The direct current circuit breakers are considered a promising option to protect the transmission line against commonly appearing line-to-ground fault. However, the challenges of losses in the nonoperational stage, escalation of response against fault current, and large fault current handling capability remain the debatable issues for direct current circuit breakers. This paper introduces a novel topology of the hybrid circuit breaker with fault-current-limiting characteristics, which contains three branches: the main branch, fault-current-limiting branch, and energy absorption branch. The main branch includes a mechanical switch, breaker impedance, and bidirectional power electronics switches. In the fault-current-limiting branch, a fault-current-limiting circuit is introduced which contains n numbers of bidirectional switches and current-limiting inductors, which are connected in series to make the design modular in nature. During the normal working stage, the current flows through the main branch of the breaker. Once a fault in the system is confirmed, the fault current is transferred to the fault-current-limiting branch. At this stage, the intensity of the fault current is reduced significantly using the fault-current-limiting circuit, and finally, the residual current is shifted to the energy absorption branch. The working principle, design considerations, and parametric analysis concerning the design of hybrid circuit breakers are incorporated in this paper. The performance of the proposed breaker is evaluated using a three-terminal voltage-source converter-based high-voltage direct current transmission network; for this purpose, a PSCAD/EMTDC simulation tool is used. The performance of the proposed breaker is also compared with other topologies. The comparative analysis shows that the proposed breaker is a good alternative considering high fault current interruption requirements, response time against fault current, and power losses.
Dual three-phase (DTP) permanent magnet synchronous motors (PMSMs) are specialized machines which are commonly used for high power density applications. These machines offer the merits of high efficiency, high torque density, and superior supervisor fault tolerant capability compared to conventional three-phase AC-machines. However, the electrical structure of such machines is very complicated, and as such, control becomes challenging. In conventional vector controlled DTP-PMSMs drives, the components of the dq-subspace are associated with electromechanical energy conversion, and two currents, i.e., Id and Iq belonging to this subspace, are used in feedback-loops for control. Such orthodox control methods can cause some anomalies e.g., the voltage source inverter’s (VSI) dead time effect and other nonlinear factors, and can induce large harmonics. These glitches can be greatly alleviated by the introduction of the two-extra current loops to directly control the currents in Z1Z2-subspace in order to suppress the insertion of harmonics. In this paper, two approaches—one with two-current loops and other with four-current loops—for vector controlled DTP-PMSMs are investigated with the aid of different MATLAB-based simulations. Furthermore, in the paper, the influence of additional current loops is quantified using simulation-based results.
This paper provides an assessment of passive islanding detection methods in DC microgrids. In order to analyse the response of a DC microgrid to an islanding event, DC voltage and current signatures are captured locally at the terminals of Distributed Energy Resources (DERs). Further analysis on DC voltage and current measurements is carried out to derive the Rate of Change of Voltage (ROCOV) and the Rate of Change of Current (ROCOC), to distinguish between genuine islanding events and other disturbances. A detailed DC microgrid has been developed in MATLAB/Simulink to analyse the response of the DERs within a DC microgrid during intentional or unintentional islanding events. The results show that these approaches cannot be used to classify and characterise between islanding and non-islanding events caused by high resistive faults for DC microgrids, as the response of the DERs are dependent on the technology and associated control systems, which influences post event analysis in distinguishing between events.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.