Research Of Photovoltaic Generation System Based On Improved Incremental Conductance Method

For the reasonable use of energy and the solution to the problem of energy shortage,500W stand-alone solar photovoltaic power generation system with a higher efficiency has an important significance. Solar as a new type of energy is favored by people, and it has brought benefits to individual consumers or public utilities. Stand-alone photovoltaic power generation system can take full advantage of solar energy, reduce operating costs, avoid transmission losses, and reduce environmental pollution. The project has very important realistic meaning to develop new energy projects in our country.For the moment, Stand-alone photovoltaic power generation system is not universal mainly due to its low efficiency but high cost. In order to reduce system cost and advance utilization efficiency of solar energy, tracking maximum power point is one of the most efficient approaches. Up to now, the methods of maximum power point tracking (MPPT) mostly are constant voltage control, incremental conductance method, perturbation and observation method and etc.Based on the single peak output characteristic of solar cell, this paper applies the characteristics of the DC/DC converter (Boost circuit) in the maximum power point control system, makes it more suitable for maximum power point tracking of solar cell. To deal with the problem of oscillations and misjudgment in basic incremental conductance method, this paper proposes an improved method, a method of the improved incremental conductance with variable step size combination with constant voltage. Through the simulation verification, the system with this method can track maximum power point of solar cell more efficiently and quickly in the situation of sudden illumination intensity changes. And the steady-state output power fluctuations of the system are smaller. It also has stronger robustness to the external disturbances. It Can not only raises efficiency, but also avoid misjudge and oscillations of the traditional method. This thesis has also researched the question that DC Bus voltage can not be stabilized deeply. And ultimately, through the battery charging/discharging circuit and the maximum power point tracker of photovoltaic cell module in parallel, it achieves the energy balance of the solar power system. The single-phase full-bridge inverter converts the DC output voltage of MPPT module to AC220V/50HZ sin wave voltage for household applications. Simulation results show that the proposed control methods have better control results.