基于Nataf变换的电网不确定性多点估计法

Uncertain Power Flow Solved by Multi-point Estimate Method Based on Nataf Transformation

在当前电力系统的规划与运行中,由于电力元件本身运行状态、数据采集及可再生能源的多点接入等因素,电力系统被引入诸多不确定性。在这些不确定性中,系统潮流的不确定性问题尤为突出。当系统的注入功率产生随机波动时,系统潮流会随之波动。针对不确定性潮流问题,在传统点估计法的基础上提出一种改进的基于Nataf变换和Gauss-Hermite积分技术的多点估计法,通过将不确定性潮流问题转化为多随机变量响应函数后进行求解。首先根据Gauss-Hermite积分技术获取标准正态空间上的多估计点及对应权重系数,经由Nataf逆变换求得原始空间的多估计点,进而通过潮流计算得到节点电压幅值和相角、支路有功功率和无功功率以及对应的统计信息。仿真结果表明,文中算法较传统的点估计法计算精度有明显提高,且精度会随着选取估计点数的增加而提高。

In the planning and operation of current power system,a number of uncertainties have been brought into the power system because of electric components’ operating state,data collection and multipoint access of renewable energy,etc.Of these uncertainties,the most prominent is the uncertain power flow,which will fluctuate when stochastic fluctuation is generated by the nodes’ inj ected power.To solve this problem,an improved multi-point estimate method of solving uncertain power flow based on Nataf transformation and Gauss-Hermite integration is proposed.The basic idea is to change the uncertain problem of power flow into a response function with multiple random variables.Firstly,the multi-estimate points in the standard normal space and the relevant weight can be obtained according to Gauss-Hermite integration.Secondly,the estimate points in the original variable space can be obtained by Nataf transformation.With the estimate points in the original variable space and the relevant weight,the node voltage amplitude and phase angle,the branch active and reactive power can be easily calculated statistically.Simulations show that the results obtained by the improved multi-point estimate method have a higher precision compared with the traditional point estimate method.In addition,the precision of the calculation results will be improved if the number of selected estimate points is increased.