A Novel Method for Measuring the Open-Circuit Loss and Short–Circuit Loss of Distribution Transformers Online

The paper proposes a novel method for online measuring the open-circuit loss (OCL) and the short-circuit loss (SCL) of distribution transformer DT, based on the consideration of the drawbacks of the offline measuring method, which is regarded as the mainly and traditionally used methods for measuring the OCL and the SCL of DT. The novel method avoids the drawbacks of the offline method which is not cost-effective and is not good for the reliability of the power supply. Firstly, the relation expression of the short-circuit impedance with respect to the voltage and current of the primary and secondary side is developed from the analysis of the equivalent circuit model of DT, and the relations between the SCL and OCL and the short-circuit impedance are also deduced according to power balance. Then, the online short-circuit impedance is computed by using linear regression technique and the value of online voltage and current of DT. Furthermore, according to the developed relations, the online OCL and the SCL of DT can be acquired by using the obtained short-circuit impedance. Numerical simulations have been carried out on Matlab/smulink and results verified feasibility and effectiveness of the novel method for online measuring the OCL and the SCL of DT.