Tunning of Phase Locked Loops for Power Converters under Distorted Utility Conditions

Freijedo, F.D., Doval-Gandoy, J., Lopez, O. and Acha, E. (2009) Tunning of Phase Locked Loops for Power Converters under Distorted Utility Conditions. In: IEEE Applied Power Electronics Conference and Exposition. APEC 2009. Twenty-Fourth Annual IEEE, Washington, DC, USA, 15-19 February 2009, (doi: 10.1109/APEC.2009.4802904)

Abstract

This paper presents a novel approach in the tuning of phase-locked loops (PLLs) for power electronic converters. PLLs are implemented inside a higher level controller to estimate the grid-voltage phase angle and then control the energy transfer between the power converter and the AC mains. The tuning of the PLL is not a trivial task, particularly when considering power-quality phenomena. In a general way, PLLs with a low bandwidth (low-gain PLLs) are required when handling distorted voltages. It is analytically demonstrated in this paper that low-gain PLLs have more tradeoffs than high-gain PLLs (e.g., PLLs for communications); it is not possible to optimize the settling time for a phase jump without making slower the PLL response to frequency variations. Existing tuning methods do not take into account low-gain features, which may result in nonoptimum designs. The proposed PLL tuning methodology is based on inspection of frequency-domain diagrams and, contrary to the other existing tuning methods, takes into account ldquolow-gainrdquo dynamics. It assures an optimized performance in the presence of any kind of disturbances in the grid. From a practical point of view, the proposed tuning procedure is very intuitive for controller designs. Some significant design examples and experimental results, obtained from a discrete implementation (dSpace platform), are provided in order to validate the theoretical approaches.

• Item Type: Conference Proceedings
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Acha, Prof Enrique
• Authors: Freijedo, F.D., Doval-Gandoy, J., Lopez, O., and Acha, E.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering