Virtual Inertia Compound Control Strategy for Interconnection System with Wind Turbines

Variable inertia presents a potential alternative method for improving transient stability in power systems, due to the increased penetration of new types of generators that have more controllable inertial response, such as wind generators. This paper investigates a novel control strategy of interconnected power grids to improve transient angle stability by coordinating with the variable inertia of regional networks of wind turbines. Based on the dynamic model derived from a two-area, interconnected power system, the impact of controlled inertia on a generator's rotor-angle swing is evaluated theoretically. As a new variable parameter in operation, the proposed scheme not only keeps the controlled inertia's original function of providing rapid frequency response, but also utilizes it to prevent large rotor-angle swing. A two-area power system containing four synchronous generators and two doubly-fed-induction-generator-based wind farms with a high 30% wind penetration is simulated to validate the proposed control strategies. The simulation results show that utilizing wind-power generation to control inertia in the system can reduce power angular deviation following transient events for a significant level of dynamic support, thus greatly reducing the burden of maintaining system transient stability on synchronous generators.