Photovoltaic power generation high-voltage DC transmission device and method thereof

Abstract

The invention discloses a photovoltaic power generation high-voltage DC transmission device and a method thereof. The photovoltaic power generation high-voltage DC transmission device comprises a plurality of photovoltaic units which are connected in series, a plurality of DC-DC converters, a plurality of energy storage units, a plurality of first local controllers, a second local controller and acentral controller. The serially connected photovoltaic units are in circuit connection with the input end of a high-voltage grid-connected inverter. The output end of the high-voltage grid-connectedinverter is connected with an AC power grid. The input ends of the plurality of DC-DC converters are connected with the output ends of the photovoltaic units in the one-to-one correspondence mode. The plurality of energy storage units are connected with the output ends of the plurality of DC-DC converters in the one-to-one correspondence mode. The plurality of first local controllers are connected with the control ends of the plurality of DC-DC converters in the one-to-one correspondence mode. The first local controllers are used for controlling each photovoltaic unit to run at a maximum power point thereof under the preset current of a high-voltage bus. The second local controller is connected with the control end of the high-voltage grid-connected inverter. According to the invention, the DC-DC converters are not directly connected with a high-voltage DC bus, so that the cost is reduced. The power generation efficiency is improved. Meanwhile, the generation of the hot spot phenomenon is avoided as much as possible.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation high-voltage direct current transmission device and a method thereof. Background technique [0002] New energy is an important part of the energy supply system. Large-scale development of new energy has become the core content of many countries' promotion of energy transition and an important way to deal with climate change. The low-voltage distribution network has limited ability to accept new energy, so direct access to the high-voltage power grid will become an inevitable trend for large-scale new energy grid-connected power generation. Due to the low output voltage of a single photovoltaic unit, in order to realize its high-voltage grid connection, it is usually necessary to use photovoltaic units in series to increase the voltage level of the photovoltaic power generation system. [0003] At present, DC-DC converters ar...

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Problems solved by technology

[0004] However, in this way, since the DC-DC converter is directly connected to the high-voltage DC bus, the withstand voltage level of all DC-DC converters must be higher than the voltage of the high-voltage DC bus, resulting in a substantial increase in the cost of the photovoltaic power generation system

Due to the high cost, it is impossible to configure a parallel DC-DC converter for each photovoltaic unit, then the currents of several series photovoltaic units controlled by the same DC-DC converter are equal, so in the case of partial shading, facing these photovoltaic units The units cannot work equally from the maximum power point, the power generation efficiency is low, and hot spot phenomenon occurs, causing damage to photovoltaic units, etc.

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