Control of offshore MMC during asymmetric offshore AC faults for wind power transmission

Research output: Contribution to journalArticle

Abstract

The adoptions of medium-voltage in AC collection networks of large DC connected wind farms significantly increase the AC current magnitudes during normal and fault conditions. Controlling fault currents at zero during asymmetric AC faults is possible, but it has several drawbacks such as increased risk of protection mal-operation due to absence of fault currents, which also tends to prevent the recovery of AC voltage in post-fault. Therefore, this paper presents an enhanced control strategy that exploits the induced negative sequence voltages to facilitate controlled injection of negative sequence currents during asymmetric AC faults. The proposed control not only defines a safe level of fault current in the offshore AC network but also instigates immediate recovery of the AC voltage following clearance of AC faults, which avoid protection mal-operation. In addition, the positive sequence voltage set-point of the offshore modular multilevel converter (MMC) is actively controlled by considering the negative and zero sequence voltages, which effectively avoids the excessive overvoltage in the healthy phases during asymmetrical AC faults. The theoretical basis of the proposed control scheme is described, and its technical viability is assessed using simulations.
LanguageEnglish
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Early online date22 Jul 2019
DOIs
Publication statusE-pub ahead of print - 22 Jul 2019

Fingerprint

Power transmission
Wind power
Electric fault currents
Electric potential
Recovery
Farms

Keywords

  • offshore wind farms
  • wind power transmission
  • OWFs
  • HVDC
  • AC voltage
  • modular multilevel converter (MMC)

Cite this

@article{176b4e93a8ea4bc6bfdce849f0de8027,
title = "Control of offshore MMC during asymmetric offshore AC faults for wind power transmission",
abstract = "The adoptions of medium-voltage in AC collection networks of large DC connected wind farms significantly increase the AC current magnitudes during normal and fault conditions. Controlling fault currents at zero during asymmetric AC faults is possible, but it has several drawbacks such as increased risk of protection mal-operation due to absence of fault currents, which also tends to prevent the recovery of AC voltage in post-fault. Therefore, this paper presents an enhanced control strategy that exploits the induced negative sequence voltages to facilitate controlled injection of negative sequence currents during asymmetric AC faults. The proposed control not only defines a safe level of fault current in the offshore AC network but also instigates immediate recovery of the AC voltage following clearance of AC faults, which avoid protection mal-operation. In addition, the positive sequence voltage set-point of the offshore modular multilevel converter (MMC) is actively controlled by considering the negative and zero sequence voltages, which effectively avoids the excessive overvoltage in the healthy phases during asymmetrical AC faults. The theoretical basis of the proposed control scheme is described, and its technical viability is assessed using simulations.",
keywords = "offshore wind farms, wind power transmission, OWFs, HVDC, AC voltage, modular multilevel converter (MMC)",
author = "Lei Shi and Adam, {Grain Philip} and Rui Li and Lie Xu",
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.",
year = "2019",
month = "7",
day = "22",
doi = "10.1109/JESTPE.2019.2930399",
language = "English",
journal = "IEEE Journal of Emerging and Selected Topics in Power Electronics",
issn = "2168-6777",
publisher = "Institute of Electrical and Electronics Engineers Inc.",

}

TY - JOUR

T1 - Control of offshore MMC during asymmetric offshore AC faults for wind power transmission

AU - Shi, Lei

AU - Adam, Grain Philip

AU - Li, Rui

AU - Xu, Lie

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 - 2019/7/22

Y1 - 2019/7/22

N2 - The adoptions of medium-voltage in AC collection networks of large DC connected wind farms significantly increase the AC current magnitudes during normal and fault conditions. Controlling fault currents at zero during asymmetric AC faults is possible, but it has several drawbacks such as increased risk of protection mal-operation due to absence of fault currents, which also tends to prevent the recovery of AC voltage in post-fault. Therefore, this paper presents an enhanced control strategy that exploits the induced negative sequence voltages to facilitate controlled injection of negative sequence currents during asymmetric AC faults. The proposed control not only defines a safe level of fault current in the offshore AC network but also instigates immediate recovery of the AC voltage following clearance of AC faults, which avoid protection mal-operation. In addition, the positive sequence voltage set-point of the offshore modular multilevel converter (MMC) is actively controlled by considering the negative and zero sequence voltages, which effectively avoids the excessive overvoltage in the healthy phases during asymmetrical AC faults. The theoretical basis of the proposed control scheme is described, and its technical viability is assessed using simulations.

AB - The adoptions of medium-voltage in AC collection networks of large DC connected wind farms significantly increase the AC current magnitudes during normal and fault conditions. Controlling fault currents at zero during asymmetric AC faults is possible, but it has several drawbacks such as increased risk of protection mal-operation due to absence of fault currents, which also tends to prevent the recovery of AC voltage in post-fault. Therefore, this paper presents an enhanced control strategy that exploits the induced negative sequence voltages to facilitate controlled injection of negative sequence currents during asymmetric AC faults. The proposed control not only defines a safe level of fault current in the offshore AC network but also instigates immediate recovery of the AC voltage following clearance of AC faults, which avoid protection mal-operation. In addition, the positive sequence voltage set-point of the offshore modular multilevel converter (MMC) is actively controlled by considering the negative and zero sequence voltages, which effectively avoids the excessive overvoltage in the healthy phases during asymmetrical AC faults. The theoretical basis of the proposed control scheme is described, and its technical viability is assessed using simulations.

KW - offshore wind farms

KW - wind power transmission

KW - OWFs

KW - HVDC

KW - AC voltage

KW - modular multilevel converter (MMC)

U2 - 10.1109/JESTPE.2019.2930399

DO - 10.1109/JESTPE.2019.2930399

M3 - Article

JO - IEEE Journal of Emerging and Selected Topics in Power Electronics

T2 - IEEE Journal of Emerging and Selected Topics in Power Electronics

JF - IEEE Journal of Emerging and Selected Topics in Power Electronics

SN - 2168-6777

ER -