中文摘要：

为提高锁相环（phase-locked loop,PLL）的动态性能和锁相精确度,提出一种基于dq变换的改进锁相环,其通过平均值环节而不是延时信号消除（delayed signal cancellation,DSC）或低通滤波器（low pass filter,LPF）预先将负序与谐波分离出去,大幅缩短了暂态响应时间,同时亦消除了系统电压不平衡或畸变对锁相精确度的影响.详述了该PLL的工作原理;给出了关于负序与谐波分离方法的讨论;推导了控制环的线性化模型及其PI参数的整定方法.仿真与实验结果表明,由于采用平均值环节和不存在传统软件锁相环（soft ware phase-locked loop,SPLL）具有的耦合关系,该PLL可快速而准确地锁定系统电压中正序基波分量的相位,具有高动态性能和锁相精确度,适用于动态电压恢复器（dynamic voltagerestorer,DVR）或统一电能质量控制器（unified power quality controller,UPQC）等对电压变化敏感的柔性交流输电系统（flexible AC transmission system,FACTS）.

英文摘要：

In order to improve dynamic performance and phase-locked precision of phase-locked loop （PLL）,an improved phase-locked loop based on dq transformation was proposed,which separated negative sequence and harmonics through mean value links instead of delayed signal cancellation （DSC） and low pass filter（LPF） in advance and reduced transient response time greatly and also eliminated the effects on locking precision caused by system voltage unbalance and distortion.The working principle of this PLL was described in detail; The negative sequence and harmonic separation methods were discussed; The linear model of the control loop and the setting principle of PI parameters were deduced.Simulation and experimental results show that,because the proposed PLL adopts value links and does not have the coupling relationship which traditional SPLL processes,it can quickly and accurately lock the phase of the positive sequence fundamental component of system voltage and is suitable for flexible AC transmission systems （FACTS） which are sensitive to voltage changes like dynamic voltage restorer （DVR） or unified power quality controller（UPQC）.