Research On Low-voltage Crossing Technology Of Wind Farm With Different Models

People are increasingly aware of environmental protection and fossil energy in the context of depletion,in recent years,the rapid development of new energy industry,which is also the rapid development of wind power industry.With the power system grid-connected fan capacity continues to increase,when the grid voltage drops,the need for fans with low pressure through the ability.Therefore,this paper studies the different types of wind farms of DFIG and PMSG models,so as to study the method of improving the low pressure crossing ability when the voltage drops.In the process of research,first in the MATLAB / Simulink software to build all kinds of simulation needs of the wind farm model.Then,the simulation results show that the DFIG model is the main problem that the DFIG and PMSG wind turbines are integrated into the grid.Power,wind turbine side of the low-voltage and machine-side over-current,but also need to improve the unit stator current,unit rotor current and speed.PMSG model voltage drop in the main problem to be solved is the converter DC side voltage is too high,in addition to the need to improve the machine side of the low voltage,the machine side over current and the unit from the system to absorb reactive power problems.In order to solve the above problems when the grid drops,the paper puts forward three methods to improve the low pressure crossing ability of the hybrid wind farm.The first method is to connect the SDBR and DFIG unit rotor side to the crowbar protection circuit.The simulation results show that this method can obviously improve the low wear capacity of the hybrid wind farm,but after the end of the doubly-fed wind field fault,the reactive power is absorbed from the system,which is not conducive to the stability of the whole system.The second method is to compare the shortcomings of the first method by comparing the STATCOM and PMSG unit converter DC-side access to the Chopper protection circuit at the outlet of the hybrid wind farm.The results show that this second method compensates for the shortcomings of the first method and Effectively improve the low capacity of hybrid wind farm,but in the course of the study found that hybrid wind farm equipped with STATCOM capacity is relatively large,resulting in STATCOM economic costs are too high.The third method is to simulate the voltage drop at the same time when the hybrid wind farm is connected to the DVR and STATCOM.The results show that this method not only solves the above problems,but also improves the low pressure crossing ability of the hybrid wind farm.To solve the mixed wind farm STATCOM cost is too high.Finally,by comparing the response characteristics of the above methods to determine the different models of wind power to improve the ability of lowpressure through the best program.