Equalizing current control method for H-bridge cascaded energy-storing system

Abstract

The invention provides an equalizing current control method for an H-bridge cascaded energy-storing system and belongs to the technical field of battery energy storage. The H-bridge cascaded energy-storing system employs carrier phase-shifting modulation. All sub modules use successively-shifted triangular carriers and respective modulating waves. According to the state of charges (SOC) of batteries measured by a battery management system (BMS), the optimum charging current of the batteries is acquired and respective given power instructions are acquired. Finally, the given modulating wave amplitudes of the sub modules are allocated according to the proportions of the power instructions to a total power instruction, thereby controlling the current of the battery pack in an equalized manner. The equalizing current control method prevents overcharging and over-discharging of the battery pack, improves the utilization rates of the batteries, and prolongs the service lives of the batteries.

Description

technical field [0001] The invention belongs to the technical field of battery energy storage, in particular to a balanced current control method for an H-bridge cascaded energy storage system. Background technique [0002] With the development of smart grid, a large amount of renewable energy has been integrated into the grid. However, due to the randomness and instability of renewable energy, an energy storage device with a certain capacity is often added to the AC grid or DC grid system to stabilize the power fluctuations caused by the access of renewable energy to the grid and improve the reliability of power supply. The purpose of improving power quality. A battery energy storage system generally consists of two parts: an energy storage battery and a high-power energy storage power conversion system (PCS). Traditional battery modules generally connect battery cells directly in series and parallel, and then add a simple equalization and protection circuit to cut off th...

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Problems solved by technology

[0004] Aiming at the problem that the utilization rate and life of the battery pack in the battery energy storage system are restricted by the difference between the single batteries, the purpose of the present invention is to provide a balanced current control method for the H-bridge cascaded energy storage system, through the H-bridge level In the federated energy storage system, the amplitude of the modulation wave of each sub-module is distributed in proportion to control the charge and discharge current of the energy storage battery in a balanced manner, so as to improve the utilization rate and service life of the battery

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