Impact of Variable Time Delay on Oscillatory Stability in Power System with Wind and Solar Farms using Wide Area Damping Control

Abstract Renewable energy sources such as wind and solar farms have increasingly participated in modern power grids in order to supply inflated demands. In addition, wind and solar farms equipped with the wide area damping controller (WADC) can be adopted to enhance an oscillatory stability. However, the time delay in the communication of input and output signals of the WADC is an unavoidable problem. In previous works, the time delay is assumed to be a fixed value. In fact, the time delay may be variable in both input and output sides of the WADC. Such type of delay is defined as variable time delay. This paper focuses on the impact analysis of variable time delay on an oscillatory stability in wind and solar farms equipped with WADC. The new mathematical model of the power system with wind and solar farms with WADC including variable time delay is formulated. The technique for analyzing the influence of variable time delay is presented. Small signal and transient stability analysis results in an IEEE 50-machine 145-bus signify that the variable time delay significantly affects the damping performance of WADC. In the worst case, it may bring about the system instability.