N.R. Ullah, O. Olasumbo, and J. Daalder (Sweden)
Power switching, Reliability and stability, PMU, ESPRIT.
In this paper a PMU (Phasor Measurement Unit) based resistive damping algorithm of power swing has been simulated. Based on the angle difference signal extracted from the PMU, a resistive load has been switched on and off to damp the oscillation. The simulation has been done in SIMPOW. Three phase faults were applied to obtain transient instabilities. These instabilities were characterized by ESPRIT method (frequency of oscillation, time constant) and were damped out by load switching. Besides the simulation, measurement with a PMU has been carried out in the Power System lab of the department. The angle difference signal derived from the PMU proved to be a reliable indicator of power swing. In the simulation voltage angle difference between two buses has been taken as an indicator for power swing and a resistive load is switched on when the derivative of this angle difference signal is positive. It has been found that resistive load switching with appropriate value improves both transient stability margin and damping of the power swing. The already existing district heating system can be used for this purpose.
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