A voltage fault detection method for a medium-voltage grid-connected converter based on a Kalman observer

By employing a fault detection method based on Kalman observers and multi-dimensional criteria, the problem of medium-voltage grid-connected converters being susceptible to electromagnetic noise interference is solved, improving the accuracy of voltage fault detection and system stability. This method is suitable for complex grid environments where new energy sources are connected to the grid, and reduces retrofit costs.

CN122449239APending Publication Date: 2026-07-24WOLONG ELECTRIC GRP CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
WOLONG ELECTRIC GRP CO LTD
Filing Date
2026-03-19
Publication Date
2026-07-24

AI Technical Summary

Technical Problem

Voltage fault detection in medium-voltage grid-connected converters is susceptible to electromagnetic noise interference, which can lead to false triggering of protection mechanisms, affecting the stability of the power system and the safety of equipment.

Method used

A state-space model is established using a Kalman observer to perform optimal estimation of the current signal. Fault judgment is performed by combining multi-dimensional criteria of amplitude and phase deviation. An auxiliary module for abnormal operating conditions is designed to support the stability of the phase-locked loop and avoid malfunctions.

Benefits of technology

It improves the accuracy of voltage fault detection and system stability, reduces malfunctions caused by noise interference, adapts to the complex power grid environment with a high proportion of new energy access, and reduces the cost of transformation.

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Abstract

The present application relates to the field of power electronics, and more particularly to a voltage fault detection method for medium-voltage grid-connected converters based on Kalman observer, which converts three-phase signals to dq rotating coordinate system; establishes state space model and discretizes; adopts Kalman observer to estimate state, and obtains optimal estimated current value; calculates theoretical grid voltage estimation value based on inductance volt-ampere characteristic calculation theory; inputs actual voltage and estimation value to fault judgment logic, calculates amplitude deviation and phase deviation, starts duration timing and deviation integral evaluation; when duration or integral value reaches threshold value, determines as real fault and triggers alarm. The present application has the advantages that: Kalman observer is adopted to effectively filter electromagnetic noise and transient distortion, and distinguish transient interference and real fault; double criteria of duration and deviation integral are introduced, and only when deviation duration exceeds limit or cumulative influence reaches threshold value, the fault is determined, which significantly avoids misoperation, and improves detection accuracy and system stability.
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