| With the world energy crisis and people's increased awareness of environmental protection, people all around the world began to focus on new energy research and application. In all the new renewable energy sources, wind energy with the advantage of its pollution-free, wide range and high efficiency is fastest growing, currently becoming the most promising new energy sources.This paper first analyzes the the current world's wind power situation ,and advantages and disadvantages of the current wind generators, come up the conclusion that doubly fed induction generator is mainstream wind turbine.Introduces the reason of Grid code require wind turbine must have low voltage ride through (LVRT) fountion. Following this, by analyzing of DFIG through the electrical structure and operating principle, establishes the mathematical model of this type of motor respectively based on d-q rotating coordinates system and detailed analysis of the DFIG under different operating conditions ,the law of power flow between the different states are summarized .The paper built a strategy based on stator flux vector control block diagram of the control system, analysis of power control strategy for the current variable speed constant frequency generator under different wind speed,find out the reference active and reactive power component, Combined with DFIG d-q mathematical model, build a grid-based power control voltage rotating vector model and the decoupling control of active and reactive.Finally the paper analysis in depth the requirement of LVRT, introduced the advantages and disadvantages of the current solution,propose a LVRT control strategy Simulative analysis on a wind turbine with capacity of 2MW is carried out and the simulation results show that the proposed that the strategies can meet the requirement of Grid code. This paper verifies the electrical characteristics of variable speed constant frequency in grid voltage dip.Establish the foundation for further in-depth study of LVRT. |
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