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Observer-based pulsed signal injection for grid impedance estimation in three phase systems

Garcia, Pablo; Sumner, M.; Navarro-Rodríguez, Ángel; Guerrero, Juan M.; Garcia, Jorge

Authors

Pablo Garcia

M. Sumner mark.sumner@nottingham.ac.uk

Ángel Navarro-Rodríguez

Juan M. Guerrero

Jorge Garcia



Abstract

This paper addresses the estimation of the grid impedance and the control of grid-tied converters by combining pulsed-signal injection and observer based techniques. A Luenberger based observer is used for controlling the grid-side current of an LCL filter by only measuring the converter-side currents and the grid-side voltage. This configuration mitigates the effects of parameter variation at the LCL filter. Under grid impedance changes, the observer control signal will be used for triggering the signal injection. A Pulsed Signal Injection (PSI) approach is employed for estimating online the grid impedance using an RLS algorithm. Compared with existing grid-impedance estimation techniques, the proposed method can: 1) identify a generic RL grid impedance, even under unbalanced conditions; 2) reduce the distortion induced by the excitation signal by relying on the observer to triggering the injection when a grid impedance change is detected; 3) Identify grid impedance values much lower than the converter filter impedance, which is the usual situation when the converter rated power is well below the grid rating. Finally, it is worth pointing out that the proposed estimation technique is well suited to be incorporated into an adaptive current controller scheme.

Journal Article Type Article
Journal IEEE Transactions on Industrial Electronics
Print ISSN 0278-0046
Electronic ISSN 1557-9948
Publisher Institute of Electrical and Electronics Engineers
Peer Reviewed Peer Reviewed
APA6 Citation Garcia, P., Sumner, M., Navarro-Rodríguez, Á., Guerrero, J. M., & Garcia, J. (in press). Observer-based pulsed signal injection for grid impedance estimation in three phase systems. IEEE Transactions on Industrial Electronics, doi:10.1109/TIE.2018.2801784
DOI https://doi.org/10.1109/TIE.2018.2801784
Keywords Impedance, Observers, Voltage control, Voltage measurement, Frequency estimation, Adaptation models
Publisher URL http://ieeexplore.ieee.org/document/8281120/
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf
Additional Information 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution.

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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