A control strategy with complex-coefficient filter to suppress SVG-DFIG sub-synchronous oscillation

Abstract

The rapid expansion of wind power integration has intensified the stability issues in power systems. Static var generators (SVGs) are commonly used to maintain voltage balance and provide reactive power compensation for doubly-fed induction generator (DFIG) wind farms. However, conventional SVG control lacks targeted inter-harmonic compensation capability, which limits its effectiveness in dynamically suppressing sub-synchronous oscillations (SSOs). To address this problem, this paper proposes a novel control strategy based on a complex-coefficient filter (CCF). Leveraging the high-precision filtering capability of the CCF, this strategy fully utilizes the harmonic signals of SSOs, enabling the SVG to dynamically suppress SSOs. To thoroughly investigate the suppression mechanism, a frequency-domain impedance model of the DFIG system incorporating an SVG is first established, and the possibility of SSO occurrence is verified using the Nyquist stability criterion. Subsequently, a topological structure of the CCF suitable for three-phase systems is proposed, and its superior performance in oscillation suppression is analyzed. Finally, through MATLAB/Simulink simulations, the accuracy of the theoretical analysis and the excellent effectiveness of the proposed strategy in eliminating SSOs are verified.

Keywords

doubly-fed induction generator static var generator sub-synchronous oscillation complex-coefficient filter oscillation suppression

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