摘要
在电网"强直弱交"新形势下,直流送受端交流系统之间的相互影响逐渐突显,需要开展多回直流换相失败后送端三机群交流系统的稳定机理和影响因素研究。文章推导了三机系统的转子运动方程,根据2个稳定模式固有的周期比例关系实现了解耦,采用等面积法则分析了多回直流换相失败后的送端三机群系统稳定机理,并分析了机组转动惯量、换相失败形式、换相失败范围等关键因素对送端三机群系统稳定性的影响,最后采用三机等值系统算例和"三华"实际系统算例进行了验证。研究表明,送端三机群系统2个稳定模式之间的耦合作用将使得系统的稳定性变差。文中研究将直流功率扰动后送端两机系统的稳定机理扩展到三机系统,可以为电网实际运行提供依据和参考。
Under new situation of "strong DC and weak AC", interaction between sending-and receiving-side AC systems interconnected with DC links becomes significant. It is necessary to conduct studies on stability mechanism and influential factors of sending-side three-machine system after multiple HVDC commutation failure. In this paper, rotor motion equation of three-machine system is derived. Decoupling of two stability modes is realized according to their inherent periodic relationship. Stability mechanism of sending-side three-machine system after multiple HVDC commutation failure is analyzed with equal-area criterion. Impact of key factors, including inertia moment of machines and form and range of commutation failure, on stability of sending-side system is analyzed. Results are verified with three-machine equivalent case system and "North-Central-East China" actual system. The study shows that coupling effect between two stability modes of sending-side three-machine system will make system stability worse. The study extends stability mechanism of sending-side two-machine system after DC power disturbance to three-machine system, providing basis and reference to practical power grid operation.
引文
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