The Research On Grid-connected With PV And Energy Storage System

As we all know, With the rapid development of economy, the demand for fossil energy is increasing. However the fossil energy is non-renewable energy, so the reasonable development and use of renewable energy has become the only way to solve the problem of the world’s energy. Photovoltaic power generation is the world’s attention as a kind of clean and renewable energy, However, the inherent randomness and intermittent of the photovoltaic power characteristics will cause on the safe and stable operation of large power grid, the influence of power flow distribution, dynamic characteristics and the quality of electric energy when they are large-scale grid-connected. The introduction of the energy storage system can improve the stability and quality of power supply for the system. The main content of this paper includes the following four aspects:1. According to the mathematical model of photovoltaic cells, In the MATLAB simulation software platform, the general simulation model of photovoltaic cells was established, and its characteristics are simulated; secondly the variable step perturbation and observation method is chosen as the maximum power tracking control is studied, Simulation is made in different external conditions to verify the correctness of the building model.2. With the lead-acid battery as an example, the model of the lead-acid battery is given under the general equivalent circuit and at the same time the charge-discharge curves are given. The double loop cascade control strategy is proposed to control the bi-directional DC/DC converter. Finally, to simulate the control strategy of double loop cascade.3. The mathematical model of the grid inverter is deduced under the synchronous rotating coordinate system, the control strategy of the grid voltage orientation vector control is selected to control the grid inverter. Finally the three-phase grid-connected photovoltaic system is validated by the simulation.4. This paper proposes a novel optical storage grid structure, which is added energy storage system in the DC side, inhibition of DC side voltage fluctuation using the quick charge and discharge characteristics, so as to achieve the purpose of inhibiting power fluctuation. The simulation model has set up in the MATLAB simulation software platform for the optical grid storage system, and carried on the simulation confirmation in different external conditions.