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

Yifei Wang,Youxin Yuan

doi:10.3390/su11051400

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.

Highlights

The wind power generation system offers solutions to energy shortage and environmental contamination with the effective application of the clean, abundant, ever-renewable wind energy [1]
This paper focuses on the mechanisms of the phase-locked loop (PLL) model alone on the output characteristics of the doubly-fed induction generator (DFIG).TAhciscopradpinergftoocu[2s3e]s, tohnetahcetimveecphoawneisrminscorefmtheenPtsLoLf mthoedDelFIaGlonareeodnettehremoiuntepdubt ychtawroacptearritsst:ictsheof acthtieveDpFoIGw.eAr cccoonrtdroinlglotoop[2a3n]d, tthheeaPcLtiLvecopnotwroelrloinocpr,emwhenicths oafrethsehoDwFnIGinarFeigduerteer2m
Aiming at reduced inertia and weak damping properties of the wind-integrated power system, this paper derives the synchronized swing equation of the DFIG based on the dynamic models of PLL

Summary

Introduction

The wind power generation system offers solutions to energy shortage and environmental contamination with the effective application of the clean, abundant, ever-renewable wind energy [1]. Among the current wind power technology, the doubly-fed induction generator (DFIG) based wind power generation system presents obvious dominance with high energy transfer efficiency, flexible grid connection, and power decoupling control [3,4,5]. Different from the synchronous generators (SGs), the DFIG operates at the maximum power producing point for a given wind speed [7]. For this reason, the system frequency is decoupled from the partially rated power converter, which results in a loss of ability in the DFIG to provide inertia and frequency support [8,9]. This paper aims to improve both the inertia and oscillation damping of the power grid

Objectives

Discussion

Conclusion