换相失败预测控制对电压稳定性影响及优化措施

对于直流馈入受端电网,避免换相失败与维持电压稳定是两个重要问题。为降低换相失败发生风险,实际直流控制系统通常配置有换相失败预测控制功能模块。扰动过程中,预测控制通过减小逆变器触发角α,增大换相裕度。这一控制将改变逆变站无功特性,甚至影响受端电网电压稳定性。文中基于实际工程的直流控制系统,建立了特高压直流仿真模型;揭示了换相失败预测控制及预测参数对逆变站非线性无功轨迹和电压稳定性的影响;在此基础上,提出了改善逆变站大扰动无功需求特性的预测参数优化措施。特高压直流受端电网大扰动时域仿真结果,验证了优化预测控制参数提升受端电网电压稳定性的有效性。

Impact of Commutation Failure Prediction Control on Voltage Stability and Its Optimization Measures

Prevent commutation failure and maintain voltage stability are two important issues for high voltage direct current(HVDC)receiving end power grid. In order to reduce the threat of commutation failure, the actual HVDC control system is usually equipped with the module of commutation failure prediction. Predictive control will reduce the inverter trigger angle in the process of disturbance, and then affect the reactive power and the voltage stability of the receiving end power grid. Based on the control system used in the actual project, the simulation model of ultra-high voltage direct current(UHVDC)is established. Considering the function commutation failure module, the characteristics of reactive power nonlinear trajectory of inverter station is revealed. The influence of parameters in the predictive module on the reactive power characteristic is analyzed. On this basis, the parameter optimization scheme is put forward for enhancing the reactive power characteristic of large disturbances in inverter station. Simulation results obtained from the receiving end power grid of UHVDC verify that voltage stability of the receiving end power grid can be significantly enhanced.