JPH1066349A - Power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of a power supply apparatus which supplies an AC power into which a DC power obtained from a solar cell, a fuel cell, etc., is converted by an inverter in the power supply apparatus while it is put into operation linked with a power system. SOLUTION: A control circuit 31 by which an inverter 12 is put into operation linked with a power system 2 when the power system 2 is in normal operation and put into single operation when the power system 2 is interrupted is provided to supply a power to a load 3 consistently from the secondary side of a transformer 13 connected to the output of the inverter 12. With this constitution, a large and expensive changeover switch which is provided in a power supply route to the load 3 in a conventional constitution and has a latch function can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a direct current of a solar cell, a fuel cell or the like into an alternating current by an inverter, and supplying power to a load while interconnecting with a power system.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional configuration example using a solar cell as this kind of power supply device. 2, reference numeral 1 denotes a solar cell, 10 denotes a power supply, 2 denotes a power system, and 3 denotes a load. The power supply 10 includes a circuit breaker 11, an inverter 12 including a semiconductor switch element, and the like. A transformer 13 for matching the output voltage with the voltage of the power system 2, a capacitor 14 for removing harmonic components generated from the inverter 12, and a system interconnection reactor 15
, An electromagnetic contactor 16, a circuit breaker 17, a changeover switch 18 for switching a power supply path to the load 3, a circuit breaker 19, and a control circuit 20 for controlling these components.
It is composed of

The operation of the power supply device 10 having the configuration shown in FIG. 2 will be described below. When the power system 2 is healthy, the inverter 12 via the circuit breaker 11 converts the DC voltage of the solar cell 1 into an AC voltage by a control signal from the control circuit 20,
This AC voltage is matched with the voltage of the power system 2 by the transformer 13, and the AC power generated from the inverter 12 on the secondary side of the transformer 13 is supplied to the system interconnection reactor 15,
The power system 2 is connected to the power system 2 via an electromagnetic contactor 16 that is closed by a command from the control circuit 20 and a circuit breaker 17 using the power system 2 as an operation power source. At this time, inverter 1
The operation coil of the changeover switch 18 using the AC power from the operation power supply 2 as a power supply is non-excited according to a command from the control circuit 20, and the load 3 is connected to the system interconnection reactor 15, the closed electromagnetic contactor 16 and the wiring. AC power from the inverter 12 via the circuit breaker 17 and power from the power system 2 are supplied via the changeover switch 18 and the circuit breaker 19 for wiring.

When the amount of solar radiation is small in the above-described state, the AC power output from the inverter 12 is also small.
There is also a state in which AC power from the inverter 12 and power from the power system 2 are fed in parallel (a so-called forward power flow state). When the AC power output from the inverter 12 exceeds the required power of the load 3, The surplus power is supplied to the power system 3 (a so-called reverse power flow state).

When the power system 2 is sound and the inverter 1
When the motor 2 is stopped, the electromagnetic contactor 16 is opened by a command from the control circuit 20, and power is supplied to the load 3 from the power system 2 via the changeover switch 18 and the circuit breaker 19. When a power failure occurs in the power system 2, the control circuit 20 detects the power failure and opens the electromagnetic contactor 16, excites the operation coil of the changeover switch 18, and supplies power to the load 3 via the transformer 13. When the required power of the load 3 exceeds the AC power output from the inverter 12 in this state, the control circuit 20 detects this and stops the inverter 12.

[0006]

According to the above-described conventional power supply device, a power failure occurs in the power system 2 and the AC power from the inverter 12 is used as an operation power supply for switching the power supply path to the load 3. When the operation coil of the changeover switch 18 composed of a contactor is excited, an excessive rush current flows through the operation coil, and the control circuit 20 detects the rush current to limit the output current of the inverter 12.
The output voltage of the inverter 12 is reduced to a value based on the current limit value, and this reduction may cause chattering of the electromagnetic contactor.

As a solution to this problem, a changeover switch having a latch function has conventionally been used, but this changeover switch was large and expensive. An object of the present invention is to provide a power supply device that solves the above problems.

