一种双馈风力发电机在电网电压不平衡条件下的改进控制策略

摘要

通过对双馈电机在电网电压不平衡条件下的模型进行了推导、分析以及对电网电压不平衡条件下双馈电机定子侧有功功率、无功功率以及电磁转矩的定义,提出了一种双馈风力发电机在不平衡电网电压条件下的改进控制策略,该控制策略可以根据控制目标的不同,实现定转子电流、有功无功功率和电磁转矩脉动的抑制,另外在该控制策略中采用了一种快速正负序分量分解的方法,与传统采用低通或带通滤波器进行正负序分量分离相比,该方法分离速度快,对系统稳定性影响很小,从而改善系统的控制性能。为了验证该控制策略的有效性,利用Matlab/Simulin%This paper presents the derivations and analysis of doubly-fed induction generator＇s model under grid voltage unbalance conditions.Active power,reactive power and generator torque are also defined under these conditions.Based on these analysis,an improved control strategy of doubly-fed generator（DFIG） under unbalance conditions is proposed.According to different control purposes,pulsation of stator current,rotor current,active and reactive power,electromagnetic torque can be eliminated by using proposed control scheme.In addition,a fast decomposition algorithm is used to decompose positive and negative sequence and it is much faster than decomposition method based on low pass filter or band pass filter,so the performance of control system is greatly improved.In order to validate the proposed strategy,simulation using Matlab/Simulink and experimental test are carried out and the simulative and experimental results validate the proposed control strategy.