Small-signal converter admittance in the pn-frame: systematic derivation and analysis of the cross-coupling terms

Gabriele Amico, Agustí Egea Àlvarez, Paul Brogan, Shuo Zhang

Research output: Contribution to journalArticle

Abstract

A methodology is presented to derive the small-signal admittance of a converter based control system in the pn-frame. Such a methodology makes use of a set of derived equations which link the qd-frame small-signal admittance data to the corresponding pn-frame small-signal admittance terms. Compared to existing results providing the pn-frame small-signal impedance of a grid connected converter, the presented technique allows a calculation of the pn-frame small-signal admittance (or impedance) when additional elements are present in the controller, as in many practical designs. The presented technique is therefore generic and provides a systematic way to calculate the pn-frame admittance regardless of the used converter control scheme. In the study, the method has been applied to assess how different parts of the controller affect the pn-frame admittance terms and, in particular, the cross-coupling which exists between its positive and negative sequence terms. Thereby, the results of the proposed methodology have been used to study the impact of the negative sequence current compensator on the stability performance of a grid-connected converter. Experimental tests using a real hardware set up are used to support the obtained results.
LanguageEnglish
Pages1-11
Number of pages11
JournalIEEE Transactions on Energy Conversion
Early online date28 Jun 2019
DOIs
Publication statusE-pub ahead of print - 28 Jun 2019

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Controllers
Hardware
Control systems

Keywords

  • voltage source converter
  • mirror frequency effect
  • dual vector current control
  • impedance-based stability criterion

Cite this

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title = "Small-signal converter admittance in the pn-frame: systematic derivation and analysis of the cross-coupling terms",
abstract = "A methodology is presented to derive the small-signal admittance of a converter based control system in the pn-frame. Such a methodology makes use of a set of derived equations which link the qd-frame small-signal admittance data to the corresponding pn-frame small-signal admittance terms. Compared to existing results providing the pn-frame small-signal impedance of a grid connected converter, the presented technique allows a calculation of the pn-frame small-signal admittance (or impedance) when additional elements are present in the controller, as in many practical designs. The presented technique is therefore generic and provides a systematic way to calculate the pn-frame admittance regardless of the used converter control scheme. In the study, the method has been applied to assess how different parts of the controller affect the pn-frame admittance terms and, in particular, the cross-coupling which exists between its positive and negative sequence terms. Thereby, the results of the proposed methodology have been used to study the impact of the negative sequence current compensator on the stability performance of a grid-connected converter. Experimental tests using a real hardware set up are used to support the obtained results.",
keywords = "voltage source converter, mirror frequency effect, dual vector current control, impedance-based stability criterion",
author = "Gabriele Amico and {Egea {\`A}lvarez}, Agust{\'i} and Paul Brogan and Shuo Zhang",
note = "{\circledC} 2019 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 to servers or lists, or reuse of any copyrighted component of this work in other works.",
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AU - Zhang, Shuo

N1 - © 2019 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 to servers or lists, or reuse of any copyrighted component of this work in other works.

PY - 2019/6/28

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N2 - A methodology is presented to derive the small-signal admittance of a converter based control system in the pn-frame. Such a methodology makes use of a set of derived equations which link the qd-frame small-signal admittance data to the corresponding pn-frame small-signal admittance terms. Compared to existing results providing the pn-frame small-signal impedance of a grid connected converter, the presented technique allows a calculation of the pn-frame small-signal admittance (or impedance) when additional elements are present in the controller, as in many practical designs. The presented technique is therefore generic and provides a systematic way to calculate the pn-frame admittance regardless of the used converter control scheme. In the study, the method has been applied to assess how different parts of the controller affect the pn-frame admittance terms and, in particular, the cross-coupling which exists between its positive and negative sequence terms. Thereby, the results of the proposed methodology have been used to study the impact of the negative sequence current compensator on the stability performance of a grid-connected converter. Experimental tests using a real hardware set up are used to support the obtained results.

AB - A methodology is presented to derive the small-signal admittance of a converter based control system in the pn-frame. Such a methodology makes use of a set of derived equations which link the qd-frame small-signal admittance data to the corresponding pn-frame small-signal admittance terms. Compared to existing results providing the pn-frame small-signal impedance of a grid connected converter, the presented technique allows a calculation of the pn-frame small-signal admittance (or impedance) when additional elements are present in the controller, as in many practical designs. The presented technique is therefore generic and provides a systematic way to calculate the pn-frame admittance regardless of the used converter control scheme. In the study, the method has been applied to assess how different parts of the controller affect the pn-frame admittance terms and, in particular, the cross-coupling which exists between its positive and negative sequence terms. Thereby, the results of the proposed methodology have been used to study the impact of the negative sequence current compensator on the stability performance of a grid-connected converter. Experimental tests using a real hardware set up are used to support the obtained results.

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