecting that a state where the received power or the received current from the commercial power source is less than or equal to a predetermined value continues for a predetermined time, and when the detecting means generates the detection signal, Operation control means for making a trial run of auxiliary machinery, and determination means for monitoring the detection signal of the detection means to determine the state of the current transformer when the operation control means performs a test operation. An abnormality detection device for a current transformer in a distributed power supply system,
Is to provide.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration of a distributed power generation unit connected to an electric power system, which is an application target of the present invention. In FIG. 1, there are loads L1 to L3 connected to the power system via the main circuit breaker CB0 and branch circuit breakers CB11 to CB13, and a distributed power source is configured for these loads in addition to the power system. A configuration in which power is supplied also from the power generation unit is shown.
[0013]
The power generation unit includes a power generation device, an inverter device, and a remote monitoring device. The power generation device gives the output to the inverter device, converts it into a predetermined AC output, and supplies it to the loads L1 to L3. The operating status of the engine control device CE in the power generation device is given to the remote monitoring device and transmitted to the central monitoring center.
[0014]
The power generator is configured to generate power by driving the generator G by the engine E. For this purpose, the engine controller CE energizes the relay Ry and supplies power from a commercial power source via the circuit breakers CB21 to CB23, thereby compensating for the power. The engine E is controlled after operating the pump P, the radiator fan F1 and the indoor cooling fan F2 which are the machines. The engine control device CE obtains received power data and inverter operation state data from the inverter control device CI, and controls the operation of the engine.
[0015]
The inverter device obtains the output of the generator G and converts it into predetermined AC power by the inverter. This power conversion operation is performed by controlling the inverter IN based on the current and voltage obtained from the current / voltage detector built in the inverter control device CI and the engine control signal obtained from the engine control device CE, and obtained by conversion. The output of the inverter IN is supplied to the loads L1 to L3 via the circuit breaker CB00 by controlling the contactor MC to open and close.
[0016]
The current of the power system is detected by the current transformer CT and the current detector DI, and the voltage is also detected by the voltage detector DV. The detected current and voltage are digitized via the A / D converter CON, and the inverter It is given to the control device CI.
[0017]
When the load consumes more than light load power due to the cooperation of the power generation device and the inverter device, the power generation unit is activated and cooperates with the commercial power supply to supply the generated power to the load. Then, the generator operation state data and the abnormality data of the engine control device CE representing the operation status of the power generation unit are transmitted to the central monitoring center via the monitoring device W and the communication device COM.
[0018]
On the other hand, if the required power of the load is reduced, it is uneconomical to operate the engine E at a light load, so the power generation unit is stopped. By operating / stopping the power generation unit in this way, the power supply from the power system and the power generation unit is properly used.
[0019]
When this load transfer is performed, the detection current of the current transformer CT provided outside the power generation unit becomes a reference. Therefore, if a malfunction occurs in the current transformer CT, the power generation unit cannot be operated.
[0020]
FIG. 2 is a flowchart showing the contents of the operation for monitoring the state of the secondary circuit of the current transformer CT.
[0021]
The current transformer CT is regarded as normal if a detection output is generated. In other words, the current transformer CT is normal if it is detected that the power generation unit is operating and supplying power of a predetermined value or more to the power system load.
[0022]
Therefore, with reference to the secondary output of the current transformer CT, if the current corresponding to the normal operation flows, the current transformer CT is normal, and the operation of circulating step S1 is repeated.
[0023]
Thereafter, when the load decreases and becomes light, the process proceeds to step S2 and the power generation unit stops the engine by stopping the engine. Then, even if the received power from the power system is a light load, it is determined whether or not it is a predetermined value 1 or more (step S3). The predetermined value 1 indicates, for example, a minimum power value required for slight lighting and convenience store operation in a convenience store. If the predetermined value is 1 or more, the engine is stopped and waits. Here, the predetermined value 1 <light load power <normal operation power.
[0024]
On the other hand, when the received power is less than or equal to the predetermined value 1, it is determined whether or not the time exceeds the set time (step S4). If not, the circulation operation returning to step S3 is repeated. When it exceeds, the process proceeds to step S5, and it is determined whether or not the received voltage exceeds the set value V.
[0025]
When the received voltage does not reach the set value V, it is an abnormality of the power system, so that the undervoltage is displayed, the starting circuit is closed (step S6), and the central monitoring center is notified in step S7.
[0026]
If the received voltage is equal to or higher than the set value V in step S5, a certain load is applied to check whether the current transformer is normal. In order to apply a certain amount of load, the auxiliary machinery is operated (step S8).
[0027]
As a result, whether or not a current of a certain level has flowed through the current transformer CT is determined by the magnitude of the power (step S9). At this time, if the received power exceeds the predetermined value 2, the process proceeds to step S11 to stop the auxiliary machinery and shift to a standby state. Here, predetermined value 2 <required power for auxiliary machinery <normal operating power.
[0028]
When the received power does not reach the predetermined value 2, the process proceeds to step S10 to display “CT disconnection” and close the starting circuit so that the power generation unit is not operated. Then, the process proceeds to step S7 and reports to the central monitoring center. Thereby, the central monitoring center recognizes the disconnection of the current transformer.
[0029]
(Modification)
In the above embodiment, the disconnection of the current transformer has been described. However, the secondary circuit of the current transformer may be short-circuited, and this can be similarly detected.
[0030]
In the above embodiment, the disconnection of the current transformer is determined based on the magnitude of the received power, but may be determined based on the magnitude of the current.
[0031]
【The invention's effect】
As described above, according to the present invention, when the received power or the received current from the power system is reduced in the power generation unit in the distributed power supply system, the auxiliary equipment is trial-run to check whether there is a change in the secondary output of the current transformer. Therefore, it can be determined whether or not the current transformer is healthy, so it is possible to accurately detect abnormalities in the current transformer simply by changing the program of the control device, and the reliability of the operation of the power generation unit. Can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a flowchart showing an operation for detecting whether or not the current transformer is abnormal in the embodiment of FIG. 1;
[Explanation of symbols]
CT Current transformer DI Current detector DV Voltage detector L Load CB Breaker E Engine G Generator CE Engine controller D Display device Ry Relay IN Inverter CI Inverter controller MC Contactor CON A / D converter W Monitoring device COM Communication equipment

