Abstract
With the popularization of electric private cars and the increase of charging facilities in residential areas, disorderly charging will affect the power supply efficiency of their distribution transformers and the quality of electricity used by users in residential areas. In severe cases, it may even cause vibration of the power grid, causing serious three-phase imbalance problems such as single-phase burnout of transformers or insulation breakdown of household appliances. This paper analyzes the influencing factors of the unbalanced operation of each phase of the distribution transformer and the electrical load characteristics of typical residential areas. Based on the photovoltaic output of the station area, the charging and discharging capacity of the energy storage system, and the orderly charging plan of residential electric vehicles, a local orderly charging strategy for electric vehicles based on energy routers under the three-phase balance of the residential area is proposed. This strategy can realize the three-phase balance control of the distribution transformer. The effectiveness of the method is verified by a typical scenario example. The control method is changed to minimize the three-phase imbalance in residential areas and improve the low utilization rate of the distribution network and the comprehensive utilization efficiency of adjustable resources in residential areas.
Highlights
In recent years, as the depletion of petroleum resources, environmental pollution, global warming, and other issues have become increasingly prominent, energy conservation and emission reduction will be the direction of future industrial development, and photovoltaic and other renewable energy power generation and electric vehicles have been vigorously promoted [1,2]
In 2021, domestic private car-mounted charging piles will increase by 426,000 units, public AC charging piles will increase by 252,000 units, public DC charging piles will increase by 111,000 units, and charging stations will increase by 21,100 units
When electric vehicles are connected to the distribution network as a new type of load, due to the large uncertainty in their temporal and spatial distribution, the phenomenon of simultaneous charging may occur in a certain period of time in a local area [3]
Summary
As the depletion of petroleum resources, environmental pollution, global warming, and other issues have become increasingly prominent, energy conservation and emission reduction will be the direction of future industrial development, and photovoltaic and other renewable energy power generation and electric vehicles have been vigorously promoted [1,2]. Coupled with the continuous increase in the penetration rate of residential users of electric vehicles and the high overlap between the charging period and the peak power consumption [9], the problem of load three-phase imbalance has become more serious. Reference [17] analyzed the serious problems caused by disordered charging and studied the impact of electric vehicles on the three-phase imbalance of the distribution network under different penetration rates. Reference [18] proposed a novel unbalanced active distribution network electric vehicle orderly charging control strategy based on inverter’s reactive power injection and three-phase selection, which realized the optimization of the grid’s operation within 24 h. D ing the low hours of the morning, the load is below 200 kVA, which can accommo multiple electric vehicles charging at the same time
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