Multi-Objective Optimization of the Safe Operation of the Electrical Distribution System by Placing D-FACTS and Network Reconfiguration

The distribution networks of agglomerated areas of the developing countries are generally the seat of overloads, voltage drops, and untimely interruptions of the power supply. This paper consisted of optimizing the grid topology and placement of a DSTATCOM in a SBEE real distribution network in order to improve its technical performance. The modified ant colony algorithms solved this difficult combinatorial problem, which integrated among the criteria, the minimization of the losses and the deviation of the node voltages under operational constraints about distribution networks operation. According to the results obtained, the optimization of the topology of a distribution network and the placement of DSTATCOM contributed qualitatively to improve the losses, voltage and stability plans of the Togba distribution network. Actually, the hybridization of optimization means such as the placement of DSTATCOM and the reconfiguration of the networks applied to the Togba HVA network made the power of DSTATCOM optimization possible by almost 50.71% and reduce losses to 83.57%. The implementations of those algorithms are very efficient and effective, and can be implemented to help distribution system operators, developing countries and in particular, the operators of the Beninese Electric Power Company to perform their electrical network.

Comparative Evaluation of the Thermal Aging of Solid Insulation in Mineral Oil and Methyl Ester of Palm Kernel Oil

The purpose of this work is to determine the impact of thermal aging on the dielectric and physicochemical properties of the oil/paper mixed insulation. We performed a comparative analysis of dielectric paper dipped in two cooling fluids: palm kernel oil methyl ester (MEPKO) and mineral oil (MO). Two types of dielectric paper were used: Thermally Upgraded Kraft paper (TUK) and Nomex-910 paper (NP-910). An accelerated aging test was realized at 110°C during a total of 96 hours. Samples of oil and paper were collected after 0, 48, 72 and 96 hours for analyses purposes. The analyses performed included the measurement of the Breakdown voltage (BDV) of the dielectric papers, the Total Acid Number (TAN) and the Decay Dissolved Products (DDP) of the liquid dielectrics. The BDV of NP-910 is greater than the BDV of TUK. Concerning the type of oil, the BDV of dielectric papers impregnated with MEPKO is greater than the BDV of similar papers impregnated with MO, indicating a better preservation of paper when dipped in methyl esters. The analyses of TAN and DDP revealed that Nomex-910 improves the oxidation stability of MO, but reduces the oxidation stability of MEPKO. These results prove that methyl esters can be used as a substitute to replace mineral oils in power transformers. Furthermore, they show that NP can be used mainly in areas of transformer where solid insulation is subjected to high thermal and electrical stress, and TUK other places where solid insulation is required. Such combination could assure money savings and a better preservation of the oil viscosity.