Development Of The Remote Terminal Unit For Pipeline Leakage Detection

In order to guarantee the pipelines work safely and minimize the losses caused by leakage accidents, the pipeline leakage detection and localization system has become an important part in the field of pipeline transportation. SCADA systems are used to monitor and control a plant or equipment in industries such as telecommunications, water and waste control, energy, oil and gas refining and transportation. It is significant to integrate these two systems. The remote terminal unit RTU, working in the SCADA is a device installed at a remote location that collects data, codes the data into a transmittable format and transmits the data back to a central station. The main effort of this paper is to build the proper RTU based on the embedded system, to meet the requirements of the pipeline leakage inspection using the suction wave method.To fulfill the basic demand of the pipeline leakage inspection, the RTU has been designed for collecting, logging and transmitting the parameters of analogue or digital signals. After the signal modulation, the parameters of the pipeline situation, such as pressure, temperature signals, are converted to digital signal via the ADC. In detail, the real time sampling subprogram is triggered by the RTC included in the RTU. Meanwhile,the data storage system based on the USB interface has been designed for the purpose of improving the capacity of the data management. Applying Ethernet to industry's network control system is the development direction of control network.To make the data transmission between the RTU and the central monitor accurate and timely, the network communication system based on the TCP/IP protocol is built. Given the undetermined response time lead by the network, however, the program adds the sample time to the data frame in the program and builds the interactive communication processing.One of the key technologies of the suction wave method is to determine the time between suction waves going through the two measuring points of the pipeline. To synchronize the time benchmark of the measure sites, the GPS OEM is applied to correct the RTC of the RTU periodically, which picks up the precise UTC time and offers the precise 1pps .Finally, the wavelets transform and the Kalman filter have been proved to be effective among the digital signal processing technologies to get the featured inflection point of pressure wave covered by noise. Considering the requirement of arithmetic for the hardware and software of RTU, the thesis discusses the application of the Kalman filer to reduce the noise and the lift waveform to locate the singularity. It can be seen that this method is effective through the experiment of pressure signals.