考虑低电压穿越全过程控制策略切换的双馈风机电气量研究

Study on Electrical Quantities of Doubly Fed Wind Turbines Considering Control Strategy Switching During the Entire Low Voltage Ride Through Process

双馈感应发电机(doubly fed induction generator,DFIG)的电气特性在低电压穿越(low voltage ride through,LVRT)全过程均易受电网电压变化影响,而现有研究多关注故障期间DFIG的电气特性,未考虑故障清除后不同情形下DFIG电气特性的差异,且较少研究LVRT全过程DFIG的功率特性,LVRT全过程电气特性分析尚不全面。为此研究了LVRT全过程DFIG的运行状态,在故障清除前,将LVRT全过程分为故障发生、无功功率优先控制启动两个阶段,故障清除后分为撬棒二次投入、有功功率爬坡恢复两种情形进行分析。在此基础上,推导了LVRT全过程定子侧输出电流、功率的表达式,并在PSCAD中建立了DFIG仿真模型,时域仿真结果与解析表达式波形可较好吻合,证明了所提方法的有效性。

The electrical characteristics of doubly fed induction generators(DFIGs)are easily affected by changes in power grid volt⁃age throughout the entire process of low voltage ride through(LVRT).However,existing researches mostly focuse on the electrical characteristics of DFIGs during faults,without considering the differences in electrical characteristics of DFIGs in different scenarios after fault clearance.There is also limited research on the power characteristics of DFIGs throughout the entire process of LVRT,and the analysis of electrical characteristics throughout the entire process of LVRT is not yet comprehensive.For this purpose,the opera⁃tion status of DFIG in the entire LVRT process is studied.Before the fault is cleared,the entire process of LVRT is divided into two stages:fault occurrence and reactive power priority control startup.After the fault is cleared,it is analyzed in two situations:second⁃ary use of the pry bar and active power ramp recovery.On this basis,the expressions for the stator side output current and power throughout the entire process of LVRT are derived,and a DFIG simulation model is established in PSCAD.The time-domain simula⁃tion results closely match the analytical expression waveform,demonstrating the effectiveness of the proposed method.