The flexible algorithm for identifying a disturbance and transient duration in power systems

The problem of identifying a disturbance and transient duration in power systems at the appropriate time is crucial. The necessity of an early disturbance detection is driven by the essential aims of dispatching control and automatic emergency control systems, both local and centralized. The paper proposes a flexible algorithm for identifying a disturbance and transient duration, based on the "hinge joint" technique: the initial data interval is fitted iteratively by two linear sections connected one after another. The key element of the algorithm is tracking the difference between the sections' angles of descent. Applying the technique allows to detect the point where the signal changes rapidly and significantly, which indicates the transient start. The significant changes in the state parameters behavior may be driven by a power imbalance when power signals are considered or by other emergencies along with relay protection and automatic control systems actions. The primary aim of the algorithm is to identify the disturbance with the highest possible accuracy in terms of time based on the power system state parameters measurements. The algorithm is applied to processing both Wide-Area Monitoring System (WAMS) data of the sampling rate corresponding to the rated network frequency (obtained from Phasor Measurement Units - PMUs) and instantaneous state parameters measurements (obtained from Digital Fault Recorders - DFRs) as well. The algorithm is validated involving physical simulation results along with the actual WAMS data collected from power system entities. The algorithm processing speed is sufficient to ensure operation on a real time basis.