混合级联式电力电子变压器拓扑结构及控制策略

Hybrid Cascaded Power Electronics Transformer Topology and Control Scheme

对现有的几种典型电力电子变压器(power electronics transformer,PET)拓扑结构及优缺点进行分析,在此基础上,将谐振变换器及两电平方波变换器引入到传统级联型电力电子变压器,提出一种适用于中高压配电网的新型电力电子变压器拓扑结构。与传统PET相比,所提拓扑的优势在于可以显著减少体积,提高运行效率,并能够灵活切换于纯有功模式及无功补偿模式。对所提拓扑结构及工作原理进行了详细的论述,并建立了系统的交流侧及直流侧的平均模型;在此基础上,结合谐振变换器的工作特性提出了一种单级统一控制策略,简化了PET的控制系统。搭建了10 k V/1.5 MW的PET仿真系统,仿真结果表明了所提拓扑结构及其控制策略的可行性和有效性。

Several existing typical power electronic transformer （power electronics transformer, PET） topologies and their advantages and disadvantages were analyzed. Resonant converter and two-level square-wave converter were introduced into traditional cascaded power electronic transformer. A new power electronic transformer topology was proposed for MV and HV distribution network. Compared with conventional PET, new topology volume was significantly reduced, and its operational efficiency was improved. It could operate in flexible switching between pure active and reactive power compensation modes. In this paper, the proposed topology and operating principle were discussed in detail, and an average model of AC and DC sides of the System was established. On this basis, combined with operating characteristics of resonant converter, a single-stage unified control strategy was presented and PET control system was simplified： A 10 kV/1.5 MW PET simulation systemwas built. Simulation results show that new power electronic transformer topology and control strategy are feasible and effective.