谐波畸变电网下的增强型锁频环方法

Enhanced Frequency Locked Loop Under Adverse Grid Conditions

传统的电网同步方法在电网电压畸变的条件下难以有效、准确地获取电网信息,危害并网变流器的可靠运行。针对此问题,这里提出增强型锁频环方法。所提方法在锁频回路中插入梳状滤波器,通过在各次谐波频率处引入"零点",完全消除电网电压中的直流分量、谐波畸变等对锁频环精度的影响。相比现有的谐波畸变条件下的电网同步方法,具有结构简单、运算量小、稳态精度高及动态响应优异等优点。搭建实验平台,用可编程交流源模拟各种畸变电网条件,验证了所提算法的可行性和优势。

The traditional grid synchronization methods have the disadvantage of poor performances under adverse grid conditions,unable to effectively and accurately extract grid information.To address this problem,an enhanced frequency locked loop is proposed, which incorporates a comb filter and improves the filtering abilities by introducing purely imaginary zeros to eliminate the negative influences of direct current component and harmonics in the grid voltage.In comparison with typical existing solutions, the proposed method features simple structure, low computational load, high accuracy and fast dynamics.Experimental prototype is built with the programmable alternating current source to simulate adverse grid conditions.Experiment and comparisons are provided to validate the proposed method.