Investigation of phase imbalance characteristics and phase balancing in low voltage distribution networks
University of Bath, 2021
Online
Hochschulschrift
Zugriff:
Phase imbalance, also known as phase unbalance, includes phase voltage imbalance and phase current imbalance. Take voltage imbalance as an example; it refers to the fact that either the voltage magnitudes are not the same or their phase angles are not 120° apart from each other, or both. A similar definition applies to current imbalance. Phase voltage and phase current imbalances will lead to phase power imbalance, which means that the three phases' power flows are not equal to each other. Phase imbalance is a widespread and severe problem in distribution networks, especially in low voltage (415V, LV) distribution networks. It causes energy losses and capacity wastes that lead to high costs. Major causes for this problem are uneven load allocations across the three phases and random load behaviours. Analysing phase imbalances is difficult as only LV substations are equipped with monitoring devices in existing distribution networks in the UK and the monitored data are only collected once a year. Low carbon technologies (LCTs), active customers and new business models in the electrical distribution system add to the complexity; the increased elements and interactions introduce uncertainties to load behaviour, which affects phase imbalances. Understanding phase imbalance in the distribution system helps the distribution network operators (DNOs) to understand phase balancing business cases and design suitable phase balancing solutions. This thesis completed the following tasks and delivered contributions: 1) Developed a new method to decompose the annual three-phase power series into a directional phase imbalance and a non-directional phase imbalance, thus revealing the nature of phase power imbalance. A phase imbalance direction indicates the phase that is heavier or lighter loaded on average compared to the other two phases. A directional phase imbalance can be addressed by phase swapping, which is a relatively cheap solution. A non-directional phase imbalance can only be addressed by online phase balancing, e.g., demand-side management, which is relatively expensive. 2) Developed a new data-driven cost-benefit analysis framework of phase balancing solutions for data-scarce LV networks. The framework uses a customised clusterwise Gaussian process regression (CGPR). The framework serves as an effective tool to assist DNOs to evaluate the cost-benefit of phase balancing solutions for data-scarce networks with no need to invest in additional monitoring devices. 3) Explored the impacts of two different low carbon technologies (LCTs) on phase imbalances through a new Monte Carlo simulation framework. The LCTs considered are single-phase connected electric vehicles and household solar generation. The developed framework helps the DNOs understand the possible imbalance-induced cost for different LCT penetration levels in the LV distribution network.
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Investigation of phase imbalance characteristics and phase balancing in low voltage distribution networks
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Autor/in / Beteiligte Person: | Kong, Wangwei ; Ma, Kang ; Li, Furong |
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Veröffentlichung: | University of Bath, 2021 |
Medientyp: | Hochschulschrift |
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