Design and Implementation of a Stand-Alone Remote Terminal Unit

Abstract

A Remote Terminal Unit (RTU) plays a vital role in substation automation. It consists of various sections that can handle different types of field parameters. This paper discusses a stand-alone RTU on a single board and its various sections: analog inputs section, digital inputs section and digital outputs section. The main objective of this paper is to check the accuracy of measurement of field inputs by the controller. A number of testing is done on each type of analog input to prove its accuracy. RTUs were once dumb devices that served as an extension of the central computer to the local Input/output. They had no intelligence but could only read the inputs and activate the control outputs. With the development and use of 8 -bit, 16-bit and 32-bit microcontrollers, RTUs are now dedicated microcomputers with stand-alone capability (3). With the RTUs sharing data base management with the central computer, the central computer becomes an operator interface device. Chen Qi.et.al developed a low-power remote terminal unit (RTU) based on GPRS/GSM (general packet radio service / global system for mobile communication) hybrid communications for data acquisition and transmission from distributed monitoring points in industrial environments. During the GPRS network congestion problem, the Short Message Service (SMS) mode is used for data transmission with guaranteed integrity. The ultra-low powered MSP430 microprocessor is used in this RTU. Thus, power consumption obtained during the working cycle was 200 milliWatts (mW) and 0.2 mW during the low power mode. Also, no data losses were obtained with the hybrid communication system during a 48 h test (4). Chen Peijiang and Jiang Xuehua designed and implemented a remote monitoring system based on GSM. The system includes two parts: monitoring centre and the remote monitoring station. The communication between these two parts is done using a TC35 communication module of GSM. MSP430F149 MCU is used in the monitoring station. The result of demonstration showed that the system can monitor and control the remote communication between the monitoring centre and the remote monitoring station (5). Chang.et.al developed a DNP3.0 protocol based on the high performance remote terminal unit (RTU) which was applied to the feeder automation system of substations. The Harvard architecture advanced microcontroller using pipeline processing technology would be used as the control core, to improve the system efficiency. The RTU proposed in this paper could measure the voltage and current of the feeder, monitor the