Techno-Economic Assessment of Energy Efficiency in 10–35 kV Cable Distribution Networks Relevance

Abstract

Relevance: In 10–35 kV distribution networks, the justified selection of nominal voltage and cable conductor cross-section directly affects electrical energy losses, voltage deviations, capital investment, and operating costs. In conventional design practice, these parameters are often assessed separately. However, load growth, increasing electricity tariffs, and changes in the cost of network components require their selection based on interconnected technical and economic criteria. Therefore, assessing the energy efficiency of medium-voltage cable networks while considering discounted costs, permissible heating, short-circuit currents, and voltage losses is an important task.

Aim: o develop a method for the rational selection of nominal voltage and cable conductor cross-section in 10, 20, and 35 kV cable distribution networks based on technical constraints and discounted costs.

Methods: The study applies methods for determining the calculated current and economic current density, checking cable heating under normal and short-circuit conditions, calculating voltage losses, active power and electrical energy losses, and comparatively assessing discounted costs. The technical and economic indicators of 10, 20, and 35 kV cable lines are compared.

Results: The results show that increasing the cable-line voltage reduces the calculated current and active power losses when transmitting the same power. Compared with 10 kV networks, the use of 20 kV cable networks makes it possible to reduce cable cross-section, increase the service radius under permissible voltage-loss conditions, and decrease electrical energy losses. It is substantiated that the final assessment of the 35 kV option should consider not only cable-line costs but also capital costs for substation and switching equipment. The proposed approach enables the selection of the technically feasible solution with the minimum discounted cost.