光伏并网逆变系统谐波综合分析  

Comprehensive Analysis of Harmonics of Photovoltaic Gridconnected Inverter System

作　　者：晏坤 甘景福 杜鹏 张梦茹 YAN Kun;GAN Jingfu;DU Peng;ZHANG Mengru(State Grid Jibei Electric Power Co.,Ltd.,Tangshan Power Supply Company,Hebei Tangshan 063000,China;Shandong University,Jinan 250061,China;Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]国网冀北电力有限公司唐山供电公司,河北唐山063000 [2]山东大学,济南250061 [3]华中科技大学,武汉430074

出　　处：《电力电容器与无功补偿》2024年第5期98-107,共10页Power Capacitor & Reactive Power Compensation

基　　金：国网冀北电力公司唐山供电公司成本项目(B3010322000Q)。

摘　　要：由于光伏系统的随机性和波动性,与电网的交互过程中,将给电网引入一定的谐波和间谐波,引起次同步振荡、电能质量等问题,严重时将导致电网崩溃。针对光伏并网系统的谐波问题,本文从光伏并网系统逆变器本体PWM调制、输出侧与电网的交互影响及输入侧光伏电源出力波动三个方面对谐波的影响进行综合分析,以期为谐波治理和电网的安全运行提供谐波分析依据。首先,分析了并网逆变器PWM调制会引起高次谐波,计及死区效应时引入低次谐波。其次基于直流纹波形成机理,进一步研究非理想电网对并网系统谐波的交互影响;同时,当电网三相不平衡运行时,逆变器输出电流将出现3次谐波分量。然后,从MPPT算法和环境因素两个方面研究光伏电源波动对系统谐波影响,建立基于MPPT周期振荡的逆变器输出电流间谐波分析模型,并利用光照强度日变化曲线进行仿真,结果表明并网电流总谐波畸变率随光照强度的增大而减小,为谐波检测和谐波治理提供基础。In the interaction with power grid,the randomness and volatility of photovoltaic(PV)system will introduce certain harmonics and interharmonics to the power grid,causing such problems as subsynchronous oscillation and power quality as well as,in case of serious,collapse of the grid.Aiming at the harmonic problem of PV gridconnected system,the influence of harmonics is analyzed from such three aspects as PWM modulation of inverter body,interaction between output side and the grid,and fluctuation of PV power output on input side in order to provide harmonic analysis basis for harmonic control and safe operation of power grid.First,the highorder harmonics caused by PWM modulation of gridconnected inverter is analyzed and the loworder harmonics introduced when the deadtime effect is considered.Then,the interaction effect of nonideal grid on the harmonics of gridconnected system is further investigated based on the formation mechanism of DC ripple;At the same time,in case of threephase unbalanced operation of the grid,the output current of the inverter will have a third harmonic component.After that,the effect of PV power fluctuation on system harmonics is studied from such two aspects as MPPT algorithm and environmental factors and the daily variation curve of the illumination intensity is used for simulation.The result shows that.the total harmonic distortion rate of gridconnected current decreases with the increase of light intensity,which provides basis for harmonic detection and control.

关 键 词：光伏发电 并网逆变器 谐波 间谐波 

分 类 号：TM615[电气工程—电力系统及自动化]