The New Doubly Fed Induction Generator System Based On DC Microgrid And Power Control

As the pollution of environment and the short of the fossil energy,more and more people pay attention to the use of renewable energy sources.Wind energy is more and more popular with people all over the world for its abundant reserves and mature technology.DFIG become a major typle of wind power generation because of its flexible control and lowcost.Dc-grid and dc transmission have bright future.And it is a trend to develop them.So more and more scholar and expert pay attention to the topology of DFIG connected to dc-link.Nowadays the study of DFIG connected to dc-link still in the start stage.If we want to use the traditional technology,we should more converter,then we will pay more money for it,and this behavior will have Lower energy utilization.This paper majorly study a new topology of DFIG connected to dc-link.This new topology stator connected through a diode rectifier to a dc-link,and its rotor connected to a common dc-link through a converter.Because the difference between trouditional topology and the new topology mainly appear to the stator.So we builed a detail modeling for the stator.The voltage and current,power and harmonics of the stator side when the stator side is not controlled rectifier bridge are analyzed in detail,Combined with the rotor side and comprehensively analysis othe overall characteristics of the system combined with the rotor side.In order to improve the efficiency of energy transfer in the new system and reduce energy loss,this parper study the loss modeling,by take the derivation of the function about loss,we got the minimum value of system’s loss,and depicts the best radio of dq rotor current.The correctness of the theoretical calculation results is verified by MATLAB simulation.Secondly,based on builed the detail modeling,we propose two vector control strategies which based on the air-gap orientation.Different from trouditional control strategy about flux-oriented,the purpose of air-gap orientation in this parper is to ensure produce uniform flux by rotor exciter.Aim at the system by air-gap orientation,this parper study design adjuster of the rotor current design,and calculate special item decoupled,it realized the decoupling control of dq rotor current,meanwhile it optimized system performance when stator were open circuit.For the harmonics contained in the system,by introducing a PIR current controller,so that the rotor current can be better to follow the given,thus effectively suppressing the active power fluctuation.Finally,based on matlab we set up the simulation platform of system,and verify the feasibility of the control strategy by air-gap orientation,the validity of the best radio about dq rotor current.Meanwhile we build the experimental platform of system based on 11 KW doubly-fed wind power generation,and use the DSP2812 as the core of control system.By the experiment we verify the effectiveness of the power control strategy.