Photovoltaic energy storage system in DC distribution network and its operation control method

Abstract

The invention relates to a photovoltaic energy storage system in a DC power distribution network and an operation control method thereof, and belongs to the technical field of power electronics. The system comprises the DC power distribution network, a photovoltaic power station module, a limited energy storage module, a grid connection module and a main control module. The grid connection module enables the photovoltaic power station module and the energy storage module, which are connected to a low-voltage DC bus, to be connected to a medium-voltage DC bus in the DC power distribution network; and the grid connection module comprises a DC solid-state transformer and a third DC circuit breaker. The main control module is used for finishing general communication control, maximum power point tracking MPPT of the photovoltaic power station module, charge and discharge control of the energy storage module, control of the grid connection module and on-off control of a photovoltaic energy storage system in the DC power distribution network. Through the system and the specific method, the problem of grid connection of a small / middle-power-level photovoltaic grid-connected power generation system is solved, photovoltaic utilization rate is improved, and the phenomenon of "photovoltaic power abandonment" is reduced.

Description

technical field [0001] The invention relates to a photovoltaic energy storage system in a DC distribution network and an operation control method thereof, belonging to the technical field of power electronics. Background technique [0002] The traditional AC distribution network is facing many severe challenges such as insufficient power supply capacity, continuous improvement of user requirements for power quality and power supply reliability, and distributed power access. Flexible DC distribution network has better performance than AC distribution system in terms of transmission capacity, controllability, power quality and power supply reliability. Flexible DC distribution network has received extensive attention and research. [0003] Due to the influence of natural factors such as light intensity and temperature, the active output of photovoltaic power sources in power stations has large fluctuations, so direct grid-connected operation will cause a series of problems, s...

AI Technical Summary

Problems solved by technology

[0004] A simple combination of energy storage devices and photovoltaics cannot fundamentally solve the problem. When the requirements for grid connection cannot be met, the problem of voltage stability on the grid side will be solved by "abandoning light", resulting in a large area of ​​"abandoning light". "Abandoning light" refers to abandoning the photovoltaic power that does not meet the grid-connected requirements, and directly abandoning the use of this part of the energy, resulting in energy waste

Therefore, a simple combination of energy storage devices and photovoltaics cannot achieve sufficient or improved utilization of photovoltaics.

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