JPH08236134A - Power supply control device for fuel cell - Google Patents

Abstract

PURPOSE: To continue power supply from a fuel cell to a specified load when power transmission from a substation becomes abnormal by specifically constituting a power supply control device used in load operation jointly using power from the substation and that from the fuel cell. CONSTITUTION: A load line 3 is connected to a power transmission line 2 from a substation through a line protecting breaker MC1, directly connected to an uninterruptible power load 8 having a load capacity less than the power generating capacity of a fuel cell 4, and connected to a plurality of general loads 9-11 through capacity limiting breakers MC 3-5. An inverter 5 having a converting function for converting a d.c. output from the fuel cell 4 into an a.c. output of voltage, frequency, and phase detected from the power transmission line 2, and an abnormality detecting function for detecting the state of the power transmission line 2 and abnormality of the power transmission line 2 when a failure of the line 2 occurs, and controlling the line protecting breaker MC1 and the capacity limiting breakers MC 3-5 by detected signals is installed at the output end of the fuel cell 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects electric power from a fuel cell such as a polymer electrolyte fuel cell or a solid oxide fuel cell with electric power from a transmission system from a substation to supply power to a load. It relates to the power supply control device that was made possible,
In particular, the present invention relates to a fuel cell power supply control device capable of continuing and operating power supply from a fuel cell only to a specific load when an abnormality occurs such as a power failure in a power transmission system.

[0002]

2. Description of the Related Art Electric power generated by fuel cells, solar cells, etc. and electric power from a power transmission system, that is, a power station,
There is so-called interconnection power operation in which a load is operated by using electric power from a commercial power source that is sent via a transmission line via a substation. For this operation, in order to ensure the safety of the power transmission system, when the power transmission system is lost, that is, when there is a power failure, such as a power failure that cuts off the power supply from the commercial power source, the fuel cell and solar The power supply from the battery to the grid must be stopped. Therefore, a circuit breaker for system protection is installed at the system interconnection point for interconnection of both power sources. As a result, even if power generation by fuel cells etc. continues, such as when the power transmission system is lost, the power supply to the power transmission system is stopped due to the opening of the circuit breaker installed at the grid interconnection point. Will be retained. However, a power generation device such as a fuel cell must supply all the electric power required by a load provided up to the grid interconnection point (hereinafter referred to as the power generation device side). May exceed the output capacity of the generator and the generator may trip.

In general, a power generator using a fuel cell installed in a building or the like, which is operated in connection with a power transmission system, has almost no vibration and does not generate harmful exhaust gas, is consumed by the building. The one having a capacity smaller than the maximum electric energy is selected and set. Therefore, if the circuit breaker at the grid interconnection point is opened when the power transmission system is lost, the power consumption of the load installed on the generator side may exceed the maximum power generation capacity and the generator may trip. .

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention stops the power supply to a part of the load installed on the side of the power generation device at the time of loss of the power transmission system and consumes the power. A power supply control device for a fuel cell that prevents the power generation device from tripping by allowing the power to be smaller than the maximum power generation capacity of the power generation device so that some other loads that continue to supply power can continue to operate. The challenge is to provide.

[0005]

Therefore, the fuel cell power supply control device of the present invention has the following means.

(1) A load that is connected to a power transmission system that supplies commercial power from a substation through a system protection circuit breaker, and uses the commercial power supplied from the power transmission system and the power generated by a fuel cell in combination. The line that is connected to the uninterruptible load whose load capacity is less than the power generation capacity of the fuel cell and the line that is connected to a plurality of general loads via the capacity limiting circuit breakers The provided load system is provided.

(2) A conversion function for converting a DC output generated by the fuel cell into an AC output having the same voltage, frequency and phase as commercial power supplied by the power transmission system, and a detection function (UVR, OVR, UFR, OFR or its equivalent function and independent operation detection function) detect an abnormality in the power transmission system, open the system protection circuit breaker by the detection signal, and disconnect the load system from the transmission system. At the same time, the inverter with a fault detection function that opens the capacity limiting circuit breaker to cut off the power supply to the less important general load and continuously operates only the unimportant uninterruptible load It was installed at the output end of the fuel cell that supplies power to the system.

In addition to the above (1) and (2), another fuel cell power supply control device of the present invention has the following means.

(3) The power supply from the fuel cell to the load system or from the load system to the fuel cell is cut off at the output end of the inverter, which is interposed in the line for supplying power from the fuel cell to the load system. An output circuit breaker was installed.

[0010]

The fuel cell power supply control device of the present invention uses the above-mentioned means (1) and (2) to: (1) When the electric power supplied from the power transmission system has no abnormality such as a power failure, The power required for each of the uninterruptible load directly connected and the general load connected via the capacity limiting circuit breaker is generated by the fuel cell, and the voltage of the power of the transmission system is converted by the conversion function of the inverter. Power supplied to the load system through the system protection circuit breaker and the power supplied at the same frequency and phase, and supplied by the power that complements the power from the fuel cell, and the entire load operates. . This allows the fuel cell to maximize its availability and supply power to the load.

