Characteristic Analysis And Control Strategy Of Wind-solar Complementary Power Supply System

Confronting the global energy shortage and increasingly environmental pollution situation,countries are exploring and developing new energy use urgently.Among them,the use of a variety of distributed energy,such as solar power technology and wind power technology,has been proficiently and widely applied,A variety of distributed generation devices based on wind power and solar power generation have been developed to varying degrees,such as distributed power generation systems of wind-solar storage,wind-solar-diesel storage,and solar storage.In this thesis,an off-grid wind-solar complementary power supply system which is equivalent to the DC micro-grid of isolated island of operation,has been built.The wind-solar complementary power-supply system gives current directly,while free to consider the frequency and phase,so needless to control a complex structure.On the one hand,it can improve the quality of electricity,on the other hand,can reduce system losses,having development advantages.Due to the large randomness of solar energy and wind energy,the power generation is unstable.In order to give full play of the advantages of wind and solar power supply system,it is necessary to formulate appropriate control strategy.We analyzed,in this thesis,the operating principles and equivalent mathematical models of wind turbine,photovoltaic cell and battery firstly.The wind power generation model of permanent magnet synchronous machine,photovoltaic array power generation model,battery energy storage system model has been built by Matlab/Simulink according to equivalent model of each part respectively.The output characteristics of the wind turbine and the photovoltaic cell were analyzed by simulation under different working conditions,and furtherly the correctness of simulation model was testified.Secondly,we further improved the control strategy of various parts.The maximum power tracking of wind power generation was realized by machine side converter control.The maximum power tracking and the on-demand output of photovoltaic array power generation was realized by using disturbance observation method and constant voltage control method respectively.Simulation model was furtherly established respectively to verify the maximum power tracking.For the system energy storage unit,the theory of charge/discharge control circuit of bidirectional Buck/Boost converter was introduced.Then the charging and discharging control strategy of energy storage system,namely constant voltage charging(discharge)control,is determined,and the discharge process is simulated.At the same time,owing to cost is high cost of battery,the limits of battery charge and discharge has been set up in order to protect the battery.Finally,based on the modeling of above sub-module,the overall simulation model of the wind-solar complementary power supply system was established,and the energy management mode of the system was analyzed.We furtherly improved control strategy and analyzed the concrete work condition of the system in the corresponding energy management mode.Finally corresponding simulation examples were set to verify correctness of the system model and feasibility of the control strategy.