The Research Of Distance Protection For Transmission Line Of Wind Power System Based On Non Power Frequence

With the development of power electronics technology and the problem of environmental damage caused by traditional energy,all kinds of clean energy become the important direction of energy development in the future.Among them,wind energy has become the research focus because of its mature technology and high conversion efficiency.At present,both in the world and in our country,wind power installed capacity is changing with each passing day,so it is very important to study the impact of wind power integration on power system.The wind power generation mainly in large-scale,centralized grid pattern.With the wind power grid capacity increasing,the control strategy of wind power system has also been improved greatly,equivalent model has been established for the symmetrical fault and asymmetric fault.There is also some simulation analysis of the fault current.When the wind power system fault occurs,whether the fault phase of DFIG and PMSG is similar to the experience,the characteristics of wind turbine bring great influence on the traditional relay protection principle,this paper firstly introduces the fault modeling process of wind and existing causes of frequency offset,weak characteristics,and the huge impact on existing relay protection.This paper points out the problems existing in the current protection configuration,as well as the difficulties existing in the construction of the protection configuration.At last,Protection configuration recommended was pointed out.As one of the main protection wind power system feeders,distance protection was greatly influenced by frequency offset and weak feed back,this paper discusses in detail the mechanism of frequency characteristic and different extraction methods of non frequency characteristics,and testing the performance of Prony algorithms minimum and least square method with different signal components.This paper introduces the detailed distance protection strategy of the line protection,and analyzes the influence of frequency offset on the specific distance protection elements in detail.Finally,the concept of non power frequency phasor is put forward,and the protection components are improved by the method of non power frequency extraction.The analysis shows that the principle of distance protection based on non power frequency extraction is another way to construct the protection principle becides time model,which can overcome the influence of frequency offset effectively.