Agus Indarto

Manufacturing process of oil immersed Power Transformer (PT) has significant effect to the value of its partial discharge (PD). PD is one of the most important parameters of PT to ensures the reliability and quality of the PT's operation PT. As PT is one of the most important parts in electrical power system, PD becomes one of the key performance indicators for PT. The quality of manufacturing process of both liquid and solid insulations will reflect to the PD value of PT. Both solid and liquid insulation will form the overall insulation of integration of PT. One of the important manufacturing processes is vacuum and oil impregnation process. These processes ensure the removal of the moisture from PT insulation and keep maintaining PT from moisture ingress. In this study, the experiment is conducted to investigate the relation between vacuum and impregnation process duration to partial discharge value of 167 MVA 500/150 kV on single phase power transformer. Twelve (12) samples are investigated during manufacturing process and final acceptance testing by measuring vacuum and impregnation process duration as well as the value of partial discharge. The result shows that vacuum process duration has significant effect to PD values. Combined with oil impregnation process of the insulation, the results show that to achieve PD below 70pC (<70pC), the optimum vacuum duration is 57 hours and the oil impregnation duration is ranged 75-120 hours. This practical study is beneficial for both the owner and the manufacturer of PT, so it gives the optimum duration for manufacturing process to get lower partial discharge at optimum duration and cost.

Power transformer (PT), essential equipment in electrical power system proceeds complicated manufacturing process to meet high standard design. During manufacturing process of PT, the drying stage is of importance to remove excessive moisture contaminant on the solid insulation. This study investigated the effects of drying duration on partial discharge test of 83.3 MVA 275/160 kV PT. The partial discharge test measurements were carried out using IEC 60270 standards comprising of the capacitive network model based on the main quantity apparent charge concept. We found that the lowest partial discharge of 21 pC was achieved at 68 hours drying duration, while the highest value of 60 pC was reached at 81 hours drying time. The longer drying time may lead to initial degradation of cellulose insulation due to excessive heating. The amount of water extracted during drying effect to partial discharge also investigated. We conclude that the drying time at a higher and lower than 68 hours significantly contributes to the increased partial discharge values of PT.

The selection of power plants in the upstream oil and gas business is highly dependent on the availability of gas from its own production, to be used as a power source for its own exploration process. Oil and gas working areas, mostly located in remote areas are very far from the power grids, hence the employment of diesel power plants are often chosen as the power supply. This study investigates solar power generation as an alternative of electricity supply in upstream oil and gas field by utilizing empty open space in the area of oil and gas well as the location where the solar panel is installed. With project scenarios following the development plans or drilling of oil and gas wells, we found that the development of solar power plants could provide greater revenue/benefits to the Production Sharing Contractors and the Government, rather than using diesel engine and hybrid power plants.

Power transformer (PT) is one of the most important parts in electrical power system. In some cases, many electric utilities do not consider to capitalize the power losses, resulting in uneconomical decision during the purchasing. In this study, to evaluate the best purchase choice of a 60 MVA 150/129 kV PT, we examine the total cost of ownership (TCO) as the basis for determining the total economic value of PT. When purchasing and designing the PT, the optimum parameters are not only solely determined by the design and the lowest cost, but also influenced by material cost, power losses and its typical operation. Hence, design optimization and calculation of TCO of PT is of importance to provide a reliable and economical product. Here it is realized by reviewing the existing design and fabrication as well as the cost structure, design optimization and total cost ownership calculation. The result shows that the PT design optimization employing losses capitalization exhibits the most economical value, reducing TCO up to 3%. We found that the losses capitalization and TCO of PT are sensitively affected by interest rate, economic life of PT, electricity cost, load factor and losses. Those factors are key components to determine the suitable specification, design evaluation and operation of the transformer. This practical study is beneficial both for the owner and manufacturer of PT, thus giving the right specification and design to support purchasing process of PT.