Analytical Examination on the Effect of Network Topology of the Grid-connected Wind Turbine Generators on Oscillation Stability

Abstract

The oscillation stability of the grid-connected wind turbine generators (WTGs) depends on two key factors, namely the interconnected network topology of WTGs and the dynamic characteristics of independent WTG. The maximum eigenvalue of the network impedance matrix (NIM) determined by the interconnected network topology is proportional to the degree of the unfavorable dynamic interactions between WTGs. This paper further analytically examines the properties of the maximum eigenvalue of the NIM to explore the effect of network topology on oscillation stability. Theoretical analysis shows that the risk of oscillation instability of series-connected WTGs may be higher than that of parallel-connected WTGs. Analytical examination reveals the mechanism of how the increase in the number of WTGs and the length of transmission line, i.e., weak grid condition, affects the oscillation stability. The numerical simulation results of an example wind power system verify the analysis and conclusions in this paper.