适用于双馈风电系统的九开关型统一电能质量调节器

摘要

为减小电压谐波、电压跌落与骤升、电压不平衡等电能质量问题对双馈感应发电机(DFIG)风电系统的影响,在对多种统一电能质量调节器(UPQC)拓扑结构研究对比和九开关变换器建模分析的基础上,提出一种应用于双馈风电系统的九开关型UPQC方案.在对UPQC电压、电流补偿单元运算电路建模的基础上,设计相应的控制策略.按照电网工况,设定谐波电流补偿、轻度电压补偿、重度电压补偿3种工作模式,优化UPQC运行方案.仿真与实验结果表明,九开关型UPQC可以有效治理电压、电流谐波,消除电压偏差与相位跳变,提高DFIG机端电能质量,使机组可以在多种故障电压工况下实现柔性故障穿越.%In order to reduce the influence of electric energy quality problems,such as voltage harmonic,voltage sag or swell, voltage unbalance,on the doubly-fed induction generator(DFIG)wind power system,a scheme of a nine-switch unified power quality conditioner (UPQC) applied to a DFIG wind turbine system is proposed after a contrastive study on the topological structures of various UPQCs and modeling analysis of nine-switch converter.On the basis of modeling the operation circuit of voltage and current compensation unit in UPQC,the corresponding control algorithm is designed.According to the power grid condition,3 types of working scenario are set up to optimize the operation scheme of UPQC,including harmonic circuit compensation,mild voltage compensation,and heavy voltage compensation.Simulation and experiments are made to verify the validity of the scheme.The results show that,the nine-switch UPQC can suppress harmonic voltage and current,eliminate voltage deviation and phase j ump to significantly improve power quality of DFIG,thereby realizing flexible fault ride-through (FFRT) in a wide range of fault voltage conditions.