REVEALING LOADS HAVING THE BIGGEST INFLUENCE ON POWER-SYSTEM SMALL DISTURBANCE STABILITY

The paper presents a novel approach to reveal loads having the biggest impact on damping of small-disturbed oscillations in power systems. T he technique is based on a quasi-optimization procedure with the cost function reflecting shifts of selected eigenvalues along the real axis when all unknown load parameters are varied within their constraints. The cost function takes into consideration a variety of power system operating conditions. All points of the cost function steepest descent trajectory, obtained in the space of unknown load parameters, corresp ond locally to biggest shifts of eigenvalues. Participation factors of load parameters are computed along the steepest descent trajectory, a nd they give ranks of load importance. Small ranks indicate loads whic h have no influence on damping of selected modes. Big ranks reveal loa ds whose parameters cause the biggest change in damping under the most unfavourable combination of unknown parameters. Parameters with bigge st ranks should be measured first of all to avoid mistakes in evaluati on of damping properties and power system stability margins.