JP2009079935A - Failure diagnosis method of received power measuring system in distributed power source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure diagnosis method of a received power measuring system in a distributed power source capable of detecting surely a failure of a power measuring device, even when a control device of a power generation device recognizes wrongly the received power owing to an abnormality of the power measuring device. <P>SOLUTION: In this failure diagnosis method of the received power measuring system in the distributed power source wherein a power generation device is used as the distributed power source having a system link operation function and an autonomous operation function, the received power from a commercial power source system and the transmitted power from the power generation device are measured by the power measuring device, and the measured power is input into a control device of the power generation device by means of a signal by a current or a voltage, and when a power measuring signal does not change for a fixed period, is determined that the power measuring device is out of order. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a failure diagnosis method for a received power measurement system in a distributed power source.

  When installing an in-house power generator such as a cogeneration system in a general household, install a transducer-type wattmeter in addition to a current sensor (CT) or CT as a power meter on the main power distribution board for houses. For the purpose of preventing the occurrence of so-called reverse power flow, the received power and generated power at the power receiving point in the home are measured, and the received power and generated power are respectively controlled. By inputting the measurement signal of the current or power at the power receiving point to the control device of the power generator, the received power is grasped, and based on this, the received power is monitored, the output of the power generator is controlled, and the overload protection to the neutral line It is carried out.

In Patent Document 1, in the case where a power generation device having a grid interconnection operation and a self-sustaining operation function is connected to a household load in parallel with power purchase, a residential distribution board (single-phase two-wire or single-phase three) is disclosed. A method of monitoring the received power and the transmitted power at a power receiving point of a general household and controlling the output of the power generating device using this is disclosed in a form in which the power generating device is connected to a line).
Japanese Patent Laid-Open No. 11-069634

  When a single-phase two-wire 100V, single-phase two-wire 200V or single-phase three-wire 200V power generator is connected, the neutral wire overload state may continue under certain conditions. In some cases, a CT may be installed in addition to the normal wire to provide overload protection.

  However, in the method of Patent Document 1, when a failure such as disconnection occurs in the circuit of the power meter, the current or voltage signal sent from the power meter to the control device is erroneous measurement information. The control device may misrecognize the received power, and the power generation device may continue to operate in a state where no abnormality can be detected.

  In addition, if the control device of the power generator is operating by controlling the inverter so as not to generate reverse power flow, if the power meter fails, the control device monitors the received power and reverse power flow occurs. There is a risk that the power generator will continue to operate in a state where reverse power flow has occurred. In order to prevent continuation of the operation of the power generation apparatus in these abnormal occurrence states, it is necessary to detect that the power measuring instrument itself that measures the received power has become abnormal.

  The present invention has been made to solve the above-described problem, and even when the control device of the power generation device misrecognizes the received power due to an abnormality of the power measurement device, the failure of the power measurement device is reliably detected. It is an object of the present invention to provide a fault diagnosis method for a received power measurement system in a distributed power source.

  A fault diagnosis method for a received power measurement system in a distributed power source according to the present invention is a fault diagnosis method for a received power measurement system in a distributed power source in which a power generator is used as a distributed power source having a grid interconnection operation and a self-sustaining operation function. The power measuring device measures the received power from the commercial power supply system and the transmitted power from the power generation device, and inputs the measured power to the control device of the power generation device as a current or voltage signal, and the power measurement signal When the power does not change for a certain period, it is determined that the power measuring device has failed.

  In the present specification, “system interconnection operation” refers to an operation method in which a private power generation facility is connected to a commercial power supply system to supply power to a load.

  In addition, “a power generation device having a self-sustaining operation function” refers to a power generation device that itself can operate and generate power independently without using an external power source. For example, the fuel cell system can be said to be a power generation device having a self-sustaining operation function.

