Research And Application On Intelligent Distribution Network Relay Protection

Relay protection is "security guard" of the power grid, any equipment is not allowed to run unprotected. What’s more, distribution network is the end part of the grid with the very difficult issue of the protection coordination, basic there’s no differential. Distribution network protection relies mainly on line protection of lOkV substation currently. When distribution network failure occurs, the substation line switch trip directly, causing the entire line user blackouts. Massive blackout affects a large area, bring about immeasurable direct economic losses.In this paper, we study the intelligent distribution network relay protection which colligates the advantages of centralized type feeder automation and intelligent distributed feeder automation, a new method of distribution network protection control is proposed on the basis of EPON communication network. This protection control method put forward the concept of time and space dimensions on the system structure. Through the coordination, power relay protection performance and the ability to quickly restore power of the fault zone is promoted. In terms of spatial dimension, the architecture is mainly divided into three levels:the master layer, control layer region and the terminal layer. Coordination at all levels of the system is achieved though layered, distributed and open network system. On the time dimension, intelligent distribution network of three layers protection defense is constructed in order to achieve no differential relay protection of distribution network. In the protection action principle, the distribution network is divided into the grid region firstly. Then the protection criterion of fault area is studied according to the line fault and the characteristics of different regions. It can also adapt to various operation modes such as open-loop & closed-loop & distributed power distribution network access, etc. The intelligent power distribution network protection communication network is determined, and the intelligent terminal is connected with EPON network. By using IEC61850 GOOSE technology to conduct lateral communication with the adjacent nodes, fast positioning and isolation of fault point is realized with millisecond precision which is independent on the host system. Regional control substation starts when the fault is successfully isolated, the non-fault regions recover power supply and a self-healing function of smart distribution network is studied. For self-healing function, the priority principle, the method of implementation and the charge & discharge of the regional BZT strategy are discussed. It can adapt to the access of distributed power and adaptive to grid operation mode adjustment. Network protection and regional control station GOOSE communication test shows that the control system can accurately locate the fault coverage and quickly isolate the fault, the continued supply of non-fault zone recovery is achieved by regional control station BZT switching function, which is significant to reliability improvement of the power system.