分布式发电系统电网同步锁相技术

Grid Synchronization and PLL for Distributed Power Generation Systems

电网同步锁相是大规模可再生能源分布式发电系统并网运行需要解决的关键问题之一。为实现快速准确的电网同步,提出一种基于交叉解耦频率自适应复数滤波的锁相方法,分析其工作原理,建立其频域数学模型和时域数学模型,阐明电压正序分量和负序分量解耦的机理,从特征值角度对其稳定性和动态性能进行评估,给出离散域数字化实现方法,并对其在单相系统中的应用进行了探讨。最后在电网电压畸变/不平衡情况下对所提锁相方法进行了实验测试,结果验证了该锁相环的有效性。

Grid Synchronization is one of the key techniques for integration of distributed generation systems with high penetration of renewable energy sources into grid. In order to achieve the fast and accurate grid synchronization, a new phase-locked loop based on the cr0ssing-decoupling frequency-adaptive complex filter was proposed. The operation principle was analyzed. Mathematical models in the frequency-domain and time-domain were built, which clarify the mechanism of decoupling the voltage positive and negative sequences. From the eigenvalue analysis point of view, the stability and dynamic performance were evaluated. The digital implementation method was also provided. In addition, its application to the single-phase system was discussed. Finally, the performance tests were carried out under the distorted and unbalanced grid voltage conditions. The experimental results verify the effectiveness of the proposed method.