单相CHB光伏并网逆变系统谐波补偿策略研究

Research on Harmonic Compensation Strategy of Single-phase CHB Photovoltaic Grid-connected Inverter System

受部分遮挡、自身损坏等因素的影响,单相级联H桥光伏并网逆变系统的H桥模块间传输功率不平衡,导致传输功率高的H桥模块易发生过调制,造成并网电流的恶化,甚至影响系统的稳定运行。为此,提出一种优化的三次谐波补偿策略,通过对过调制模块补偿三次谐波的准确计算,使其调制波幅值为1。同时,结合反相三次谐波在正常模块间的优化分配,最大限度地避免各H桥模块过调制的发生。在Matlab/Simulink中搭建仿真模型,将采用所提控制策略与常规三次谐波补偿策略、混合调制策略的仿真结果进行对比,对所提控制策略的优良性能进行验证。

Affected by partial shading,self damage and other factors,the transmission power between H-bridge modules of single-phase cascaded H-bridge photovoltaic grid-connected inverter system is unbalanced.As a result,the H-bridge module with high transmission power is prone to overmodulation,which leads to the deterioration of grid current and even affects the stable operation of the system.Therefore,an optimized third harmonic compensation strategy is proposed,through the accurate calculation of the third harmonic compensated by the overmodulation module,the amplitude of their modulation wave is 1.At the same time,combined with the optimal distribution of inverse third harmonic among the normal modules,the overmodulation of each H-bridge module is avoided to the maximum extent.The simulation model is built in Matlab/Simulink,and the simulation results of the proposed control strategy are compared with the conventional third harmonic compensation strategy and hybrid modulation strategy,and the excellent performance of the proposed control strategy is verified.