基于广域支路响应的低频振荡威胁动态评估及紧急控制

Dynamic Threat Assessment and Emergency Control of Low Frequency Oscillation Based on Wide Area Branch Response

低频振荡是威胁互联电网安全稳定运行的重要形式之一,机群功角相对摇摆时网络电气量随之动态变化,基于易于量测的网络受扰响应评估振荡的威胁程度并决策是否实施振荡抑制控制对保障电网稳定运行具有重要意义。首先针对典型机网系统低频增幅振荡过程,分析了节点电压和支路功率变化特征及其与机组振荡的关联关系。其次,提出了可降维表征系统功角稳定性的关键支路识别方法、评估低频振荡演变为功角失稳威胁的判据以及降低威胁的紧急控制策略。针对典型系统和交直流混联实际大电网,仿真验证了关键支路识别、失稳威胁评估判据以及降低威胁的紧急控制策略的有效性。

Low frequency oscillation is one of the important forms threatening the safe and stable operation of the interconnected power grid. When the rotor angle of the generators swing, the network electrical quantity changes dynamically. Therefore, it is of great significance to evaluate the oscillation risks and make decision-making control based on the easily measured network disturbed responses. Firstly,aiming at the low-frequency amplitude oscillation process of the typical generator network system, the variation characteristics of the node voltage and the branch power and their relationship with the generator oscillations are analyzed.Secondly, the key branch identification is proposed to characterize the rotor angle stability of the system by reducing the dimensions. The criterion to evaluate the evolution of the low-frequency oscillation into the rotor angle instability and the emergency control strategy to reduce this risk are also put forward. The effectiveness of the key branch identification, the low-frequency oscillation risk assessment criterion and the emergency control strategy to reduce the rotor angle instability are verified by simulation in the typical systems and the AC/DC hybrid power grid.