Medium-voltage photovoltaic grid-connected inverter system and photovoltaic power generation system

Abstract

The invention discloses a medium-voltage photovoltaic grid-connected inverter system and a photovoltaic power generation system. The medium-voltage photovoltaic grid-connected inverter system comprises a photovoltaic inverter of which the DC input end is connected with a DC bus; a medium-voltage transformer of which the low-voltage side is connected with the alternating-current output end of the photovoltaic inverter; a medium-voltage switch which has an input terminal connected with the high-voltage side of the medium-voltage transformer and an output terminal used for being connected into amedium-voltage power grid and is internally integrated with a current sensor so as to detect the grid-connected current of the medium-voltage photovoltaic grid-connected inverter system and output a current detection signal; and an inverter grid-connected controller which is connected with the controlled end and the current output end of the medium-voltage switch, and is used for, when receiving agrid-connected instruction, determining that the grid-connected current of the medium-voltage photovoltaic grid-connected inverter system is greater than a preset current threshold according to the current detection signal, controlling the photovoltaic inverter to stop and / or controlling the medium-voltage switch to open.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a medium-voltage photovoltaic grid-connected inverter system and a photovoltaic power generation system. Background technique [0002] Existing technical solutions, such as "A Photovoltaic Grid-connected Inverter System and Photovoltaic Power Generation System Using It", usually connect the medium-voltage grid-connected contactor between the high-voltage side of the step-up transformer and the medium-voltage grid, and connect the grid The two detection ports of the voltage detection circuit are respectively connected to the two ends of the medium-voltage grid-connected contactor, and the voltage detection results at both ends of the medium-voltage contactor are output to the first control circuit. The DC voltage detection circuit detects the DC voltage UDC and outputs the result to the first and second control circuits. The grid-connected current detection ...

AI Technical Summary

Problems solved by technology

The existing technical solution realizes the medium voltage disconnection / grid connection of the photovoltaic inverter system by controlling the opening / closing of the medium voltage grid contactor, but its disadvantage is that an external current detection circuit is required in the system to detect the grid connection current, expanding the installation space and cost of the equipment

In addition, the current detection circuit is located on the low-voltage side, so it cannot detect the short circuit on the medium-voltage side before grid connection

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