Stability Criterion of Subsynchronous Oscillation of Direct Drive Permanent Magnet Synchronous Generator Based on Impedance Polynomial Fitting

Impedance analysis is the leading method of solving the stability issues of grid-connected renewable energy generation systems. Taking the grid-connected system of direct drive permanent magnet synchronous generator (D-PMSG) as an example, the characteristics and application scope of the existing Ny...

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Bibliographic Details
Main Authors: Yongjun YU, Lichao WANG, Mingyuan ZHANG, Shiwu XIAO, Xinyuan ZHANG
Format: Article
Language:English
Published: Editorial Department of Power Generation Technology 2020-08-01
Series:发电技术
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Online Access:https://www.pgtjournal.com/EN/10.12096/j.2096-4528.pgt.19140
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Summary:Impedance analysis is the leading method of solving the stability issues of grid-connected renewable energy generation systems. Taking the grid-connected system of direct drive permanent magnet synchronous generator (D-PMSG) as an example, the characteristics and application scope of the existing Nyquist stability criterion were analyzed. In order to make up for the deficiency of the existing impedance stability criterion, a quantitative stability criterion based on the fitting of fractional polynomial function of impedance characteristic was proposed, which applied port impedance characteristics of wind turbine derived or measured by equivalent fitting theory of fractional polynomial function. Within the fitting frequency band, the fractional polynomial was equivalent to original impedance characteristic. The oscillation frequency and the damping level of the given system were calculated by finding the zero point of fitting polynomial, which could analyze quantitatively the stability characteristics of the system. Finally, the correctness and effectiveness of the fractional polynomial fitting criterion were verified by theoretical analysis and time domain simulation.
ISSN:2096-4528