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In recent years, electricity has been a daily necessity for people to help their activities. Along with technological developments, energy demand has increased rapidly. In Indonesia, electric energy is mostly supplied from conventional generators using fossil fuels. One of the impacts of using conventional power generation is air pollution which is caused the global warming. Thus, researchers have developed a renewable energy power generation in the form of a PV system that has no air pollution. PV can generate electricity during the day but often than not can be blocked by bad weather conditions. To solve that problem, a device to optimize the PV output is needed. One of the important components in a PV system is a DC-DC converter. This device can be used as a PV output voltage amplifier and power controller. In this research, PID controller is applied to stabilize the output power of the HVGT (High Voltage Gain Transformerless) topology DC-DC converter. Using the state-space averaging method, a bode plot graph is obtained to determine the stability of the control system of the converter. Similar topologies of DC-DC converter are compared to HVGT topology to know its performance. Simulation and experimental have also been done to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

In general, aerodynamic barriers can be affected by wind gradients in wind flows. Besides, the wind speed will increase with increasing altitude above the ground. Flow near the surface encounters obstacles that can reduce wind speed. Technically, the reduction in a speed close to the surface is a result of the function of surface roughness. In addition, the wind speed is very different for different types of terrain. However, this condition will also give random effects on the vertical and horizontal velocity components in the main flow direction, as discussed in these studies. These works are subjected to evaluate the wind gradient impact on the wind energy profile considering the ground launch on various levels. Specifically, wind gradients are modeled and approached by shifting vertical velocities which are designed in various exponential coefficients that refer to the type of surface. The results show that the gradient has a significant effect on changes in wind speed patterns that are in line with potential changes in the generated energy. The ground launch also leads to the energy profile as presented on the speed at the high. [ABSTRACT FROM AUTHOR]

This paper presents the results analysis of switching’s effect when capacitor bank operation against the amount of inrush current on the circuit breaker. The capacitor bank switching causes inrush current and high-frequency oscillation if there are two or more capacitor banks connected on the same bus. When it occurs repeatedly, the insulation from the electric equipment will weaken and breakdown. For this reason, we propose a method to reduce the inrush current using new controlled switching. Switching control is used to find the time (t) of circuit breakers’ switching. So it can be seen the configuration of capacitor banks’ switching causes minimal inrush current. We have done a case study 3 capacitors using Simulink. Variables used are inrush current (ii), controlled switching time (t), and damping reactor (Lreactor). Inrush currents can be reduced by 99.8% using the proposed switching control method. The amount of inrush current is below the capability of the power breaker rating so that it does not cause a power breaker to interrupt and also does not cause overcurrent in the system. If the circuit breaker does not trip when there is a high inrush current in a short time, it can be dangerous for the electrical system equipment. [ABSTRACT FROM AUTHOR]

This paper presents the maintenance scheduling of transformer oil in Banaran Substation, Indonesia. Based on the function of the transformer is important to distribute electricity. If there was a fault, it can decrease the reliability of the transformer. Therefore, it is necessary to schedule the periodic maintenance of transformer oil to improve the power transformer reliability. So in this research using Markov method to analyze the reliability and availability of transformer oil. It happened because of Markov method can increase estimates effectively. This research adds the used parameters, namely the results of the DGA test with TDCG and the results breakdown voltage test. These parameters will be processed by using Markov method to find the value of reliability and availability with calculated using the deterioration rate (λ) and the repair rate (μ). The calculation results are simulated using Matlab R2014a, and the results show us that the reliability and availability of transformer oil decrease every month. The biggest decrease occurred on day 180 in a period of 365 days, with the value of TDCG is 9.844% and 3.395% while the value of breakdown voltage is 32.19% and 24.83%. Therefore, maintenance is carried out at least twice a year to improve the quality of transformer oil which functions as an isolation transformer and prevents transformer failure. [ABSTRACT FROM AUTHOR]