Analysis of the load of power transformers with a higher voltage of 6‑10 kV

Power transformers 6‑10/0.4 kV feeding 0.4 kV rural electric networks operate with low load factors. This leads to significant electricity losses. Optimization of the load of 6‑10/0.4 kV power transformers will increase their energy efficiency. To assess the load and loss of electricity in power transformers with a higher voltage of 6‑10 kV of rural electric networks in the Orel district of electric networks (DEN) of the branch of PJSC Rosseti Tsentr – Orelenergo, the authors carried out an analysis of statistical data obtained from operational and technological group dispatcher logs on the load of power transformers 6‑10/0.4 kV of electric networks for 2016‑2022. As a result, it was found that 880 power transformers (74% of the total number) operate with a load factor of less than 20%. Among the 6‑10/0.4 kV power transformers with rated powers of 63, 100, 160, and 250 kVA, the load factor of less than 20% accounts for 72‑77%. It is established that in power transformers 6‑10/0.4 kV of the Orel DEN, annual losses of idle power are 1.8‑2.9 times higher than the short circuit losses. It is revealed that the share of idling losses for different nominal capacities of power transformers 6‑10/0.4 kV is 65‑74% of the total annual electricity losses. The assessment of the load of power transformers is necessary to develop a number of measures to reduce electricity losses in the 0.4 kV electrical networks of the Orel DEN: disconnecting transformers with seasonal loads; replacing underloaded and overloaded transformers with transformers of the required capacity; reequipping the fleet of 6‑10 kV power transformers with modern power transformers with energy efficiency of class X2K2 and higher.

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