Wind turbine effects on VOR system performance

The implementation of wind farms establishment in France is increasing. When wind farms are located close to radionavigation systems, it becomes important to evaluate their electromagnetic effects on existing radionavigation instalations. In this study, the radionavigation system is a VOR (VHF omnidirectional radio) operating at about 110 MHz. Because rotor blades are made of a balsa and dielectric multilayers composition, their electromagnetic behavior differs from that of metal blades at VHF frequences. In this study, we first obtain an electromagnetic CAD model from a real structural design; then we calculate the far field scattering matrix from an integral method (CESC code [1] method of moment) for a (30 m) dielectric blade and compare it with a metal one using RCS (radar cross section) calculation. The impact of (40 m long) dielectric blades is compared with the (65 m high) metal mast effect in terms of scattered field, and then the VOR error (bearing error) is evaluated. These results are analyzed for several geometrical configurations of a three-bladed rotor and compared with the mast. The study is extended on wind farms to discuss geometrical configuration effects with regard to a VOR location.