An adaptive data-driven based pilot relaying scheme for protecting UPFC-compensated transmission line connected to wind farms

Transmission line conventional current differential schemes are significantly impacted by the dynamic fault current features, transient behavior, and unpredictable power generation of large-scale doubly fed induction generator-based wind farms (DFIG-WFs). Further, combined effects of WFs and flexible alternating current transmission system (FACTS) controller have adverse effect on various unit protection schemes. Normal transmission lines have a current differential between the two ends that rises with line length. If the WFs power output is low, the capacitive charging current may match the load current. Conventional differential protection methods are facing difficulties in the presence of WFs. This research proposes a data-driven approach to determine the effects of several scenarios with significant offshore WFs coupled to transmission lines on differential relay characteristics. The per-phase differential current is calculated using the short-term matrix pencil method (STMPM) based signal reconstruction technique. The net change in the current magnitude is then determined by estimating the first- and second-order derivatives of this data. Lastly, a disturbance detection index (DDI) is derived from the Euclidean distance between these first and second derivative components. The PSCAD/EMTDC simulation studies that were carried out show that the suggested strategy functions satisfactorily for a variety of disturbances, such as internal and external faults, fault resistance, fluctuating fault position, WF penetration changes, and other types of non-fault switching events.