JP2001177995A - Hybrid power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem such that power conversion efficiency decreases due to the different in charge/discharge power when nighttime power from a power company is converted to DC by a charge/discharge conversion device for charging a battery for storing power, and DC power from a battery for storing power or a solar battery is converted to AC for feeding to a load. SOLUTION: In a charge/discharge conversion device 4A, a plurality of charge/discharge converters PCS1-PCS4 in units are connected in parallel, and an operation/stop control part 5 selectively operates a plurality of chare/discharge converters to reach minimum, and required power conversion capacity when converting power from DC to AC or from AC to DC. Also, a plurality of charge/ discharge converters individually connector or separate a solar battery 2, a battery 3 for storing power, and a system and individually forms a charging path from the solar battery to the battery for storing power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid power supply system in which a power storage battery is charged by using a midnight power or a solar battery of a power company and discharged from the power storage battery when the load increases during the daytime. The present invention relates to a charge / discharge method for a power storage battery.

[0002]

2. Description of the Related Art FIG. 3 shows a power supply system of this kind. The power supply to the load 1 can use the power obtained by converting the DC power from the solar cell 2 or the power storage battery 3 into the charge / discharge converter 4 having a bidirectional conversion function, in addition to the purchased power from the power company. To do.

In the nighttime, the charge of the battery 3 is carried out by using the late-night power of a low-priced power company for power leveling at night.
Utilizes the DC converted power. In the daytime, the surplus power from the solar cell 2 is used.

[0004] When a wind power generator is also provided, unlike a solar cell, the power generated by the wind power generator is converted into direct current during a windy time regardless of day and night to charge the battery 3 and supply power to a load. Can be used for

[0005]

In the above-mentioned hybrid power supply system, the charging and discharging of the power between the charging / discharging converter 4 and the battery 3 is performed by charging the battery 3 by converting the cheap midnight power from AC to DC. Then, during the daytime load increase time period, the device 4 converts the stored power of the battery 3 from DC to AC and supplies it to the load.

For this reason, the power conversion by the charging / discharging conversion device 4 is performed in such a manner that the power required to charge the battery 3 in a short time zone in which the midnight power can be used and the power discharged in a short time according to the load power in the daytime. The load factor differs greatly from the power required to perform the operation.

For example, the time zone of midnight power is 4 hours (from 1:00 to 5:00), during which the charging / discharging converter 4
25 kW (100 kWH) for power conversion of 00 kWH
/ 4H). On the other hand, in the daytime power conversion, when the charge / discharge converter performs 100 kWH in 10 hours (from 8:00 to 18:00), 10 kW (100 kW) is used.
H / 10H).

As described above, the power conversion capacity of the charging / discharging conversion device 4 differs between charging and discharging of the battery by 2.5 times, and the device 4 needs a device configuration having a large power conversion capacity of 25 kW. Becomes As a result, the device 4 has a problem that the size and cost are increased and the efficiency is reduced such as an increase in power conversion loss.

This problem becomes more pronounced as the time difference between the charging time and the discharging time increases. Actually, the charging time is 6 hours (from 0:00 to 6:00), and the discharging time is 16 hours (from 6:00 to 22).
Hour) about.

It is an object of the present invention to provide a hybrid power supply system capable of increasing the power conversion efficiency of a charge / discharge conversion device even when the charge / discharge time of a battery is different, and improving the operation efficiency of the system.

[0011]

SUMMARY OF THE INVENTION According to the present invention, the power conversion capacity required when charging and discharging a battery by a charge / discharge converter is greatly different.
Focusing on the AC conversion, in addition to the conversion of the discharge power of the battery, also performs the conversion of the generated power, such as a solar cell, whose time zone is limited. The minimum required conversion capacity at the time of charging and discharging is ensured by selective operation / stop of the unit, and is characterized by the following configuration.

[0012] The power storage battery can be charged by converting the late-night power from the power company into DC by a charge / discharge converter, and the charge / discharge converter can convert the DC power from the power storage battery or a solar cell or a wind power generator. In a hybrid power supply system that can convert AC to AC and supply power to a load, the charge / discharge conversion device connects a plurality of unitized charge / discharge converters in parallel and converts the DC to AC power or AC to DC. In the above power conversion, the plurality of charge / discharge converters are selectively operated so as to have a required minimum power conversion capacity.

[0013] The plurality of charge / discharge converters can individually connect / disconnect the solar cell or wind power generator to / from a power storage battery and system, and can store the power storage power from the solar cell or wind power generator. The charging path to the battery can be formed individually.

[0014]

FIG. 1 is a configuration diagram of a hybrid power supply system showing an embodiment of the present invention. FIG.
The different part is in the charge / discharge conversion device 4A.

The charge / discharge converter 4A has a parallel configuration of four charge / discharge converters PCS1 to PCS4. Each converter P
The operation / stop control of the operation CS / PCS 4 is individually performed by the operation / stop controller 5. This operation / stop control is performed by current detection by the current transformer 6.

For example, for short-time charging of the battery 3 by midnight power, all the charge / discharge converters PCS1 to PCS4 are operated by AC-DC conversion. In the daytime when power is supplied from the battery 3 to the load 1, some converters are operated according to the load, and the remaining converters are stopped.

The amount of power discharged from the battery 3 changes according to the difference in the power generated by the solar cell 2, and the shortage is supplied from the solar cell 2. When the load is extremely light and there is surplus power of the solar cell 2, it is used for charging the battery 3.

