不平衡电网下三相PWM整流器预测直接功率控制  

Predictive Direct Power Control of Three Phase PWM Rectifier Under Unbalanced Grid

作　　者：赵峰 李述特 陈小强 王英[1,2] 张帆 牛鑫强[1] 甘延奇 ZHAO Feng;LI Shute;CHEN Xiaoqiang;WANG Ying;ZHANG Fan;NIU Xinqiang;GAN Yanqi(School of Automation&Electrical Engineering,Lanzhou Jiaotong University,Lanzhou 730070,Gansu Province,China;Key Laboratory of Opto-technology and Intelligent Control(Lanzhou Jiaotong University),Ministry of Education,Lanzhou 730070,Gansu Province,China)

机构地区：[1]兰州交通大学自动化与电气工程学院,甘肃省兰州市730070 [2]光电技术与智能控制教育部重点实验室(兰州交通大学),甘肃省兰州市730070

出　　处：《电网技术》2022年第3期870-879,共10页Power System Technology

基　　金：国家自然科学基金项目(51767013,52067013);兰州交通大学“天佑创新团队”(TY202010)。

摘　　要：三相脉宽调制(pulse-width modulation,PWM)整流器中,当电网电压不平衡时,传统的预测直接功率控制(predictive direct power control,PDPC)策略导致输入电流严重畸变,另外,网压传感器使整个系统变得更复杂,且耗费成本。为了改善PWM整流器输入电流质量,并降低系统成本,将基于改进型二阶广义积分器(second-order generalized integrator,SOGI)的无网压传感器算法与PDPC策略相结合,采用改进型二阶广义积分器产生同频率的正交信号,估算电网电压,实现无网压传感器PDPC。根据扩展pq理论分析电网不平衡情况下产生有功、无功功率二倍频振荡的原因,在此基础上推导出了消除功率振荡的整流器交流侧电压方程,进而通过空间矢量调制(space vector pulse width modulation,SVPWM)确定开关状态。在仿真平台对所提方法在电网平衡和不平衡情况下进行仿真,仿真结果表明,所提方法降低了不平衡电网对输入电流波形的影响,消除了功率二倍频振荡,准确估算电网电压,实现电网平衡和不平衡情况下的正常工作,通过对比这2种情况下的仿真结果,验证了该方法的有效性。In a three-phase pulse-width modulation(PWM)rectifier, due to the unbalanced grid voltage, the input current may be distorted seriously under the traditional predictive direct power control(PDPC) strategy. In addition, the whole system more complex and costly because of the grid voltage sensor. In order to improve the input current quality of the PWM rectifier and reduce the cost of system, the grid voltage sensor free algorithm based on a improved second-order generalized integrator(SOGI) is combined with the PDPC strategy. The improved SOGI is used to generate orthogonal signals with the same frequency to estimate the grid voltage and realize the grid voltage sensor free PDPC. Based on the extended pq theory, the reasons of the active and reactive power double frequency oscillation under the unbalanced grid are analyzed. On this basis, the AC side voltage equation of the rectifier to eliminate the power oscillation is derived. Then the switching state is determined by the space vector pulse width modulation(SVPWM). In the simulation platform, the proposed method is simulated under the balanced and unbalanced grids. The simulation results show that the proposed method reduces the influence of unbalanced grid on the input current waveform, eliminates the double frequency oscillation of the power, accurately estimates the grid voltage,and realizes the normal operation under the balanced and unbalanced grids. The effectiveness of the proposed method is verified by comparing the simulation results of the two cases.

关 键 词：三相PWM整流器 电网不平衡 预测直接功率控制 无网压传感器算法 改进型二阶广义积分器 扩展pq理论 

分 类 号：TM721[电气工程—电力系统及自动化]