Design Of Relay Protection Setting For A District Power Grid And Optimization Research For Settings Verification

Relay protection is crucial safeguard of power grid operation with reliable and secure. Following the process of local power grid development and the increasingly of complicate of power grid structure and method of power supply, the promising characteristic of relay protection device that include reliable, quickness, selectivity, and delicacy have a higher requirement because of "8" type and other complicate operation structure circuit gird emerged. On the other hand, realization of function and requirement of these four characteristic is through precisely and reliable relay protection setting value. This value would not have any variety during operation, but occasionally happen incident with special or extreme situation will let protection device violet these four principle. The consequence will have series breakdown in a short time that is the reason why require to verify and adjust protection setting value.In this paper, we combine the situation in one district local power grid to analysis this "8" type circuit structure and operation mode in this district HOkV power grid. Also, we particularly discuss how to select system operation mode and neutral point grounded mode in this type of circuit grid. According to the current situation of relay protection allocated in this district, we obtain related relay protection setting value principle of 110kV power line through analysis it. Under the guidance of this principle, focus on this loop network circuit setting value with meticulous and specifically calculations include zero sequence protection, phase distance protection and phase distance protection. The result of calculations are every switch-gear in this network proper protection movement performance. And finally form a scheme of relay protection of that focus on "8" type ring network.Aim at traditional setting value verify has characteristic is random and aimless. This paper prove a new optimize algorithm base on overall consideration of protection dynamic important value and static value, and use objective weight allocation model to rearrange order of verify setting value. This algorithm from relay protection device malfunction result in generator isolation, power line overloaded and load-losses these three factor to define protection dynamic important value; and from protection system cooperative relation of main backup protection to define static importance value according event tree theory, utility theory and risk theory. Additionally, algorithm using grey correlation factor to ensure range of weight variation and variance fluctuation range of every important value index. Utilize this factor to establish objective allocation model base on maximums entropy principle. On the other hand, protection device comprehensive important value is accumulation of protection dynamic important value and static value. Finally, according to the amplitude of protection comprehensive important value to rearrange verify order for discover hidden danger of breakdown and avoid accident cause by human.Final project of relay protection for "8" type ring network is using on district HOkV protection system mention in this essay. And the result of success operation during latest tree year prove this project have exceptional feasibility. This result have significant meaning of specification and refining "8" type ring network relay protection. In the meantime, the optimize algorithm of verify order can objectively distinguish level of importance from different protection device. And the protection important value evaluate result of this 110kV local power grid shows that high coincide rate in high important value protection device and history accident branch. This result prove the method mention in this paper possess rationality and effectiveness, offer beneficial guidance of work of protection setting verification.