Abstract
Series compensations have been widely used in modern power systems to extend the power transfer capacity. Since more and more renewable power generation systems are installed in power systems, the grid-connected inverters (GCIs) used by the renewable power generations may interfere with series-compensated power lines, which introduce subsynchronous resonance (SSR) causing power system failure that has been observed in real cases. The phase-locked loop (PLL) of the GCI's control system is the main factor that can cause the SSR in the series-compensated power grid. To mitigate the impact of the PLL and obtain the stable operation of the power system, a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage feedback method has been proposed in literature to damp the harmonic oscillations in the weak power grid where, however, the series compensation is not considered. Because the real <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage cannot be obtained, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage output from the PLL is used as the feedback variable in literature. However, due to the dynamic response of the PLL, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage output from the PLL is different from the real <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage, and the direct use of it for the damping of the SSR in the power grid with series compensations is invalid, which is investigated in this article. Besides, an observed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage feedback method is proposed in this article to damp the SSR in the series-compensated power grid with GCIs being connected. By putting an observer in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage feedback path, the real <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage can be estimated and applied to damp the SSR. Simulation and experimental results have been provided to verify the effectiveness of the proposed observed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis voltage feedback method in the damping of the SSR.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
