并网换流器采样和PWM边带次生谐波特性研究

Research on Sampling and PWM Sideband Secondary Harmonic Characteristics of Grid Connected Converter

在高比例新能源接入电力系统背景下,配电网中部署的并网换流器数量日益庞大,并网换流器自身非线性特性产生的次生谐波逐渐成为电网谐波污染的重要的来源之一。为此,针对并网换流器A/D采样和脉宽调制(pulsewidth modulation,PWM)过程产生的边带次生谐波分量开展研究,分析采样和PWM调制边带次生谐波产生机理以及频率耦合机理,提出不同采样方式下PWM边带谐波分析方法,建立并网换流器采样和PWM边带次生谐波定量分析模型,分析影响边带次生谐波含量的主要因素,揭示边带次生谐波耦合效应对并网换流器端口谐波阻抗特性的影响规律。通过半实物仿真平台的测试结果验证理论分析的正确性。

Under the background of high proportion of new energy connected to the power system,the number of grid connected converters deployed in the distribution network is increasing,and the secondary harmonic generated by the nonlinear characteristics of grid connected converters has gradually become one of the important sources of harmonic pollution in the distribution grid.Therefore,the secondary harmonic components of the sideband generated from A/D sampling and PWM modulation of grid connected converters are studied.The generation and frequency coupling mechanisms of the secondary harmonic components of the sampling and PWM sideband are analyzed.The analysis method of PWM sideband harmonics under different sampling methods is presented.The quantitative analysis model of the secondary harmonic components of grid connected converters sampling and PWM sideband is established.The main factors affecting the secondary harmonic content of the sideband are analyzed.The influence of sideband secondary harmonic coupling effect on the impedance characteristics of grid connected converter is proposed.The accuracy of the theoretical analysis is verified by the test results of the hardware in the loop simulation platform.