Research On The Transmission Mode Of Electric Power Data Network

Power dispatching data network is the transmission network of electricity production real-time information. The main transmitted message includes power transmission scheduling real-time data, production management data, communication monitoring data and so on. It is the basis of power safety production and automation and plays a key role in the coordination of power production, transmission, substation, distribution, electricity and other components and ensures secure, economic, stable and reliable operation of electric network. Power dispatching data network transmission system is a special system to complete this task, a good transport system will provide a great help to achieve these goals. In the other power systems (such as GIS systems, MIS systems, distribution automation systems, real-time alarm messaging system) or a higher level dispatching automation system, real-time or historical data from the dispatching automation system are needed. In order to ensure the SCADA system security, SCADA system need to supply various kinds of secure interface (data transfer mode) to transmit the required data to other systems.It can be seen that data transmission is very important in power system to ensure the safety operation according to the above analysis. While the data transmission mode in turn determines the performance of data transmission system, so only the correct data transfer mode is selected, the performance of data transmission system can greatly improved (data transmission capacity, real-time, safety, convenience, etc.).In this paper, four kinds of data transfer modes-RTU communication protocol, dynamic link libraries, shared memory, as well as Web Services, were introduced and their characteristics were analyzed (strengths, defects, etc.), and improvement measures were proposed. At the same time, Specific application examples were given.Tele-control communication protocol provides frame format and transmission rules interface for data communication, which affects the quality of tele-communications. In the actual data transmission, protocol is selected according to the capacity and type of transmitted data, the nature of transmission channels, which can improve the real-time, accuracy, expansibility of data types. Dynamic Link Library are called in different ways and programming changes in different operating system, which is its advantages and also its shortcomings. The data provided by dynamic library interface functions can not be placed on the stack generally. Otherwise, the programs that use the interface can not get the correct data. Data size in general is dynamic provided by interface function to the interface called by the program. The principle is that dynamic memory is released by the program who applies it to prevent memory leaks. Dynamic library interface functions should be paid attention to its state back to avoid internal blockage in the interface functions. Share memory is the fastest, the most useful IPC method of system. The use of shared memory can be a smaller overhead for higher performances; it is the best solution to carry out rapid exchange of large amounts of data. When multiple directions update shared memory data at the same time, you need various security mechanisms, and you must arrange the order of data writing to ensure the accuracy and security of data. Web Service is the simplest mechanism to achieve systems integration and interoperability which allows the transmission of data steping over the firewall, and puts data into XML format. XML format data will facilitate the use of different programming languages software from different software vendors. Improvements of each model had been verified in many practical projects.The four kinds of data transfer model had been successfully applied to a data transmission system in some regional power system, and the results were very good. Within the integrated automation system, IEC103 protocol was used to ensure the transmission of basic power data and protection of information. Different substation/integrated automation system using different protocol transmitted data to control center to ensure data transmission. Data platform was used to transmit the needed data between the various control centers. We use the data transfer modes of shared memory and dynamic-link library. All SCADA/DMS/EMS system software vendors based on the unified dynamic link library interface functions to access their own shared memory system to ensure consistency of data formats and improve the data transmission efficiency. Web Service model was used in some Control Center EMS systems, the messages were send to the phone when power system generated failure (including the switch changing bits, protection action information, etc.). Also some of the important data (such as the total of system load, load of each substation, etc.) were send by message. So the related staffs could know the operation of the system to ensure the safe operation of power systems no matter where they were.