实际电网频率概率分布特性演变及成因分析

Analysis on Variation of Frequency Probability Distribution and Causes in Actual Power Grid

基于某区域电网海量频率实测数据,分析了不同年份、联网和孤网方式下频率的概率分布特性及其成因。该电网和相邻区域电网联网方式下,频率概率分布从边缘陡峭的带状分布逐渐变为双峰分布,原因是系统功率不平衡量的标准差不断增大,导致频率波动变大,机组一次调频频繁动作将频率偏差概率密度函数在死区以外的部分堆积到死区附近,形成双峰。孤网方式下,电网频率概率分布均呈现出明显的双峰分布,原因是网络规模减小导致频率波动变大,同样使得机组一次调频频繁动作。电网进一步优化频率控制工作的重点是加强超短期预测和日内计划平衡,减小系统功率不平衡量。

The probability distribution and the corresponding causes of frequency in different years,in interconnected mode and isolated mode, are analyzed based on massive measurements in an actual regional power grid. In the interconnected mode, the probability distribution changes from band distribution with shape edges to bimodal distribution. The reason is that the standard deviation of the system power imbalance is increasing, resulting in a large frequency fluctuation, and the primary frequency regulation frequently acts to form the bimodal distribution. In the isolated mode, the probability distribution exhibits an obvious bimodal distribution. The reason is that the decrease of grid scale leads to severer frequency fluctuation and frequent action of primary frequency regulation. The key work for improving frequency regulation of power grid is to strengthen ultra-short-term prediction and intraday planning balance and reduce system power imbalance.