Research On Microgrid Relay Protection Based On ARM

With the tensions of the conventional energy and environmental problems, the distributed generation technology is developing rapidly. Micro network as the effective use of distributed generation, as well as the beneficial supplement of the utility grid, micro-grid has received more and more attentions. When connected to power system, microgrid power flows tow-way within the network may result in the traditional distribution network protection being no longer suitable for fault diagnosis and start in this double-ended power flow situation. As a result, the relay protection has become an urgent problem to solve in the application of microgrid. In view of the micro network interconnection after the problems caused by the relay protection of power grid so this paper advanced a protection schemeFirst, it introduces the microgrid and analyses the influence of the relay protection when microgrid is connected to the large power grid. Including the three phase current protection, distance protection, small current system of single phase grounding protection and automatic coincidence gate.In inter-phase short circuit fault, according to the grid longitudinal protection thoughts proposed the longitudinal protection on the basis of comparison of the direction. The protection is based on communication and can realize the full speed protection.This paper analysis the zero sequence current characteristics of line for the small current grounding system in single phase ground fault. Introduce the wavelet transform, signal singularity detection and traveling wave distance principle. It put forward fault location method based on extracting transient components through wavelet transform. Through the comparison transforming zero sequence current modulus maximum size and polarity, fault line can be detected and fault location can be achieved. Finally, the simulation model is built in Matlab / Simulink environment. Then calculated and analyzed the sampling frequency, decomposition layers and the order of dbN wavelet influence to the ranging accuracy.Finally, according to the proposed protection scheme, the slave protection controller is designed. When the fault occurs, the controller uploads the fault information to the master station, receives the master station switching orders and implements the specific operation.