Optimum resistive type fault current limiter: An efficient solution to achieve maximum fault ride-through capability of fixed speed wind turbines during symmetrical and asymmetrical grid faults
This paper proposes an optimum resistive type fault current limiter (OR-FCL) as an efficient solution to achieve maximum fault ride-through (FRT) capability of fixed speed wind turbine (FSWT) during various grid faults. A dedicated control circuit is designed for the OR-FCL in a way that enables it to insert an optimum value of resistance in the FSWT's fault current path. Therefore, the OR-FCL significantly improves transient behavior of the FSWT. It will be shown that, the optimum resistance value depends on fault location and pre-fault active power. So, the control circuit of the proposed OR-FCL is capable to calculate the optimum resistance value for all the pre-fault conditions. In this way, the FSWT achieves its maximum FRT capability during symmetrical and asymmetrical faults even at zero grid voltage, as recommended by some new grid codes. The analytical analysis is provided in detail to highlight the process of calculating the optimum resistance of the OR-FCL. Moreover, the effect of the resistance value of the OR-FCL on the FRT behavior of FSWT is investigated, too. To show the high efficiency of the proposed OR-FCL, its performance during various operation conditions of the FSWT, will be studied. It will be proved that each operation condition needs its own optimum resistance value during the fault to achieve the maximum FRT capability of the FSWT. The comprehensive sets of simulations are carried out in PSCAD/EMTDC software; the results approve efficiency and effectiveness of the proposed approach.