REACTIVE POWER INJECTION BY WIND FARMS DURING ASYMMETRIC FAULTS - APPLICATION TO PORTUGUESE DISTRIBUTION GRID

The Portuguese national grid code [1] specifies minimum technical requirements for fault ride through capacity and reactive power injection during faults which are applicable to all wind farms above 6MVA. However, it was established that the wind generators, even the most recent ones, can only inject symmetrical reactive power even in the presence of an asymmetrical fault. This could potentially lead to high overvoltages in the MV network (low impedance grounded) or in the HV network (solidly grounded only at the TSO substation). To evaluate the consequences to the Portuguese Distribution Grid of the symmetrical reactive power injection by the wind generators, EDP Distribuicao requested LABELEC’s collaboration. Two cases were considered: the connection of the wind farm (WF) to the HV network; and to the MV network. For each of these, different scenarios were simulated. This study gave a conclusive answer to EDP Distribuicao since it allowed to answer its doubts.