Transient stable region of power systems incorporating stochasticity of variable renewable energies and system contingencies

Abstract

The stochasticity of grid-connected renewable energies, such as wind farms, is challenging the deterministic engineering practices of power system operation. In this paper, a stochastic transient energy function (STEF) model based on the Lyapunov theory is proposed to evaluate the stability of the power system with doubly-fed-induction generator (DFIG). Based on the STEF, the methodology for construction of the stable region is proposed. And the stability degree of each bus under the different fault types and locations are evaluated by the bus stable nominal value (BSNV). To this end, the STEF is derived first from the operation mechanism of synchronous generators and DFIGs. Sequentially, the stable region of the power system with DFIG is constructed by using the stable region theory; the operation locations of every buses are marked on the stable region by the stochastic matrix theory. Case study based on the New England 9-Bus System with DFIG demonstrates the robustness of the proposed STEF to determine the stable region and the results show its potential applications for transient stability incorporating stochasticity of the wind farms based power grid.