Co-ordination of transformer tap and capacitor operation for reactive power voltage control in a distribution primary substation

This paper presents a method employing fuzzy dynamic programming (FDP) technique to determine a hourly dispatch schedule for the capacitor bank switching and on-load tap changer (OLTC) position in a distribution primary substation. The schedule co-ordinates OLTC and capacitor operation so as to reduce their number of operation while satisfying the constraints on bus voltage limits and the tolerable worst power factor for the main transformer. This will reduce the tap changer/transformer maintenance frequency, and hence improve the overall supply security. Historical data of a distribution primary substation in Hong Kong is applied to simulate the reactive power/voltage control operation in the substation. The results are analysed and compared with the current control mechanism, and the effectiveness of the proposed method is demonstrated.