电气工程学报 ›› 2019, Vol. 14 ›› Issue (2): 79-85.doi: 10.11985/2019.02.014

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提高弱电网下LCL型并网逆变器稳定性的改进电网电压前馈策略 *

于文倩1,同向前1,燕聪1,焦攀2   

  1. 1. 西安理工大学自动化与信息工程学院 西安 710048
    2. 国网昌吉换流站 昌吉 831100
  • 收稿日期:2019-05-05 出版日期:2019-06-25 发布日期:2019-10-25
  • 作者简介:于文倩,女,1995年生,硕士研究生,主要研究方向为有源电力滤波器的应用设计。 E-mail: 736481556@qq.com。|同向前,男,1961年生,教授,博士研究生导师,主要研究方向为电力电子技术在电力系统中的应用。E-mail: lstong@mail.xaut.edu.cn
  • 基金资助:
    *国家自然科学基金资助项目(51677151)

An Improved Grid Voltage Feedforward Strategy for LCL-type Grid-connected Inverters in Weak Grid

YU Wenqian1,TONG Xiangqian1,YAN Cong1,JIAO Pan2   

  1. 1. Faculty of Automation and Information Engineering, Xi’an University of Technology, Xi’an 710048 China;
    2. State Grid Changji Converter Station, Changji 831100 China
  • Received:2019-05-05 Online:2019-06-25 Published:2019-10-25

摘要:

并网逆变器常采用电网电压前馈策略来提高系统输出对电网电压扰动的抑制能力和装置起动性能,但在弱电网下,电网电压直接比例前馈会削弱并网逆变器的稳定裕度。基于对弱电网下无前馈和直接比例前馈控制的开环频率特性的对比分析,提出一种在前馈通道中加入滞后选频环节的改进前馈方案,改进后的系统稳定裕度得到明显改善。最后,搭建了一套采用氮化镓(GaN)器件的LCL型并网逆变器的试验样机,试验结果表明采用改进前馈策略的并网逆变器对弱电网的适应性更强。

关键词: LCL并网逆变器, 弱电网, 电网电压前馈控制, 稳定性

Abstract:

Grid-connected inverters often use grid voltage feedforward control to improve the suppression capability and startup performance of the system. When the grid behaves a weak grid, the direct proportional feedforward control of the grid voltage will weaken the stability margin of the grid-connected inverter control system. Based on the comparative analysis of the open-loop frequency characteristics of no feedforward and direct proportional feedforward control under weak grids, an improved feedforward scheme is proposed with a lag transfer function for frequency selective in the voltage feedforward channel. Thus the system stability margin improves obviously. Finally, the verification is carried out on a set of LCL-type grid-connected inverter experimental platform. The experimental results demonstrate that the adaptability of improved voltage feedforward strategy under weak grid is more stronger.

Key words: LCL-type grid-connected inverter, weak grid, grid voltage feedforward control, system stability

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