互联电网失步解列过程中的暂态动能变化规律研究

Study on the change law of transient kinetic energy in the process of out of step splitting of interconnected power grid

新能源高占比系统已成为我国电网未来发展的必然趋势。新能源出力的不确定性,使得振荡中心漂移风险增大,现有失步解列技术面临严峻挑战。受扰系统在故障清除后其机组间的动态行为可以划分为群间相对运动和群内相对运动,在此基础上通过选取不同的参考坐标系构造了群间暂态能量和群内暂态能量函数。分析计算发现,在解列时刻系统的暂态能量动能具有群间暂态动能突变为0,群内暂态动能保持不变的规律。依据这一规律,指出解列过程中群间暂态动能的突变是使系统解列后的暂态稳定性能够得到较大改善的重要原因之一。从能量的角度分析了在非振荡中心处解列与在振荡中心处解列之间的联系。通过IEEE 39节点系统及我国某区域电网模型对以上结论进行了验证。

High-proportion of renewable energy system has become an inevitable trend in the future development of China′s power grid.The uncertainty of power output has increased the risk of oscillation center drift,and the existing out of step splitting control technology is facing severe challenges.The dynamic behavior of the disturbed system after fault elimination can be divided into the dynamics between generator groups and the dynamics within groups,respectively.On this basis,the functions of transient energy between groups and transient energy within the groups are constructed by selecting different reference coordinate systems.Through the analysis and calculation,it is found that the transient kinetic energy of the system at the moment of islanding control has the rule that the transient kinetic energy between groups changes to 0,and the transient kinetic energy within the groups remain unchanged.According to this rule,it is pointed out that the mutation of transient kinetic energy between the groups is one of the important reasons that the transient stability of the system can be improved greatly.Moreover,the connection between splitting at the non-oscillatory center and the oscillatory center is analyzed from the perspective of energy.Finally,the IEEE 39-bus system and an actual power grid model in China are employed to verify the conclusions.