Faculty of Engineering and Built Environment
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Item Evaluating the model of multi : Global Navigation Satellite Systems (GNSS) constellation to mitigate the multipath signals(2023-05) Madonsela, Bhekinkosi Pheneas; Davidson, Innocent Ewaen; Mukubwa, E.; Moloi, K.The Global Navigation Satellite Systems (GNSS) are evolving continuously and are being used in many applications across the world. The GNSS is used in electrical industries, the banking sector, the agricultural sector, the transportation and logistics sectors, etc. The architecture and operation of the GNSS is made up of three subdivisions: the space section, control section, and user section. The space segment consists of the satellite constellation to generate and emit the GNSS code phase and carrier phase signals. The space segment further stores and broadcasts the navigation data that is uploaded to the system by the GNSS controllers. For accurate Position, Velocity and Time (PVT), the satellite constellation must have at least three or four satellites visible to the GNSS receiver. The control segment is also known as the ground segment and is accountable for the complete operations of the GNSS. The ground segment further controls and preserves the conformation files of the satellite constellation, updates the navigation data to all satellites, controls the atomic clock of the GNS, and predicts the satellite ephemeris. The user segment is made up of GNSS receivers; their purpose is to receive the GNSS signal that contains the code phase and carrier phase to determine the pseudorange and other observables. There numerous issues that obstruct the application of the GNSS across all sectors mentioned above; those are signal attenuation in the satellite channels, signal diffraction, and signal multipath. Hence, this thesis focused on mitigating the GNSS multipath signal by investigating the concept of Combined Signal Detection (CSD). The purposes was to reduce the impact of signal degradation and further enable the GNSS receivers to withstand the signal degradation in deep rural areas. There are numerous existing methodologies to mitigate multipath signal and improve the positioning, velocity and timing in urban areas. However, the proposed CSD approach provided the better performance by using the vector detection of all visible satellites to improve (DP) Direct Positioning , High Sensitivity (HS) and clock bias. Furthermore, the capabilities of the Global Positioning Systems (GPS) and Galileo satellites are integrated to accommodate the adoption of CSD concept. The CSD concept require the GNSS receiver that is capable of processing multi-frequencies. The multi-constellation GNSS receiver use numerous satellites that are in space, such as Global Positioning Systems (GPS) satellites, BeiDou satellites, Galileo satellites, and Glonass satellites. However, the similarities between the constellations is investigated before the system is integrated for multi-constellation. The concept of CSD proved to be capable of mitigating the signal multipath without introducing an external device or circuit. This thesis further provided the comprehensive analysis of sources that contribute towards the signal degradationItem Integrating the power transformer protection scheme to Telecontrol Terminal Unit (RTU)(2018-12) Madonsela, Bhekinkosi Pheneas; Davidson, Innocent Ewaen; Mulangu, T. C.Automated substations and distribution networks are key element of smart grid, however not all substations and distribution networks are automated to date due to the numerous reasons such as cost related to automation and scarcity of skilful workforce. With the drive to integrate renewable energy to the national smart grid, the advanced and innovative integrating methodologies need to be investigated. Automating the power system is the effort to improve power supply security, availability and reliability. Reliability is very important in substation automation systems and is achieved through real-time monitoring of the substation data. The interconnection of substation through substation automation devices is crucial because it provide the backup link to the network in case one substation fails. The utilities has developed a remarkable interest in substation automation due to the benefit its offers such as; reduction in maintenance and, operating cost and improved revenues due to stable power system networks. Substation automation is made up of four main functions that need to be fused together; protection, control, monitoring and, local and remote communications. There are numerous communication protocols available in the market for substation automation applications. However not all of them are utilized in the current application of smart grid.DNP3 and IEC61850 are the leading communication protocols currently. DNP3 has proved its technical advantages over the past few years in substation automation applications. On other hand IEC61850 was only published in 2003 and became more popular in substation around 2006; the standard is only fifteen years old. IEC61850 define the protocols such as; GOOSE, SMV, GSSE, GSE and MMS using its communication profiles. This research will investigate the possibilities of integrating DNP3 data point into IEC61850 data model. With this approach; the legacy substation shown in figure 1.1 will inherit the advantages of IEC61850 such as high speed data exchange, interoperability and interchangeability