  ADVANTAGE OF THE INVENTION According to this invention, even when the control apparatus of a generator is misrecognizing received electric power by abnormality of an electric power meter, a failure of an electric power meter can be detected reliably.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the accompanying drawings.

(First embodiment)
The outline of the apparatus used in the first embodiment of the present invention will be described with reference to FIG.

  The commercial power supply system 1 is connected to a household load 9 via a power receiving point 2, a power meter 3, and a home distribution board 11. In a general home, the received power P1 is supplied from the commercial power supply system 1 to the power receiving point 2, and further, the power is supplied to the household load 9 via the home distribution board 11. The distribution board 11 includes a service breaker 12, a leakage breaker 13, and a plurality of branch breakers 14a to 14d connected in series from the power receiving point 2 side. The plurality of branch breakers 14a to 14d are connected in parallel and connected to a load 9 in the home. The household load 9 includes electronic devices compatible with Internet home appliances in addition to normal home appliances.

  A fuel cell power generation system is installed as a power generation device 4 for home private power generation. The power generation device 4 includes a power generation unit 5 including a fuel cell stack, an inverter 6, a control device 7, and an auxiliary device 10. The fuel cell stack of the power generation unit 5 includes a membrane electrode assembly (MEA) in which a solid electrolyte membrane, an anode catalyst layer, and a cathode catalyst layer are integrally joined, an anode channel plate, a cathode channel plate, a fuel supply source, and a blower fan have. The inverter 6 adjusts the electric power generated by the power generation unit 5 and outputs it as output power P <b> 2 to the household load 9 via the distribution board 11. The control device 7 receives the measurement signal S1 from the power meter 3, and controls the output operation of the inverter 6, the driving of the household load 9, the driving of the auxiliary machine 10, and the like based on the measurement signal S1. The control device 7 stores a plurality of failure diagnosis modes in the memory unit so that they can be read out at any time. The auxiliary machine 10 is a fuel supply pump, a blower fan, a heater, or the like that is driven by the output power P3 from the inverter 6 and controlled by the control signal S2 of the control device 7.

  When the above-described private power generation device 4 is installed in a general household and a so-called grid-connected operation in which a part of the received power P1 is covered by the transmission power P2 from the power generation device 4, the power consumed by the load 9 of the home is grasped. Therefore, the power measuring instrument 3 is installed at or near the power receiving point 2 to measure the received power P1 and the generated power P2. The power meter 3 may be a current sensor (CT) or may be used in combination with a transducer type wattmeter.

  In general, a consumer who performs grid connection operation desires to supply his / her power consumption from the private power generator 4 as much as possible, and to replenish the shortage with the power from the commercial power supply system 1, that is, the power company. In grid-connected operation, there is “no reverse power flow” that is not allowed to send surplus power from the private power generation equipment to the power company, and “with reverse power flow” that is allowed to be sent under certain conditions and purchased by the power company. There are two methods, and at the time of a power reception contract, it is determined whether any method is used for grid interconnection operation. However, there is a problem of the unit price for purchasing surplus power by the power company, and “with reverse power flow” is hardly recognized, and in general households are operated under the condition of “no reverse power flow”.

  In such grid connection operation, the power meter 3 measures the received power P1 and the generated power P2, and sends these measurement results to the control device 7 of the power generator 4 as a signal S1. The control device 7 outputs a signal S3 to the household load 9 based on the input signal S1, and also outputs a signal S4 to the inverter 6 to adjust and control the received power P1 and the transmitted power P2 according to household demand, respectively. To do.

  The received power P1 from the commercial power supply system 1 is directly measured by the power meter 3 at the power receiving point 2. On the other hand, the output power P2 from the power generator 4 is received from the inverter 6 via the branch breaker 14a and at the load 9, and is received from the inverter 6 via the branch breaker 14a, the earth leakage breaker 13, and the service breaker 12. It is divided into electric power going to point 2. The power meter 3 measures the latter part of the output power P2.

  Next, the failure diagnosis method of the first embodiment will be described with reference to FIG.

