A method for starting a photovoltaic inverter

Abstract

The invention discloses a photovoltaic inverter starting method and relates to the technical field of photovoltaic power generation. The method comprises the steps of a photovoltaic inverter enteringa waiting state and executing the waiting operation, after an auxiliary power supply is started, enabling the photovoltaic inverter to enter a sleep mode through an MPPT algorithm, turning off the driving in the photovoltaic inverter, wakening up photovoltaic inverter every preset time interval through the MPPT algorithm, opening the driving in the photovoltaic inverter, detecting whether the power change amount of the output power of the photovoltaic inverter reaches a variation threshold value or not, starting normal power generation if the power change amount reaches the change amount threshold value, and executing the MPPT algorithm to track the output power of the photovoltaic inverter. The method greatly reduces the number of times that the photovoltaic inverter is restarted due to low energy when the photovoltaic inverter is started in a weak light environment, so that the machine is protected.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a method for starting a photovoltaic inverter. Background technique [0002] Photovoltaic inverter is a power adjustment device composed of semiconductor devices, which is used in photovoltaic solar power generation systems to convert direct current output from solar panels in photovoltaic solar power generation systems into alternating current and output them to AC loads , as one of the core equipment of the photovoltaic solar power generation system, its performance plays a key role in realizing the conversion of solar energy and electric energy. [0003] Such as figure 1 As shown, a photovoltaic inverter generally includes an inverter switch circuit, a control unit, a drive circuit, and an auxiliary power supply. The unit controls the work of the entire photovoltaic inverter, and the drive circuit drives each power element in the photovoltaic inverter. ...

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Problems solved by technology

However, when the photovoltaic inverter is powered on, the auxiliary power supply, control unit and drive circuit all need to absorb a certain amount of power, and the figure 2 The power voltage (PV) curve of the solar panel shown shows that in the case of insufficient light such as morning and evening, the power that the solar panel can provide is very small, and the load capacity is very low, while the solar panel The open circuit voltage of the solar panel is very high. After the auxiliary power supply is started, the output power of the solar panel usually cannot bear the auxiliary power supply, causing the auxiliary power supply to be turned off. At this time, the solar panel is equivalent to an open circuit, and its high open circuit voltage will make the auxiliary power supply again. Start-up, repeated, caused frequent start-stop of the auxiliary power supply, and then caused frequent start-stop of the photovoltaic inverter, which will not only cause aging and damage of various components in the photovoltaic inverter, affect the life of the photovoltaic inverter, but also The impact on the power grid will cause pollution, and if multiple photovoltaic inverters are connected in parallel, if they are started at the same time, the voltage fluctuation and harmonics of one photovoltaic inverter will cause other photovoltaic inverters to fail to start normally, affecting the entire system. Normal work of photovoltaic solar power generation system

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