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This paper presents a detailed analysis of PLL structures for utility connected systems. The three-phase PLL (Phase-Locked Loop) structure capable of fast tracking the utility voltage vector is studied. A single-phase PLL structure, derived from the three-phase PLL topology, is discussed and its behavior under distorted utility conditions is analyzed. Additionally, the conventional zero-crossing PLL is studied and an alternative implementation for this PLL is proposed in order to improve its dynamic behavior. Simulation and experimental results from a DSP-based system are included to support the theoretical analysis.

ReuseThis article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can't change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.Multi-objective energy storage power dispatching using plug-in vehicles in a smart-microgrid is beneficial for the environment, since they are going to be used when needed. 88The proposed model also tries to obtain energy storage planning scenarios which 89 minimize maximum power flow between the smart-microgrid and the main grid. 90The two latter objectives evaluate the schedule compared to its extreme scenar- 91ios and also to a wide range of possible scenarios. This is done by measuring 92 the current expected cost compared to other possible costs using Sharpe Ratio the Branch and Bound (BB) optimization tree. 147The major contributions of the current work are: forecasts in order to test best-case and worst-case energy storage scenarios; 152• A novel multi-objective power dispatching problem. 153The remainder of this paper is organized as follows. Section 2 describes the 154 microgrid scenario. Section 3 describes, in detail, the proposed energy storage 155 management framework. Section 4 presents the computational experiments, 156and, finally, Section 5 details our final conclusions and future work.

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Insulation failures are among the most important problems affecting electric machines. Although standard procedures are widely used to assess the insulation condition of these machines, no alternative is available to allow the identification of the stress agents affecting the insulation system. Another limitation of the standard procedures is the fact that they are based on tests that require the interruption of the operation of the machine. This study presents a technique that allows the online assessment and protection of the insulation of low-and medium-voltage electric machines, along with the identification of the stress agents responsible for the degradation of the insulation. The proposed technique is based on the use of a highly sensitive current transformer, an algorithm to identify the most affected phase, and an artificial neural network to indicate the stress agent affecting the machine. The presented experimental results show that the proposed system can identify thermal degradation, moisture absorption and contamination by oil. The low current levels that can be measured by the developed system enable the application of the proposed technique to low-and medium-voltage machines.