Comparison And Application Of The Substation Automation System Communication Protocols

Electronical equipments in substations are usually distinguished into primary equipments and secondary equipments. Primary equipments refer to those high voltage, high current equipments which generate, transmit and distribute electrical energy directly. Secondary equipments refer to those low voltage equipments which provide monitor, control, measurement, adjustment and protection to those primary equipments. Conventional secondary systems are passive systems before the establishment of SAS. Secondary systems suffer from high failure rate, and do not provide self-check functions. Therefore the systems might enter a failure status without alarm. The hardware modules of secondary systems are mainly configured independently based on their functions, which result in low relativity, incompatibility and complexity.As a result, the above secondary system cannot achieve those features such as direct monitor and efficient failure analysis. SAS appears with the development of computer, electronics, communications and DSP technology. The purpose of SAS is providing automatic supervisions, measurements and protections to the primary equipments and feeders in the entire substation with the aid of computer, electronic, communication, and DSP technologies.IEC61850, established by IEC TC57, is a standard of substation communication networks and systems. IEC61850 represents the trends of substation automation technology. Before IEC61850, former substation communication protocols mainly consist of IEC60870-5 series standards and those specified by vendors. For some reasons, those previous protocols did not perform as expected.