A novel method for evaluating the secondary voltages of transformers in primary substations based on sensitivity coefficients

摘要

This paper provides a novel method to evaluate the secondary voltage of transformers in primary substations. The method is focused on the secondary voltage deviation which is a function of real power, reactive power, tap position, and primary voltage of the transformer in transmission systems. It helps dispatchers calculate and predict voltage deviation before introducing voltage regulation and reactive power compensation. The proposed approach is first to derive the formula of secondary voltage sensitivity coefficients from power flow equations. Real operational data are then substituted into the formula to get sensitivity coefficients. Finally, the corresponding secondary voltage is calculated with the sensitivity coefficients obtained. Implementing historical data of three substations in the above algorithm shows that the errors between calculated and actual voltages are less than 0.15%. The proposed method can not only accurately estimate the secondary voltage of the primary substation, but also be used to calculate the compensating reactive power as well as determine the tap position of the transformer, thereby improving the voltage and reactive power control strategies of power transmission systems.