Dual Reclosure Lockout System With Adaptive Modules For Extinction Judgment And Transient Stability

Automatic reclosure is an important means of power system protection and control, because the fault of high-voltage transmission line mainly is transient fault, so the use of automatic reclosure technology can greatly improve the reliability and stability of power system. However, we must fully consider the following situation:1.Under the conditions of different fault properties, we should take different measures according to effective criterion; 2. We must consider the case that if arc reignition happens, or error of data transmission and calculation occur, fault will reclose to the permanent fault. We should consider reducing the impact for the system when malfunction happens after the adaptive judgment.For the above two problems, solutions mainly need to develop a reasonable criterion of adaptive reclosure to make the system can judge more accurately whether the arc extinguishes after fault. When the transient fault occurs and arc extinguishes, the system needs to reclose to make the system restore to normal operation in a short time; When a permanent fault occurs, or transient fault arc does not extinguish, the system needs reliable atresia for reclosure to avoid reclosing to the permanent fault,otherwise this will result in a secondary impact on the system.Because practical factors have big uncertainty, the extinguished arc may reignite that is caused by the conditions of induced voltage and harsh weather in the situation that the fault is not ruled out completely, and this can cause misjudgment and misoperation that are caused by the errors of line data transmission in the situation that the logic algorithm can accurately and efficiently judge the fault properties. Extensive research and experience indicate that the impact of transient stability for reclosure is influenced by reclosure time in the situation that the system recloses mistakenly to the permanent fault, so increasing atresia time and avoiding operation time of system instability can increase more effectively reliability of reclosure operation on the basis of adaptive reclosure algorithm.This graduation design mainly is as follows:1)It makes us read extensively books and papers about adaptive automatic reclosure and tuning method of automatic reclosure which is based on transient stability discrimination, understand research status about adaptive reclosure and its criterion at home and abroad, and analyze association and methods about the system transient stability and reclosure.2) It analyses the process of changes of electrical quantities when the system has transient faults and permanent faults in the high-voltage electric transmission lines, and analyses main bases for judgment which are discrimination criterions of fault properties which include:1.the combustion characteristics of arc 2.first arc 3.secondary arc 4.recovery voltage of fault phase etc in the case of transient faults and permanent faults after fault according to the existing research results.3)It analyses reclosure tuning mode about stage definite time and considering the system transient stability and explores viable reclosure atresia mode after fault.4)It analyses change of reclosure criterion about the single-phase reclosure, three-phase reclosure and other hardware system according to adaptive reclosure to improve the adaptive algorithm.5)It explores energy atresia methods which have a small amount of computation and are applied in online application by analyzing and simplifying the reclosure methods of the optimal time of transient energy function,and designs improved adaptive reclosure ways that can reduce effectively impact for system after free reclosure,miscalculation and malfunction by combining it with adaptive enclosure that have recovery voltage criterion.6)It describes software architecture, procedure and block diagrams of the improved reclosure atresia algorithm and part of the required hardware support.7) It takes advantage of software of matlab to simulate for related models, and simulates final improved adaptive applied algorithm; it simulates output of power angle curve model of real system with software of BPA, and compares results of improved reclosure program with software of BPA among this design.8)It summarizes this design, proposes the advantages of the research direction, expansion and further research directions.