考虑受端换流器动态特性的LCC-HVDC系统稳定性评估与影响分析

With the increasing installed capacity of wind power, the line-commutated converter-based high-voltage direct-current (LCC-HVDC) in sending AC grid encounters potential issues of sub/super-synchronous oscillations (SSSOs), posing a threat to the stable operation of power system. The impedance-based approach has proven to be a useful tool for investigating SSSOs in power electronic device-based systems, relying on the accurate impedance model. However, most existing studies on the stability of LCC-HVDC system simplify the receiving-side converter to an ideal DC voltage source, which ignores the AC-DC dynamics of the receiving-side converter and grid, causing inaccuracy in stability assessment. Moreover, there is a lack of clarity regarding the effect of the receiving-side system on oscillation stability. Thus, this paper establishes the complete impedance model of the LCC-HVDC considering the receiving-side system, by proposing a unified small signal transfer path framework for the LCC converter. Subsequently, the stability of the complete LCC-HVDC system is assessed, and the effect of the receiving-side system on the oscillation characteristics of SSSOs is investigated based on the DC impedance network in detail. Finally, a second-order quantitative index is defined to evaluate the influence factors on the receiving-side interaction, and the conditions for neglecting this interaction are discussed.