0　Introduction

With the development of technologies such as electronics, computers, networking, communication, and embedded systems, new microprocessor-based measurement and protection IEDs (Intelligent Electronic Devices) have been widely applied in substation automation systems. Due to the lack of a unified standard, the communication methods and protocols adopted by various IED manufacturers are inconsistent and incompatible with each other. To address this, the IEC developed and promulgated IEC61850[1-3], an international standard for substation automation systems and communication networks. However, the acceptance and widespread adoption of the standard require a lengthy process, and a large number of IEDs that do not support the IEC61850 standard will continue to be used for some time. Therefore, this paper designs a communication management unit for substation automation systems, based on an ARM platform and utilizing an embedded operating system.

As an interface device between communication networks and measurement and control equipment, the communication management unit is responsible for protocol conversion, interface matching, and data aggregation and storage. A communication management unit can interconnect IED terminals (slave devices) from different manufacturers, process the collected measurement, relay protection, and other data, and then transmit it to local monitoring terminals (SCADA) or to remote dispatch and monitoring centers via the Internet or wireless networks. It also distributes commands, data, and other information from local monitoring terminals or remote dispatch and monitoring centers to the respective slave devices [4]. Thus,