Research And Realization Of Adaptive Distance Protection Strategy In 110KV Transmission Lines

Distance protection is the chief protection for 110kv in our country. Operation condition often varies in large scale, and especially load often varies acutely. III setting of existing computer distance protection equipments is decided on maximal load, so often can not meet with the demand of sensitivity. Most of 110kv transmission lines of our country are dated, and failure frequency is high, especially for frequency of earth failure. Existing computer distance protection equipments all have ability to breast earth failure, but this ability is not mightly still. In my paper, according to characteristics of 110kv transmission lines and its distance protection, adaptive setting scheme and its achievement to distance protection III, adaptive setting scheme to distance protection with earth fault, and achievement to adaptive distance protection I with earth fault are investigated to improve sensitivity of distance protection III, and ability to breast earth failure of high resitance .This article is made up with six chapters.In Chapter 1 significance and reason of this rearsch, development and status quo of adaptive distance protection of 110kv transmission lines are summarized at first, and then what the author have done in the article is introduced briefly.Chapter 2 discussed at length. the scheme to achieve basic functions of adaptive distance protection of 110kv transmission lines, adaptive setting scheme and its achievement to distance protection III, adaptive setting scheme and its achievement to distance protection with earth fault .To implement the proposed principle in this paper, Chapter 3 introduced hardware design and structure of adaptive distance protection equipment for 110kv transmission lines.In Chapter 4 main algorithms used to implement principle of adaptive distance protection are discussed briefly. Chapter 4 mainly stated the software flow to achieve the principle. The software is divided into main program module, interrupt module, fault disposal module. These subroutines of each module are designed respectively. Moreover, program flows are explained at length.Chapter 5 validates the availability of these principles by experimentations.Chapter 6 makes a conclusion and expectation toward the network-based adaptive distance protection for transmission lines principle and equipment.