Inertia Provision and Small Signal Stability Analysis of a Wind-Power Generation System Using Phase-Locked Synchronized Equation

Abstract

The inertia and damping of the modern power system are consistently decreased when wind energy has a high penetration level into the grid. This paper proposes a novel solution through transforming the wind turbine generator into an equivalent motion equation mimicking the basic characteristics of the synchronous generator (SG). This synchronized equation builds upon the phase-locked loop (PLL) model of the doubly-fed induction generator (DFIG), which characterizes the inertia constant, damping coefficient, and synchronizing torque. Thanks to this work, the dynamic performance of the inverter-based asynchronous generator could be analyzed from the perspective of the classical rotor motion equation. It further enables us to employ the analogy method to provide the DFIG with automated frequency response ability and to estimate the inertia constant quantitatively. Results also manifest that based on the synchronized equation, the PLL forms a power system stabilizer to enhance the power system oscillation. Hence, parameters tuning in PLL for coordinating inertia provision and damping enhancement are introduced. The contribution of this study lies in that the equivalent synchronized equation is established to optimize the system operation without alterations in the existing control structure of the DFIG. The theoretical analysis and the strategy are verified through the power system simulator.