Grid-connected inverter control method based on state observer

Abstract

The invention discloses a grid-connected inverter control method based on a state observer. The grid-connected inverter control method comprises the steps that (1) a bridge arm current iL1 and network voltage eg are detected, and a phase angle theta is obtained through phase locking of a phase-locked loop; (2) an observation state quantity is obtained through the state observer based on an internal model; (3) a state quantity feedback signal Xfd is obtained through a state feedback matrix K; (4) grid currents of an observational network are processed, and then grid current error signals ed and eq are obtained; (5) closed-loop processing is carried out on the grid current error signals ed and eq through a PI controller, and then through coordinate inverse transformation, wave generation voltage ui1 is obtained; (6) the wave generation voltage ui1 and the state quantity feedback signal Xfd are subtracted from each other to generate a SVPWM control signal ui of an inverter bridge switching tube, output of a three-phase full bridge inverter is controlled, and therefore a distributed power generation system is controlled to be combined to the grid. Practices show that the control method obtains good dynamic and steady-state performance for a grid-connected current.

Description

technical field [0001] The invention belongs to the technical field of power grid converter control, and in particular relates to a control method for a grid-connected inverter based on a state observer. Background technique [0002] With the continuous application of renewable resources such as photovoltaic power generation, wind power generation, and fuel cells, distributed power generation systems have become the focus of research in recent years and have attracted widespread attention. Grid-connected inverter is the core part of distributed power generation system, and its filter design often adopts LCL filter structure. Compared with the L filter, the LCL filter can more effectively suppress the higher harmonics of the current and reduce the total inductance. However, LCL filters have low-damping high-order characteristics, which can easily lead to system resonance. [0003] In order to suppress the resonance of the LCL grid-connected inverter, some scholars have prop...

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Problems solved by technology

However, the realization of state feedback needs to detect multiple state quantities of the system, adding additional sensors

For this reason, scholars have begun to study the observation of state feedback variables by designing traditional state observers to replace the additional sensors added by the active damping link and state feedback, but this method does not consider the change of the characteristic matrix parameters of the state observer and the input of the state observer The impact of deviation on the observation effect cannot guarantee the system control performance

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