Direct-current side control method for midline arm control model of four bridge arm photovoltaic inverter

Abstract

The invention discloses a direct-current side control method for a midline arm control model of a four bridge arm photovoltaic inverter. The midline arm control model comprises a photovoltaic direct-current input, a stabilized voltage capacitor, a direct-current booster circuit, two groups of inverter side storage capacitors, two equivalent bleeder resistors connected in series, a midline inductor and a midline arm. The invention discloses a direct-current side midpoint balance control method and a controller design method suitable for the midline arm control mode., wherein an average value of signals in a switching period of a midline arm switching function is used as a control variable; an H-infinity controller is designed by adopting an H-infinity control method; and the H infinite norm of the input midline current, measurement error, equivalent external disturbance, half of the sum of the output voltages of the two capacitors relative to a neutral point and midline arm midpoint voltage is minimum; and the invention provides implementation of a corresponding generalized controlled object, a controller structure and a corresponding weighting function selection method. The method can ensure that the stability of the direct-current side midpoint of the four bridge arm photovoltaic inverter still can be kept in high midline current.

Description

technical field [0001] The invention relates to a DC side control method for a control model of a line arm of a four-arm photovoltaic inverter, belonging to the technical field of photovoltaic grid-connected system control. Background technique [0002] With the consumption of non-renewable energy, harsh environmental conditions, and continuous rise in energy demand, new energy technology, as a feasible energy solution for the future development of mankind, has received widespread attention. Photovoltaic grid-connected system is an effective platform for the application of solar power generation technology. Photovoltaic grid-connected inverters suitable for low-voltage distribution networks usually need to obtain neutral wires. In the way of obtaining the neutral line, the four-leg photovoltaic inverter has a stronger zero-sequence compensation capability than the three-leg photovoltaic inverter, and is more suitable for adopting advanced control methods to balance the midp...

AI Technical Summary

Problems solved by technology

[0004] Using classical control theory to control the center line arm must adopt a sufficiently large amplitude gain and phase margin, so that the feedback system can still maintain system performance and effectively suppress interference under large disturbances; and it cannot be directly applied to multi-input multi- output system

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