Microgrid Protection Strategy Based On Transient Signal

Compared with traditional power systems,distributed generation technology has the advantages of low loss,near load,high energy efficiency,low investment,and good environmental compatibility.As a whole,the microgrid is a combination of distributed power supply,energy storage device,power electronic device and load.It solves the problem of limited number and capacity of distributed power supply to the power grid.An effective means of increasing the proportion of renewable energy in distribution networks.The traditional three-stage current protection and inverse time-over-current protection scheme cannot adapt to the fault characteristics of the micro-grid under the new situation.Therefore,this paper designs a protection scheme suitable for microgrid.This paper first introduces the research status of microgrid and its protection technology.By analyzing the impact of traditional protection on the microgrid,it is proposed to design a set of protection strategies for different operating modes of microgrid for the operating characteristics of microgrid.Based on the research of inverter and distributed power control methods,a suitable microgrid control operation strategy is developed,and the model is built on PSCAD for simulation verification.By analyzing the traveling wave characteristics of transmission line faults,a protection strategy is proposed to compare the polarity of the modulus maxima obtained by extracting the transient current traveling wave signals at both ends of the microgrid line and transforming the signals.If the signal polarity at both ends of the line is the same,it is an area fault,and vice versa.In the built microgrid simulation model,different failure types,different fault locations,and faults with different initial phase angles and transition resistance short-circuit faults are set in single-circuit and double-circuit lines,respectively.The effectiveness of the designed protection strategy in different operating modes,different fault lines and different fault conditions of the microgrid is verified.