Probabilistic assessment of oscillatory stability margin of power systems incorporating wind farms

Abstract

With the increase in penetration of wind power which is essentially intermittent and random, the dynamic performance of the power system will change significantly, and so will the characteristics of the oscillations and their stability margins. This paper provides an attempt to include probabilistic character of wind power into the power system oscillatory stability margin (OSM) analysis. Nataf transformation approach is applied to generate the wind speed samples, which models the correlation between the various wind farms. The mathematical model of OSM for wind farm integrated power system is formulated and is calculated by the integration-based eigenvalue tracing approach. Considering the uncertainties of the wind power, several statistical indices are presented to evaluate OSM. Monte Carlo simulation (MCS) is used to calculate these statistics. The impact of wind power uncertainty on OSM restricted by inter-area mode is investigated in four-machine two-area test system and 16-machine five-area test system, respectively, for different wind farm locations, wind power penetration levels and wind speed correlation (WSC) degrees. Appropriate conclusions are finally drawn.