Double-current loop control method of LCL (Inductor Capacitor Inductor) filtering grid-connected inverter

Abstract

The invention relates to a double-current loop control method of an LCL (Inductor Capacitor Inductor) filtering grid-connected inverter, belonging to the field of inserter control. The method comprises the steps of: respectively sampling inductive currents at a grid side and inductive currents at an inverter bridge side by using two groups of current sensors; respectively converting the inductive currents ia1, b1 and c1 at the grid side and the inductive currents ia2, b2 and c2 at the inverter bridge side under a stationary coordinate system into currents id1 and q1 as well as id2 and q2 under a two-phase rotating coordinate system; and then by taking id1 and id2 as feedback variables of an active current control loop and taking iq1 and iq2 as feedback variables of the active current control loop, sending output signals of the two control loops and phase signals of a power grid voltage to a SVPWM (Space Vector Pulse Width Modulation) module, wherein the SVPWM module is used for outputting corresponding switch driving signals so as to control the quality of grid current waveform of the inverter. The method disclosed by the invention has the advantages of high control precision, high power factor, convenience for protecting a bridge-arm switching tube and the like.

Description

technical field [0001] The invention relates to a double current loop control method of an LCL filter grid-connected inverter, which is used to realize the direct grid-connected current control of the LCL filter grid-connected inverter, so as to improve the waveform quality and power factor of the grid-connected current. technical background [0002] Since the output side of the grid-connected inverter is connected to the grid through a series LCL filter, it is more conducive to the inverter to obtain high-quality grid-connected current at a lower switching frequency, so the grid-connected inverter with LCL filter is used as a new energy source. The key equipment for grid-connected power generation has received extensive attention in recent years. However, the introduction of LCL filters has increased the order of the system and put forward higher requirements for the control strategy of the system. The LCL filter grid-connected inverter system with direct single closed-loop...

AI Technical Summary

Problems solved by technology

The LCL filter grid-connected inverter system using direct single closed-loop control of typical grid-connected current is unstable; the control method of series-parallel damping at the inductor or capacitor end can avoid system instability, but it causes power loss; Controlling the current of the bridge arm, or realizing the indirect control method of the grid-connected current by controlling other current variables, improves the stability of the closed-loop system, but the indirect current control is difficult to achieve the unit power factor operation of the grid current, and is easily affected by the power grid Effect of Voltage Distortion and Background Harmonic Interference

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