Abstract
This paper presents a special protection scheme (SPS) that mitigates natural oscillations in the power system by enabling selected adaptive power oscillation damping (APOD) controllers in wind farms or synchronous generators. The SPS activation is triggered by an online power oscillation detection algorithm. Furthermore, to tackle the intricacies of time delays within the control system, an adaptive time delay compensator (ATDC) has been integrated into the SPS control scheme. The SPS is tested on the New England 39 bus system by numerical simulations and in the Nordic 44 system by experimental testing with a hardware-in-the-loop approach. The numerical results show that the proposed SPS can increase the damping of lowfrequency natural oscillations (LFOs) significantly and even avoid unstable situations with growing oscillations. Moreover, the laboratory validation demonstrates that the system is able to run in real-time and that the time delays caused by PMU measurements, communication, and computation can be handled correctly. Thus, the proposed SPS concept can possibly be implemented to serve as an additional and automatic tool for the system operators to damp natural power oscillations by coordinated control of multiple sources
