Comparative evaluation of DG and PV-DG capacity allocation in a distribution system

This paper presents a comparative evaluation of distributed generation (DG) and photovoltaic distributed generation (PV-DG) capacity allocation in a distribution system. The optimal location and size of DG are calculated in order to minimize only the total system loss using the loss sensitivity factor method. The optimal PV-DG size taking environment uncertainties into account is then calculated assuming the PV-DG is installed at the same bus as DG. Voltage level and harmonic distortion constraints are also included in the optimal PV-DG size calculation. An actual 51-bus medium voltage distribution system in Thailand is used as a test system. Results show that the higher rated capacity of PV-DG should be installed compared with the capacity of DG at its optimal location due to significantly different in the operation characteristics. The reduced system loss after PV-DG installed is lower than the DG case. The results can be utilized in the utility system planning when interconnecting a DG or PV-DG into a distribution system.