Wide-area phasor power oscillation damping controller: A new approach to handling time-varying signal latency
Using the present technology, latency associated with remote feedback signals can be determined from the time stamp information at both the phasor measurement unit (PMU) location and the control centre. This study illustrates how this latency could be accounted for in the implementation of a wide-area phasor power oscillation damping controller (phasor POD). The basic idea is to adjust the position of the rotating reference frame - used for phasor extraction - to account for the extra phase shift introduced because of latency. The oscillatory component of the original PMU measurement is retrieved out of the delayed signal received at the control centre. Thus, continuous compensation is achieved without requiring any Pade approximation and/or gain scheduling, unlike the techniques reported in the literature. With the proposed modification, a phasor POD is shown to continuously adapt to the actual latency and maintain the desired dynamic performance over a range of different operating conditions.