When an abnormality occurs in the electric power supplied from the power transmission system, the inverter has an abnormality detection function (UVR,
OVR, UFR, OFR or its equivalent function and independent operation detection function) detect the abnormality and cut off the system protection circuit breaker (MC1) by the detection signal to establish the interconnection between the load system and the transmission system. By stopping the power supply from the fuel cell to the power transmission system, the safety of the power transmission system is secured. Further, the inverter cuts off the capacity limiting circuit breakers (MC3, MC4 ...) Of the load system by the detection signal, and supplies electric power through these capacity limiting circuit breakers. The power supply to the less important general load is cut off. This prevents the fuel cell from tripping due to over capacity, and allows continuous operation without stopping the power supply to the unselected uninterruptible load that is directly selected and directly connected to the fuel cell. Machine or UPS (Uninterruptible Power Supply) for computer is not required.

Further, when the abnormality of the electric power supplied from the power transmission system is eliminated, the DC output of the fuel cell is converted by the inverter to the voltage of the electric power of the transmission system in which the abnormality is eliminated,
While making the AC output the same as the frequency and phase,
After confirming the restoration of the power transmission system by the anomaly detection function, close the system protection circuit breaker and the capacity limiting circuit breaker to connect the power transmission system and the load system to operate the general load. It is possible to shift to driving.

Further, another fuel cell power supply controller of the present invention is the above (3) in addition to the above (1) and (2).
In addition to the above (1), (2) when there is no abnormality in the power transmission system, the output circuit breaker is opened until the start of the fuel cell is completed and the power from the fuel cell can be supplied. Power can be supplied to all loads without interfering with the fuel cell, and
When the power from the fuel cell can be supplied, such as when the fuel cell starts up, the output circuit breaker can be closed and the power from the fuel cell can be used together with the power from the transmission system. The battery can be protected.

Further, when a fuel cell trips due to a short circuit, a ground fault, or the like during normal operation or when power is supplied to an uninterruptible load due to an abnormality in the power transmission system, the output circuit breaker is opened to close the fuel. The fuel cell can be protected by disconnecting the battery from the load system.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel cell power supply control device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a fuel cell power supply control device of the present invention.

As shown in the figure, a power transmission system 2 for supplying commercial power from a substation is drawn into the building indicated by reference numeral 1. Power transmission system 2 and loads 8 inside building 1
A grid protection circuit breaker MC1 is provided at a grid connection point that is connected to a load grid 3 that supplies power to 11, and when power supplied from the grid 2 is abnormal, for example, a power failure occurs, This is opened to prevent a flow of electric power from the load system 3 to the power transmission system 2, that is, a so-called reverse power flow, so that the power transmission system 2 is protected.

Further, the load system 3 is required to have an electric device used in the building 1, that is, a so-called load, an emergency light which is required to be equipped for safety reasons and which is lit in an emergency, and a stable operation at all times. , An uninterruptible load 8 consisting of important, preselected equipment such as a large-scale computer, and other general lighting, and even if the power supply to the air conditioner is stopped, no serious trouble will occur. General loads 9 to 11 made up of low equipment are connected. The load system is always connected to the uninterruptible load 8 among them, and is open / closed to the general loads 9 to 11 so as to be able to connect / disconnect the circuit breaker MC3, MC4, MC for capacity limitation.
5 are interposed and connected.

On the other hand, in the building 1, it is possible to generate electric power by electrochemically reacting hydrogen in the supplied fuel with oxygen in the air, such as a polymer electrolyte fuel cell or a solid electrolyte cell. A fuel cell 4 capable of being installed is installed so as to cover a part of the electric power required in the building 1. In particular, the fuel cell 4 that does not generate noise associated with power generation and that does not generate harmful exhaust gas is an optimal power generation device in the building 1. As described above, the power generation capacity of the fuel cell 4 is selected to have a capacity smaller than the maximum amount of power consumed by the load installed in the building 1, and normally operates near the power generation capacity limit to increase the operating rate. Maximize.

Next, an inverter 5 is installed in the line provided for supplying the electric power generated by the fuel cell 4 to the load system 3. The inverter 5 is connected to the power transmission system 2 via the instrument transformer PT, and exchanges the power supplied from the power transmission system 2 to the load system 3 such as the voltage, phase, and frequency of the power transmission system 2 side. The index peculiar to the current is grasped by detecting the induced alternating current induced on the secondary side of the instrument transformer PT by its control unit. The inverter 5 has a conversion function of converting the DC output input from the fuel cell 4 into an AC output having at least the same voltage, frequency and phase as the power of the power transmission system 2 based on the grasped index specific to the AC of the power transmission system 2. It is equipped with In addition, the inverter 5 has the following protection relays: ・ Overvoltage relay (OVR) ・ Undervoltage relay (UVR) ・ Frequency rising relay (OFR) ・ Frequency lowering relay (UFR) When the abnormality of the power transmission system 2 is detected from the induced alternating current of the instrument transformer PT, the circuit protection circuit breaker MC1 is opened to protect the power transmission system 2 and the fuel In order to prevent the trip of the battery 4, the capacity limiting circuit breakers MC3 to MC5 for continuing the conduction between the load system 3 and the general loads 9 to 11 are opened, and the electric power generated by the fuel cell 4 is supplied to the fuel cell 4 It has a function of supplying only to the uninterruptible load 8 whose power generation capacity is less than or equal to.

