考虑直流输电控制方式的受端电网电压稳定性机理分析

随着交直流混合电网的不断发展,大功率、远距离直流输电的受端电压稳定性问题备受关注。针对交直流有机耦合的受端电压稳定性问题,将逆变器与补偿滤波电容统称为逆变站,借助直流输电功率可表达为交流受端电压函数的特性,构建了受端系统供给无功特性及逆变站需求无功特性的新表达形式,揭示了两者不匹配是受端电压不稳定的根本原因。在此基础上,计及直流输电系统的不同控制方式,通过受端系统的在线戴维南等值,给出了受端系统电压稳定判据的解析表达式,便于进行各种控制方式和策略的比较与分析,为控制的有效性奠定了基础。算例分析表明,该方法简洁有效。

Analysis on Voltage Stability of Receiving Grid Considering Control Strategy of DC Transmission Line

With the development of AC/DC power system, much attention is focused on the voltage stability of the receiving system of the high-power and long-distance DC transmission system. In order to analyze the interconnected AC/DC system, the inverter and the compensation capacitor are referred to as the inverter station. By virtue of the trait that the power of DC transmission system can be described as a function of the receiving line voltage, new forms of the characteristics of the reactive power supplied by the receiving system and the reactive power absorbed by the inverter station are proposed, revealing that the mismatch of the reactive power is the root cause of voltage instability. Considering the control strategy of the DC transmission line, a dominance index is proposed on the basis of Thevenin equivalent parameters, which can be used to compare the stability level of various strategies. Test results prove its conciseness and effectiveness.