A Grid-Connected Capacitor-Tapped Multi-Module Converter for HVDC Applications

Operational Concept and Control

Ahmed Elserougi, Ahmed Massoud, Shehab Ahmed

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In this paper, a dc-ac buck converter is proposed as a grid-side converter in HVDC transmission systems for high-power renewable energy source grid integration. The proposed architecture consists of multi-modules of Half-Bridge Voltage Source Converters (HB-VSCs). The dc terminals of the HB-VSCs are connected in series across the entire dc-link (i.e. capacitor-tapped), while their ac outputs are connected to multi-winding transformers to provide the three-phase terminals for ac grid integration. The proposed grid-connected Capacitor-Tapped Multi-module Converter (CT-MC) architecture, inspired from the HVDC shunt tap proposed by ABB, provides a dc-ac conversion with a relatively moderate voltage rating of semiconductor devices. It also provides operation with a lower number of semiconductor devices, gate driver circuits, voltage sensors, and lower total MVA rating of semiconductor devices (67%) compared to the conventional three-phase HB Modular Multilevel Converter (HB-MMC), which affects positively the system cost, and reduces the computational burden of the employed controller. In this work, the operational concept and control of the CT-MC are presented along with a capacitor voltage balancing approach. Simulation results are presented during normal and abnormal conditions to show the viability of the proposed architecture. Finally, a scaled down prototype for the CT-MC is employed to validate the converter operation.

Original languageEnglish
JournalIEEE Transactions on Industry Applications
DOIs
Publication statusAccepted/In press - 29 Dec 2017

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Capacitors
Semiconductor devices
Electric potential
Transformer windings
Controllers
Networks (circuits)
Sensors
Costs

Keywords

  • AC integration
  • Capacitor-tapped
  • Capacitors
  • HVDC converters
  • HVDC transmission
  • Insulated gate bipolar transistors
  • Multi-module converter
  • Reactive power
  • Renewable energy sources
  • Renewable energy sources
  • Voltage control
  • Voltage measurement

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

Cite this

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title = "A Grid-Connected Capacitor-Tapped Multi-Module Converter for HVDC Applications: Operational Concept and Control",
abstract = "In this paper, a dc-ac buck converter is proposed as a grid-side converter in HVDC transmission systems for high-power renewable energy source grid integration. The proposed architecture consists of multi-modules of Half-Bridge Voltage Source Converters (HB-VSCs). The dc terminals of the HB-VSCs are connected in series across the entire dc-link (i.e. capacitor-tapped), while their ac outputs are connected to multi-winding transformers to provide the three-phase terminals for ac grid integration. The proposed grid-connected Capacitor-Tapped Multi-module Converter (CT-MC) architecture, inspired from the HVDC shunt tap proposed by ABB, provides a dc-ac conversion with a relatively moderate voltage rating of semiconductor devices. It also provides operation with a lower number of semiconductor devices, gate driver circuits, voltage sensors, and lower total MVA rating of semiconductor devices (67{\%}) compared to the conventional three-phase HB Modular Multilevel Converter (HB-MMC), which affects positively the system cost, and reduces the computational burden of the employed controller. In this work, the operational concept and control of the CT-MC are presented along with a capacitor voltage balancing approach. Simulation results are presented during normal and abnormal conditions to show the viability of the proposed architecture. Finally, a scaled down prototype for the CT-MC is employed to validate the converter operation.",
keywords = "AC integration, Capacitor-tapped, Capacitors, HVDC converters, HVDC transmission, Insulated gate bipolar transistors, Multi-module converter, Reactive power, Renewable energy sources, Renewable energy sources, Voltage control, Voltage measurement",
author = "Ahmed Elserougi and Ahmed Massoud and Shehab Ahmed",
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N2 - In this paper, a dc-ac buck converter is proposed as a grid-side converter in HVDC transmission systems for high-power renewable energy source grid integration. The proposed architecture consists of multi-modules of Half-Bridge Voltage Source Converters (HB-VSCs). The dc terminals of the HB-VSCs are connected in series across the entire dc-link (i.e. capacitor-tapped), while their ac outputs are connected to multi-winding transformers to provide the three-phase terminals for ac grid integration. The proposed grid-connected Capacitor-Tapped Multi-module Converter (CT-MC) architecture, inspired from the HVDC shunt tap proposed by ABB, provides a dc-ac conversion with a relatively moderate voltage rating of semiconductor devices. It also provides operation with a lower number of semiconductor devices, gate driver circuits, voltage sensors, and lower total MVA rating of semiconductor devices (67%) compared to the conventional three-phase HB Modular Multilevel Converter (HB-MMC), which affects positively the system cost, and reduces the computational burden of the employed controller. In this work, the operational concept and control of the CT-MC are presented along with a capacitor voltage balancing approach. Simulation results are presented during normal and abnormal conditions to show the viability of the proposed architecture. Finally, a scaled down prototype for the CT-MC is employed to validate the converter operation.

AB - In this paper, a dc-ac buck converter is proposed as a grid-side converter in HVDC transmission systems for high-power renewable energy source grid integration. The proposed architecture consists of multi-modules of Half-Bridge Voltage Source Converters (HB-VSCs). The dc terminals of the HB-VSCs are connected in series across the entire dc-link (i.e. capacitor-tapped), while their ac outputs are connected to multi-winding transformers to provide the three-phase terminals for ac grid integration. The proposed grid-connected Capacitor-Tapped Multi-module Converter (CT-MC) architecture, inspired from the HVDC shunt tap proposed by ABB, provides a dc-ac conversion with a relatively moderate voltage rating of semiconductor devices. It also provides operation with a lower number of semiconductor devices, gate driver circuits, voltage sensors, and lower total MVA rating of semiconductor devices (67%) compared to the conventional three-phase HB Modular Multilevel Converter (HB-MMC), which affects positively the system cost, and reduces the computational burden of the employed controller. In this work, the operational concept and control of the CT-MC are presented along with a capacitor voltage balancing approach. Simulation results are presented during normal and abnormal conditions to show the viability of the proposed architecture. Finally, a scaled down prototype for the CT-MC is employed to validate the converter operation.

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