  First, the control device 7 transmits a signal S4 to the inverter 6, and determines whether or not the power generation device 4 is in operation based on the signal S5 returned from the inverter 6 (step K1). When the determination result is NO, that is, when the power generation device 4 is stopped, the process proceeds to steps S1 to S4 of the second embodiment shown in FIG.

  When the determination result of the process K1 is YES, that is, when the power generation device 4 is in operation, the power at the power receiving point 2 over a certain period (for example, 1 hour) based on the measurement signal S1 sent from the power meter 3. The control device 7 determines whether or not there is a change (step K2). If the determination result is NO, that is, if the power at the power receiving point 2 changes during a certain period, it is determined that the power meter 3 has not failed and the process returns to the first step K1.

  If the determination result in step K2 is YES, that is, if the power at the power receiving point 2 does not change during a certain period, it is determined that the power meter 3 has failed due to disconnection or the like, and the next step K3 Proceed to

  Next, the control device 7 selects a plurality of diagnosis modes in descending order of priority (step K3). The priority order of the diagnosis mode can be appropriately determined according to the preference of the customer. Such selection of the diagnosis mode may be performed by a person manually pressing a button on the display panel of the power generation device 4 and inputting it manually.

  When the diagnosis mode 1 is selected, the control device 7 sends a signal S4 to the inverter 6 to forcibly change the transmitted power P2 from the inverter 6 (step K4-1). When the diagnosis mode 2 is selected, another signal S4 is sent from the control device 7 to the inverter 6, power supply to the gate electrode of the inverter 6 is stopped for a short time, the inverter 6 is gate-blocked, and the output power from the inverter 6 P1 is stopped for a short time (step K4-2). When the diagnosis mode 3 is selected, a signal S2 is sent from the control device 7 to the auxiliary machine 10 and another signal S4 is sent to the inverter 6 to change the output of the auxiliary machine 10 in the fuel cell power generator 4 (step K4). -3). There are various types of auxiliary equipment 10 such as a fuel supply pump, a blower fan, and a heater. For example, the power generation amount in the power generation unit 5 is reduced by reducing the amount of power supplied to the heater and reducing the vaporization amount of the liquid fuel. When the diagnosis mode 4 is selected, a signal S3 is sent from the control device 7 to the home load 9 to change the home load 9 (step K4-4). The home load 9 can be a load corresponding to an Internet home appliance such as a notebook personal computer.

  The selected diagnostic mode is not limited to one. The control device 7 may select not only one from a plurality of diagnosis modes but also select two or more and perform diagnosis using the combination mode. For example, when the failure diagnosis is performed using the mode 1 + 3 in which the mode 1 and the mode 3 are selected and combined, the output power P2 from the inverter 6 is changed and the output of the auxiliary machine 10 (for example, a pump) is changed (step K4). -1, step K4-3). As a result, it is possible to more reliably diagnose whether or not the power meter 3 has failed.

  Further, when the failure diagnosis is performed using the mode 2 + 3 obtained by selecting and combining the mode 2 and the mode 3, the inverter 6 is gate-blocked for a short time and the output of the auxiliary machine 10 (for example, the pump) is changed (step K4-2). Step K4-3).

  Further, for example, when failure diagnosis is performed using mode 3 + 4 in which mode 3 and mode 4 are selected and combined, the output of auxiliary machine 10 (for example, a heater) is changed and household load 9 is changed (step K4- 3, Step K4-4). Even in this case, the accuracy of failure diagnosis is further improved.

  Furthermore, failure diagnosis of the power meter 3 can be periodically repeated at regular intervals. For example, by periodically sending a signal S4 for executing the diagnosis mode 1 from the control device 7 to the inverter 6 (for example, every 3 minutes), the power meter 3 can be continuously monitored almost always. Become. As a result, the probability of finding the failure of the power meter 3 can be dramatically improved, the failure can be found at an early stage, and the abnormal operation of the fuel cell power generator 4 can be stopped quickly.

