Allocating Power Quality Monitors in Electrical Distribution Systems to Measure and Detect Harmonics Pollution
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The growth of non-linear devices has increased the harmonics pollution in distribution systems. Under industrial competition, the concern over power quality, especially harmonic distortion, has increased due to the new generation of load equipment. This equipment has been fully automated electronically, so it is very sensitive to any power quality disturbances. Electrical power organizations have set standards to limit the harmonics pollution in the distribution systems; however, the enforcement of the standards has to be disciplinal, by applying a penalty fee for any customer or utility that exceeds the standard limits. In order to apply the penalty fee properly, precise detection of harmonics pollution sources must be considered. The bus voltages and the line currents in the entire system have to be known in order to obtain accurate identification, which can be achieved by monitoring the distribution system. The large number of sensors needed to monitor the distribution system increases the cost of the monitoring system; therefore, the sensors have to be installed in an optimum way that decreases their quantity and their construction fixed costs. This thesis offers a new optimization approach for allocating the monitors in the distribution system. The Vertex-Colouring approach reduces the monitoring system cost by placing the harmonics pollution monitors in minimum cost locations where they can observe all the buses and branches of the distribution system. The number of monitors is affected by the percentage of nonlinear loads in the distribution network; thus, investigations on lightly polluted systems, medium polluted systems, and heavily polluted systems have been presented. The relation between the harmonics pollution level from one side, and the nonlinear load types, power ratings, and voltage levels from the other side has been highlighted as important observations of the polluted systems investigation. The Total Harmonic Powers (THP) method has been used to identify the harmonics pollution sources. In addition to its simplicity, The THP method is efficient, and requires the network voltage and current values which can be provided by the proposed monitoring system. The ability to apply the THP method on any distribution system has been scrutinized in order to confirm its validity for distribution systems.