基于小信号模型的柔性直流输电网络运行稳定性研究

小信号稳定性是动态系统在小扰动情况下保持稳定运行的能力。柔性直流输电网络作为交流系统、新能源及无源网络互联的枢纽,其小信号稳定性直接关系到区域电力系统的稳定运行。首先推导电压源型换流站、换流站控制系统、直流输电网络的小信号数学模型,通过仿真对比验证小信号模型的准确性,根据状态空间法,列出柔性直流输电网络的状态矩阵;然后通过李雅普诺夫稳定性判据及参与因子矩阵分析方法推导柔性直流输电网络的小信号稳定性判据;最后通过算例分析,证明此小信号稳定性分析法的适用性及准确性,并总结出PI参数优化规律,为柔性直流输电网络工程应用时控制器的设计以及稳定性优化提供研究基础。

Research on the Small Signal Stability of VSC-HVDC Network

Small signal stability is the ability to maintain stable operation of dynamic systems under small disturbance.VSC-HVDC network is the key to the interconnection of AC system, new energy and passive network.The small signal stability of VSC-HVDC network is directly related to the stable operation of the regional power system.This paper firstly deduces the small signal mathematical models of voltage source converter, convertor controlling system and DC transmission network, and verifies the correctness of the small signal model by the simulation comparison;and then, it lists the state matrix of VSC-HVDC based on state-space method, and deduces the stability criterion of small signal through Lyapunov stability criterion and Participation factor matrix analysis method.Finally, the applicability and accuracy of the small signal stability method are demonstrated by case analysis, and optimization principle of the PI parameter is also summarized, which provides the research foundation of controller design and decoupling mechanism for VSC-HVDC engineering application.