Unit Commitment of Distribution Main Transformers Considering PV Penetration

This paper presents the unit commitment of main transformers to meet the service reliability criterion in distribution substations by considering the growth of photovoltaic (PV) installation with the probabilistic power generation in the service area. The historical data of solar irradiation over one year period are collected to derive the annual duration curve of solar energy to derive the probabilistic distribution of PV power generation. All PV power systems of each study year are considered as an equivalent virtual main transformer with probabilistic capacity. By the integration of probabilistic PV power generation model and the risk model of main transformer outage, the loss of load expectation (LOLE) of the distribution substation is analyzed according to the annual growth of customer loading and PV penetration level. When the LOLE is less than the service reliability criterion, one new unit of main transformer has to be added to improve system reliability.