Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults
Harmonic distortion caused by phase jumps in the phase-locked loop (PLL) during asymmetric faults poses a significant threat to the secure operation of renewable energy grid-connected systems. A harmonic suppression strategy based on Vague set theory is proposed for offshore wind power AC transmissi...
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| author | Yanjiu Zhang Shuxin Tian |
| author_facet | Yanjiu Zhang Shuxin Tian |
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| description | Harmonic distortion caused by phase jumps in the phase-locked loop (PLL) during asymmetric faults poses a significant threat to the secure operation of renewable energy grid-connected systems. A harmonic suppression strategy based on Vague set theory is proposed for offshore wind power AC transmission systems. By employing the three-dimensional membership framework of Vague sets—comprising true, false, and hesitation degrees—phase-locked errors are characterized, and dynamic, real-time PLL proportional-integral (PI) parameters are derived. This approach addresses the inadequacy of harmonic suppression in conventional PLL, where fixed PI parameters limit performance under asymmetric faults. The significance of this research is reflected in the improved power quality of offshore wind power grid integration, the provision of technical solutions supporting efficient clean energy utilization in alignment with “Dual Carbon” objectives, and the introduction of innovative approaches to harmonic suppression in complex grid environments. Firstly, an equivalent circuit model of the offshore wind power AC transmission system is established, and the impact of PLL phase jumps on grid harmonics during asymmetric faults is analyzed in conjunction with PLL locking mechanisms. Secondly, Vague sets are employed to model the phase-locked error interval across three dimensions, enabling adaptive PI parameter tuning to suppress harmonic content during such faults. Finally, time-domain simulations conducted in PSCAD indicate that the proposed Vague set-based control strategy reduces total harmonic distortion (THD) to 1.08%, 1.12%, and 0.97% for single-phase-to-ground, two-phase-to-ground, and two-phase short-circuit faults, respectively. These values correspond to relative reductions of 13.6%, 33.7%, and 80.87% compared to conventional control strategies, thereby confirming the efficacy of the proposed method in minimizing grid-connected harmonic distortions. |
| format | Article |
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| institution | OA Journals |
| issn | 1996-1073 |
| language | English |
| publishDate | 2025-04-01 |
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| spelling | doaj-art-6ddde211391f4e6ab26b66bc2e4a2cb02025-08-20T02:30:46ZengMDPI AGEnergies1996-10732025-04-01189220210.3390/en18092202Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical FaultsYanjiu Zhang0Shuxin Tian1College of Electrical Engineering, Shanghai University of Electric Power, Shanghai 200090, ChinaOffshore Wind Power Research Institute, Shanghai University of Electric Power, Shanghai 200090, ChinaHarmonic distortion caused by phase jumps in the phase-locked loop (PLL) during asymmetric faults poses a significant threat to the secure operation of renewable energy grid-connected systems. A harmonic suppression strategy based on Vague set theory is proposed for offshore wind power AC transmission systems. By employing the three-dimensional membership framework of Vague sets—comprising true, false, and hesitation degrees—phase-locked errors are characterized, and dynamic, real-time PLL proportional-integral (PI) parameters are derived. This approach addresses the inadequacy of harmonic suppression in conventional PLL, where fixed PI parameters limit performance under asymmetric faults. The significance of this research is reflected in the improved power quality of offshore wind power grid integration, the provision of technical solutions supporting efficient clean energy utilization in alignment with “Dual Carbon” objectives, and the introduction of innovative approaches to harmonic suppression in complex grid environments. Firstly, an equivalent circuit model of the offshore wind power AC transmission system is established, and the impact of PLL phase jumps on grid harmonics during asymmetric faults is analyzed in conjunction with PLL locking mechanisms. Secondly, Vague sets are employed to model the phase-locked error interval across three dimensions, enabling adaptive PI parameter tuning to suppress harmonic content during such faults. Finally, time-domain simulations conducted in PSCAD indicate that the proposed Vague set-based control strategy reduces total harmonic distortion (THD) to 1.08%, 1.12%, and 0.97% for single-phase-to-ground, two-phase-to-ground, and two-phase short-circuit faults, respectively. These values correspond to relative reductions of 13.6%, 33.7%, and 80.87% compared to conventional control strategies, thereby confirming the efficacy of the proposed method in minimizing grid-connected harmonic distortions.https://www.mdpi.com/1996-1073/18/9/2202asymmetric faultsvague setinterval controlharmonic content |
| spellingShingle | Yanjiu Zhang Shuxin Tian Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults Energies asymmetric faults vague set interval control harmonic content |
| title | Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults |
| title_full | Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults |
| title_fullStr | Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults |
| title_full_unstemmed | Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults |
| title_short | Grid-Connected Harmonic Suppression Strategy Considering Phase-Locked Loop Phase-Locking Error Under Asymmetrical Faults |
| title_sort | grid connected harmonic suppression strategy considering phase locked loop phase locking error under asymmetrical faults |
| topic | asymmetric faults vague set interval control harmonic content |
| url | https://www.mdpi.com/1996-1073/18/9/2202 |
| work_keys_str_mv | AT yanjiuzhang gridconnectedharmonicsuppressionstrategyconsideringphaselockedloopphaselockingerrorunderasymmetricalfaults AT shuxintian gridconnectedharmonicsuppressionstrategyconsideringphaselockedloopphaselockingerrorunderasymmetricalfaults |