电压源换流器式高压直流输电的动态建模与暂态仿真

基于节点电流注入法建立了交直流统一基准值下的电压源换流器式高压直流输电(VSC-HVDC)的详细动态模型.该模型包括电压源换流器模型、直流系统内部动态模型以及控制系统三个部分,具有一般性.利用电力系统分析综合程序提供的用户自定义功能(PSASP/UD)对VSC-HVDC交、直流并联输电系统进行的暂态仿真分析验证了VSCHVDC动态模型的正确性.仿真结果还表明,VSC-HVDC的直流侧电容以及换流变压器漏抗的大小对抑制功角振荡无明显效果;两端VSC采用定交流电压控制方式时系统具有较好的电压稳定性,但在这种控制方式下,在系统受扰期间VSC的过载程度较两端定无功功率控制方式下更为严重.

DYNAMIC MODELING AND TRANSIENT SIMULATION FOR VOLTAGE SOURCE CONVERTER BASED HVDC

Based on the method of injecting current at nodes, a detailed dynamic model for voltage source converter based HVDC (VSC-HVDC) is built up, which includes three parts, i.e., the voltage source converter, the internal dynamic model of DC system and control system. By use of the user-defined function provided by Power System Analysis Software Package (PSASP), the correctness of the built dynamic model for VSC-HVDC is verified by transient simulation of parallel VSC-HVDC/AC transmission system. Simulation results also show that: (A) the value of capacitors at DC side of VSC-HVDC and that of the leakage impedance of converter transformer do not take evident effect in damping load angle oscillation; and (B) when constant AC voltage control mode is applied to VSCs at both ends of VSC-HVDC, a better voltage stability is obtained, but when the system is disturbed the overload extent of VSCs at both ends of VSC-HVDC is more severe under this control mode than overload extent of VSCs at both ends of VSC-HVDC under constant reactive power control mode.