Research On Relay Protection Scheme Of Microgrid System

With the continuous development of society,today’s grid structure is more and more complex,microgrid applications are more and more widely.Microgrid is to achieve the new energy and renewable energy as the main form of power generation in distributed power generation scale of the grid,.it is composed of four parts: distributed power supply(DG),energy storage device,control device and load,which can be connected to the grid or run off-grid.Distributed power is the power of tens of millions to fifty megawatts of small modular independent power supply.The traditional relay protection will no longer be fully applicable to microgrid..This paper introduces the characteristics of microgrid distributed power supply first.Through the calculation and simplification,several main types of distributed power supply mathematical models are established,including wind power generation,photovoltaic solar power generation,fuel cell power generation And micro-gas turbine power generation,and summarizes its electrical characteristics,thus simulating the micro-grid system,which is a good foundation for establishing the simulation software model of power grid with micro-grid system.After that,the influence of distribution network fault characteristic and conventional relay protection in microgrid system is discussed.The influence of different location and capacity of distributed power supply on current protection is also different.The influence of micro-network access on the traditional relay protection is analyzed theoretically.Then,the different types of faults are simulated to verify the incompatibility of the traditional relay protection in the microgrid system.Finally,this paper presents a microgrid system protection scheme by means of communication.The current protection device is installed on the line and the next line,and a communication unit is formed.The protection action of the line through the next line Information transmission,determine the fault point and fault range,and then determine the protection action behavior.The simulation model of power distribution system with microgrid is established by using PSCAD software.The fault characteristics of the microgrid under different access modes of distributed power are simulated and analyzed,and the validity of the proposed scheme is verified.At last,the setting principle of microgrid relay protection equipment is given.