Super capacitor pre-charging circuit of grid-connected and off-grid energy storage system and control method

Abstract

The invention discloses a super capacitor pre-charging circuit of a grid-connected and off-grid energy storage system and a control method. The circuit comprises a rapid grid-connected and off-grid switching circuit, a three-phase alternating current circuit breaker, a two-phase LCL alternating current filter circuit, a single-phase full-bridge uncontrolled rectifying circuit, a direct current circuit breaker, a direct current capacitor filter circuit, a direct current pre-charging circuit and a super capacitor bank. The control method comprises the following steps of constructing a super capacitor pre-charging circuit based on a common grid-connected and off-grid energy storage system, and then fully utilizing an original voltage sampling circuit, a current sampling circuit, a rectifier circuit, a thyristor driving circuit and a system controller of the system, and on the basis of a provided current-limiting peak value control algorithm, peak value-limiting current pre-charging of the super capacitor being realized. Through circuit reconstruction of an original grid-connected and off-grid energy storage system, an original system circuit structure is not changed at all, no component is added, and the method improves pre-charging efficiency of the super capacitor, simplifies the system structure, reduces the system cost and improves reliability of the system.

Description

technical field [0001] The invention relates to a supercapacitor precharging circuit and a control method of an off-grid energy storage system, belonging to the application field of power electronics technology. Background technique [0002] With the large-scale development of wind power and photovoltaic power generation, more and more distributed power systems based on renewable energy are gradually connected to the active distribution network. Due to the strong random fluctuations of renewable energy, energy storage systems, especially electric energy storage systems, are gradually connected to active distribution networks on a large scale due to their flexible control and convenient use, so as to stabilize the random fluctuations of renewable energy. Electric energy storage systems can generally be divided into energy-based energy storage systems with large-capacity energy storage and power-type energy storage systems with fast response characteristics. Generally speakin...

AI Technical Summary

Problems solved by technology

Such high-voltage and high-power chargers are mostly dedicated chargers, and there are few options in the market, and the cost is high and the volume is large.

[0006] 2. The current-limited charging scheme based on the pre-charging resistor. In order to achieve fast pre-charging, the system needs to be equipped with additional high-power power resistors and corresponding control switches. Although the scheme is simple, it will increase the system power loss and the pressure of system heat dissipation design.

Images