The Research Of The Adaptive Protection For Microgrid Based On Path Searching

Into the21st century, developing the clean energy, solving the environmental problem, responsing to the climate chance, are the core content of the current round of the energy revolution. Distributed generation (DG) not only can be used as an important complement of the centralized power generation, but also occupies a very important position in the energy utilization. Micro-grid combines distributed power, load, energy storage and control device to form a controlled independent power supply system, fully uses of the capacity of the DG equipment, meets the flexibility, stability and security needs of the power system. Due to the flexible topology of the micro-grid, and different characteristics in grid-connected and islanded mode, the traditional relay protection is difficult to meet the micro-grid protection requirements. However, the researches on the micro-grid protection have not yet come to an effective method at home and abroad. In this paper, based on in-depth analysis of the micro-grid failure characteristics, an adaptive protection method of micro-grid based on path searching has been proposed and the simulation of the proposed model has been taken to verify the theory. Primarily works as follows:(1) Analyze the failures characteristics of the micro-power and micro-grid. According to the structural characteristics of the micro-grid, different control strategies are used to the micro-grid different operating modes. Build a simulation model of the micro-grid to analysis the fault output characteristics of DG and the failure characteristics at the fault point of the micro-grid.(2) Propose an adaptive protection method of the micro-grid based on path searching. Targeted the flexible characteristic of the micro-grid topology, the tree node search method is used to adaptively set the operation value of the micro-grid protection device and the node path algorithm is used to adaptively set the time limit of the protection devices.(3) Combination of the new protection and control technology and the advanced communication models in the smart grid, the construction of the micro-grid adaptive protection and control system has been explored. Based on this, the micro-grid communication model based on IEC61850-7-420has been proposed.(4) Verify the effectiveness of the proposed method by building the micro-grid simulation model. Through the establishment of the micro-grid different operation modes and different topology simulation model, respectively, from several types of failures of the micro-grid different position to verify the effectiveness of the proposed method.