Pre-filtered synchronization structure for grid-connected power converters to reduce the stability impact of PLL dynamics
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Rights accessOpen Access
Grid-connected converters under weak grid conditions could present instability associated with the synchronization elements and not directly with the current control loop. The impedance-based stability criterion is an effective tool to address the problem. To solve the negative effect of the synchronous reference frame phase-locked loop (SRF-PLL) on grid current control under weak grid conditions, a synchronization structure with pre-filter, based on a filtered quadrature signal generator (FQSG), is proposed in this paper to improve the dynamics of the controller's performance. The small-signal impedance model, implemented as a multi-input multi-output system in the dq-frame, characterizes the effect of the FQSG-PLL dynamics on the current control loop. From it, the impedance-based analysis shows the reduction of the stability issues of the converter. The analysis results were verified by time-domain simulations and by experimental tests in a full-scale 2 MW converter test-bench.
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CitationGarcia, I.; Candela, J.; Catalan, P. Pre-filtered synchronization structure for grid-connected power converters to reduce the stability impact of PLL dynamics. "IEEE Journal of emerging and selected topics in power electronics", 2020, p. 1-9.
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