含LC低通滤波器的VSC-HVDC系统的新型控制策略

摘要

通过引入LC低通滤波器来滤除逆变器产生的高次电压谐波,以提高向无源网络供电的VSC-HVDC系统的供电质量.在同步旋转坐标系下,包含LC低通滤波器的VSC-HVDC系统表现出强耦合、非线性特性,不利于控制器设计.首先采用逆系统方法将原系统线性化解耦成伪线性系统,再利用变结构控制理论设计伪线性系统的闭环控制器,既可以降低设计控制系统的难度,又可以使控制系统获得较好的动态性能.利用PSCAD/EMTDC进行仿真试验.仿真结果表明,LC低通滤波器用于滤除高次电压谐波有很好的滤波效果,并且所采用的控制策略使VSC-HVDC系统获得了良好的控制性能.%In order to improve the quality of power fed by VSC-HVDC(High Voltage Direct Current transmission based on Voltage Source Converter) system to passive network,a LC low-pass filter is employed to eliminate the high-order voltage harmonics generated by the inverter. The strong coupling and nonlinearity of VSC-HVDC system with the LC filter in the synchronous rotating frame brings difficulty to the design of its controller. The inverse system method is adopted to convert it into a pseudo linear and decoupled system and the variable structure control is used to design its close-loop controllers,which lowers the design difficulty and improves the dynamic performance of VSC-HVDC control system. Simulation is carried out with PSCAD/EMTDC and the simulative results indicate that,the LC low-pass filter eliminates the high-order voltage harmonics effectively and the VSC-HVDC system with the proposed control strategy achieves excellent control performance.