交流励磁系统功率单元并联控制策略研究

多功率单元并联型交流励磁系统在励磁阶段存在相间环流,导致系统不稳定。同时由于并联模块自身参数差异导致均流效果差。为了解决以上问题,分析了其在励磁阶段和并网运行阶段控制上的差异性,研究了多功率单元并联型交流励磁系统在励磁阶段产生相间环流的机理,提出了一种适用于交流励磁系统多功率单元并联的混合控制策略。在Matlab/Simulink中搭建了1台300 MW的交流励磁控制可变速抽水蓄能机组系统,仿真结果表明,与传统的单一控制策略相比,提出的混合控制策略能够在不增加变流器输出侧电感的前提下,实现相间环流的抑制和均流效果的提高,验证了所提控制策略的正确性及可行性。

Research on Parallel Control Strategy of the Power Unit Used in AC Excitation System

Multipower unit paralleling AC excitation system(AES)has the problem of interphase circulation flow,which leads to instability. Another problem is the poor average flow effect which caused by the parameters of the parallel converters. To solve the prolems above,the differences between the excitation stage and grid-connected stage were analyzed. The mechanism of interphase circulation flow in multipower unit paralleling AC excitation system was studied. Finally,a hybrid control strategy was presented. The model of a 300 MW variable speed pumped storage plant was built in Matlab/Simulink. The results show that compared with the traditional unified control strategy,using hybrid control strategy can decrease the interphase circulation current and improve the effect of parallel average flow without increasing the inductance,and the correctness and feasibility of the proposed control strategy are verified.