JPH05168160A - AC / DC converter system - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an AC / DC converter system that effectively stores and discharges late-night power without causing a power outage or reverse power flow. [Configuration] A converter with charge / discharge function connected between a power system and a power storage device, and a power receiving point provided at a power receiving point connecting a consumer load between the converter with charge / discharge function and the power system A power detection device and a conversion device control that inputs the detected received power detection value and controls the conversion device with a charging / discharging function so as to maintain the power reception point power value at a set value, and supplies the stored power to a consumer load. And a control device having a system and having a received power control function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC / DC converter system for connecting a power storage device to a power system and utilizing nighttime power.

[0002]

2. Description of the Related Art Recently, the development of electric power storage technology has been advanced. Many of these are aimed at supplementing the peak power in the daytime with surplus power at night and averaging the power demand in the day. In particular, introduction to general consumers is being considered. In order to introduce such a facility to general consumers, it is necessary to store inexpensive late-night power and use the stored power during the daytime to bring about a cost advantage. Further, in these electric power storage technologies, nighttime electric power is often stored in the form of direct current, and therefore an AC / DC converter system is used for conversion between AC and DC.

Conventionally, in such a system, in order to prevent so-called reverse power flow in which electric power is supplied to the electric power system, the electric power charged at night is operated separately from the electric power system at the time of discharging in the daytime. When the power exceeds the capacity of the converter or the discharged power exceeds the stored power, it is necessary to disconnect the converter and connect it to the power system. However, there is a need for improvement in practical application.

An example of a conventional structure is shown in FIG. In FIG. 3, the power system (1) is connected to the rectifier (3) via the power receiving switch (2). A power storage device (4) is connected to the DC circuit of this rectifier. An inverter (inverse conversion device) (5) is also connected to this DC circuit. The AC output side of the inverter (5) and the power system (1) are connected to a customer load (7) via a switching device (6). Further, the rectifier (3) and the inverter (5) have a control device (8) for controlling their operation.

This AC / DC converter system (9) is shown surrounded by a one-dot chain line. In this system, the power receiving switch (2) is turned on for nighttime operation, the switching device (6) turns on the power system side, opens the inverter side, operates the rectifier, and stores the electric power by the storage battery (4). ) Store electricity.

For daytime operation, the power receiving switch (2) is opened, the switching device (6) is turned on only on the inverter (5) side to operate the inverter (5), and the power storage device (4).
Power is supplied from the customer to the customer load (7). At this time, the inverter performs constant voltage control. The control device (8) controls the switching operation and the stoppage of the operation of the rectifier and the inverter. In this system, at the time of daytime operation, when the power of the customer's load exceeds the capacity of the inverter or the storage power of the storage battery is completely consumed, the operation cannot be continued, so the switching device (6) is promptly operated. It is necessary to switch from the inverter (5) side to the power system (1) side, turn on the power receiving switch (2), disconnect the inverter, and connect the system side. There were many problems such as power failure, and improvement was desired for practical use.

[0007]

As described above, the conventional configuration has the following problems. That is,
In order to prevent so-called reverse power flow that flows electric power into the electric power system, it is configured to operate by disconnecting it from the electric power system when discharging the electric power charged at night, during the daytime discharge.
When the load power exceeds the capacity of the converter or the discharge power exceeds the charge power, the operation cannot be continued, the inverter is disconnected, and the switching operation to connect to the power system is required. As a result, the control becomes complicated and an instantaneous power failure is inevitable at the time of switching.

The object of the present invention is to solve the above-mentioned problems and to continuously supply electric power to a customer load without a power failure without performing a complicated switching operation, which simplifies a driving operation and reverses the operation. An object of the present invention is to obtain an AC / DC converter system that does not generate a tidal current and effectively uses late-night power.

[0009]

In order to achieve the above object, in the present invention, a converter with charge / discharge function connected between a power system and a power storage device, and a converter with charge / discharge function are provided. A received power detection device provided at a power receiving point that connects a customer load to the power system, and the charging / discharging function so that the detected power receiving point detection value is input and the power receiving point power value is maintained at a set value. And a controller having a converter control system for controlling the auxiliary converter to supply stored power to a load in the customer, and having a received power control function.

[0010]

According to the above construction, the received power is controlled to a set value in the daytime, the shortage of the stored power is received from the power system, the stored power is supplied to the consumer load, and the inexpensive power is supplied at night. Can be stored as before. Especially, since the converter with charge / discharge function is controlled, it does not require complicated switching operation, and it can continue to supply power to the customer's load without power failure and can be operated easily. Thus, it is possible to effectively use the late-night power without causing reverse power flow.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Between the power system (1) and the power storage device (4) such as a storage battery, the power receiving point (1
A conversion device (10) with a charging / discharging function is provided via a).
At the power receiving point (1a), there is a current transformer (CT) and an instrument transformer (P).
The received power detection device (11) using T) is connected to the in-consumer load (7). The received power detection value (Wmv) output from the received power detection device (11) is input to a comparator (13) in a control device (hereinafter, referred to as a control device) (12) having a received power control function, and the control device By comparing the received power (Wref) set value (14) set in (12), the midnight power is stored in the power storage device (4) through the output limiter (15) and the converter control system (16), and during the daytime Connect the converter (10) with charge / discharge function so that the input from the power system is suppressed to a set power close to zero and discharged, and the power system (1) supplies power only for the amount exceeding the capacity of the converter (10). To do.
In the figure, the AC side is shown as AC and the DC side is shown as DC. The AC / DC converter system (9) of the present embodiment is illustrated by being surrounded by a chain line.

