Study Of Functional Realization Of Reserve Power Supply Automatic Connection Device

With development of the power industry and the power market, more and more attention has been given to the reliability of the uninterrupted power transmission. In modern power systems, to satisfy the economic operation of network and ensure the reliable power supply, network connection, generally, is designed as the closed loop and operates as the open loop.At the substation with open loop operation, where backup power switchover unit is installed, in case of the main power faults, the backup power will automatically input, thus the power supply for users will be immediately restored.Based on analysis on the current status of the backup power switchover unit applied by power companies and operation problems involved, the thesis has studied the function realization of the backup power switchover unit.Firstly, the thesis has put forward the realization theory of the backup power switchover unit; secondly, it has designed the software of the backup power switchover unit; thirdly, it has thoroughly analyzed the realization processes of the backup power switchover and detailedly explained several typical steps of the backup power switchover unit, i.e., charging process, starting process, action process and discharging condition; finally, in view of the various primary connection methods and various operation methods of the backup power switchover unit, it has used the ladder program for the development of the backup power switchover unit in order to meet requirements of different spots. The ladder program, combined by the ladder symbols according to the grammatical rules, can express the program language of Boolean logic relation, and apply the different backup power switchover methods to realize the action process of the backup power switchover. Through the analysis on the grammatical rules of the ladder editing surroundings and the demonstration of the sectional backup power switchover action ladder, the thesis has displayed the superiority of the ladder suiting various operation methods of different spots, and shown that the ladder can greatly improve the flexibility and applicability of the unit.