Further, when the abnormality of the power transmission system is resolved, the inverter 5 outputs the output of the fuel cell 4 which supplies power to the uninterruptible load 8 to the voltage and frequency of the power of the transmission system 2 whose abnormality is resolved. And the same AC output as the phase, by correcting the conversion function, by the abnormality detection function,
After confirming the restoration of the power transmission system, the circuit protection circuit breaker MC1
Can be closed, the power transmission system 2 and the load system 3 can be interconnected, and the capacity limiting circuit breakers MC3 to MC5 can be opened and closed to operate a general load and shift to normal operation.
As a result, when the power from the power transmission system is restored, the uninterruptible load 8 can be smoothly supplied with power without any phase shift or the like.

An output circuit breaker MC2 is installed at the output end of the inverter 5. This output circuit breaker MC2
Is the fuel cell 4 when there is no abnormality in the power transmission system 2.
Until the power is set up so that the power from the fuel cell 4 can be supplied, all the loads 8 to 1 are opened.
1, the electric power from the power transmission system 2 can be transmitted without interfering with the operation of the fuel cell 4, and the electric power from the fuel cell 4 is waited for, and then closed.
The electric power from the fuel cell 4 can be used together with the electric power from the power transmission system 2.

By installing this output circuit breaker MC2, the fuel cell can be protected by the input of electric power from the power transmission system 2. Further, when the uninterruptible load 8 directly connected to the load system 3 is short-circuited, grounded, or the like during normal operation, or when power is supplied to the uninterruptible load when the power transmission system is abnormal, and the fuel cell trips, It is also possible to protect the fuel cell 4 by opening the output circuit breaker MC2 and disconnecting the fuel cell 4 from the load system 3. In this embodiment, when an abnormality occurs in the power transmission system 2, the inverter 5 has an abnormality detection function (a protective relay (UVR, OVR, UFR, OFR) or a function equivalent thereto and an independent operation detection function). The abnormality is detected, and by the detection signal, the capacity limiting circuit breaker MC3 ...
The MC5 is cut off all at once and the power supply to the general loads 9 to 11 is stopped at the same time. However, if the power capacity of the uninterruptible load 8 is not constant, the power supplied to the uninterruptible load 8 The amount of electricity is detected, and only electric power is supplied to a general load exceeding the power generation capacity of the fuel cell 4, for example, the general load 11.
It can be stopped. Further, the general loads 9 to 11 may be given priorities so that they are supplied in descending order of priority.

[0023]

As described above, according to the power supply control device for a fuel cell of the present invention, by the structure shown in claim 1, (1) the importance of the operation stop due to the abnormality occurrence of the power transmission system Eliminates the need for emergency generators and computer UPSs to supply power to high uninterruptible loads.

(2) The fuel cell is sufficiently protected, and stable power sharing is possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply system according to an embodiment of a fuel cell power supply control device of the present invention.

[Explanation of symbols]

 1 Building 2 Transmission system 3 Load system 4 Fuel cell 5 Inverter 8 Uninterruptible load 9, 10, 11 General load MC1 System protection circuit breaker MC2 Output circuit breaker MC3, MC4, MC5 Capacity limiting circuit breaker PT Meter transformer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Sakurai 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya City Mitsubishi Heavy Industries, Ltd. Nagoya Machinery Works (72) Inventor Masayuki Morimoto 1 Takamichi, Iwatsuka-machi, Nakamura-ku, Nagoya Address: Mitsubishi Heavy Industries, Ltd., Nagoya Machinery Works

Claims (2)

[Claims] 1. A power supply control device for a fuel cell used for load operation in which electric power supplied from a substation and supplied by a power transmission system and electric power generated by a fuel cell are used together. And a load system that is directly connected to an uninterruptible load whose load capacity is less than or equal to the power generation capacity of the fuel cell, and is also connected to a plurality of general loads via capacity limiting circuit breakers, and the fuel cell. DC output from the conversion function for converting the voltage output detected from the power transmission system, the frequency, and the AC output of the phase, and the state of the power transmission system, to detect an abnormality of the power transmission system at the time of a power transmission system fault, the An inverter having an abnormality detection function for controlling the system protection circuit breaker and the capacity limiting circuit breaker by a detection signal is provided at each output end of the fuel cell. Power supply device for fuel cell to be collected. 2. The fuel cell power supply control device according to claim 1, wherein an output breaker is provided at an output end of the inverter.