A grid-connected inverter hybrid damping adaptive control method considering short-circuit ratio

By introducing adaptive control of the short-circuit ratio and weighting coefficient into the grid-connected inverter system, combined with passive and active damping, the system instability problem caused by changes in grid strength in traditional methods is solved, and stability and harmonic suppression effects are achieved in high-penetration systems.

CN115764992BActive Publication Date: 2026-07-24YANSHAN UNIV
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Patent Information

Application Number
CN202211415197.6
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-11-11
Publication Date
2026-07-24
Estimated Expiration
2042-11-11

AI Technical Summary

Technical Problem

In grid-connected systems with high penetration rates, traditional hybrid damping control methods cannot adapt to wide variations in grid strength, leading to system instability, especially when renewable energy generation is highly volatile.

Method used

An adaptive control method for grid-connected inverters that takes into account the short-circuit ratio is adopted. By constructing the main circuit of a three-phase grid-connected inverter, an adaptive control equation is introduced with the short-circuit ratio, passive weighting coefficient, and active weighting coefficient. The inverter output impedance is adjusted, and adaptive control is achieved by combining passive and active damping.

Benefits of technology

It effectively suppresses LCL filter resonance, improves system stability, adapts to a wide range of grid strength variations, maintains system phase margin, and avoids cross-resonance.

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Abstract

This invention discloses a hybrid damping adaptive control method for grid-connected inverters that considers the short-circuit ratio, belonging to the field of power conversion technology. The steps include: constructing a three-phase grid-connected inverter main circuit system; obtaining an error signal by subtracting the inverter grid-connected current from a reference current, and using the error signal as the input to a quasi-resonant controller; and obtaining a feedforward signal u from the capacitor current through an improved hybrid damping control loop. hr An adaptive control equation consisting of the short-circuit ratio λ, passive weighting coefficient K1, and active weighting coefficient K2 is introduced. Optimal hybrid damping control parameters K1 and K2 are generated based on the real-time detected value of the short-circuit ratio λ. The output signal u of the quasi-resonant controller is then... pr Subtract the feedforward signal u hr The modulation signal is obtained; the modulation signal is compared with the carrier control signal to control the switching on and off of the three-phase inverter power transistors. This invention, applied to LCL-type grid-connected inverter systems, can adapt to a wide range of grid strength variations, maintain sufficient phase margin in the system, and improve system stability.
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