摘要
阐释了能量函数中不可积项的积分路径。考虑转移电导时,首积分法构造的暂态能量函数含有不可积项。现有的理论将故障后系统的稳定平衡点作为积分路径的初始点,并在计算临界能量时虚构了稳定平衡点和不稳定平衡点间的线性路径。分析表明,故障轨线上的点在故障后系统中的轨道上存在零势能点,不可积项的积分路径是故障后系统中从该零势能点出发的轨线。由此得到一种能量计算方法,能够逼近准确值,可用于分析现有方法的准确性。示例表明,线性路径法采用了上述积分路径的线性近似,有时结果接近准确值,有时偏差较大;梯形近似法不一定能提高能量计算的准确性。
This paper investigates the integration path of non-integrable term in the transient energy function. A non-integrable term is present in the transient energy function constructed by first integral. Conventional methods take the stable equilibrium point (SEP) of the post-fault system as the initial point of the integration path. An imaginary path from the SEP to an unstable equilibrium point is taken in getting the critical energy. By ergodic theory, it is proved that energy of a point in the stability region is equal to the kinetic energy of the special point on the orbit of this point, where angular coordinates are equal to or infinitely close to those of the SEP of the post-fault system. Hence this paper proposes a method in energy calculation, which can be arbitrary close to the exact value, and helps to measure the accuracy of the prevailing methods. Analyses on some examples reveal that, the linear path method takes a linear approximation of the correct path, and sometimes it can give results close to the exact value, but sometimes it may result in large deviance. The trapezoidal approximation method is not certain in improving the accuracy in getting the transient energy.
出处
《电力系统自动化》
EI
CSCD
北大核心
2004年第20期12-16,42,共6页
Automation of Electric Power Systems
基金
国家杰出青年科学基金资助项目(59925718)~~
关键词
电力系统
暂态稳定
能量函数
遍历理论
power systems
transient stability
energy function
ergodic theory