  If the measured power signal S1 entering the control device 7 from the power meter 3 changes accordingly as a result of the above fault diagnosis, it is diagnosed that the power meter 3 is operating normally. Return to the first step K1 (K5 → K1).

  On the other hand, if the measured power signal S1 does not change at all even after performing the above-described failure diagnosis, the control device 7 diagnoses that the power meter 3 has failed, and sends a stop signal to the power generation unit 5 and the auxiliary device 10. The operation of the power generation device 4 is stopped (step K6). Thereby, the electric power generating apparatus 4 is protected from abnormal operation. Then, after repairing or replacing the failure of the power meter 3, the reset button is pressed to restart the operation of the power generator 7.

  According to the present embodiment, the existing control device 7 that monitors the power change at the power receiving point 2 is used to control the transmission power P2 from the inverter 6 without newly adding a failure detection device. The failure of the power meter 3 can be reliably diagnosed.

  In addition, according to the present embodiment, since the state in which the active power and the reactive power are always unstable can be created by periodically changing the transmission power P2 from the inverter 6, it is possible to detect the isolated operation prevention function. An improvement in sensitivity can be expected.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.

  The second embodiment is a method for diagnosing a failure of the power meter 3 while the power generation device 4 is stopped.

  The control device 7 first transmits a signal S4 to the inverter 6, determines whether or not the power generation device 4 is in operation based on the signal S5 returned from the inverter 6 (step K1), and if the determination result is NO, That is, when the power generation device 4 is stopped, the diagnosis mode is selected from the plurality of diagnosis modes according to the wired order (step S1). The priority order of the diagnosis mode can be appropriately determined according to the preference of the customer. Such selection of the diagnosis mode may be performed by a person manually pressing a button on the display panel of the power generation device 4 and inputting it manually.

  In this embodiment, since the power generator 4 is stopped, the inverter 6 cannot be used for failure diagnosis. Therefore, either diagnosis mode 3 or 4 is selected. When the diagnosis mode 3 is selected, a signal S2 is sent from the control device 7 to the auxiliary machine 10 and another signal S4 is sent to the inverter 6 to change the output of the auxiliary machine 10 in the fuel cell power generator 4 (step S2). -1). There are various types of auxiliary equipment 10 such as a fuel supply pump, a blower fan, and a heater. For example, the power generation amount in the power generation unit 5 is reduced by reducing the amount of power supplied to the heater and reducing the vaporization amount of the liquid fuel. When the diagnosis mode 4 is selected, a signal S3 is sent from the control device 7 to the home load 9 to change the home load 9 (step S2-2).

  The selected diagnostic mode is not limited to one. The control device 7 may select not only one from a plurality of diagnosis modes but also select two or more and perform diagnosis using the combination mode. For example, when the failure diagnosis is performed using the mode 3 + 4 in which the mode 3 and the mode 4 are selected and combined, the output of the auxiliary machine 10 (for example, the heater) is changed and the household load 9 is changed (steps S2-1 and S2-1). Step S2-2). Even in this case, the accuracy of failure diagnosis is further improved.

  Furthermore, failure diagnosis of the power meter 3 can be periodically repeated at regular intervals. For example, the power meter 3 can be continuously monitored almost constantly by sending a signal S3 for executing the diagnosis mode 4 from the control device 7 to the household load 9 periodically (for example, every 10 minutes). It becomes like this. As a result, the probability of finding the failure of the power meter 3 can be dramatically improved, the failure can be found at an early stage, and the abnormal operation of the fuel cell power generator 4 can be stopped quickly.

  If the measured power signal S1 entering the control device 7 from the power meter 3 changes accordingly as a result of the above fault diagnosis, it is diagnosed that the power meter 3 is operating normally. Return to the first step K1 (S3 → K1).

