不平衡电网下并网逆变器多目标模型预测功率控制*

doi:10.11985/2023.01.008

摘要/Abstract

摘要：

针对并网逆变器在电网电压不平衡故障时电网电流畸变过大、功率脉动大、直流侧电压不稳定等问题，提出一种多目标模型预测功率控制(Multi-objective model predictive power control，MOMPPC)降低电流总谐波失真，消除有功/无功功率振荡及平衡网侧电流。首先对不平衡电网时瞬时功率进行详细分析，得出瞬时有功/无功功率；然后通过调节有功/无功功率基准，改变基准系数矩阵，实现三个灵活控制目标；为避免逆变器切换频繁，优化设计成本函数，增加开关切换次数、直流侧中点电压加权函数，有效降低直流电压脉动。Matlab/Simulink仿真及3.8 kW样机试验对比显示MOMPPC能实现三种目标的灵活控制，传统模型预测功率控制(Model predictive power control，MPPC)与所提MOMPPC控制策略网侧电流谐波THD分别为4.8%、3.7%，结果表明MOMPPC策略的有效性。

关键词: 有功/无功功率, 三相逆变器, 模型预测控制, 电流谐波, 中点电压

Abstract:

Under unbalance grid voltage, grid-tie inverter have the problem of excessive grid current distortion, large power ripple, and DC side voltage instability. In order to solve these problems, a mulit-objective model predictive power control(MOMPPC) is proposed to address the issue of the distorting grid current in grid-tied inverter. Firstly, the instantaneous power when the grid is unbalanced is detailed analyzed to obtain instantaneous active/reactive power; then adjust the active/reactive power reference and change the reference coefficient matrix to achieve three flexible control goals. In order to avoid frequent inverter switching, optimize the design of the cost function, increase the number of switching times, and the DC side midpoint voltage weighting function to effectively reduce the DC voltage ripple. The comparison of Matlab/Simulink simulation and 3.8 kW prototype experiment show that MOMPPC can achieve flexible control of three goals. The traditional MPPC and MOMPPC control current harmonics THD of the grid side are 4.8% and 3.7%, respectively. The results show the effectiveness of MOMPPC strategy.

Key words: Active and reactive power, three-level inverter, model predictive power control, grid current distortion, neutral point voltage

中图分类号:

TM464

刘偲艳. 不平衡电网下并网逆变器多目标模型预测功率控制^*[J]. 电气工程学报, 2023, 18(1): 77-85.

LIU Siyan. Multi-objective Model Predictive Control of Grid-connected Inverters in Unbalanced Grids[J]. Journal of Electrical Engineering, 2023, 18(1): 77-85.

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参数	数值
滤波电感L/mH	6
直流侧电容C/µF	1 000
直流侧电压u_c /V	350
电网频率f/Hz	50
电网线电压e/V	220
给定有功功率P_ref /kW	3.8
给定无功功率Q_ref /kVar	0
采样频率f_s /kHz	10