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dc.contributor.advisorDjokic, Sasaen
dc.contributor.advisorMacpherson, Ewenen
dc.contributor.authorXu, Xiaoen
dc.date.accessioned2018-10-16T09:57:19Z
dc.date.available2018-10-16T09:57:19Z
dc.date.issued2018-11-29
dc.identifier.urihttp://hdl.handle.net/1842/33106
dc.description.abstractAlthough the overall levels of harmonics in modern power supply systems are in most of the practical cases still below the prescribed tolerance limits and thresholds (e.g. these stipulated in [IEC 61000-3-2 and 61000-3-12]), the sources of harmonics are constantly increasing in numbers and are expected to increase even more in the future. Some of the examples of modern non-linear power electronic (PE) devices that are expected to be employed on a much wider scale in LV networks in the future include: light-emitting diode (LED) lamps, switched-mode power supplies (SMPS’), electric vehicle battery chargers (EVBCs) and photovoltaic inverters (PVIs), which are all analysed in this thesis. The thesis first reviews the conventional harmonic analysis methods, investigating their applicability to modern PE devices. After that, the two most widely used forms of harmonic models, i.e. component-based models (CBMs) and frequency-domain models (FDMs), are applied for modelling of the four abovementioned types of modern PE devices and their models are fully validated by measurements. The thesis next investigates the impact of supply voltage conditions and operating modes (e.g. low vs high operating powers) on the device characteristics and performance, using both measurements and developed CBMs and FDMs. The obtained results confirm that both supply conditions and operating modes have an impact on the characteristics of most of the considered PE devices, which is taken into account in the developed models and demonstrated on a number of case studies. As the next contribution, the thesis proposes new indices for the evaluation of current waveform distortions, allowing for a separate analysis of contributions of low and high frequency harmonics and interharmonics to the total waveform distortion of PE devices. As the modern PE devices are normally based on high-frequency switching converters or inverters, the impact of circuit topologies and control algorithms on their harmonic emission characteristics and performance is also investigated. Special attention is given to the operation of PE devices at low powers, when there is a significant increase of current waveform distortion, a substantial decrease of efficiency and power factors and when input ac current might lose its periodicity with the supply voltage frequency. This is analysed in detail for SMPS’, resulting in the proposal of a new methodology (“operating cycle based method”) for evaluating overall performance of PE devices across the entire range of operating powers. Finally, a novel and simple hybrid harmonic modelling technique, allowing for the use of both time-domain and frequency-domain models in the same simulation environment, is proposed and illustrated on the selected case studies. This is accompanied with a frequency-domain aggregation approach, which is applied in the thesis to investigate the impact of increasing numbers of different types of modern PE devices on the LV network. The implementation of the developed hybrid harmonic modelling approach and frequency-domain aggregation technique is demonstrated on the example of a typical (UK) urban generic LV distribution network and used for the analysis of different deployment levels of EVs and PVIs. The presented harmonic modelling framework for individual PE devices and, particularly, for their aggregate models, fills the gap in the existing literature on harmonic modelling and characterisation of modern PE devices, which is important for the correct evaluation of their harmonic interactions and analysis of the impact of their large-scale deployment on the overall network performance.en
dc.language.isoen
dc.publisherThe University of Edinburghen
dc.relation.hasversionX. Xu, A. J. Collin, S. Z. Djokic, S. Yanchenko, F. Möller, J. Meyer, R. Langella and A. Testa, “Analysis and Modelling of Power-Dependent Harmonic Characteristics of Modern PE Devices in LV Networks,” IEEE Trans. on Power Delivery, vol. 32, no. 2, pp. 1014-1023, Apr. 2017.en
dc.relation.hasversionX. Xu, A. Collin, S. Djokic, R. Langella, and A. Testa, “Operating Cycle Performance, Lost Periodicity and Waveform Distortion of Switch-Mode Power Supplies,” IEEE Trans. on Instr. and Measurement, vol. 67, no. 10, pp. 2434- 2443, Oct. 2018.en
dc.relation.hasversionS. Djokic, R. Langella, J. Meyer, R. Stiegler, A. Testa and X. Xu, “On Evaluation of Power Electronic Devices’ Efficiency for Nonsinusoidal Voltage Supply and Different Operating Powers,” IEEE Trans. on Instr. and Measurement, vol. 66, no. 9, pp. 2216-2224, Sept. 2017.en
dc.relation.hasversionX. Xu, A. Collin, S. Z. Djokic, R. Langella, A. Testa and J. Drapela, “Experimental evaluation and classification of LED lamps for typical residential applications,” 2017 IEEE PES Innovative Smart Grid Technologies Conf. Europe (ISGT-Europe), Torino, pp. 1-6, Sept. 2017.en
dc.relation.hasversionX. Xu, S. Djokic, R. Langella and A. Testa, “Performance comparison of three main SMPS types under sinusoidal and distorted supply voltage,” 2017 IEEE Manchester PowerTech, Manchester, pp. 1-6, Jun. 2017.en
dc.relation.hasversionX. Xu, S. Djokic, R. Langella and A. Testa, “Impact of Lost Periodicity on Efficiency and Current Waveform Distortion of SMPS',” 2017 IEEE Int. Workshop on Applied Measurements for Power Systems (AMPS), Liverpool, pp. 1-6, Sept. 2017.en
dc.relation.hasversionA. J. Collin, X. Xu, S. Z. Djokic, F. Möller, J. Meyer, L. Kutt and M. Lehtonen, “Survey of harmonic emission of electrical vehicle chargers in the European market,” 2016 Int. Symp. on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), Anacapri, pp. 1208-1213, Jun. 2016.en
dc.relation.hasversionX. Xu, H. Molin, P. Kourtza, A. Collin, G. Harrison, S. Djokic, J. Meyer, S. Müller and F. Möller, “Component-based modelling of EV battery chargers,” 2015 IEEE Eindhoven PowerTech, Eindhoven, pp. 1-6, Jul. 2015.en
dc.relation.hasversionJ. Meyer, S. Müller, P. Schegner, S. Z. Djokic, A. J. Collin and X. Xu, “Comparison of methods for modelling electric vehicle chargers for harmonic studies,” 2016 Power Systems Computation Conf. (PSCC), Genoa, pp. 1-7, Aug. 2016.en
dc.relation.hasversionX. Xu, A. J. Collin, S. Z. Djokic, R. Langella, A. Testa, J. Meyer and F. Möller, “Harmonic emission of PV inverters under different voltage supply conditions and operating powers,” 17th Int. Conf. on Harmonics and Quality of Power (ICHQP), Belo Horizonte, pp. 373-378, 2016.en
dc.relation.hasversionX. Xu, A. Collin, S. Djokic, S. Müller, J. Meyer, J. Myrzik, R. Langella and A. Testa, “Aggregate Harmonic Fingerprint Models of PV Inverters. Part 1: Operation at Different Powers,” 18th Int. Conf. on Harm. and Quality of Power (ICHQP), Ljubljana, pp. 1-6, 2018.en
dc.subjectharmonic analysis methodsen
dc.subjectcomponent-based modelsen
dc.subjectfrequency-domain modelsen
dc.subjectwaveform distortionsen
dc.subjecthybrid harmonic modelling techniqueen
dc.subjectnetwork performanceen
dc.titleHarmonic modelling and characterisation of modern power electronic devices in low voltage networksen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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