含风电光伏电力系统概率潮流计算改进方法研究

Research on probabilistic power flow calculation improvement method of power system including wind and photovoltaic power generation

新能源出力的波动性会导致新型电力系统运行的风险增加。针对使用A型Gram-Charlier级数展开拟合概率密度函数出现负值的问题,在含风电、光伏接入的电力系统概率潮流计算中,引入LHS技术与C型Gram-Charlier级数展开方法,提出一种基于LHS-CGC方法的电力系统概率潮流计算方法。以蒙特卡洛法的计算结果为参照,在改进IEEE 30测试系统验算夏大、冬小、新能源大发3种运行方式中系统各状态变量与输出变量的概率密度分布情况,验证方法的准确性和有效性,且具有较高的运算速度。通过比较分析不同运行方式下系统的概率潮流计算结果,发现系统在新能源大发方式下的支路潮流与电压越限风险增加,因此在电网规划与调度中需要重点关注风电、光伏出力季节性变化对系统运行风险的影响。

The fluctuation in the output of new energy sources can increase the operational risks of the new type of power system.To address the issue of negative values that arise when using the A-type gram-charlier series expansion to fit probability density functions,in probabilistic power flow calculations for electrical systems with wind and photovoltaic integration,the Latin hypercube sampling(LHS)technique and the C-type Gram-Charlier(CGC)series expansion method are introduced.Then a power system probabilistic power flow calculation method is proposed based on the LHS-CGC approach.Taking the calculation results of the monte-carlo method as the reference,the probability density distribution of various system state variables and output variables is verified in three operational modes:summer peak load,winter off-peak load,and high penetration of new energy sources,using the improved IEEE 30 test system.This validates the accuracy and effectiveness of the method proposed in this paper,which also exhibited a high computational speed.Through comparative analysis of probabilistic power flow calculation results under different operational modes,it is found that the system branch currents and voltage exceedance risks increase during high penetration of new energy sources.Therefore,in grid planning and dispatching,special attention needs to be given to the impact of seasonal variations in wind and photovoltaic output on the operational risks of the system.