无直流储能直接AC/AC动态电压恢复器及其预测控制

Research on DC energy-storageless direct AC/AC dynamic voltage restorer and its predictive control

基于电压源型逆变器的传统动态电压恢复器,需使用大容量电解电容进行直流储能,体积重量大,成本高。为此,提出一种基于直接AC/AC变换的动态电压恢复器,该方案不需使用直流储能元件,易于维护,换流过程简单,动态响应速度快,能够有效补偿电网电压波动。针对所提出的动态电压恢复器,设计与之相适应的工作模式、非互补控制换流过程,并使用离散全维状态观测器设计预测控制策略。与现有的瞬时电压控制策略相比,由于控制信号已在前一周期经状态预测并执行控制算法后得到,当前周期可直接更新控制信号,省去了算法执行时间,提高电压恢复能力。设计实验样机,实验结果验证了所提方案的有效性。

Traditional dynamic voltage restorer based on voltage source inverter needs energy storage de- vices, such as electrolytic capacitor, which are heavy and high cost. A new type of dynamic voltage restor- er based on improved DC energy storageless direct AC/AC power conversion was proposed. This new type of restorer does not use energy storage devices and has simple commutation process, fast dynamic response and low cost, which can compensate the grid voltage fluctuations effectively. Non-complementary control commutation strategy ,work modes and predictive control method were designed. By using a discrete state observer, the control signals were obtained by predicting the system state and performing its algorithm in previous cycle, which was updated in current cycle directly. Compared with the existing instantaneous voltage control, the proposed predictive control strategy saves the algorithm execution time and improves the voltage recovery ability. An experimental prototype was designed. Experiment results show that the load voltage can be kept stable under line voltage swells or sags circumstances, which verifies the validity of the proposed plan.