The third thermal power plant is one of the largest in Mongolia, generating about 30% of Mongolia's electricity and more than 60% of Ulaanbaatar's thermal energy. Although Mongolia's electricity consumption has grown steadily, no new power plants have been built to meet this increased demand. This increase in load and the intermittent characteristic of renewable energy have adversely affected thermal power plants' sustainability. Therefore, to study how the static and dynamic transition process of the power plant is affecting the operation, the 110kV 35kV 10kV 6kV general circuit scheme was fully modelled on Powerfactory software to analyse the performance of the load flow, load loss, voltage level, determination of the loading condition, balanced and unbalanced short circuit calculation results are demonstrated.