The faults in a power distribution system do not only impact to power outage directly. They also cause voltage sag problem spread over the system. A single-line to ground fault is about 70% of the overhead system faults. The magnitude and duration of voltage sag causes the economic damage of the system. This paper presents an analysis of the different systems grounding to mitigate the voltage sag in a power distribution system by using the technical analysis system in case of one phase to ground fault. The objective is to minimize voltage drop for users using the simulation with single line to ground fault in distribution system voltage level at 22 kV PEA’s test system by the computer program. The results show that the grounding method can mitigate the voltage sag and reduce the damage of the economic system.

This article presents how the analysis an insulation of high voltage transformer bushing. The purpose is to analysis the moisture in the bushing to evaluate the approach for maintenance. The analysis rely on the principle of the Polarization and Depolarization Current (PDC) technique which is a technique for analyzing the insulation of high voltage equipment to test high voltage transformer bushing for a case study. This method is performed by energize 1000 Vdc into a bushing in period of time and then switch off the circuit for discharge current. Finally we calculate the moisture of main insulation of high volt bushing as well compare with standard moisture of criteria. The method is useful of preventive maintenance plane of high volt bushing and reduce the failure in the power system.

This paper presents about the defrosting time of evaporator in refrigerator by using the temperature different between evaporator and chilling area. This temperature different concept could control the defrosting system to operate according to the load. It also helps controlling the operation of fan motor to be able to operate in accordance with the defrosting time. In general system the timer is set at the highest humidity season which cause the unneccessary defrosting cycle even in low humidity season. This general system create the west of power usage colling system. These can cause time-consuming in defrosting process in the low humidity season and cause the unnecessary usage of power to cooling system. This research is to develop the controller for the defrosting system at evaporator from the investigation. As the results we have found that the defrosting system at evaporator according to its load made the refrigerator can decrease the power about 8% when comparing to constant time evaporator system

This paper presents an efficient algorithm for optimization of radial distribution systems by a feeder reconfiguration to balance feeder loads and eliminate overload conditions. The system load-balancing index is used to determine the loading conditions of the system and maximum system loading capacity. The index value has to be minimum in the optimal feeder reconfiguration of load balancing. A method based on Tabu search algorithm The Tabu search algorithm is employed to search for the optimal feeder reconfiguration. Simulation results for a radial 69-bus system with reconfiguration and capacitors placement. The study results show that the distribution system with capacitor placement and optimal on/off patterns of the switches feeders reconfiguration can be load balancing in distribution systems.

This research presents an Analysis of Voltage Sags on the Installation of Distributed Generation in the Distribution System. The computer program PSCAD/EMTDC (Power Systems Computer Aided Design / Electromagnetic Transient in DC system) version 4.2 is applied to provide electrical parameters for the modeling and simulation and to analyze the fault occurred which resulted in voltage sag. Test results from PSCAD/EMTDC show the values of voltage sag when 5 types of fault are occurred (Single Line to Ground Fault Double Line to Ground Fault Three Phase to Ground Fault Line to Line Fault and Three Phase Fault). For all cases the value of root mean square voltage before fault is 100% or 1.0 pu. It can be seen that for both radial line and closed circuit when DG are installed in the system the value of phase to ground RMS residual voltage and phase to phase RMS residual voltage at the bus of Bang-pa-in 2 substation are more than the values in case of the system without DG.