To main content

Demonstration of Converter Control Interactions in MMC-HVDC Systems

Abstract

Although the control of modular multi-level converters (MMCs) in high-voltage directcurrent (HVDC) networks has become a mature subject these days, the potential for adverse interactions between different converter controls remains an under-researched challenge attracting
the attention from both academia and industry. Even for point-to-point HVDC links (i.e., simple
HVDC systems), converter control interactions may result in the shifting of system operating voltages, increased power losses, and unintended power imbalances at converter stations. To bridge
this research gap, the risk of multiple cross-over of control characteristics of MMCs is assessed in
this paper through mathematical analysis, computational simulation, and experimental validation.
Specifically, the following point-to-point HVDC link configurations are examined: (1) one MMC
station equipped with a current versus voltage droop control and the other station equipped with
a constant power control; and (2) one MMC station equipped with a power versus voltage droop
control and the other station equipped with a constant current control. Design guidelines for droop
coefficients are provided to prevent adverse control interactions. A 60-kW MMC test-rig is used to
experimentally verify the impact of multiple crossing of control characteristics of the DC system
configurations, with results verified through software simulation in MATLAB/Simulink using an
open access toolbox. Results show that in operating conditions of 650 V and 50 A (DC voltage and
DC current), drifts of 7.7% in the DC voltage and of 10% in the DC current occur due to adverse
control interactions under the current versus voltage droop and power control scheme. Similarly,
drifts of 7.7% both in the DC voltage and power occur under the power versus voltage droop and
current control scheme.
Keywords: HVDC; MMC; control; interaction; experimental demonstration

Category

Academic article

Client

  • EC/FP7 / 612748

Language

English

Author(s)

  • Jinlei Chen
  • Sheng Wang
  • Carlos Ernesto Ugalde-Loo
  • Wenlong Ming
  • Oluwole Daniel Adeuyi
  • Salvatore D'Arco
  • Salvador J. Ceballos
  • Max Alexander Parker
  • Stephen Jon Finney
  • Andrea Pitto
  • Diego Cirio
  • Iñigo Azpiri

Affiliation

  • Cardiff University
  • Scotland
  • SINTEF Energy Research / Energisystemer
  • Tecnalia
  • University of Strathclyde
  • The University of Edinburgh
  • Italy
  • Spain

Year

2022

Published in

Electronics

ISSN

2079-9292

Publisher

MDPI

Volume

11

Issue

2

View this publication at Cristin