Quick charging station system with energy storage device

Abstract

The invention discloses a quick charging station system with an energy storage device. The system is characterized by comprising a flywheel, a bidirectional AC / DC unit, a DC bus, a bidirectional DC / AC unit, a power grid, a quick charging unit, a bidirectional DC / DC unit and a storage battery; the flywheel is connected with the bidirectional AC / DC unit; the bidirectional AC / DC unit is connected with the DC bus; the storage battery is connected with the bidirectional DC / DC unit; the bidirectional DC / DC unit is connected with the DC bus; the power grid is connected with the bidirectional DC / AC unit; the bidirectional DC / AC unit is connected with the DC bus; the DC bus is connected with the quick charging unit; and the quick charging unit is composed of a plurality of DC chargers. According to the quick charging station system with the energy storage device of the invention, a double-closed-loop control system containing power feed-forward and a control system for suppressing the negative influence of a phase-locked loop are designed, the defects of a grid-connected charging control method in the aspect of voltage stability control are overcome, and the stability of the phase-locked loop in a weak power grid environment is also improved.

Description

technical field [0001] The invention belongs to the technical field of power electronics application, and in particular relates to a fast charging station system including an energy storage device. Background technique [0002] The rapid development of electric vehicles in China has given birth to the prosperity of related industries, which has led to the rapid expansion and technological upgrading of electric vehicle charging facilities. For internal commuting, users are more willing to choose to drive fuel vehicles instead of electric vehicles on intercity expressways. [0003] There are many reasons for this phenomenon, the main reasons are as follows: (1) The charging speed of fast charging devices on expressways is still not satisfactory, which is the main reason why users are unwilling to drive electric vehicles on expressways. The average fast charging time is 4-5 times the average time for fuel vehicles to refuel. Although the current technical means can greatly inc...

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Problems solved by technology

[0003] There are many reasons for this phenomenon, the main reasons are as follows: (1) The charging speed of fast charging devices on expressways is still not satisfactory, which is the main reason why users are unwilling to drive electric vehicles on expressways. The average fast charging time is 4-5 times the average time for fuel vehicles to refuel. Although the current technical means can greatly increase the charging power, most expressway fast charging stations in China are located in rural and suburban areas with weak grid structures. In grid areas, high-power and fast-changing charging loads will inevitably have an impact on the weak grid, causing large fluctuations in frequency and voltage. Therefore, it is necessary to implement more effective control methods for the grid to improve system reliability. When the load is charging , because when the fast charging load power change rate is too large, adding an energy storage device can play a buffer role, but the traditional control strategy cannot solve the problem of the bus voltage drop of the DC charging pile well, so the control strategy during charging It is necessary to carry out relevant optimization; (2) The utilization efficiency of intercity fast charging stations is low. At present, most of the charging stations that only realize income by charging electricity fees and charging service fees are in a state of loss, which limits the promotion of fast charging technology. At this time, if the energy storage device in the station is used to feed power to the grid during idle hours, additional income can be increased, but grid-connected power feeding in a weak grid environment will also cause the following problems: When the energy storage device in the charging station feeds power to the system, It can be equivalent to the grid-connected inverter model under the weak grid, and the research shows that the phase-locked loop has negative effects such as frequency coupling and stability reduction on the inverter feed of the converter under the weak grid condition, and the weak grid environment needs to be considered The Influence of Power Station Converter's Inversion Working State on the System During Power Feed

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