Voltage drop is one of the power quality problems affecting power users. This happens due to the higher demand for electric power. Or a short circuit in the transmission system. This causes a voltage drop is one of the power quality problems affecting power users. This happens due to the higher demand for electric power. Or a short circuit in the transmission system. This results in drop in Solving of voltage drop problems in power distribution model with distributed generator were presented with MATLAB program by installing a generator in the distribution system. Therefore simulated a case study 5 case 1 simulation by not installing a generator at any bus case 2 simulation by installing a Generator at bus 1 case 3 Simulation by installing a Generator at bus 18 case 4 simulation by Generator installed at bus 33 and case 5 simulation by Generator installed at bus 13 17 21 31 to study the suitable location of generator installation to solve the problem of voltage drop.

This thesis presents the Power Quality (PQ) analysis of solar power plant 1MW and economic impacts in the distribution power networks. The case study focuses on the penalty fee (fine) from consume the reactive power less than the limit of the Provincial Electricity Authority (PEA) of Thailand. The fine have been charged up to 900000 baht per year. Therefore the thesis studies and purposes the possible solution by analysing the operating function of the inverter (supports reactive mode) installing the adjustable capacitor bank 1500kVar in the Medium Voltage (MV) level and lastly installing the adjustable capacitor bank 1500kVar in the Low Voltage (LV) level. The results shown that the possible solution that reduces the fine is installed the adjustable capacitor bank 1500kVar in the MV. The investment of this installation is cost 1800000 baht with the nominal operation over 10 years. The analysis of financial investment which bases on the Net Present Value (NPV) the Benefit-Cost ratio (B/C) the Pay Back period (PB) is presented the NPV at 4902971 baht B/C 3.72 and PB 2 year (with the Internal Rate of Return; IRR 49.7 percent).