不对称故障下光伏逆变器的最优电压支撑策略  

Optimal Voltage Support Strategy for Photovoltaic Inverters Under Asymmetric Faults

作　　者：彭星 姜飞[1] 涂春鸣[2] 郭祺[2] 梁细恒 PENG Xing;JIANG Fei;TU Chunming;GUO Qi;LIANG Xiheng(School of Electrical and Information Engineering,Changsha University of Science&Technology,Changsha 410114,Hunan Province,China;National Electric Power Conversion and Control Engineering Technology Research Center(Hunan University),Changsha 410082,Hunan Province,China;Hunan Key Laboratory of Energy Internet Supply-demand and Operation(Economic and Technological Research Institute,State Grid Hunan Electric Power Co.,Ltd.,),Changsha 410114,Hunan Province,China)

机构地区：[1]长沙理工大学电气与信息工程学院,湖南省长沙市410114 [2]国家电能变换与控制工程技术研究中心(湖南大学),湖南省长沙市410082 [3]能源互联网供需运营湖南省重点实验室(国网湖南省电力有限公司经济技术研究院),湖南省长沙市410114

出　　处：《电网技术》2021年第11期4259-4268,共10页Power System Technology

基　　金：湖南省自然科学基金面上项目(2021JJ30715);湖南省教育厅资助科研项目(20B029)。

摘　　要：电网不对称接地故障下,充分利用逆变器容量,最大化支撑电网电压有助于提升光伏逆变器的低电压穿越能力,减少其大面积切机风险,保障电网的可靠运行。针对该问题,提出电网不对称接地故障下光伏逆变器的最优电压支撑策略。介绍了逆变器对并网点电压的支撑原理;以正序电压支撑最大化为首要控制目标,正序电流为约束条件,构建拉格朗日函数,推导正序有功电流与无功电流的最佳分配关系;以负序电压最优抑制为次要控制目标,逆变器最大允许电流为约束条件,构建拉格朗日函数,推导负序有功电流与无功电流的最佳分配关系;在此基础上,综合考虑有功功率波动与并网点相电压幅值约束,整定了正负序有功电流与无功电流的参考值。仿真与实验结果验证了所提控制方法的正确性与有效性。In the case of asymmetrical ground fault in the power grid, making full use of the inverter capacity and maximizing the support of the grid voltage is beneficial to improve the low voltage ride-through capability of the photovoltaic inverter, reduce the risk of its large-area disconnection, and guarantee safe operation of the power grid.To overcome this problem, an optimal voltage support strategy for photovoltaic inverter under asymmetrical ground faults is proposed. The inverter’s support principle for the grid-connected point voltage is elaborated. Taking the maximization of the positive sequence voltage support as the primary control objective, and the positive sequence current as the constraint condition, the Lagrangian function is constructed to derive the optimal distribution relationship between the positive sequence components of active current and the reactive current. Taking the optimal suppression of the negative sequence voltage as the secondary control objective, and the maximum allowable current of the inverter as the constraint condition, the Lagrangian function is constructed to derive the optimal distribution of negative sequence components of active current and the reactive current. Based on this, the constraints of active power fluctuation and grid-connected point phase voltage amplitude are considered comprehensively, and the reference value of positive and negative sequence components of active current and reactive current are set. Simulation and experimental results verify the correctness and effectiveness of the proposed control method.

关 键 词：不对称接地故障 光伏逆变器 最优电压支撑 

分 类 号：TM721[电气工程—电力系统及自动化]