高压直流输电送端水电站孤网频率稳定性

Frequency Stability of Isolated Hydropower Plant with a Surge Tank at HVDC Sending Terminal

为分析高压直流输电送端的带调压室水电站的孤网频率稳定性,本文采用了系统理论分析和时域数值模拟相结合的方法,利用系统的传递函数和霍尔维兹判据,得到了系统在不同特征参数下的稳定域。本文着重分析了水电站水力-机械子系统的影响机制,包括调速器参数和调压室相关特征参数等。研究结果表明,本文得到的稳定域与时域数值模拟结果一致,水电站的水力不稳定性将引发系统超低频振荡,不利于高压直流输电送端的频率稳定性。因此,对于高压直流输电送端的稳定性评估及改善,建议不仅应考虑电气侧的因素,还应考虑水力-机械子系统的因素。

To analyze the frequency stability of an isolated hydropower plant with a surge tank at the high-voltage direct current(HVDC)sending terminal,the theoretical analysis and time-domain numerical simulation are combined in this paper.The stability region of the system with different featured parameters is obtained using the transfer function and Hurwitz criterion.The focus of this paper is on the influencing mechanism of the hydraulic-mechanical subsystem of a hydropower plant(HPP),e.g.,the governor parameters and the featured parameters related to the surge tank.Results show that the stability region and the time-domain numerical simulation results agree well.The hydraulic instability of the HPP will lead to the ultra-low frequency oscillations in the system,which is adverse for the frequency stability at the HVDC sending terminal.Therefore,for the stability assessment and improvement at the HVDC sending terminal,it is recommended that both the factors on the electrical side and those of the hydraulic-mechanical subsystem should be taken into account.