## General mathematical model for the calculation of economic cross sections of cables for wind farms collector systems

A model for calculation of the economic cross sections of cables within the internal network of a wind farm is presented. The economic cross sections of the internal wind farm cables provide maximisation of the profit generated by the wind farm within its life-span through an optimisation of the balance between the investment and operating costs. This study presents a practical mathematical model for determining the optimal cable cross section based on: the wind statistics at the wind turbine location, wind turbine power curve, price of the electric energy, price of the cable, and interest rate. By using the developed model in the planning phase of a wind farm project each of the connection feeders within the internal cable network can be optimised. The proposed model is demonstrated by the example of a perspective wind farm with a rated power of 25 MW located in the region of Banat, Serbia. The calculations done for the observed wind farm show that the optimisation of the interconnecting cable cross sections makes profit increase of nearly 1 million Euro, compared to the model for the calculation of cable cross sections based only on technical limitations.