Electrical or thermal failure that occurred in the transformer oil can produce a dangerous gas called gas fault. By indicating the content of dissolved gases in the transformer oil, can be obtained information about what happened to the oil so it can be estimated indication of the type and cause of the failure in the transformer. The method used to identify and analyze the dissolved gases in oil is called Dissolved Gas Analysis (DGA). In this study conducted by the DGA Duval Triangle method for transformer oil used in geothermal power plant UPJP Kamojang PT. Indonesia Power. The results using Duval Triangle method produces thermal failure and partial discharge.

Cirata subsystem is part of the 150 kV interconnection system 150 kV West Java which is supplied by two units of IBT 500/150 kV with a power capacity of each IBT is 500 MVA. It has 15 transmission line connecting the substation 13 (GI), while the generation units that exist in the subsystem Cirata is PLTP Patuha with a power of 55 MW and 180 MW hydropower Jatiluhur. The reliability of the power system must be maintained in order to supply power from the generator to the consumer to keep going well. At peak load conditions and contingencies, an electric power system will undergo changes in value, both current and voltage. In this study, which analyzed disorder is a contingency (N-2), a discharge of the two components of transmission line system and generator. The aim is to evaluate and improve the reliability of electric power systems of 150 kV Subsystem Cirata, analyzing the effects of disturbance contingency (N-2) to changes in current and voltage, identify the bus voltage is outside the operating limits, identifying the transmission line that experienced the imposition of critical / exceeds limit operation, and perform load shedding (load sheeding) to overcome the weaknesses of the power system due to disruption contingency N-2. The study was conducted by collecting data required for power flow simulation using Newton-Raphson method in ETAP 12.6.0. The simulation results show the power flow interruption due to voltage profile under the standard contingency SPLN 150 kV + 5% and -10%, and becomes critical channel loading over 50% of the nominal current conductor. While after the release of the load (load sheeding) voltage profile in Subsystem Cirata back normal or standardized SPLN and loading the channel becomes lighter.

Pakenjeng village is one of the villages in the subdistrict Pamulihan, Garut. Garut regency has the potential of natural resources is quite large and varied, namely water resources, energy, and mineral resources. Energy resources available in the form of the potential of renewable energy such as geothermal energy (geothermal), micro-hydro, solar, wave, and wind. Judging from potential micro hydro, Pakenjeng village crossed by two rivers with a flow of water large enough, the river Cikondang and Cibatarua. Currently, both the river Cikondang and river Cibatarua been used for hydroelectric power plant, with a capacity> 100 kW (scale mini-hydro), ie power plants Kombongan (river Cikondang) with a capacity of 165 kW and a power plant Panyairan (river Cibatarua) with capacity of 3 x 200 kW. The result of the potential study (pre-feasibility study) showed that Sungai Cibatarua have the quality and quantity of water that is eligible to be a source of hydroelectric energy for water discharge stable and constant reaches 5100 liters / sec. Cibatarua River has a waterfall that has a head that is high enough that Niagara Panyairan with head up to 63 meters. Hydraulic power that can be generated to reach 3248 kW and a power that can be awakened by the turbine reaches 2404 kW. Potential analysis (pre- feasibility study) of the mechanical and electrical indicates that the turbines are suitable for the MHP in the River Cibatarua namely Cross Flow Turbine Type TC 15 BO 650 with power up to 1 MW.

This paper presents experimental results from the operation of the prototype of Pico Hydro-Solar Photovoltaic Hybrid System. This device includes a pico hydro power with a capacity of 600 VA, a 3x200 WP solar panel, 4x60Ah energy storage, solar charge controller, a 1500 W inverter, and a 15-200 watt variable load. In this experiment, measurements of the current flow and terminal voltage were carried out at the output of photovoltaic, picohydro, battery, and inverter at various different load values, ranging from 15 watts to 200 watts. Measurements are made during the day when the intensity of solar radiation is quite high. The measurement results show that the output voltage on each component is relatively stable at various load values, and the load energy requirements are supplied more by solar photovoltaic components in sunny weather and more by pico-hydro in cloudy weather.

The power transformer is an important component in the power system, as it is directly related to the reliability of the electric power system operation. Therefore, the diagnosis of disturbances in power transformers is important for device safety as well as electrical system stability. Dissolved Gas Analysis (DGA) is a disruptive diagnostic technique in power transformers that has been recognized effectively, because it provides knowledge of the state of the transformer based on the dissolved gas content in the transformer oil. The DGA test results can be represented by different methods such as Doernenburg ratio, Rogers ratio, IEC ratio, Duvals triangle, and key gases. The problem presented here is that two methods namely Doernenburg ratio and Rogers ratio, for the same data inputs give two different results from the error diagnosis to know the actual state of the transformer. In this paper, a combination method is proposed to solve the problem of conflict between Doernenburg ratio and Rogers ratio by utilizing multi-layer artificial neural network perceptron to localize and identify the error on the transformer and to select the most appropriate method.