Modeling of AC-DC Converters with Controlled DC Fault Blocking Capability for DC Protection Studies

William Leterme, Paul D. Judge, James Wylie, Tim C. Green

Research output: Contribution to journalArticlepeer-review

Abstract

Fault current characteristics in dc systems depend largely on the response, and hence also the topology, of the ac-dc converters. The presently used ac-dc converter topologies may be categorized into those with controlled or uncontrolled fault-blocking capability and those lacking such capability. For topologies of the former category, generic models of the dc-side fault response have not yet been developed, and a characterization of the influence of control and sensor delays is a notable omission. Therefore, to support accurate and comprehensive dc system protection studies, this article presents three reduced converter models and analyzes the impact of key parameters on the dc-side fault response. The models retain an accurate representation of the dc-side current control, but differ in the representation of the ac-side and internal current control dynamics, and arm voltage limits. The models have been verified against a detailed (full-switching) simulation model for the cases of a full-bridge and a hybrid modular multilevel converter and validated against experimental data from a laboratory-scale prototype. The models behave similarly in the absence of arm voltage limits, but only the most detailed of the three retains a high degree of accuracy when these limits are reached.
Original languageEnglish
Number of pages1
JournalIEEE Transactions on Power Electronics
Publication statusPublished - 1 Nov 2019

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