不对称故障下考虑电压跌落程度的新能源逆变器控制策略  

Control strategy of renewable energy inverter considering voltage sag degree under asymmetric faults

作　　者：李红 粟时平[1] 唐铭泽 苏乾坤 胥朝夫 LI Hong;SU Shiping;TANG Mingze;SU Qiankun;XU Chaofu(Changsha University of Science and Technology,Changsha 410114,China;Yueyang Power Supply Branch,State Grid Hunan Electric Power Co.,Ltd.,Yueyang 414000,China)

机构地区：[1]长沙理工大学,湖南长沙410114 [2]国网湖南省电力有限公司岳阳供电分公司,湖南岳阳414000

出　　处：《电力系统保护与控制》2023年第1期21-32,共12页Power System Protection and Control

基　　金：国家自然科学基金项目资助(51708194)。

摘　　要：电网发生不对称故障会影响新能源并网系统可靠运行,严重情况下还会存在切机风险。针对上述问题,提出一种不对称故障下考虑电压跌落程度的电压支撑策略。首先根据逆变器在不对称故障下的输出特性,分析了对公共连接点(point of common coupling,PCC)电压的支撑原理。然后推导了任意不对称故障下PCC电压幅值的通式,进而分析了改变无功电流注入方式的临界点。最后在上述基础上,以逆变器输出电流峰值和已利用容量为约束条件,分别对3种典型的不对称故障进行了分析。确定了每种故障在不同电压跌落阶段的最优无功电流,并推导了各电压跌落阶段的电流参考值计算公式。仿真验证了所提控制策略的有效性与优越性。The occurrence of asymmetric faults in the power grid will affect the reliable operation of the new energy grid-connected system,and there will be a risk of shutdown in severe cases.Given this,this paper proposes a voltage support strategy considering the degree of voltage sag under asymmetric faults.First,according to the output features of the inverter under asymmetric faults,the support principle of the point of common coupling(PCC)voltage is analyzed.Then the general formula of the PCC voltage amplitude under any asymmetrical fault is deduced,and after that the critical point of changing the reactive current injection mode is analyzed.Finally,considering the peak value of the inverter output current and the used capacity as constraints,three typical asymmetric faults are analyzed on the above groundwork.The optimal reactive current of each type of fault in a variety of voltage sag stages is determined,and the calculation formula of current reference value in each voltage sag stage is deduced.The effectiveness and superiority of the proposed control strategy is verified by the simulation results.

关 键 词：不对称故障 不同电压跌落阶段 最优电压支撑 逆变器 低压穿越 

分 类 号：TM464[电气工程—电器] TP273[自动化与计算机技术—检测技术与自动化装置]