An integrated method to simultaneously optimise a wind farm’s internal network layout, cable cross-sections and substation location

The internal power grid of a wind farm resembles an extensive network structure. The farm’s main power station (MPS), wind turbines, and the cables connecting them are usually spread over large areas of land or seabed. The cost of each component of such a network represents a considerable proportion of the total investment. By investing significant funds in the overall project, the investor expects to minimise the costs associated with the investment while making the highest possible profit from operating the planned wind farm. Therefore, even at the design stage, efforts should be made to locate the MPS and configure the internal connections of the wind farm in such a way that the costs are as low as possible while meeting the technical requirements. The paper proposes an integrated methodology for solving the problem of simultaneously determining the location of the MPS, selecting the connection structure and cable cross-sections of the internal network of a wind farm while complying with the technical constraints required by the regulations, such as the current carrying capacity of the cables and the permissible voltage drops. The primary objective of the optimisation is to find a location for a substation and the internal structure of the wind farm network that minimises the cable-related costs (investment and active power losses) for such a specific network structure. The authors demonstrate the effectiveness and usefulness of using an integrated algorithm based on Mixed Integer Nonlinear Programming with binary variables (MINLP). The calculations also show the usefulness and necessity of considering the active energy losses in the cables of the designed network. These costs are comparable to the costs of laying cables and have a major influence on the final shape and structure of the designed network and the cross-sections of the cables used.