The Research And Development Of New Computer Protection Device For High-Voltage Transmission Line

In recent years, with the development of the HV electric networks and especially the coming of ultra-high voltage electric networks, the higher and newer performances of protective relaying for HV transmission lines are requested. A new protection device for HV transmission lines which meets the needs of power system at present is developed based on faster and more powerful microprocessor and DSP along with other high-power hardware in the thesis.At first this thesis gives a current review and summarizes the new development of computer protection for transmission lines. Then it introduces the design principia and object of the new protection device. Following this, the total design scheme, hardware structure, characteristics of some plug-in modules and function configurations of the protection device are presented in the article. The differential protection based on fiber communication and distance protection is the most important functions in the device.The thesis has done some research in the methods of data synchronization in fiber differential protection currently, and emphases on inserting data .It also analyses the characteristics of steady phasor differential protection, fault components differential protection, zero-sequence components differential protection, sample value differential protection, and differential protection on currents correlated analysis. Then the author designed a stable and applied differential protection system.Following the topic the thesis studies the characteristics of TA error and the influence on the performance of differential protection system as a result of TA saturation and TA circuit break. The author provides a solution based on added-on restraint zone to the problem of TA saturation.The distance protection is another important content. The thesis compares the relays based on operation equation with relays based on distance measuring. And then puts forward some viewpoints in changeable characteristics Mho relay, grounding fault distance relay, delta-Z relay and the power system swing and protection blocking. Some key concepts of the new device are set.The software design is important work during the development of the device. Compared to conventional software design based on flow chart, the protection software is developed based on logic function module, which leads to the separation of time sequence and logic. The modular structure makes the development and maintenance of software more convenient. The software project structure is listed out, which is a layered and modularized structure.The first new microprocessor protection device for HV line has been made out, and it has passed the EMC test. The basic function been built has passed the static test. The continued tasks are listed in the end of the paper, and the author will finished these work after the thesis.