Developing Distance Protection Scheme for Double Circuit Transmission Lines Integrated Into Wind Energy System

Abstract

Wind energy integration into the grid presents a major challenge to the conventional Permissive Underreach Transfer Trip (PUTT) distance protection scheme. This technical challenge arises from variations in power generated by wind turbines connected to double-circuit transmission lines. This paper proposes an enhanced PUTT scheme to improve the accuracy of the Mho-type distance protection relay in such systems. The Developed PUTT (DPUTT) scheme incorporates compensation techniques for residual and mutual coupling currents in the zero-sequence network. Since variations in wind generation impact the security of conventional compensation methods, the DPUTT scheme compares earth current magnitudes at both ends of the system to distinguish between faulted and healthy circuits. Simulation results from a MATLAB model show the apparent impedance trajectories observed by the relays at both terminals. These results demonstrate the mechanism of the proposed tripping scheme across three protection zones and show improved performance over the traditional PUTT. The supervision signal generated by the DPUTT effectively blocks tripping of healthy terminals while correctly initiating trips for faulted circuits. The simulation confirms that the proposed DPUTT scheme reduces false tripping events by up to 99% compared to PUTT, significantly enhancing protection reliability and system stability under variable wind conditions.