Analysing the effects of power swing on wind farms using instantaneous impedances

Abstract

Most of the grid disturbances happen due to the presence of faults and power swing. This article focuses on power swing in view of the amount of penetration of renewable energy resources especially the wind farms. There are two sections. First section approached power swing by deriving a mathematical expression which would be able to track the locus of impedance in time domain and subsequently analyze resistance and reactance simultaneously with respect to time. It used a grid comprising of generator, transmission line and load. The derived expression was compared with a power swing generated using RTDS model and the results were analyzed in R-X plane. Second section analyses the impedance during power swing with respect to penetration of renewable energy resource (wind farms). A wind farm was added in steps to the grid. Results indicated that the derived expressions from first section were in agreement with simulated power swing using RTDS. The larger penetration of wind farms into the grid used in second section created limitations during power swing indicating threat to system at marginal stability conditions. Usage of dynamic impedance plots (R-X-t space) gave better insight on the instantaneous movement of resistance and reactance.