Design On Photovoltaic Generation System Based On Sliding Mode Variable Structure Control

The technology of photovoltaic generation is not only a supplement of energy resource, but also has the potentiality to become the major energy resource in the future. It is the main form of solar power that converting solar energy into electric energy through photovoltaic grid-connected generation system, and transporting the electric energy to power grid. In order to maximize the use of solar energy, a deep research on maximum power point tracking (MPPT) methods and control strategies of grid-connected inverter is made, and simulation verifications are performed.Sliding mode variable structure control is essentially a kind of special nonlinear control technology, with the advantages of stability, fast dynamic response and strong robustness of parameter variation and disturbance. This control method has strong applicability of the inverter which is a periodic varying structure system with its switching characteristics. In this paper, the principle, mathematical model and design process of sliding mode variable structure control are introduced in details.The key problems of PV grid-connected system are studied in depth, namely MPPT and the control strategies of inverter. By constrasting the common methods of MPPT, a method of sliding mode variable structure control is proposed to solve the problems of tracking speed and steady state accuracy. The proposed method is also applied to control a double Boost inverter.After analyzing this method, the simulation model of MPPT control and grid-connected double Boost inverter control are built on the platform of MATLAB/Simulink. The simulation results show the feasibility and superiority of the control strategies proposed in this paper.