Extension of life of distribution transformer using Volt-VAr optimisation in a distribution system

In the literature, many works detail the benefits of Volt-VAr control to minimise the losses in a distribution system. However, it is also important to understand the impact of it on the life of the other assets in a distribution system. Since, distribution transformers (DTs) are the important assets of a distribution system, the main objective of this paper is to appraise the impact of Volt-VAr control on the life of DTs. The paper presents a detailed methodology to estimate the loss of life (LoL) of the DTs under various Volt-VAr control schemes, such as base-case (without any control), voltage control, and Volt-VAr control (VVC). The proposed methodology is implemented on modified IEEE 13-bus and IIT-Roorkee distribution systems considering the voltage-dependent load models, seasonal load influences, and harmonics. The simulation results are presented to explore the ability of VVC in reducing the hottest-spot temperature in the DTs during peak hours. The results reveal that the life of the DT can be extended by a considerable amount by optimally controlling the voltages and reactive power flows in the distribution system. Moreover, it gives a significant reduction in energy losses and improvement in power factor in distribution systems.