混合直流双桥换相失败机理及抑制措施研究

Research on the Mechanism and Suppression Method of Double Bridge Discontinuous Commutation Failure in Hybrid HVDC

随着高压直流(HVDC)输电技术的发展,混合直流输电已经成为一种趋势。分析了逆变侧交流三相故障造成混合双馈入直流中电网换相换流器高压直流(LCC-HVDC)双桥换相失败的机理,区别了造成双桥连续换相失败与双桥非连续换相失败的主要影响因素。通过对LCC-HVDC在不同交流故障程度及故障触发时刻下仿真分析,研究了这2个因素对换相失败类型的影响,并发现交流系统轻微故障下的电压波形畸变是双桥非连续换相失败现象的主要成因。通过单纯形算法对混合双馈入系统中电压源换相换流器高压直流(VSC-HVDC)控制参数进行优化,抑制了在交流系统轻微故障情况下发生的LCC-HVDC双桥非连续换相失败。

With the development of high voltage direct current（HVDC） transmission technology, hybrid multi-infeed direct current transmission become a development trend. The mechanism of double bridge commutation failure of line commutated converter based high voltage direct current （ LCC-HVDC ） in hybrid double-infeed system is analysized. And the major influence factors of double bridge continuous and discontinuous commutation failure are distinguished. Through simulation under different AC system fault extent and trigger time, the effect of these two factors on commutation failure types is studied, and it is found that the AC voltage waveform distortion under slight fault is the main cause of double bridge discontinuous commutation failure. Then the control parameter of voltage source converter based high voltage direct current（VSC-HVDC） is optimized by Simplex algorithm to suppress double bridge discontinuous commutation failure of LCC-HVDC in slight fault.