光伏发电-超级电容储能并网系统的直流母线电压稳定控制

A Study on the DC-Bus Voltage Stability Control of Photovoltaic Power Generation-Supercapacitor Energy Storage Grid-Connected Systems

光伏发电并网系统因太阳能的周期性和间歇性会对电网造成扰动,影响电网的安全稳定运行。针对双级式光伏并网发电系统,在直流母线侧增加超级电容储能可以平抑光伏发电功率的波动。从控制功能的角度,将光伏发电-超级电容储能并网系统分为光伏发电、逆变器和超级电容储能3个功能独立的子系统;建立了各子系统的数学模型,并在此基础上分析确定各子系统分别实现最大功率跟踪控制、恒功率控制和直流母线电压稳定控制的具体方案;针对直流母线电压的稳定控制,提出一种基于鲁棒渐近跟踪控制的方法。通过模拟不同辐照强度,不同电网有功-无功功率需求等多种工况进行仿真验证。结果表明,所提控制功能划分合理,控制方法有效且兼有较好性能。

Due to the periodic and intermittent characteristics of solar energy,the grid-connected photovoltaic(PV)power generation system causes disturbances to the power grid and affect its safety and stable operation.For the two-stage PV grid-connected power generation system,the fluctuation of PV power generation can be smoothed by adding supercapacitor energy storage system(SESS)on the DC-bus.From the perspective of control function,the PV-SESS grid-connected system is divided into three functional independent subsystems,i.e.,PV subsystem,inverter subsystem and supercapacitor subsystem.The mathematical model of each subsystem is established,furthermore,the specific schemes of realizing maximum power tracking control,constant power control and DC-bus voltage stability control are analyzed and determined.For the stability control of DC-bus voltage,a method based on robust asymptotic tracking control is proposed.The simulation verification is carried out by setting various working conditions such as different irradiation intensities and different active-reactive power demands of the power grid.The results indicate that the proposed control function division is reasonable,the control method is effective,and has good performance.