Next, the operation of this embodiment will be described with reference to FIG.

First, night driving will be described. During nighttime operation, the converter with charge / discharge function (10) is operated as a rectifier to charge the power storage device (4) consisting of a storage battery with electric power from the power system (1). At this time, the operation is performed with the maximum capacity of the converter with charge / discharge function (10) to complete the charging. (The judgment of the completion of charging at time a in FIG. 2 is usually due to the secondary voltage of the battery reaching the set value and the integrated charging current value reaching the set value, but this is not the essence of the present invention. (Details are omitted here.) At the time point b in FIG. 2 when starting the daytime operation, the storage battery of the power storage device (4) is fully charged. From that state, the output of the converter with charge / discharge function (10) is set so that the received power (Wmv) detected by the power detection device (11) at the power receiving point is set to a daytime set power value (Wref1) that is set to near zero. Take control.
As a result, during the daytime hours, the received power is operated at the set power (Wref1) that is close to the minimum value that does not cause reverse power flow, and the power required for the customer load (7) that exceeds the set value is automatically generated. Will be supplied from the power storage device (4) through the converter device (10) with a charging / discharging function. When the load in the consumer (7) exceeds the capacity of the converter with charge / discharge function (10) (point c in FIG. 2), the converter with charge / discharge function (1
Since the output of 0) is limited to the rated maximum output, the received power exceeds the set value, but this shortage is supplied from the power system (1). Further, when the stored power is completely consumed (the judgment that the discharge is completed at time point d in FIG.
Although the voltage of the power storage device has reached the minimum set value and the discharge current integrated value has reached the set value, this is not the essence of the present invention, so details will be omitted here). (10) stops the operation, but at this time as well, since the received power (Wmv) can be continuously supplied from the power system (1), the customer load (7) continues to be supplied with power without a power failure. Will be done.

As described above, in the above embodiment, the received power is detected at the power receiving point, and the output of the converter with charge / discharge function is controlled so that the detected received power has a set value close to zero. Therefore, during the daytime, the minimum set received power (Wref
The converter with charge / discharge function is operated so as to be 1). As a result, the electric power required for the internal load exceeding the set value can be supplied from the power storage device via the conversion device with charge / discharge function, and the internal load is greater than the capacity of the conversion device with charge / discharge function. If it exceeds, the shortage will be automatically supplied from the power grid. In addition, even when the stored power is completely consumed, the power can be continuously supplied from the power grid, so that it is possible to continue supplying power to the customer load without a power failure, and there is no complicated switching operation. It is possible to realize a system that simplifies the operation, does not cause reverse power flow, and effectively uses nighttime electricity.

(Other Embodiments) In the embodiment described above,
Although the example using the storage battery as the power storage device has been described, it goes without saying that the present invention can be applied to the case of other power storage devices such as using a superconducting coil. Also,
In the above-mentioned embodiment, the night operation is performed with the maximum capacity of the converter, but it goes without saying that the operation can be performed by changing the set value by using the constant received power control according to the present invention.

[0016]

As described above, when the AC / DC converter system according to the present invention is used, it is possible to continue supplying electric power to the load in the customer without power failure without complicated switching operation. It is possible to realize a switching converter system that simplifies the operation, does not cause reverse power flow, and effectively uses nighttime power.

[Brief description of drawings]

FIG. 1 is a single-line circuit diagram showing an embodiment of the present invention.

FIG. 2 is a curve diagram with respect to changes in time such as the charge amount of the device of FIG. 1, the input / output of the converter, the received power, and the load power of the customer.

FIG. 3 is a single-line circuit diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electric power system 4 ... Electric power storage device 7 ... Consumer load 9 ... AC / DC converter system 10 ... Converter with charge / discharge function 11 ... Received power detection device 11a ... Received power (Wmv) detection value 12 ... Received power control function Control device 14 ... Power receiving point power (Wref) set value 15 ... Output limiter 16 ... Converter control system

Claims (1)

[Claims] 1. A conversion device with a charging / discharging function connected between a power system and a power storage device, and a power receiving point connecting a consumer load between the conversion device with a charging / discharging function and the power system. And a converter for supplying the stored electric power to a customer's internal load by controlling the converter with a charging / discharging function so that the detected electric power detected value is inputted and the electric power at the electric power receiving point is kept at a set value. An AC-DC converter system, comprising: a controller having a device control system and a power reception power control function.