Research On MPPT Control Algorithms And Energy Management Of A Wind-solar Hybrid Power System

Due to ever increasing energy crisis, environment degradation and the continuous exploitation of the non-renewable energy, there is a rising public awareness of environmental protection and the development of new energy.Wind energy and solar energy as two representatives of the new energy have gained extensive attention in recent years. The Maximum Power Point Tracking(MPPT) has become a hotspot of renewable energy field both home and abroad. The main purpose of MPPT is to improve the output efficiency of both wind power system and solar power system, as well as the response speed of system. The performance of a MPPT algorithm directly influence the effective utilization rate of wind energy and solar energy, while which influence the operation performance of the whole system. A highly efficient MPPT algorithm is very essential considering the further development of the new energy electric power system. For the wind and solar energy are complementary in some points(the wind energy is weak while the solar energy is rich by day, and the reverse situation happens in the night), the wind-solar hybrid system which has a better output characteristics can decreases the effect of environment changing compared with the stand-alone wind power or photovoltaic system.This paper started with the analysis on the photovoltaic(PV) and wind power system respectively. Then photovoltaic cell model and wind turbine model were built to analyze their output characteristics. The maximum energy capture control methods of distributed wind-solar hybrid system are discussed in this paper. An efficient MPPT algorithm is proposed for PV and small-scale wind turbine generator system(WTGS) respectively. The simulation results prove the effectiveness of the proposed MPPT algorithm in improving the output power efficiency and the response speed. The main contents and innovations include:(1) The output characteristics of PV under the ideal condition and its MPPT control using a Boost Chopper are analyzed, as well as the common MPPT strategies. A variable step size INC controlling the duty cycle algorithm is proposed. The advantages of the proposed MPPT method include rapid tracking speed, good tracking precision and easy to implement. It shows a good dynamic and static performance.(2) The operational mechanism of WTGS and the output characteristics of wind turbine are analyzed. The common maximum energy capture control algorithms are discussed. Then P&O method embedded into an S-Function control strategy is proposed to capture the maximum energy. It is easy to implement and more efficient. It shows a good dynamic and static performance as well.(3) Considering our lab does not have the wind farm environment, a simulation program of WTGS using PMSG dragged by a DC-motor is introduced in this paper. A variable step size P&O controlling the duty cycle MPPT algorithm is proposed. It can track the MPP efficiently.(4) After taking different weather conditions, different load conditions and different battery conditions into consideration, fourteen operating modes and their energy matching strategies are proposed respectively.