The Research On Setting Calculation Of General Protection For High-voltage Grid

With the rapid development of microcomputer relays technology, microcomputer relays are developing from special type to general type step by step, and this characteristic is especially outstanding in overseas protection devices. With the constant deepening of reform and opening, overseas general protection devices have been applied in power system, and been broadly applied in overseas projects which are built by domestic enterprises. General protection has the advantages of good opening quality, high adaptability and flexible functions. But on the contrary, its setting calculation is relatively complex and difficult because there are not only conventional system-level value settings but also many value settings about device itself, which requires more demanding setting calculation. This paper takes the apply requests of overseas projects as an example, emphasizes on the research on setting methods of general protection.The paper first analyses the protection schemes of high-voltage grid, working principles of main protection and backup protection, principles and methods of setting calculation. These analyses include protection principles, principles and methods of setting for pilot protection, distance protection and zero sequence current protection. Then, it emphasizes on the research on characteristics of AREVA general protection devices applied in overseas project, points out its differences with domestic special type protection in design principles, protection schemes and value-setup. On the basis of these researches, the paper gives the setting principles and methods of general protection which have some guidance effect and reference value.After analyzing the significance of double circuit line and the special protection problems, the paper emphasizes on the research on the occurrence special problems of ground distance protection of double circuit line, including the choosing of zero-sequence current compensation coefficient and the determination of setting calculation formulae. Then, the paper summarizes some typical setting calculation methods of ground distance protection of double circuit line, analyses their advantages and disadvantages and gives a practical setting calculation method of 220kV line of overseas project. The practice has proved that this method brings good protection performance.Then, the paper gives the setting calculation process of general pilot protection, general distance protection and general zero sequence current protection which are used in 220kV line of overseas project, and analyses its peculiarity and function. It successfully applies the setting calculation method of general protection worked out by the above researches into practice, and received good work effect.At last, the paper summarizes the research work of the subject and looks forward to the emphases of next research work.