Research Of The Clock Synchronization Method And SCADA In Micro Grid Control System

The use of various kinds of distributed generation and energy storage devices in micro grid not only realizes the energy conservation and emissions reduction, but also greatly promote the sustainable development strategy of our country. A micro grid with a micro inverter can solve the problems of output power control of centralized inverter, low efficiency and poor security. Clock Synchronization Technology(CST) can make many intelligent electronic devices in micro grid to obtain a uniform time standards, which is very significant to micro grid data acquisition and monitoring(SCADA) system.The micro grid SCADA is an important foundation for the energy management system(EMS) and a real time data source of micro grid automation system, providing real time data for micro power grid automation system.Firstly,CST was studied in this paper. Design idea of using IEEE 1588(Precision Time Protocol, PTP) in micro grid was concluded by means of the analysis of the clock synchronization protocol.Through the analysis of factor influencing clock synchronization, the micro grid clock synchronization system based on FPGA was designed and implemented according to the characteristics of the PTP and the RS-485 communication.The measurement results show that the time error is less than 1μs, which meet the demand of the accuracy of the clock on the micro grid.Then,by analyzing the time error, it is concluded that if it is not to weaken or eliminate the causes of error, time error between the master-slave clock will be greater than 1μs, while the master-slave crystal frequency error more than 1 ppm, which cannot meet the stands of the micro grid. To solve this problem,a adjusting method of clock rate with PI control was proposed based on particle swarm optimization algorithm. Proved by Matlab simulation, results show that the clock synchronization precision reached 150 ns. Meanwhile, an implementation of the algorithm was proposed. Finally, software and hardware structure of the micro grid SCADA,which includes overall SCADA hardware structure, the transmission protocol and format between local control and centralized control layer, and the communication between centralized control layer and the monitoring center was designed. A micro grid monitoring center was designed based on LabVIEW through the analysis of micro grid structure. It contains human-computer interaction interface, communication between the PC and the centralized control layer as well as design of database, which has further perfects data acquisition and monitoring system of the micro grid.