Research On Relay Protection And Control Management System Of Microgrid

With the growing economic globalization, the world’s demand of electric energy is increasing. However, Affected by energy issues, power generation with coal, oil, and natural gas as fuel, is directly restricting the society development. In order to promote the society development, a new sustainable development road is needed. As a way to use new type energy and renewable type energy, the concept of distributed generation technology and microgrid has come into being. Microgrid means linking the distributed power to the load and form a small grid, then access into the distribution network in an integrated form. But microgrid’s joining changed the traditional distribution grid topology structure, and changed the current’s size, the current’s direction and the flow distribution of the whole system. At the same time, most of the distributed power are linked into the microgrid with power electronics, causing the short-circuit current less than double of the rated current. In summary, traditional relay protection is no longer applicable to microgrid. Therefore, researching of the microgrid protection is very meaningful.Firstly, this article uses the microgrid as the researching object, analyzed the impact to distribution network from microgrid parallel run, and made a brief introduction to the network standards of microgrid. Secondly, the article detected whether the islanding is formed with P/Q method controlling and V/F method controlling when parallel running and islanding running. The article also analyzed the characteristic variation when the microgrid fault happens, and verified the feasibility of the detecting method with Matlab/Simulink. The article configured protection and produced a detailed introduction to the failures under different running method. When the microgrid is at parallel running method, a longitudinal differential protection is used to remove the failure on sensitive load circuit. Inverse current protection is used to isolate the failure at non-sensitive load circuit. When a failure is happened at external microgrid, PCC switch protection is used to disconnect the microgrid, in order to make the isolation failure islanding. When the microgrid is on a islanding running, zero sequence current protection is used to ensure the reliable disconnection when a ground fault happens. When phase failure happened, fault component impedance protection and disturbance voltage protection is used to remove the fault.At last, the article designed a microgrid relay protection and control management system. In order to make the microgrid running safe and stable, the article proposed that the control system should have data acquisition, network protection setting, islanding detecting, fault data displaying, warning, setting value sheet generating function and disturbance memory function. The system has a simple structure, complete functions, and has a strong operability. it has a very important practical significance.