Improvements of shunt tripping circuit in AAT at themode of grand operation

With the State Grid Corporation of China (SGCC) constructing the management system of Intensive Management on Human Resource, Materials and Finance and Grand Planning, Marketing, Production, Operation and Construction, the grid will be managed with grand operation mode eventually. All levels of power transmission and transformation equipment´s operation monitoring and dispatching operation will be in a highly integrated in this mode, which can realize dispatching and control together. In this new management mode the operation of remote control will appear especially important, and it can improve the power grid fault handling efficiency and power grid emergency load transfering speed. With the fault time shortened, it can improve the stability of power grid operation. At the same time, the primary and secondary equipment including automatic device should meet the requirements of the remote control. Automatic bus transfer equipment (AAT) used in a wide range of power system, When the working power is disconnected due to fault, backup power can input to work automatically and quickly. The shunt tripping circuit is installed in AAT for three main transformer substation with four segments. After the AAT triggers, it can achieve load balancing between two transformers with the tripping function. The existing shunt-tripping-circuit has defects in the mode of grand operation. When the AAT isn´t disabled, the operation of remote control cannot be used. So it does not meet the mode of grand operation. Therefore it need to improve and perfect the shunt tripping circuit. In this paper, the principles of AAT in a 35 kV substation are analyzed in Shanghai, and the existing defects in shunt tripping circuit are elaborated. Two kinds of improvements are presented at length, which can perfectly solves the problems with existing shunt tripping circuit in AAT.