Three-phase LCL type grid-connected inverter control system and method based on pole assignment

Abstract

The invention discloses a three-phase LCL type grid-connected inverter control system based on pole assignment, and the grid-connected inverter control system restrains the influence of power grid impedance on a three-phase LCL type grid-connected inverter, can effectively solve the problem that a grid-connected system is instable due to the power grid impedance and can be used for current control over the grid-connected inverter. A grid-connected control method not only can achieve system stability and high-quality grid connection under the condition of a weak grid, but also avoids the complex design of a current controller, coordinate rotation transformation and decoupling control. Meanwhile, the grid-connected control method can automatically adjust grid-connected current reference values to achieve independent control over reactive power according to given signals of externally-set reactive power. Therefore, the grid-connected control method is more suitable for controlling the photovoltaic power station grid-connected inverter which is connected into the weak grid through a long-distance power transmission line.

Description

technical field [0001] The invention relates to the field of current control of grid-connected inverters, in particular to an LCL type grid-connected inverter current control method for suppressing the influence of grid impedance. Background technique [0002] Photovoltaic power generation is one of the most promising forms of new energy power generation at home and abroad, and grid-connected power generation has become the main development trend of large-scale photovoltaic utilization. The use of LCL filters in photovoltaic grid-connected inverters is one of the effective means to suppress high-frequency current harmonics. Under the same inductance value, the effect of LCL filters on filtering high-order harmonics is significantly better than that of L-type filters. And is widely used. [0003] However, when the distributed photovoltaic power plant is connected to the grid through a grid impedance different from its original design, the dynamic performance of the inverter ...

AI Technical Summary

Problems solved by technology

However, its controller design is complex, the dynamic response is slow, there is jitter in the control process, and it is easy to fail when the grid impedance changes greatly, which limits the wide application of the proposed control method.

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