Sub‐synchronous interaction (SSI) phenomenon is one of the dynamic system problems that have an adverse influence on the safety and stability of the system.The use of supplementary damping controllers (SDCs) in the double‐fed induction generator (DFIG) converter controllers is quite promising due to their simplicity,low costs, effectiveness, and easiness of tuning. This paper presents a new effective input control signal, rotor voltage, to the SDC for damping SSI in a series‐compensated DFIG‐based wind farm. The proposed SDC is embedded into both the q‐axis and d‐axis of the rotor‐side converter inner current loops. Particle swarm optimization algorithm is used to identify the optimum parameters of the SDC which maintain the system stability at various operation conditions. Both eigenvalue analysis and time‐domain simulations have been carried out to demonstrate the capability of the proposed SDC for enhancing the system stability and damping SSI. Compared to the conventional SDC, the proposed SDC has the best performance where it can quickly and robustly damp the SSI at different compensation levels, different wind speeds, and sub‐synchronous control interaction.

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Subsynchronous resonance (SSR) occurs mainly in series compensated transmission line connected to the wind power system. This phenomenon (SSR) can lead to electrical instability and potential turbine generator shaft failure. Thus, the protection system is an essential part to avoid the harm of SSR. In this paper, an improved fast detection method is proposed to detect the SSR phenomenon in a very short time. It consists of two stages; first, the positive or negative half-cycle time of each cycle of voltage signal is detected based on four steps, namely, signal conversion, comparison, integrator, and sample and hold; second, the obtained time is compared with the damping and trip threshold values, and the best action is determined (addressing or trip) based on the value of half-cycle time. The effectiveness and superiority of the improved fast SSR detection method are validated at different compensation levels and compared with the traditional method and subsynchronous oscillation relay (SSO). The simulation results prove that the improved method is more efficient in all types of SSR phenomenon; induction generator effect (IGE), control interactions (CI), and torsional interaction (TI) at different compensation levels. In addition, a comparative study among these three types of SSR with the proposed method is carried out, and the obtained results show that the CI is a suitable type with the proposed method.

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