VSC-HVDC输电系统的电磁暂态建模与仿真

Electromagnetic Transient Modeling and Simulation for VSC-HVDC

基于电压源换流器(VSC)的新型直流输电(VSC-HVDC)系统技术优点很多,建立能够准确描述VSC-HVDC动态特性的详细模型及仿真算法对该项输电技术的深入研究具有重要意义,还可为含有VSC-HVDC的电力系统机电、电磁混合仿真奠定基础。为此首先分析了VSC-HVDC的工作原理;利用隐式梯形积分法建立了双端VSC-HVDC的详细电磁暂态仿真模型,并利用一阶惯性环节模拟锁相环测量了VSC交流母线电压相位的动态特性;鉴于对应VSC-HVDC电磁暂态模型的差分方程为右端项含有待求变量的隐式方程,提出了相应的迭代求解数值计算算法。在VSC交流母线电压幅值和相位突变的条件下,通过与PSCAD/EMTDC中所建VSC-HVDC仿真电路电磁暂态响应的对比,验证了VSC-HVDC电磁暂态模型及其数值计算算法的正确性。

Establishing the detailed dynamic model and simulation algorithm for VSC-HVDC is significant for the study of VSC-HVDC. In this paper, the detailed electromagnetic transient model for VSC-HVDC is established. This model includes three main parts of VSC-HVDC, i.e. the model of VSC＇s converter transformer, the model of the dc transmission system and the model of its controllers. Moreover, the dynamic characteristic of phase lock loop （PLL） measuring the phase of VSC＇s ac bus voltage is also modeled by the first-order inertia loop. An iterative algorithm is proposed by considering the electromagnetic transient model of VSC-HVDC having implicit difference equations. Under disturbances such as the magnitude and phase of VSC＇s ac bus voltage varying, the correctness of the electromagnetic transient model and the validity of the iterative algorithm are verified by comparing the transient responds of VSC-HVDC electromagnetic transient model with those got from VSC-HVDC circuit model established by PSCAD/EMTDC.