电网低次谐波电压下级联H桥光伏并网逆变器控制策略

CONTROL STRATEGY OF CASCADED H-BRIDGE PHOTOVOLTAIC GRID-CONNCTED INVERTER UNDER LOW-ORDER HARMONIC VOLTAGE OF GRID

针对电网电压畸变等原因造成的级联H桥光伏逆变器并网电流畸变、低次谐波含量高等问题,提出一种基于坐标变换的电流谐波抑制方法。首先建立单相级联H桥光伏并网逆变器模型,其次通过在传统双环控制中加入特定次谐波电流环提取并网电流谐波并对其进行闭环控制从而抑制谐波电流。最后搭建单相3模块级联H桥光伏并网逆变器的Matlab仿真模型和基于TMS320F28335DSP和EtherCAT工业以太网通讯的实验平台。仿真和实验结果均可验证所提控制策略的有效性和可行性。

A harmonic current suppression method based on transformation of coordinates is proposed in this paper to solve the problem of the grid current distortion and the increase of low-order harmonics which are caused by the distortion of grid voltage in the Cascaded H-Bridge(CHB)photovoltaic inverter.Firstly,the model of single phase CHB photovoltaic gridconnected inverter is built.Secondly,the current of specified order harmonic are extracted from the grid current and then they will be effectively suppressed by the harmonic current loops which are added into the traditional double control loops.Finally,the simulation model and experiment platform based on Matlab/Simulink and TMS320 F28335 DSP-EtherCAT of single phase three modules of CHB photovoltaic grid-connected inverter are established respectively.Simulation and experimental results verify the effectiveness and feasibility of this proposed solution.