Harmonic injection-based new energy side distance protection cooperative control method and system

By employing a synergistic control method of harmonic injection and quasi-proportional resonant control in new energy grid-connected systems, the problem of impedance measurement distortion in traditional power frequency distance protection in new energy systems has been solved, achieving high-precision harmonic tracking and converter safety control, and improving the reliability and adaptability of the protection.

CN122292269APending Publication Date: 2026-06-26XI AN JIAOTONG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
XI AN JIAOTONG UNIV
Filing Date
2026-03-27
Publication Date
2026-06-26

AI Technical Summary

Technical Problem

In new energy grid-connected systems, traditional power frequency distance protection suffers from impedance measurement distortion due to the weak feed characteristics of the converter and the strong current interference from the distant power grid, leading to protection failure or false tripping. Existing harmonic injection schemes have problems such as insufficient harmonic tracking accuracy and high overcurrent risk.

Method used

A new energy side distance protection collaborative control method based on harmonic injection is adopted. By real-time acquisition of voltage and current, the third harmonic signal is tracked by a quasi-proportional resonant controller, a third harmonic injection command is constructed, and the second harmonic measurement impedance and adaptive clipping limit are combined to achieve safe control of the converter.

Benefits of technology

It improves the protection reliability and fault ride-through capability of new energy grid-connected systems, avoids impedance measurement distortion, ensures the safe operation of converters, adapts to complex grid-connected scenarios, and enhances measurement accuracy and protection performance.

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Abstract

This invention discloses a collaborative control method and system for distance protection on the renewable energy side based on harmonic injection, belonging to the field of renewable energy grid-connected protection and converter control. This invention acquires voltage and current in real time; when the voltage is below a threshold, a fault procedure is initiated; after a delay, the third harmonic is superimposed on the q-axis of the converter, and a quasi-proportional resonant controller is used to achieve zero steady-state error tracking; the second harmonic voltage and current are extracted to calculate and measure the impedance, and distance protection is executed according to the setting boundary; during fault ride-through, current capacity is dynamically clipped to ensure converter safety. This invention also discloses a corresponding system. This invention suppresses interference from transition resistance and boosting current, solving the problems of maloperation and false tripping in traditional power frequency protection. It has high harmonic tracking accuracy and low overcurrent risk, and is suitable for grid-connected systems with a high proportion of renewable energy such as wind power and photovoltaics, improving fault location accuracy and protection action reliability.
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