Smart Substation Secondary System Design And Research In Engineering Application

Smart substations, which gather data from power grid operation and carry out commands from dispatching center, are fundamental and important support for smart grid. Smart substation has close connection with other sections in power system and takes on great importance to the safety, quality, economic and automation of smart grid. Compare to normal substation, smart substation has a remarkable innovation in electric secondary system, which also gives a new task to substation design work.The paper focuses on modern study and construction of new-built smart substation, and the first part is to proof that common instrument transformer working with integrated control unit is the first choice in design stage to realize the digitized data collection, because of the disadvantages of electric instrument transformers in reliability and stability.The network system of secondary section is introduced such as its network topology structure, networking mode, network flow and network delay. Star redundant structure, sampling value message and common network transmission for GOOSE&message is recommended to be used in process level.Data sampling of relay protection and tripping method are indicated, and evaluations between direct-sampling/tripping and net-sampling/tripping are given. Direct-sampling working with direct-tripping is recommended for the smart substations at the present stage.The last part of paper extractions the design idea of dummy terminal to realize the dummy circuit connections. By this method, secondary circuit of local mounted intelligent control cabinet can be simplified.By summarizing the questions above, the paper finally gives important references for future design and construction work of smart substations.