Design Of Intelligent Controller Current

Relay box is an operational device to tripping and closing of breaker instructed by protection, breaker controlling unit, monitor unit, and auxiliary device of breaker. And it also has many hollow connections to inform its status to relaying and other device. Existing relay box has some disadvantages, for example, so many relays in box; bulky; low logic reliability result from electrical connection between relays and contacts, which cost large quantity of cables. For that, now many accidents of power system are due to relay box, such as malfunctioning action due to contacts jitter and reject-action due to imperfect connection of contacts. So that it is absolutely necessary to improve the relay box. Furthermore, the development of integrated substation automation need computing relay box because existing relay box keeping electromagnetic even though microcomputer based protection is popular.In this background, the thesis is to design an intelligent box to solve the problems mentioned above.Firstly, a secure and reliable correspond medium is chose to exchanges switch variables, and check its reliability.Secondly, the hardware design of the intelligent control circuit begins with analyzing relationship between relay boxes with protection, other second-sides device and breakers. The design would satisfy all basic needs of breaker control circuit, overmatch the conditional, suitable to all voltage class. The hardware includes two kinds of circuit board-CPU board and tripping and closing board. CPU board collects switch variables, send these variables to protection, and accept instruction to trip or close through Controller Area Network. And it makes logic judge simultaneously. On the tripping and closing board, there are two kinds of loop, one to prevent from tripping by stealth and the other tokeep itself. The CPU board indicates the tripping and closing board to operate through bare connections. The intelligent control circuit can check itself, alarming if faulting, so that its maintenance is greatly reduced.Thirdly, the thesis accomplished the logic design in case of 3/2 breaker and double bus connection. To find an appropriate connection, all kinds of connection mode are analyzed, including the digital control loop with re-closure, non-three-phase operation and current break failure protection. Finally the conclusion is deduced that the four functions can be realized by common CPU if inputted analog values.Fourthly, the intelligent control circuit can monitor mechanical state of the breaker on line as a node in distributed mechanical state of the breaker inspection web.Finally, the thesis would complete corresponding software design and the debugging of not only hardware but also software.The thesis has accomplished these content, and the upgraded relay box has more advantage than existing relay box. It can check by itself. And it enhances its reliability by replacing traditional electrical contact between relays with digital logic, which reducing number of relays and being able to checkout conveniently. In addition, devices communicate with each other by Control Area Net, decreasing cables of the second loop greatly. It will have smaller volume and can be placed easily in local controller panel of breaker, which meet with IEC61850 guide for processing device.