As described above, in the present embodiment, the charging / discharging converter 4A is unitized to include a plurality of charging / discharging converters, and the number of operating charging / discharging converters according to the amount of power required for charging / discharging. Switch. In other words, the power conversion by the charging / discharging conversion device 4A is such that all the charging / discharging converters are operated to charge the battery 3 in a short time period in which the midnight power can be used, and the charging is performed in a long time according to the load power in the daytime. To discharge, some charge / discharge converters are operated.

Thus, during operation of each charging / discharging converter, the load factor is always increased, the rate of power conversion loss is reduced, and the conversion efficiency and operating efficiency can be increased.

Further, since the discharge of the battery 3 becomes a smaller current than that during charging, the charge / discharge converters PCS1 to PCS1
A part of the CS4 can be simplified and the DC-AC conversion function can be omitted, and its size and cost can be reduced.

FIG. 2 is a block diagram showing another embodiment of the present invention. This drawing is different from FIG. 1 in the charge / discharge converter 4B.

The device 4B comprises four charge / discharge converters PCS1
~ PCS4, and a switch MC1 on its DC side and AC side.
To MC12, of which the switching devices MC1, MC3, MC3
MC5 and MC7 are the solar cell 2 and the charge / discharge converters PCS1 to PCS1.
The DCS input terminal of the PCS4 can be connected / disconnected, and the switches MC2, MC4, MC6, and MC8 can connect / disconnect the battery 3 and the DC input terminals of the charge / discharge converters PCS1 to PCS4. Is a converter PCS
1 to enable / disconnect the AC side of PCS4. Further, from these connection relations, the switching devices MC1 to MC1
The battery 3 can be charged through a plurality of routes through the MC 8.

In the above configuration, the charging and discharging of the battery 3 is performed in the same manner as in FIG. 1, and all the charging / discharging converters PCS1 to PCS4 are used for charging the battery 3 using the midnight power.
, And some of the charge / discharge converters are operated for discharging from the battery 3 in the daytime. For these charging and discharging, the control unit 5 turns on the switches MC2, MC4, MC6 and MC8 as necessary.
Performs OFF switching control and converter start / stop control.

To supply the power generated by the solar cell 2 to the load side, some or all of the switches MC1, MC3, MC5, and MC7 are turned on, and the converters PCS1 to PCS4 connected to the turned-on switches. Drive.

Further, in order to charge the battery 3 with the surplus power of the solar cell 2, a part or all of the switches MC1 to MC8 are turned on to form a current path to the battery 3.

In order to make these switching possible, the operation / stop control unit 5 is provided with a power generation measuring device for the solar cell 2.

In this embodiment, in addition to obtaining the same operation and effect as the case of FIG. 1, each unit and the batteries 2 and 3 can be separated from each other, and some converters and solar cells can be separated. When a failure occurs or maintenance is performed, the charge / discharge function of the battery 3 and the like can be ensured, and the repair work for the failure can be simplified.

Although the embodiment shows a case where four charge / discharge converters are provided, the present invention can be applied to a configuration where a plurality of converters are provided. In addition, the converters may have different power capacities, and may be operated / stopped so that the maximum efficiency is always obtained according to the required conversion power. Further, the present invention can be applied to a system having a wind power generator as a power source instead of a solar cell or as a combined power source.

[0029]

As described above, according to the present invention, the charging / discharging converter is configured in parallel with a plurality of units, and the minimum required conversion capacity during charging and discharging is achieved by selectively operating / stopping each unit. As a result, the power conversion efficiency of the charge / discharge conversion device can be increased even when the charge / discharge time of the battery is different, and the operating efficiency of the system can be increased.

Further, a part of the charge / discharge converter can be configured to have only the AC / DC conversion function, and the size and cost of the system can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a hybrid power supply system showing another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional hybrid power supply system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Load 2 ... Solar cell 3 ... Power storage battery 4, 4A, 4B ... Charge / discharge converter 5 ... Operation / stop control part PCS1-PCS4 ... Charge / discharge converter MC1-MC12 ... Switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // G05F 1/67 G05F 1/67 A F term (reference) 5G003 AA01 AA06 AA07 CC02 DA07 GB06 5G015 GA03 GA09 JA05 JA26 JA35 JA52 5G066 HA06 HB03 HB06 JA07 JB03 5H007 AA05 BB07 CB00 CC05 DB01 DC02 5H420 BB02 BB03 BB13 BB14 CC03 CC04 DD03 EB01 EB16 EB37 EB39 EB40 FF04

Claims (2)

[Claims] 1. A power storage battery can be charged by converting late-night power from a power company into direct current by a charge / discharge converter, and the charge / discharge converter can be supplied from the power storage battery or from a solar cell or a wind power generator. In a hybrid power supply system capable of converting DC power to AC and supplying power to a load, the charge / discharge converter connects a plurality of unitized charge / discharge converters in parallel, and converts power from DC to AC, or from AC. A hybrid power supply system, wherein the plurality of charge / discharge converters are selectively operated so as to have a minimum required power conversion capacity when converting power into direct current. 2. The plurality of charge / discharge converters enable individual connection / disconnection of the solar cell or wind power generator with a power storage battery and system, and the power storage from the solar cell or wind power generator. The hybrid power supply system according to claim 1, wherein a charging path to the battery can be formed individually.