Research On Self-start And Operation Control Of Wind Farms

With the large-scale application of doubly-fed induction generators(DFIG),the Control of DFIG has become a hot topic.The traditional wind control needs the generaor to be connected with the grid when the power grid fault occurs,which further increases the burden on the operation of the power grid.Along with the development of power electronic technology,DFIGs can realize the self-start ability and supply electrical power for important loads,which can enhance the robustness of the power grid operation.Therefore,research on self-start and operation control of wind f arms is of remarkable value and practical significance.The main research contents are as follows:(1)The self-start model of DFIG and its voltage and frequency response characteristics are studied.Through detailed study of the working principle and structure of the doubly fed wind turbine,the dynamic model for he self start of DFIG is selected and derived.Meanwhile,the voltage and frequency response characteristics of DFIG are studied in detail.The research shows that DFIG can be involved in the process of voltage and frequency control of wind farm.(2)A DFIG self-start control method based on energy storage system is proposed.Based on the DFIG dynamic model,a self-start controller is designed which based on the feedback control.A DFIG self-start control method is put forward which divides the self-start control process into three stages:self-start operation,load operation,frequency adjustment.Each stage adopts different switching rules and control strategy of converters.The correctness of the method is verified by simulation.(3)A start and operation control method of wind farm based on STATCOM/BESS is proposed.A detailed model and a power decoupling control strategy of STATCOM/BESS are proposed.An access point control method between self-start DFIGs and ordinary DFIGs is conducted in support of STATCOM/BESS.Aimed at the different conditions of the wind farm,the method is divided into three stages:self-start control,power quality control and coordinated start control.The simulation results show that the method can achieve the stable start-up and operation control of the whole wind farm.(4)A start and operation control method of wind farm based on fuzzy adaptive algorithm is proposed.Considering different active and reactive power demands in different stages,constant controller parameters cannot satisfy the optimal demand.A coordinated control method of STATCOM/BESS and DFIG is proposed based on the conventional vector control method and fuzzy adaptive control algorithm.By detecting the deviation of voltage and frequency in the system,the parameters of STATCOM/BESS and DFIG is continuously optimized.Compared with the access point control method,the superiority and stability of the fuzzy adaptive coordination control method are verified by simulation.