Control method of three-phase grid-connected inverter based on modified proportional resonant regulator

Abstract

The invention discloses a control method of a three-phase grid-connected inverter based on a modified proportional resonant regulator. The method comprises the following steps of: firstly, computing according to given active and reactive powers of the inverter and a voltage of a power grid to obtain required d-axis and q-axis currents under a synchronous coordinate system, and performing coordinate transformation by combining with phase information which is measured by a phase locking loop and a measured three-phase voltage signal of the power grid to obtain a current reference signal under a stationary alpha-beta coordinate system; secondly, performing coordinate transformation on an output current signal of the inverter to the alpha-beta coordinate system, controlling and tracking the current reference signal by the modified proportional resonant regulator with a harmonic compensator; and finally, returning to an abc coordinate system by coordinate transformation to generate a pulse-width modulation (PWM) pulse-control three-phase full-bridge inverter output, so as to make a distributed generation system grid-connected for power generation. By the method, a large number of complicated computation processes are eliminated, and a control structure is simplified. The control method of the three-phase grid-connected inverter based on the modified proportional resonant regulator is an accurate and high-efficiency novel inverter control method and has a bright development future.

Description

technical field [0001] The invention relates to a control method of a three-phase grid-connected inverter based on a modified proportional resonance regulator, which belongs to the technical field of electric power industry. Background technique [0002] In recent years, distributed grid-connected power generation technologies based on renewable energy, such as photovoltaic power generation and wind power generation, have received widespread attention and become an important part of the sustainable development strategy of human energy. The interface between distributed generation system and grid usually adopts inverter. The inverter control method currently adopts the traditional proportional-integral controller, which converts the three-phase current signal into the synchronous rotating coordinate system, transforms the AC quantity into the DC quantity, and controls the d-q two coordinate components of the rotating coordinate system separately. , realize the decoupling of ...

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Problems solved by technology

Although the synchronous rotating coordinate system control method based on grid voltage vector orientation has been widely used, when the proportional-integral controller is used to adjust the grid-connected current, it is necessary to perform multiple rotation transformations of the coordinate system, which increases the complexity of control and It is difficult to implement the algorithm; especially when compensating the low-order harmonics of the system, each harmonic component needs to undergo multiple complex high- and low-pass filters and coordinate transformations, and when filtering out the corresponding negative-sequence harmonic components, it will also It doubles the amount of calculation and increases the difficulty of implementing the system control algorithm. At the same time, it has no advantage in dynamic response capability.

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