电压不平衡时风电系统中基于双同步变换的锁相环设计

Design of Phase Locked Loop Based on Double Synchronous Reference Frame under Unbalance Grid Voltage in Wind Power Systems

快速准确地锁定正序基波电压分量的相位和频率是保证风力发电系统中网侧变换器、静止无功补偿装置安全可靠运行的基础。针对基于单dq坐标变换的锁相环在电压不平衡和畸变时动态过程较差等问题,提出一种基于解耦双同步参考坐标变换的锁相环设计方法,通过双dq变换和解耦计算检测出不平衡电网电压中正序分量和负序分量,从而消除电压不平衡的影响。在电压不平衡、电压畸变、频率突变和单相接地情况下进行了仿真和实验研究,结果验证了所提方法的正确性和有效性。

In order to assure grid side converter and the static reactive compensator in wind power systems of running safely and reliably under unbalanced grid voltage,it is the basic requirement that the phase and fre- quency of the positive sequence fundamental component of grid voltage are obtained quickly and accurately. Be- cause the dynamic behavior of the phase locked loop system based on the single synchronous reference frame （SSRF SPLL） is dissatisfactory,a software phase locked loop based on double synchronous reference frame （DSRF SPLL） was put forward to detect the positive and negative sequence components of unbalanced grid voltages by double dq transformation and decoupling calculation. The simulation and experiment results have verified the validity and effectiveness of the DSRF SPLL under the unbalanced and distorted grid voltage, the sudden change of grid voltage frequency and the single-phase-earthing fault.