  On the other hand, if the measured power signal S1 does not change at all even after performing the above-described failure diagnosis, the control device 7 diagnoses that the power meter 3 has failed and repairs or replaces the power meter 3 (step) S4).

  According to the present embodiment, the failure diagnosis of the power meter 3 is confirmed at the time of starting the power generation device 4 before power generation, so that the output power P2 is output from the power generation device 4 to the household load 9 in a state where the power meter 3 has failed. Can be prevented in advance.

  Moreover, according to this embodiment, even in a system such as a fuel cell that cannot change the output suddenly, failure diagnosis of the power meter 3 can be performed without directly changing the transmission power P2 of the inverter 6.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fuel cell as a distributed power source having grid interconnection operation and independent operation functions.

The block diagram of the configuration of the fuel cell power generation system in which the failure diagnosis method of the present invention is used. The flowchart which shows an example of the failure diagnosis method of this invention. The flowchart which shows an example of the failure diagnosis method of this invention.

Explanation of symbols

1 ... Commercial power system, 2 ... Receiving point, 3 ... Power meter,
4. Power generation device (fuel cell power generation system),
DESCRIPTION OF SYMBOLS 5 ... Electric power generation part, 6 ... Inverter, 7 ... Control apparatus, 9 ... Load, 10 ... Auxiliary machine,
11 ... Home distribution board, 12 ... Service breaker, 13 ... Earth leakage breaker,
14a, 14b, 14c, 14d ... branch breaker,
S1, S2, S3, S4, S5 ... signal,
P1 ... Received power,
P2, P3: Transmission power (output power, generated power).

Claims (13)

In a fault diagnosis method for a received power measurement system in a distributed power source in which a power generator is used as a distributed power source having a grid interconnection operation and a self-sustaining operation function
Measure the received power from the commercial power system and the transmitted power from the power generator with a power meter,
The measured power is input to the control device of the power generator as a current or voltage signal,
A failure diagnosis method for a received power measurement system in a distributed power source, wherein, when the power measurement signal does not change for a certain period, it is determined that the power meter has failed. The method according to claim 1, wherein when the output of the inverter of the power generation device is changed, if the power measurement signal does not change, it is determined that the power measuring device is faulty. 3. The method according to claim 1, wherein when the power measurement signal does not change when the inverter of the power generation device is gate-blocked for a short time, it is determined that the power measurement device has failed. The method described in the paragraph. The power meter is determined to be faulty when the power measurement signal does not change when the output of an auxiliary machine inside the power generator is changed. The method of any one of them. 5. The device according to claim 1, wherein when the household load is changed, if the power measurement signal does not change, it is determined that the power meter has failed. 6. the method of. When the power measurement signal does not change when the output of an auxiliary machine inside the power generation device is changed while the power generation device is stopped, it is determined that the power measurement device has failed. A method according to any one of claims 1 to 5. The power meter is determined to be faulty if the power measurement signal does not change when a household load is changed while the power generation device is stopped. The method of any one of them. When the output of the inverter of the power generation device is changed and the output of an auxiliary machine inside the power generation device is changed, if the power measurement signal does not change, it is determined that the power measurement device has failed. The method of claim 1 wherein: When the output of the inverter of the power generation device is changed and the load of a home is changed, it is determined that the power measuring device has failed when the power measurement signal does not change. Item 2. The method according to Item 1. When the power measurement signal is not changed when the inverter of the power generation device is gate-blocked for a short time and the output of an auxiliary machine inside the power generation device is changed, the power measurement device is broken. The method of claim 1, wherein the method is determined. When the inverter of the power generation device is gate-blocked for a short time and the load at home is changed, it is determined that the power measuring device has failed when the power measurement signal does not change. The method of claim 1. The method according to claim 1, wherein the output of the inverter of the power generator is periodically changed. The method according to claim 1, wherein the inverter of the power generator is periodically gate-blocked for a short time.

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