JP2000175360A - Inverse power flow method of power storing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the leveling of power by restraining power change and voltage change. SOLUTION: This power storing system is equipped with a battery for storing electric power which is connected with a power system via a converter which system interconnects dispersed power sources containing wind power generation with a commercial power source system, and performs the leveling of power by supplying the power stored in the battery to a load. This inverse power flow method turns generated power of the dispersed power sources and various kinds of information containing weather information and load information into a data base, turns inverse power flow PS to the commercial power source system into a pattern on the basis of the various kinds of information, calculates charge and discharge power PB of the battery from the patterned inverse power flow PS and the generated power PG of the dispersed power sources, charges the battery with the generated power PG of the dispersed power sources in a light load time zone containing night, discharges the stored power of the battery in a heavy load time zone containing daytime, and makes power matched with a load power flow inversely to the commercial power source system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse power flow method for an electric power storage system, for example, in a power system in which a wind power generation system or the like is connected to a commercial power system, the load power is leveled by charging and discharging a battery. The present invention relates to a reverse flow method for an electric power storage system.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, a distributed power supply 1 including a power generation system such as a wind power generation system or a small hydro power generation system is connected to a commercial power supply system (hereinafter, referred to as a power supply system) owned by a power company.
In a power system interconnected with the power system 2, power generated by the power system 2 is supplied to the load 3 and power generated by the distributed power source 1 is also supplied to the load 3. Further, surplus power generated by the distributed power source 1 is caused to flow backward to the power source system 2.

[0003]

When the above-mentioned wind power generation system is used as the distributed power source 1, the power generated by the wind power generation system changes every moment according to the wind speed as shown in FIG. When the generated power having such a large fluctuation flows backward to the power supply system 2, the output power of the power supply system 2 is not constant and varies greatly. Such power fluctuations of the distributed power supply 1 cause power fluctuations and voltage frequency fluctuations on the power supply system side, which is not desirable.

Therefore, the present invention has been proposed in view of the above-mentioned problems, and an object of the present invention is to provide a power storage system capable of suppressing power fluctuations and voltage fluctuations and realizing power leveling. It is to provide a reverse power flow method.

[0005]

As a technical means for achieving the above-mentioned object, the present invention relates to a method in which a distributed power supply including wind power generation is connected via a converter to a power supply system in which the power supply system is linked to a power supply system. A power storage system comprising a power storage battery and leveling the power by supplying the power stored in the battery to a load, wherein the power generated by the distributed power source is supplied to the battery during a light load time period including nighttime. It is characterized by charging and discharging the stored power of the battery during a heavy load time period including daytime, so that power corresponding to the load power flows backward to the power supply system.

As described above, the power generated by the distributed power source is charged to the battery during the light load time period, and the stored power of the battery is discharged during the heavy load time period, so that the power corresponding to the load power flows back into the power supply system. By doing so, it becomes easy to suppress power fluctuations and voltage fluctuations and realize power leveling.

Further, in the above-described power storage system, various types of information including the power generated by the distributed power source, weather information, and load information are stored in a database, and reverse power flow power to the power supply system is patterned based on the various types of information. It is desirable to determine the charge / discharge power of the battery from the patterned reverse power flow power and the power generated by the distributed power source, and charge / discharge the battery based on the calculation result.

In particular, when the distributed power source is a wind power generation system, the above-described various information is stored in a database, and the reverse power flow is patterned based on the various information stored in the database. By subtracting the actual power generated by the distributed power source from the power supply, the charge / discharge power of the battery can be determined. Based on this charge / discharge power, power leveling can be realized with reverse power flow having small fluctuations.

In the above-described power storage system, at the same time as the reverse power flow to the power supply system due to the charging and discharging of the battery, the reactive power and the harmonic current of the distributed power supply are compensated, and the single operation of the distributed power supply when the system is interconnected Can also be detected.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reverse power flow method for an electric power storage system according to the present invention will be described in detail below. The same parts as those in FIG. 4 are denoted by the same reference numerals.

The power storage system 4 of the embodiment shown in FIG.
In a power system in which a distributed power source 1 such as a wind power generation system is connected to a power system 2 owned by a power company, a converter 7 is connected via a switch 5 and a transformer 6, and a DC side of the converter 7 is connected. And a battery 8 connected thereto, and leveling of load power is realized by charging and discharging the battery 8.

In the power storage system 4, the battery 8 is charged during a light load time period including nighttime, the charging power of the battery 8 is discharged during a heavy load time period including daytime, and the discharge power of the battery 8 is reduced. Supply to load 3. In the power storage system 4 of the present invention, even those generated power P _G of the dispersed power supply 1 is a wind power generation system as shown in FIG. 1 is greater variation throughout the day, based on the battery 8 to the following procedure Charge and discharge.

