功频及直流电压下垂控制的光伏系统特性分析

Characteristic Analysis of Photovoltaic Power Generation System Based on Power Frequency and DC Voltage Droop Control

光伏发电依靠电力电子技术,没有固有的惯性和阻尼特性。针对光伏微网系统惯量低阻尼弱的特点,以功频及直流电压下垂控制的光伏微网系统为研究对象,建立了SSG模型,推导了惯量特性表达式,利用电转矩分析法,分析了影响光伏微网系统惯量、阻尼及同步特性变化规律,并利用MATLAB/Simulink仿真平台进行仿真验证。分析结果表明,功频及直流电压下垂控制的光伏并网发电系统惯性、阻尼和同步特征取决于系统的结构参数、PID控制系数和稳态工作点。功频环比例系数Kp越大,系统惯量越强;下垂系数Dp越小,系统阻尼性越强;直流电压外环积分系数Ki越大,系统同步性越强。仿真验证了理论分析的合理性。

Photovoltaic power generation relies on power electronics and has no inherent inertia or damping characteristics.In view of the low damping characteristics of inertia of photovoltaic microgrid system,the SSG model was established to study photovoltaic microgrid system controlled by power frequency and DC voltage drooping,and the expression of inertia characteristics was derived.The variation rules of inertia,damping and synchronization characteristics affecting photovoltaic microgrid system were analyzed by using the electric torque analysis method.MATLAB/Simulink simulation platform was used for simulation verification.The results show that the inertia,damping and synchronization characteristics of the grid-connected pv power generation system controlled by power frequency and DC voltage droop depend on the structural parameters,PID control coefficients and steady-state operating points of the system.The larger the proportional coefficient Kp,the stronger the inertia of the system.The smaller the droop coefficient Dp,the stronger the damping of the system.The greater the DC voltage outer loop integral coefficient Ki,the stronger the system synchronization.The simulation verifies the rationality of the theoretical analysis.