[0008]

Means for Solving the Problems The present invention provides a solar cell,
An inverter for converting a DC voltage to an AC voltage, such as a fuel cell, and a transformer connected to the output of the inverter for matching the output voltage of the inverter with the voltage of the power system; and a transformer connected to the secondary side of the transformer. A system interconnection reactor, an electromagnetic contactor connected between the reactor and the power system, and when the power system is healthy, the power system and the inverter are operated in an interconnected manner. Is a power supply device having a control circuit for operating the inverter independently, and supplying power to a load from a connection point between the transformer and a system interconnection reactor.

According to the present invention, since the power supply to the load is always performed from the secondary side of the transformer connected to the output of the inverter, the changeover switch provided in the power supply path to the load in the related art becomes unnecessary. .

[0010]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention. Components having the same functions as those of the conventional power supply device shown in FIG. 2 are denoted by the same reference numerals. . That is, in FIG. 1, the power supply device 30 includes a wiring breaker 11, an inverter 12, a transformer 13, a capacitor 14, a system interconnection reactor 15, and an electromagnetic contactor 1.
6, a circuit breaker 17, a circuit breaker 19, and a control circuit 31 for controlling these constituent devices.

The operation of the power supply device 30 having the configuration shown in FIG. 1 will be described below. When the power system 2 is healthy, the inverter 12 via the circuit breaker 11 converts the DC voltage of the solar cell 1 into an AC voltage according to a control signal from the control circuit 31,
This AC voltage is matched with the voltage of the power system 2 by the transformer 13, and the AC power generated from the inverter 12 on the secondary side of the transformer 13 is supplied to the system interconnection reactor 15,
The power system 2 is operated as an operating power source, and is connected to the power system 2 via the electromagnetic contactor 16 and the circuit breaker 17 which are closed by a command from the control circuit 31. At this time, the AC power output from the inverter 12 via the transformer 13 is applied to the load 3 and the AC power from the power system 2 via the wiring circuit breaker 17, the closed electromagnetic contactor 16 and the system interconnection reactor 15. Power is supplied via the circuit breaker 19.

When the amount of solar radiation is small in the above-described state, the AC power output from the inverter 12 also becomes small.
There is also a state in which AC power from the inverter 12 and power from the power system 2 are fed in parallel (a so-called forward power flow state). When the AC power output from the inverter 12 exceeds the required power of the load 3, The surplus power is supplied to the power system 3 via the system interconnection reactor 15, the closed electromagnetic contactor 16 and the circuit breaker 17 (so-called reverse power flow state).

The power system 2 is sound and the inverter 1
When the motor 2 is stopped, the electromagnetic contactor 16 is closed by a command from the control circuit 31 and the load 3 is connected to the circuit breaker 17 for wiring from the power system 2, the electromagnetic contactor 16, the reactor 15 for system interconnection, and the wiring for circuit 3. The power is supplied via the device 19. When a power failure occurs in the power system 2, the control circuit 31 detects the power failure and opens the electromagnetic contactor 16, while the inverter 12 is in an independent operation state, and the power supply to the load 3 is performed by the inverter 12 via the transformer 13. When the required power of the load 3 exceeds the AC power output from the inverter 12 in this state, the control circuit 31 detects this and stops the inverter 12.

[0014]

According to the present invention, since the power supply to the load is always performed from the secondary side of the transformer connected to the output of the inverter, the changeover switch provided in the power supply path to the load in the related art is unnecessary. Thus, this power supply device can be downsized and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power supply device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a power supply device showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solar cell 2 Electric power system 3 Load 10 Power supply device 11 Wiring breaker 12 Inverter 13 Transformer 14 Capacitor 15 Grid connection reactor 16 Magnetic contactor 17 Wiring breaker 18 Changeover switch 19 Wiring breaker 20 Control circuit 30 Power supply 31 Control circuit

Claims (1)

[Claims] 1. An inverter for converting a DC voltage of a solar cell, a fuel cell, or the like into an AC voltage, a transformer connected to an output of the inverter, and matching an output voltage of the inverter with a voltage of a power system, A system interconnection reactor connected to the secondary side of the reactor, an electromagnetic contactor connected between the reactor and the power system, and a connection operation between the power system and the inverter when the power system is healthy. And a control circuit for operating the inverter independently when the power system is out of power, and supplying power to a load from a connection point between the transformer and a system interconnection reactor.