Photovoltaic grid connected inverter output current control system

Abstract

The invention discloses a photovoltaic grid connected inverter output current control system which comprises a photovoltaic battery, wherein the photovoltaic battery generates direct current after irradiated; the direct current generates alternating current after passing through a current closed loop controller controlled bridge type inverter; the alternating current is transmitted to a grid after filtered by an output filter and amplified by an isolation transformer; and the current closed loop controller adopts a double-current closed loop control structure which comprises current inner loop control formed by filter inductive current feedback and current outer loop control formed by transformer output current feedback. Because the invention adopts the double-current closed loop control structure, the output current has favorable tracking capability on a current given value and has favorable inhibiting capability on interference, such as grid voltage and harmonic wave thereof, inverter dead area effect, and the like. The photovoltaic grid connected inverter output current control system used as a control system with innovative significance can be widely applied to a photovoltaic grid connected power generation industry.

Description

technical field [0001] The invention relates to a current control system, in particular to a photovoltaic grid-connected inverter output current control system. Background technique [0002] Photovoltaic grid-connected power generation is a form of solar power generation. Its realization process is: sunlight irradiates photovoltaic cells to generate DC power, and through some conversion device, converts the DC power generated by photovoltaic cells into AC power and transmits it to the grid. This conversion device is a photovoltaic grid-connected inverter. [0003] In order to deliver the output current to the grid, the sine wave current output by the photovoltaic grid-connected inverter must have the same frequency and phase as the grid voltage, and the harmonic content of the output current must be less than the specified value. Therefore, one of the technical cores of photovoltaic grid-connected inverters is the control technology of output current, which generally needs ...

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Problems solved by technology

However, when this method is used, the switching action of the power switching device is determined according to the error between the given value and the feedback value, so the switching frequency is not fixed, which affects the optimal design of the output filter circuit of the grid-connected inverter. When the switching frequency When it is too high, it may also cause excessive power loss

[0008] In short, the existing photovoltaic grid-connected inverter output current control technical solutions have the disadvantages of large tracking error, weak anti-interference ability, and large output current harmonic content.

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