That is, in a light load time zone including nighttime,
Since there is surplus power in the power system 2 owned by the power company,
The generated power P _G of the dispersed power supply 1 is not necessary to reverse power flow.
Therefore, in this light load hours, the battery 8 as the backward flow power P _S of the power supply system 2 is a small amount, as shown (although not shown may be zero) may be charged and discharged.

[0014] On the other hand, the heavy load time zone including the daytime, because there tends to be insufficient power supply system 2 with the power company, stably generated power P _G of the dispersed power supply 1 and a large amount of addition smaller variation It is necessary to reverse flow. Therefore,
In this heavy load time zone, the reverse power flow P _S to the power system 2
It is sufficient to charge and discharge the battery 8 so that is constant in a large amount.

[0015] Therefore, the backward flow power P _S is small in the light load time zone to the power supply system 2, to obtain a small pattern of variation to be larger in the heavy load hours (thick of Figure 1 solid lines), the generated power P _G of the dispersed power supply 1 from the backward flow power P _S
The charge / discharge power P _B (dashed line in FIG. 1) of the battery 8 of the power storage system 4 is determined by subtracting (the thin solid line in FIG. 1).

In order to charge and discharge the battery 8 in the pattern described above, the output of the converter 7 of the power storage system 4 is controlled by system control as shown in FIG. Based on the generated power P _G of the dispersed power supply 1, for example, a database of weather information and load information, the database circuits 9
Patterning the backward flow power P _S in terms of additional information, such as for example a battery charge amount based on the output from. Output command value P _B ^{re f} for charging and discharging the battery 8 is subtracted by the subtracter 11 the generated power P _G of the dispersed power supply 1 from the output command value P _S ^ref of backward flow power P _S created by the pattern generating circuit 10 Get.

The weather information includes wind information necessary for the wind power generation system, the load information includes a load capacity connected to the power system, and the battery charge amount includes a charge amount remaining in the battery at the present time. You. Various types of information other than the weather information, the load information, and the battery charge amount may be input as needed.

The output command value P _B ^ref for charging / discharging the battery 8 is used together with a compensation signal for compensating the reactive power and the harmonic current of the distributed power source 1 to detect the isolated operation of the distributed power source 1 when the system is interconnected. A disturbance signal is added to the output power control circuit 12. In this output power control circuit 12, FIG.
The output command value P _B ^ref for charging / discharging the battery 8 with the charge / discharge power P _B of the battery 8 (broken line in FIG. 1)
Is output to the converter 7.

Furthermore, the reactive power and the harmonic current of the distributed power supply 1 can be compensated based on the compensation signal described above, and the isolated operation of the distributed power supply 1 at the time of system interconnection is detected by an active method based on a disturbance signal. You can also.

[0020]

According to the present invention, when the distributed power source is a wind power generation system, the above-described various information is stored in a database,
By patterning the reverse power flow based on these various types of information in the database, the charge / discharge power of the battery can be calculated by subtracting the power generated by the distributed power source from the patterned reverse power flow power. On the basis of this charge / discharge pattern, reverse power flow with small fluctuation can be supplied to the power supply system, and power leveling can be easily realized.

[Brief description of the drawings]

FIG. 1 is a waveform diagram showing a power pattern in an embodiment of the method of the present invention.

FIG. 2 is a circuit configuration diagram showing a power storage system according to the embodiment of the present invention.

FIG. 3 is a system control block diagram for implementing the method of the present invention.

FIG. 4 is a configuration diagram showing a power system in which a wind power generation system is connected to a power system.

FIG. 5 is a waveform diagram showing generated power of a wind power generation system.

[Explanation of symbols]

1 the commercial power supply system 2 distributed power 3 Load 4 power storage system 7 Converter 8 Battery P _G distributed power generated power P _S backward flow power P _B charge-discharge electric power of

Claims (3)

[Claims] 1. A power storage battery connected via a converter to a power system in which a distributed power supply including wind power generation is linked to a commercial power supply system, and the power stored in the battery is supplied to a load. A power storage system that levels power by charging the battery with the power generated by the distributed power source during light load periods including nighttime and discharging the stored power of the battery during heavy load periods including daytime. A reverse flow of power corresponding to the load power to the commercial power supply system. 2. In the power storage system, various types of information including generated power of a distributed power source, weather information, and load information are stored in a database, and reverse power flow power to a commercial power supply system is patterned based on the various types of information. 2. The reverse power flow method for a power storage system according to claim 1, wherein the charge / discharge power of the battery is determined from the reverse power flow power and the power generated by the distributed power source, and the battery is charged / discharged based on the calculation result. 3. In the power storage system, at the same time as reverse power flow to a commercial power supply system due to charging and discharging of a battery,
2. The reverse power flow method for a power storage system according to claim 1, wherein the reactive power and the harmonic current of the distributed power source are compensated, and the isolated operation when the distributed power source is connected to the grid is detected.