计及多个风场预测误差的电力系统风险快速计算方法

A Fast Risk Assessment Method with Consideration of Forecasting Errors of Multiple Wind Farms

随着电力系统中风电的并网点不断增加,在计算风险时状态枚举法会出现组合爆炸的问题,耗费大量时间,无法满足调度运行的时效性。考虑多个风场预测误差的随机性问题,提出一种快速计算电力系统运行风险的方法,基于K-means对输入样本进行聚类,并运用半不变量和Gram-Charlier级数展开理论快速计算节点电压与支路潮流的概率分布。根据概率分布计算越限概率,用越限概率和产生影响的乘积衡量系统的风险。选取某实际电力系统作为案例进行分析,研究成果表明,所提方法能够满足调度运行在时间和精度上的要求。

As more and more wind farms are integrated in to power system,risk assessment based on enumeration method may take too much time to meet the computation time requirement of system operation because the enumeration method has combination explosion problem.With consideration of forecasting errors of multiple wind farms,this paper proposes a fast computation method for risk assessment.The paper clusters the input samples based on K-means.Cumulant and Gram-Charlier series expansion theory are applied to compute the cumulative distribution of node voltage and branch flow.According to the cumulative distribution,the probability of over-limit can be computed.Risk indices are computed by the product of the over limit probability and the impact.Case study on a practical power system demonstrates that the proposed method meets system operation’s accuracy and time requirements.