Photovoltaic grid-connected power generation device based on multilevel technique

Abstract

The invention discloses a photovoltaic grid-connected power generation device based on a multilevel technique. The photovoltaic grid-connected power generation device comprises a photovoltaic power input unit, a direct-current bus capacitor unit, a three-phase square wave inverter unit, a transformer unit and an output filter reactor unit, wherein the photovoltaic power input unit consists of N groups of photovoltaic cell arrays and direct-current / direct-current (DC / DC) converters which realize maximum power point tracking and step-up functions; the direct-current bus capacitor unit realizes direct-current bus voltage supporting and alternating-current and direct-current energy decoupling functions; and the direct-current / alternating-current (DC / AC) conversion of the three-phase square wave inverter unit adopts a square wave superposition multilevel technique, the transformer unit is used for synthesizing the output voltage of the three-phase square wave inverter unit, unit power factor control and low distortion rate of grid-connected current are realized through the output filter reactor unit, and the islanding protection of the photovoltaic grid-connected power generation device is realized through the combination of detection voltage, detection frequency and reactive power disturbance. Therefore, the photovoltaic grid-connected power generation device can be used for high-voltage high-capacity photovoltaic grid-connected power generation systems.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic grid-connected power generation, and in particular relates to a photovoltaic grid-connected power generation device suitable for high voltage and large capacity based on square wave superposition multiplexing technology. Background technique [0002] The development of new energy and renewable energy has already become the consensus of all countries in the world. In the foreseeable future, photovoltaic power generation will gradually realize extremely large-scale development and utilization, with a capacity ranging from 10MW to several GW. So far, there are two main types of high-voltage and large-capacity photovoltaic grid-connected power generation devices for industrial applications: [0003] Option 1: Single-stage photovoltaic grid-connected power generation device, which consists of multiple photovoltaic subsystems connected in parallel. Each photovoltaic subsystem includes photovoltaic...

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Problems solved by technology

[0005] Considering the three aspects of efficiency, power quality and reliability, when the above two types of schemes are applied to photovoltaic grid-connected power generation systems with a grid-connected voltage of 10-35kV and a capacity of 10MW or more, it is difficult to achieve comprehensive performance optimization.

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