A special protection scheme for damping power system oscillations by controlling wind farms

This paper proposes a special protection scheme (SPS) as an additional tool for system operators to damp power oscillations and thereby improve the overall power system stability. This SPS is activated by an online power oscillation detection algorithm and utilizes a power system stabilizer (PSS) controlling a wind farm to damp power oscillations. Moreover, an adaptive time delay compensator (ATDC) compensates for the time delays in the control system. Different alternatives for the PSS input signals are compared by time-domain simulations and by small-signal analysis. The most significant improvement in the damping of the inter-area oscillations is achieved when the PSS uses the active tie-line power as input and controls the active power of the wind farm. The results also prove that the ATDC operates correctly if the total time delay remains below 300 ms. This SPS can improve the system stability when the conventional PSSs may be insufficient.