重负荷切换下电力电子变压器的稳定性研究

Study of Power Electronic Transformer Stability under Heavy Load Changes

电力电子变压器(power electronic transformer,PET)作为在电力系统中应用的新型变压器,其运行的稳定性对电力系统而言非常重要。然而,PET是由AC-DC,DC-DC等环节组成的多级电力电子装置,当PET的负载在重负荷下切换时,系统内各级之间的耦合会导致直流侧电压出现波动,使得PET存在不稳定的情况。本文对PET在重负荷切换时的稳定性进行了初步研究,分析了直流侧电压在重负荷切换时的瞬态响应,并提出了应用于PET的一种前馈控制方法,使PET能够抑制由负荷切换所引起的不稳定情况,减小直流侧电压出现的波动。仿真结果表明,该前馈控制方法可以有效地抑制PET由负荷切换所引起的不稳定情况,减小直流侧电压出现的波动。

Power electronic transformer （PET） is a new type of transformer used in power system, and its operation stability is very important for power system. However, PET is a multistage power electronic device which is made up of AC-DC, DC-DC links and so on. When a heavy load change occurs, the coupling of all stages in the system will impact the voltage of DC link and the running stability of the PET. This paper simply represents the stability of PET under heavy load changes, exploring the DC link voltage transient response under load change, and put forward a feed-forward control method of PET. Simulation results verify that unstable situation of PET caused by the heavy load changes can be restrained and steady-state DC link voltage can also be achieved.