Ferroresonance assessment in a case study wind farm with 8 units of 2 MVA DFIG wind turbines

This paper studies the transient and sustained ferroresonance phenomenon in wind farms connected to a power distribution system. Ferroresonance can be critical for wind turbines during switching or fault conditions. This results in effects such as harmonics, voltage dips and overvoltage in the system [1]. The ferroresonance current is able to damage the machine and the rotor side converter, and as a consequence, the system must be protected [2]. In this paper, first the existence of ferroresonance in wind farms has been assessed. Software modeling and a validation method has been proposed and the simulation results for different system arrangements have been presented. In general, engineers can often work around nonlinearities using a simplified linear approximation to calculate or predict performance within the “normal” range of operation. This is not possible in the case of ferroresonance since linearized calculations will not predict it [3][4]. Therefore PSCAD-EMTDC software is used in this study to analyse the behaviour of a wind farm with Doubly Fed Induction Generators (DFIGs) [5][6]. Results show that ferroresonance is a function of network components; specifically, the lengths of cables, types of wind turbine generators, power transformers and transmission lines.