Group control method, device and system, photovoltaic inverter and photovoltaic system

Abstract

The invention discloses a group control method, device and system, a photovoltaic inverter and a photovoltaic system. An inverter unit group control method under a weak light condition comprises the following steps: acquiring input voltage parameters of each inverter unit in a multi-path MPPT (Maximum Power Point Tracking) photovoltaic inverter; adjusting the running states of the inverter units until reaching the same input voltage, wherein the input voltage is determined by the input voltage parameter; controlling DC contactors which are bridged at the DC sides of every two adjacent inverter units to be closed; controlling some of the inverter units to be stopped and the rest inverter units to be worked in the position with the maximum power, so as to raise the utilization rate of photovoltaic energy of the multi-path MPPT photovoltaic inverter and lower down the sudden change of the output power of the inverter when the DC contactor is disconnected and connected on the premise that high conversion efficiency of the multi-path MPPT photovoltaic inverter is ensured.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, and more specifically, to a group control method, a group controller, a group control system, a photovoltaic inverter and a photovoltaic system. Background technique [0002] The photovoltaic inverter is an energy conversion device in the photovoltaic grid-connected power generation system, which is used to convert the direct current output by the photovoltaic array into alternating current and then send it to the grid. figure 1 It shows a multi-channel MPPT (Maxmum Power Pont Trackng, maximum power point tracking) photovoltaic inverter, which uses a plurality of independently operable inverter units, and the DC sides of two adjacent inverter units are connected across the DC contactor. Its working principle is to disconnect the DC contactor when the light is strong, and each inverter unit operates independently to track its maximum power point; when the light is weak, clos...

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Problems solved by technology

[0003] However, since the DC contactor is easily damaged under a large inrush current and does not have the ability to break the reverse current, before closing or disconnecting the DC contactor, it is necessary to stop the inverter units on both sides first, and wait until the DC contactor is closed Then control some inverter units to restart and track the maximum power point

However, the shutdown of the inverter unit will inevitably cause a sudden change in the output power of the inverter, which will interfere with the stability of the grid voltage, and the process of restarting the inverter unit after shutdown and re-tracking the maximum power point is relatively slow. Photovoltaic energy can only be wasted during the period

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