Zero-Sequence current-based detection of electricity theft in informal settlements

M.Tech.Abstract: Losses in a power system are defined by technical and non-technical losses. Technical losses are attributed to the dissipation of power, while non-technical losses are associated with factors contributed to by external conditions such as poor administration, revenue collection and electricity theft by illegal connections or tampering. Although a pervasive worldwide phenomenon, South Africa is not immune to this situation, and is even placed in a weakened condition due to the country’s high unemployment rate, socio-economic pressures and the fact that the constitutional bill of rights affords all South African the right to electricity. The problem is specific to areas where economic activity is perceived to be more attractive, and in such case, the Gauteng province, the smallest province out of the nine South African provinces, contributes the highest portion of the country’s economic gross domestic product. This perceived economic haven creates migration of the population to areas such as Gauteng, conceiving large population densities that require the right to basic infrastructure, but failing to become economically active. These large population desities create unexpected challenges for the local supply authorities due to the formation of the informal settlements on un-proclaimed lands where legal infrastrurure services cannot be provided resulting in the population takeing matters into their own hands and connecting illegally to nearby legal power infrastructure. Supply authorities are confronted with a dilemma: 1. They have to protect the network from unintended contact incidents by humans or animals 2. Are faced with no revenue collection, and 3. Deal with poor quality of supply to the paying customer. Mitigating techniques have been suggested in literature into the management of the engineering challenges associated with this problem, but none have formulated a resolve that would address a one stop solution. Theft of electricity in worldwide utilities do not involved one specific modus operandi, and in the South African case, one such a modus operandi in informal settlements, occurs by connecting directly to the source distribution transformer with any means of cable. This results in cables laying bare on the ground or alternatively connecting the dwelling load between phase and earth, disregarding the neutral. This research focuses on these cables laying on the ground or hazard connections (phase to earth), and presents an hypothesis in the use of zero-sequence current based (ZSC) detection as a means of detection and possibly isolation of the supply of the particular network. The largest limitation variable in the calculation of these zero-sequence currents is attributed to the soil resistivity of the ground where the conductors are placed, or connected to as a return path for the load. Field tests were conducted as part of the methodology to establish various soil resistivities across the Gauteng province close to these informal settlements. These results based on the atmospheric, moisture and temperature conditions were used to calculate perspective ZSC. Further analysis was conducted using DIgSILENT Powerfactory analysis software simulation,.