直流调制对南方电网交直流混联输电系统暂态稳定裕度的影响

Study on Advancing Transient Stability Margin in AC/DC Hybrid Transmission System of Southern China Power Grid by HVDC Modulation

交直流混联输电系统中,直流系统的控制及调制措施对系统的暂态稳定具有重要影响。以南方电网2005年丰大运行方式下,贵广直流单极运行、天广直流双极运行为例,当北通道交流输电系统发生扰动时,研究了直流系统在一定的控制方式下,调制增益的变化对系统暂态稳定裕度及直流系统的影响;分别取北通道功率变化率及南通道功率变化率为调制信号对系统暂态稳定裕度及直流系统的影响;考察了直流系统运行在不同控制方式下时,大方式调制和双侧频率调制等措施对混联系统暂态稳定裕度、送端电网机组及直流系统的影响,研究结果对实际电网运行中直流调制措施的制定具有一定的参考价值。

Control and modulation measure of DC system greatly effect on transient stability in AC/DC hybrid power grid. Taking China Southern Power Grid under both flood season and large power flow in the year of 2005 for example, while Tianshengqiao-Guangdong DC system operating in bipolar mode and Guizhou-Guangdong DC system in monopolar mode, when fault occurs in north AC transmission system, the influence of the variation of modulation gain of HVDC system under a certain DC control mode on transient stability margin of the grid and HVDC itself are studied. The influence on grid＇s transient stability margin and DC system is also studied while the power slope of north or south AC transmission system is taken as modulation signal respectively. The influence of modulation measures such as large power flow modulation and frequency modulation at both sides on transient stability margin of hybrid system, generating sets in sending network and HVDC system while DC system operating under different control modes are explored. Study results are available for reference in the drafting of DC modulation measures for the operation of actual AC/DC hybrid power grid.