基于低秩逼近法的下垂控制孤岛微电网三相概率潮流计算  

Probabilistic Load Flow Calculation for Three-phase Unbalanced Droop-regulated Islanded Microgrids Based on Low-rank Approximation Method

作　　者：潘忠美[1] 刘健 吴建中[3] 付欢欢 同向前[1] PAN Zhongmei;LIU Jian;WU Jianzhong;FU Huanhuan;TONG Xiangqian(Xi'an University of Technology,Xi'an 710048,Shaanxi Province,China;State Grid Shaanxi Electric Power Research Institute,Xi'an 710054,Shaanxi Province,China;Cardiff University,Cardiff CF243AA,UK)

机构地区：[1]西安理工大学,陕西省西安市710048 [2]国网陕西省电力科学研究院,陕西省西安市710054 [3]卡迪夫大学,英国卡迪夫CF243AA

出　　处：《中国电机工程学报》2020年第20期6506-6515,共10页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51677151);中国国家留学基金资助项目(201908615087);西安理工大学博士启动项目。

摘　　要：针对下垂控制型孤岛微电网中无平衡节点且频率不恒定的特征,兼顾其三相不对称性及其中的不确定性因素的影响,提出一种基于最优乘子牛顿–拉夫逊法及低秩逼近法的三相概率潮流计算方法。首先建立计及频率变量的下垂控制孤岛微电网的三相潮流模型,采用牛顿–拉夫逊法求解,并利用潮流方程组的泰勒展开式的高阶项信息计算最优乘子,在迭代中以带最优乘子的修正量进行修正,显著改善了算法的收敛性。进而,采用低秩逼近方法计算系统的概率潮流。根据低秩逼近的原理,通过相对少量确定性潮流计算样本建立所关心的潮流分布变量的统计意义上等效的代理模型,并计算其均值、标准差,进一步可通过大量输入随机变量样本代入到代理模型,得到潮流量的概率密度、累计概率分布等概率特征。算例结果证明了该文算法的有效性与准确性。Traditional load flow algorithm is not suitable for droop-regulated islanded microgrids because there is no slack bus and the frequency is not constant. Meanwhile, considering the increasing penetration of renewable energy resources, probabilistic analysis is essential to ensure realistic and accurate load flow results. Therefore, a probabilistic load flow method for unbalanced droop-regulated islanded microgrids was proposed in this paper. Taking voltage of each node and frequency as variables, the load flow model was developed considering the philosophy of droop-controlled distributed generation in a three-phase unbalanced microgrid. A Newton-Raphson(NR) load flow method with optimal multipliers was proposed to solve the flow equations. The convergence performance of NR method was improved by utilizing optimal multiplier deduced from the higher order terms of Taylor expansions of the load flow equations in each iteration. Further, the low-rank approximation(LRA) method is employed to evaluate the probabilistic load flow solutions. Based on the LRA theory, the statistically-equivalent surrogate models for the load flow solutions are built from a small number of samples of deterministic power flow studies. Numerical examples demonstrate the effectiveness and correctness of the proposed algorithm.

关 键 词：下垂控制孤岛微电网 三相潮流计算 最优乘子牛顿–拉夫逊法 概率潮流计算 低秩逼近 

分 类 号：TM71[电气工程—电力系统及自动化]