Claims (6)

In an apparatus for detecting an abnormality of a current transformer installed at a power receiving entrance from a commercial power source of a distributed generation unit operated in connection with an electric power system,
Detection means for generating a detection signal when obtaining a current of the current transformer secondary circuit and detecting that a state where the received power from the commercial power source is less than or equal to a predetermined value has continued for a predetermined time;
When the detection means generates the detection signal, operation control means for making a trial run of auxiliary equipment in the distributed power generation unit;
And a determination means for determining a state of the current transformer by monitoring a detection signal of the detection means when the operation control means performs a test operation. Anomaly detection device. In the abnormality detection apparatus of the current transformer in the distributed power supply system according to claim 1,
The determination unit is an abnormality detection device for a current transformer in a distributed power supply system that determines a received voltage in the distributed power generation unit. In an apparatus for detecting an abnormality of a current transformer installed at a power receiving entrance from a commercial power source of a distributed generation unit operated in connection with an electric power system,
Detection means for generating a detection signal when obtaining a current of the current transformer secondary circuit and detecting that a state where the current received from the commercial power source is less than or equal to a predetermined value has continued for a predetermined time;
When the detection means generates the detection signal, operation control means for making a trial run of auxiliary equipment in the distributed power generation unit;
And a determination means for determining a state of the current transformer by monitoring a detection signal of the detection means when the operation control means performs a test operation. Anomaly detection device. In the abnormality detection apparatus of the current transformer in the distributed power supply system according to claim 1 or 3,
An abnormality detection device for a current transformer in a distributed power supply system in which the determination means generates an output signal when it is determined that the secondary circuit of the current transformer is in a disconnected state. In the abnormality detection device for a current transformer in the distributed power supply system according to claim 4,
The determination means is an abnormality detection device for a current transformer in a distributed power supply system in which the distributed power generation unit is placed in a start circuit closed state and displayed by the output signal. In the abnormality detection apparatus of the current transformer in the distributed power supply system according to claim 4,
The determination unit is an abnormality detection device for a current transformer in a distributed power supply system that notifies a central monitoring center by the output signal.

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