基于平均加权方法的大尺度范围电网功频特性

Large-Scale Power Frequency Characteristics of Power System Based on Weighted Average Method

传统的大电网功率频率特性系数在频率变化较小的范围内可以视为恒定不变。但是在系统出现大的功率波动而导致频率变化的范围较大时按照传统处理方法计算所得的电网功频特性系数会有差别,这将导致传统算法会产生误差。分析了频率偏差较大时,频率特性系数值产生误差的机制,并给出频率偏差在大尺度范围内的功频特性系数的计算方法。提出大电网在某种运行方式下,求取多组频率偏差下的系统静态频率特性系数值,通过平均加权的方法获得更为精确的结果。在此基础上,基于概率统计学的思想给出了权值的计算方法。通过PSASP软件对某一大电网进行仿真研究,基于该方法获得的电网功频特性系数较传统的算法误差更小,更能反映电网的实际情况。

In traditional methods the power frequency characteristic coefficient of large-scale power grid can be regarded as constant when frequency fluctuation is within a smaller range.However,when larger power fluctuation leading to frequency fluctuation within a wider range occurs,the power frequency characteristic coefficients calculated by traditional methods differs from the actual ones,and it shows that traditional methods are the reason causing errors.The mechanism causing error due to traditional methods under larger frequency deviation is analyzed,and a method to calculate power frequency characteristic coefficient under larger frequency deviation is given.It is proposed that for a certain operating mode of large-scale power grid a more accurate result of static frequency characteristic coefficient under multi groups of frequency deviations can be attained by means of utilizing weighted average.On this basis,based on the idea of probability statistics a method to calculate the weights is put forward.Results of power system analysis software package（PSASP）-based simulation of an actual large-scale power grid show that the errors of power frequency characteristic coefficients calculated by the proposed method are smaller than those calculated by traditional methods,and the former can reflect actual condition of power grid better.