Implementation of the IEC61850 international protocol for accurate fault location in overhead transmission lines

The rapid growth of electric power systems has resulted in many utility companies increasing the investment of Substation Automation Systems (SAS). Free marketing, deregulation and competition has brought about greater restrictive requirements to produce reliable, continuous and good-quality power supply, without a significant increase in the cost of delivery. For this reason, engineers ever since the development of the earliest microprocessor based Intelligent Electronic Devices (IEDs), have depended on digital superiority to assist personnel in the precise location of faults. The ability of these IEDs to generate an abundance of valuable network data through information exchange of relays, permits power authorities to capitalise in areas such as control, protection, monitoring, fault recording and communication. These Instrumentation and Control (I&C) devices facilitate on-site personnel to accurately establish the fault distance of a transmission line and repair any damage at reduced outage times using Supervisory Control and Data Acquisition (SCADA). However, the system inherent problem endured by the earlier IED models was the fact that the serial bus communication caused a dilemma in the overall response times of the data. This was greatly attributable to the profusion of copper wiring and the lack of compatibility between vendor specific IEDs. To contend with these concerns, a variety of standardised communication paradigms and international protocols were introduced. These incremental additions to the existing substation framework lead to the reduction of copper wiring through the use of fibre optic technologies and interoperability between different vendor specific IEDs via the use of Generic Object Oriented Substation Event (GOOSE) messaging. The majority of in-service substation protocols are still based on MODBUS and DNP3 standards. These standards however are slowly becoming replaced by Ethernet and fibre optic technologies in the form of the IEC61850 protocol. This thesis contributes to knowledge in two parts. Part I attempts to construct a portable IEC61850 testing unit capable of achieving interoperability between three different vendors including ABB, Areva and SEL. The IEC61850 testing unit is built to serve as a replica of a real-life in-service substation. The rig is equipped with copper, fibre and Ethernet capabilities in order to set and capture GOOSE messages in the form of ICD, CID, SCL and SCD files using logical nodes. Part II of the research develops an innovative fault locator algorithm to determine the distance to fault error in overhead transmission lines. The algorithm is derived using Discrete Fourier Transformation (DFT) and uses a square wave arc model to determine the fault distance, arc resistance, total fault resistance and tower footing resistance. The algorithm is simulated and tested using the portable IEC61850 testing unit and a 300km Artificial Transmission Line (ATL)