用于电池储能系统的级联式电力电子变压器均衡及协调控制

针对用于电池储能系统的级联式电力电子变压器,提出基于混合脉宽多电平调制的电池均衡及协调控制策略。级联H桥采用混合脉宽调制可实现子模块功率双向独立调节,该策略利用这一特性对各电池单元进行差异化充放电及荷电状态均衡控制,同时保证系统总功率指令要求及网侧低谐波。为抑制混合脉宽调制时各H桥开关函数非线性时变及网侧功率指令变化引起的直流链电压波动,将整流级开关函数及功率指令作为前馈,提出了隔离双向DC/DC变换器的直流链电压协调控制方法。仿真和实验结果表明,所提控制策略可实现电池荷电状态曲线快速收敛及均衡、双向功率高性能控制以及直流链电压纹波有效抑制。

Balancing and Coordinated Control of Cascaded Power Electronic Transformers for Battery Energy Storage System

For the cascaded power electronic transformer used in the battery energy storage system, this paper proposes the battery balancing and coordinated control strategies on the basis of multi-level hybrid pulse width modulation(HPWM). By using HPWM, the bidirectional power in submodule of cascaded H-bridge(CHB)can be regulated independently. Taking advantage of this feature, the proposed strategy can control different charging or discharging for the battery units, and thus state of charge(SOC)balancing can be achieved. Meanwhile, the total power reference requirement and low distortion of AC waveforms are satisfied. In order to reduce the DC-link voltage fluctuations caused by the nonlinear time-varying switching functions in HPWM and the varying power commands, a coordinated control strategy with feedforward of power reference and switching function of rectifier stage is presented for the DC-link voltage controller of isolated bidirectional DC/DC converter. Simulation and experimental results show that the proposed control strategy can achieve fast converging and balancing of battery SOC curves, high-performance control of bidirectional power and effective suppression of DC-link voltage ripple.