Double integral sliding mode controller based bridge-type flux-coupling non-superconducting fault current limiter to protect DFIG-based multi-machine power system under transient-state

This paper proposes a double-integral sliding mode controller (DISMC) based bridge-type flux-coupling non-superconducting fault current limiter (BFC-NSFCL) to enhance the fault ride-through (FRT) capability of a DFIG-based wind farm connected to a multi-machine power system. At first, a complete modeling of the BFC-NSFCL is derived to understand its behavior during the normal and fault period more accurately. Then, the DISMC is designed based on that dynamic model obeying the double-integral theory, along with the single-integral sliding mode controller (SISMC) and non-integral sliding mode controller (NISMC) for comparison purpose. Finally, the performance of the DISMC in controlling the BFC-NSFCL has been analyzed and verified by comparing with that of the SISMC and the NISMC. The DISMC removes the chattering problems induced by the traditional SMCs and improves the transient performance by reducing the overshoot and steady-state error by implementing double-integral action. All the graphical and mathematical analyzes favor the DISMC based BFC-NSFCL under symmetrical and unsymmetrical fault (both temporary and permanent) scenarios.