Enhanced Electric Vehicle Integration in the UK Low-Voltage Networks With Distributed Phase Shifting Control

Abstract

Electric vehicles (EV) have gained global attention due to increasing oil prices and rising concerns about transportation-related urban air pollution and climate change. While mass adoption of EVs has several economic and environmental benefits, large-scale deployment of EVs on the low-voltage (LV) urban distribution networks will also result in technical challenges. This paper proposes a simple and easy to implement single-phase EV charging coordination strategy with three-phase network supply, in which chargers connect EVs to the less loaded phase of their feeder at the beginning of the charging process. Hence, network unbalance is mitigated and, as a result, EV hosting capacity is increased. A new concept, called Maximum EV Hosting Capacity (HC max ) of low voltage distribution networks, is introduced to objectively assess and quantify the enhancement that the proposed phase-shifting strategy could bring to distribution networks. The resulting performance improvement has been demonstrated over three real UK residential networks through a comprehensive Monte Carlo simulation study using Matlab and OpenDSS tools. With the same EV penetration level, the under-voltage probability was reduced in the first network from 100% to 54% and in the second network from 100% to 48%. Furthermore, percentage voltage unbalance factors in the networks were successfully restored to their original values before any EV connection.INDEX TERMS Charging management, electric vehicles, low voltage networks, voltage unbalance.

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

“…F. Shahnia et al developed a control method for single-phase PV converters to provide reactive power support, thus reducing voltage unbalance [65]. E. Vega-Fluentes et al developed a coordination strategy for singlephase EV charging with three-phase power supply: when charging starts, chargers connect EVs to the lightly loaded phase of their feeder [66]. This would reduce unbalanceinduced consequences and increases the network capacity to host EVs.…”

“…Space limit in MV/LV distribution substations Use small-sized phase balancers 3. Control energy storage, EVs, DG, and micro-grids [60], [61], [62], [22], [63], [64], [65], [66] Adaptive; no new phase balancer required Costs of implementation, operation, and maintenance; scalability issue when applied to millions of LV networks Use mature and low-cost technologies for control and communication. Perform automatic control phase unbalance degree for years into the future.…”

Review of Distribution Network Phase Imbalance: Scale, Consequences, Solutions, and Future Research Direction

“…F. Shahnia et al developed a control method for single-phase PV converters to provide reactive power support, thus reducing voltage imbalance [61]. E. Vega-Fluentes et al developed a coordination strategy for singlephase EV charging with three-phase power supply: when charging starts, chargers connect EVs to the lightly loaded phase of their feeder [62]. This would reduce imbalanceinduced consequences and increases the network capacity to host EVs.…”

“…Space limit in MV/LV distribution substations Use small-sized phase balancers 3. Control energy storage, EVs, DG, and micro-grids [56], [57], [58], [22], [59], [60], [61], [62] Adaptive; no new phase balancer required Costs of implementation, operation, and maintenance; scalability issue when applied to millions of LV networks Use mature and low-cost technologies for control and communication. Perform automatic control paper suggests the following directions that will address the scalability, data-scarcity, and adaptability challenges arising from phase rebalancing: 1) use retrofit-able, maintenance-free, automatic solutions to overcome the scalability challenge; 2) use data analytics to overcome the data-scarcity challenge by extrapolating knowledge to data-scarce networks; and 3) use phase balancers or other online phase rebalancing solutions to overcome the adaptability challenge.…”

Capacity Enhancement of a Radial Distribution Grid Using Smart Transformer

“…The penetration of distributed generation (DG) sources and electric vehicles (EVs) are increasing rapidly in the modern power system [1], [2]. Accommodating the additional load/generation in the exiting feeders without violating the grid-code specified power quality limits is a major challenge.…”