Research On Small Off-grid Wind-solar Hybrid System And MPPT Control

Nowadays, energy crisis and environmental pollution is increasingly serious. It’s urgent to adopt measures to increase the development and utilization of renewable energy. Wind power and solar power generation is an important renewable energy. how to effectively control and utilize wind energy and solar energy, making efforts to increase its proportion in the energy structure, has become an important topic in our society and the later development.The theoretical basis of each component of Wind-Solar complementary system are analyzed in this paper, then, the matlab simulation models for each component are established. The paper put forward a kind of double input DC-DC converter structure which increases work voltage range of the controller, and simulation results verify its feasibility. Then some simulation results verify the duty cycle’s influence on output power, which provides a theoretical basis for maximum power tracking (MPPT) control using duty cycle. For wind power generation system, this paper verifies the equivalence between the duty ratio perturbation and disturbance of rotor speed, which lay the foundation for using DC-DC circuit duty cycle control to realize MPPT control.Photovoltaic system and wind power system are strongly nonlinear systems, their work conditions are also very difficult to accurately describe with mathematical model, so this paper adopts the fuzzy control method to study the MPPT. According to the specific conditions of photovoltaic system and wind power system, the fuzzy adaptive method is adopted to realize the MPPT control. The work includes determining input and output quantity and their membership functions, fuzzy control rule table, fuzzy reasoning and fuzzy method, etc. The simulation results show that the fuzzy adaptive MPPT control has better dynamic and steady-state performance than disturbance observation method, which manifests the superiority of fuzzy control.Aiming at the problem of how to determine the fuzzy control rules, the paper takes photovoltaic system for example, using artificial neural network to generate fuzzy inference system automatically with the acquired data. The simulation result proves that this method is simple and effective.