Switching-on control method and switching-on control circuit for alternating-current switch of grid-connected inverter

Abstract

The invention provides a switching-on control method for an alternating-current switch of a grid-connected inverter. The switching-on control method comprises the following steps: real-time sampling is performed on power grid voltage and inversion current; coordinate transformation is carried out on the power grid voltage and the inverter current to obtain a voltage component and a current component; the current component is processed through a virtual impedance loop to obtain a corresponding output current component; the voltage component of the power grid voltage and the output current component are superposed to obtain a modulated wave component; coordinate transformation is carried out on the modulated wave component to obtain a multi-phase power grid voltage modulated wave, and pulsewidth modulation is carried out on the multi-phase power grid voltage modulated wave to generate inverter circuit drive; the voltage difference between the voltages at the two ends of the AC switch and the power grid voltage is determined to be within the preset range, the AC switch is controlled to be switched on, the problem that the AC switch has no impact current is solved, and the technical problem of large open-loop control inductive current is solved.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverters, and in particular relates to a control method and a control circuit for closing an AC switch of a grid-connected inverter. Background technique [0002] Grid-connected inverters such as photovoltaic grid-connected inverters and energy storage inverters are usually equipped with AC switches such as relays or contactors at the grid-connected end. When the inverter is connected to the grid, it is necessary to detect the AC switch used at the grid-connected end to ensure its normal operation. [0003] The key action in the detection of the grid-connected AC switch is to close the AC switch, which is also an important stage for the inverter to transition from standby to grid-connected power generation. It is to ensure reliable and safe operation of the grid-connected inverter. Whether the current status of photovoltaic cells and the grid meets the closing conditions to ensure that th...

AI Technical Summary

Problems solved by technology

[0009] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, provide an advantage that can take into account both the open-loop control scheme and the closed-loop control scheme, and can solve the problem that the open-loop control scheme produces a large inductive current when the AC is switched on and connected to the grid A grid-connected inverter AC switch closing control method that leads to the problems of excessive current stress of the switch tube and weak adaptability of the closed-loop control scheme to the grid environment

Images