改进型光伏并网系统谐波电流检测和补偿算法

Improved Harmonic Current Detection and Compensation Algorithm for PV Grid-connected System

大量分布式光伏并网使得电网谐波问题日益严峻,利用光伏逆变器来补偿电网中的谐波电流,可以极大地提高光伏并网系统的设备利用率。为此,推导了不平衡工况下FBD谐波电流检测原理,基于含二阶广义积分器的锁相环(SOGI-PLL)设计改进型FBD谐波电流检测算法,并基于此提出光伏并网系统谐波电流补偿措施。改进型FBD法可以更精确地提取基波正序电压相位,减小负序电压带来的测量误差,在保留传统FBD法直观简单、计算量小等特点的同时,兼具检测精度高、稳态性能好等优势。在MATLAB/Simulink环境下的仿真结果证明了改进谐波电流补偿算法可以有效改善光伏并网点的电能质量。

A large number of distributed photovoltaic(PV)grid connection makes the harmonic problem of the power grid increasingly serious.It is able to greatly improve the equipment utilization of PV grid-connected system using the PV inverter to compensate the harmonic current in the power grid.Thus,this paper derives the principle of FBD harmonic current detection under unbalanced conditions.Based on the phase-locked loop with second-order generalized integrator(SOGI-PLL),it also designs an improved FBD harmonic current detection algorithm,and then proposes the harmonic current compensation measures of the PV grid-connected system.The improved FBD algorithm can extract the phase of positive sequence voltage of fundamental wave more accurately and reduce the measurement errors caused by negative sequence voltage.It retains the advantages of the traditional FBD method,such as intuitive and simple,small amount of calculation,and has the advantages of high detection accuracy and good steady-state performance.The simulation results in MATLAB/Simulink environment verify the improved harmonic current compensation algorithm can effectively improve the power quality of PV grid.