Control method and system of three-phase LCL type grid-connected inverter

Abstract

The invention discloses a control method and system of a three-phase LCL type grid-connected inverter. The method comprises the steps of obtaining grid current iG-a, b, c and grid voltage uG-a, b, c;obtaining iG-a, b, c* and iG [alpha], iG [beta], uG [alpha], uG [beta], iG [alpha] *, iG [beta] * in two-phase stationary coordinates; obtaining an actual control quantity u[alpha] by a first ADRC according to iG [alpha], uG [alpha] and iG [alpha] *, wherein the first virtual control quantity u '[alpha] output by the first state feedback control rate in the first ADRC and iG [alpha] are in a pureseries integral relationship; obtaining an actual control quantity u [beta] by a second ADRC according to iG [beta], uG [beta] and iG [beta] *, wherein the second virtual control quantity u '[beta] output by the second state feedback control rate in the second ADRC and iG [beta] are in a pure series integral relationship; a SVPWM controller generating a pulse width modulated PWM signal according to u [alpha] and u [beta] and outputting the pulse width modulated PWM signal to a grid-connected inverter. The advantages of the invention are that a control algorithm is simple, engineering setting of parameters can be realized, and the cost is low.

Description

technical field [0001] The invention relates to the technical field of grid-connected inverters, in particular to a control method and system for a three-phase LCL type grid-connected inverter. Background technique [0002] New energy power generation is the main way to solve the contradiction between human's ever-increasing energy demand and less and less traditional fossil energy. The grid-connected utilization of new energy power generation is the main way for large-scale promotion and utilization of new energy power generation. The grid-connected inverter is the interface between the electric energy generated by the new energy source and the grid. In order to suppress harmonics generated by PWM (Pulse Width Modulation, pulse width modulation) chopping of the grid-connected inverter, a filter needs to be added between the inverter and the common point of the grid. Among them, commonly used filters include L-type filters and LCL-type filters, but since the high-frequency ...

AI Technical Summary

Problems solved by technology

The existing state observer-based methods are only used to observe the required current and voltage state variables, and then use the observed state variables as inner loop feedback variables for control, still need to combine PID controllers, PR controllers, and repetitive controllers It is also difficult to control parameters, and it is impossible to simplify the complexity of the control algorithm while reducing the number of sensors.

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