A low-voltage ride-through control method for grid-connected photovoltaic power generation systems that can provide reactive power support

Abstract

The invention discloses a low-voltage ride through control strategy for a grid-connected photovoltaic power generation system capable of providing the reactive support. The strategy comprises the steps of control over a preceding-stage DC / DC converter and control over a backward-stage grid side inverter. When grid faults occur, the backward-stage grid side inverter is controlled to provide needed reactive power for a power grid according to the voltage drop depth of the power grid; the feed-forward compensation dosage reflecting photovoltaic array output power and direct-current voltage fluctuation is added into a direct-current side voltage control ring of the inverter, and therefore over-voltage of the direct-current side of the inverter is reduced in the fault occurring process; a controller of the preceding-stage DC / DC converter controls a photovoltaic array to output active power according to the voltage drop depth and the rated capacity of the inverter, so that unbalanced energy in a photovoltaic system when the faults occur is reduced, and the purpose of reducing over-current and over-voltage in the photovoltaic system is achieved. According to the strategy, no hardware device is additionally arranged, the response speed is high, realizing is simple, the low-voltage ride through capacity of the photovoltaic system can be effectively improved, the reactive power can be provided for the power grid, and the voltage recovery of the power grid is supported.

Description

technical field [0001] The invention belongs to the field of operation control of a photovoltaic power generation system, and in particular relates to a low-voltage ride-through control method for a grid-connected photovoltaic power generation system that can provide reactive power support. Background technique [0002] In order to reduce the negative impact of large-scale photovoltaic power generation connected to the grid on the reliability of the power system as much as possible, the new grid operation guidelines require that when the grid fails, large and medium-sized grid-connected photovoltaic generators can still maintain non-off-grid operation, After the removal, the photovoltaic unit can quickly resume normal operation, which means that the photovoltaic generator set can realize low-voltage ride-through operation. In order to better defend against severe power grid accidents in terms of voltage and frequency, traditional thermal power units are not only required to ...

AI Technical Summary

Problems solved by technology

However, these control algorithms are usually too complex to be suitable for industrial applications, and most of them do not consider the problem of reactive power support provided by the photovoltaic power generation system to the grid under fault conditions.

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