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Your search keyword '"Xu, Dianguo"' showing total 1,108 results
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1,108 results on '"Xu, Dianguo"'

14. A Protection Scheme for Multi-Terminal VSC-HVDC Transmission Systems

Author

Ali Raza, Amin Akhtar, Mohsin Jamil, Ghulam Abbas, Syed Omer Gilani, Liu Yuchao, Muhammad Nasir Khan, Tahir Izhar, Xu Dianguo, and Barry W. Williams

Subjects
Back-up protection, Naïve Bayes classifiers, protection system, primary protection, multi-terminal VSC-HVDC, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

High-voltage direct-current (HVDC) power transmission is becoming increasingly important due to steadily rising need for bulk power delivery and interconnected power transmission and distribution systems. DC grids are vulnerable to dc faults, which lead to a rapid rise in dc fault currents. The dc faults must be cleared within the timeframe of milliseconds to avoid the collapse of the HVDC system. In the event of primary protection (PP) failure, back-up protection (BP) must be applied to clear the fault. In this paper, a novel algorithm based on a Naïve Bayes classifier is proposed to determine threshold levels and operational time frames for primary and back-up protection in multi-terminal voltage source converter-based HVDC. Local voltage and currents are measured to detect and identify the kind of fault. A four-terminal HVDC transmission system is developed in PSCAD/EMTDC and is subjected to line-line faults at different locations and time, to assess the designed protection schemes. Results show that a relaying algorithm effectively detects the fault and expedite the primary protection operation. On malfunctioning of PP, BP is accelerated in a short delay of 0.2 ms. Furthermore, the relaying algorithm provides faster protection compared with techniques available in the literature. The resulting reduced fault clearance time truncates the maximum fault current and, inevitably, leads to reduced power ratings required for dc grid equipment.

Published
2018
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15. Power Dispatch and Voltage Control in Multiterminal HVDC Systems: A Flexible Approach

Author

Ali Raza, Yuchao Liu, Kumars Rouzbehi, Mohsin Jamil, Syed Omer Gilani, Xu Dianguo, and Barry W. Williams

Subjects
DC voltage droop control, offshore wind farms, power dispatch, VSC-based multiterminal HVDC grids, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

This paper deals with the power dispatch and direct voltage control in multiterminal high voltage direct current (MT-HVDC) systems. Generalized voltage droop (GVD) control is adopted for voltage source converters (VSC)s of a MT-HVDC system. A mechanism has been designed based on the power ratio within the GVD controlled stations to achieve flexible autonomous coordination control among VSC-HVDC stations, without need for communication. In this paper, several alternatives are considered to guarantee fault ride through of onshore converter stations. The performance of the proposed control strategy is analyzed with time-domain dynamic simulations, in an EMDTC/PSCAD platform, and experimentally validated. Results demonstrate the robust performance and capabilities of the proposed control strategy during changes in the power demand of the ac grids, unexpected change in wind power generation, and eventual permanent VSC-HVDC station disconnection.

Published
2017
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