超高压变电站接入弱交流系统情况不可避免,故障发生后可能引起近区电网暂态稳定问题.系统失稳可能呈现电压失稳和功角失稳两种表现形式,不同运行方式下系统的稳定特征和表现形式不同.在大负荷且地区电源开机不足方式下以电压失稳模式为主导,在小负荷且电源开机较多时以功角失稳模式为主导.部分方式下两种稳定问题相互交织,共同导致系统失稳.以某超高压变电站 A 接入电网的情况为例,分析了系统存在的稳定问题和相关影响因素,识别了不同运行方式下系统的主导失稳模式,并制定了相应的安全稳定控制措施.
Study on Stability Problem of Power Angle and Voltage of EHV Substations Connected to Weak AC Systems
Some EHV substations may be connected to weak AC systems and the resultant AC fault near the EHV sub-station may lead to transient stability issues in the system.There are two instability models,voltage instability and power angle instability.The stability characteristics and expressions vary under different operating modes.In the case of regional heavy load and insufficient power supply,the dominant mode is voltage instability.While in the case of light load and suf-ficient power supply,the dominant mode is power angle instability.In some cases,power angle and voltage stability prob-lems are intertwined,leading to system instability.Taking the connection of an EHV substation A to the power grid as an example,this paper analyzes the stability problems and related influencing factors of the system.The dominant instability modes of the system under different operating modes are identified and corresponding safety and stability control measures are provided.
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