Grid-connected photovoltaic power generation system and control method thereof

Abstract

The invention discloses a grid-connected photovoltaic power generation system and a control method of the grid-connected photovoltaic power generation system. The system comprises a plurality of photovoltaic cell arrays, a plurality of maximum power point tracking devices correspondingly connected with the photovoltaic cell arrays one to one, a converging unit and a grid-connected inverter. The grid-connected inverter comprises a chopper assembly unit and an inversion unit which are sequentially and electrically connected. The chopper assembly unit comprises a first switching tube and an energy consumption resistor which are connected between direct-current buses of the grid-connected inverter in series, and further comprises an inverter control unit. The grid-connected photovoltaic power generation system and the control method have the advantages that when the voltages of the direct-current buses rise due to the fact that faults such as low voltage ride through and high voltage ride through happen to a power grid, the first switching tube in the chopper assembly unit is controlled to be powered on, releasing is conducted through the energy consumption resistor, and therefore the voltages of the direct-current buses are reduced and made to rapidly return to normal, and reliable running of the whole grid-connected photovoltaic power generation system is ensured.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation systems, and more specifically, to a photovoltaic grid-connected power generation system and a control method thereof. Background technique [0002] In order to improve the efficiency of photovoltaic power generation system, there is a kind of figure 1 In the photovoltaic grid-connected power generation system shown, each photovoltaic cell array branch is connected in series with a maximum power point tracking (MPPT) device, which includes a DC / DC boost circuit. The maximum power point tracking (MPPT) device is scattered and installed in different locations following the power generation components. The output of multiple MPPT devices is sent to the DC input of the grid-connected inverter through long-distance cables or bus bars, and then passed through the grid-connected inverter. The inverter is connected to the grid to output power. Since the maximum power point tracking (MPPT) de...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is that once the faults such as low-voltage ride-through or high-voltage ride-through of the power grid occur in the prior art, the DC bus voltage of the grid-connected inverter is too high and the DC bus overvoltage protection is prone to occur, thereby affecting the entire photovoltaic system. In view of the defects in the reliability of the grid power generation system, a photovoltaic grid-connected power generation system is provided, including several photovoltaic cell arrays, several maximum power point tracking devices connected to the plurality of photovoltaic cell arrays in one-to-one correspondence, a confluence unit, and a grid-connected power generation system. Inverter; each of the plurality of maximum power point tracking devices is connected to the confluence unit, the confluence unit is connected to the grid-connected inverter, and the confluence unit is used for converging multiple channels of direct current Generate a direct current output, and then convert the direct current into alternating current through the grid-connected inverter and then input it into the grid;

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