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Open AccessArticle

A PMSG Wind Energy System Featuring Low-Voltage Ride-through via Mode-Shift Control

by Rania A. Ibrahim and Nahla E. Zakzouk

Appl. Sci. 2022, 12(3), 964; https://doi.org/10.3390/app12030964 - 18 Jan 2022

Cited by 27 | Viewed by 3959

Low-voltage ride-through (LVRT) and grid support capability are becoming a necessity for grid-tied renewable energy sources to guarantee utility availability, quality and reliability. In this paper, a swap control scheme is proposed for grid-tied permanent magnet synchronous generator (PMSG) MW-level wind turbines. This scheme shifts system operation from maximum power point tracking (MPPT) mode to LVRT mode, during utility voltage sags. In this mode, the rectifier-boost machine-side converter overtakes DC-link voltage regulation independently of the grid-side converter. The latter attains grid synchronization by controlling active power injection into the grid to agree with grid current limits while supporting reactive power injection according to the sag depth. Thus grid code requirements are met and power converters safety is guaranteed. Moreover, the proposed approach uses the turbine-generator rotor inertia to store surplus energy during grid voltage dips; thus, there is no need for extra hardware storage devices. This proposed solution is applied on a converter topology featuring a minimal number of active switches, compared to the popular back-to-back converter topology. This adds to system compatibility, reducing its size, cost and switching losses. Simulation and experimental results are presented to validate the proposed approach during normal and LVRT operation. Full article

(This article belongs to the Special Issue Wind Energy: Current Trends, Implementations and Future Developments)

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16 pages, 1841 KB

Open AccessArticle

Novel Protection Coordination Scheme for Active Distribution Networks

by Muhammad Fawad Shaikh, Sunny Katyara, Zahid Hussain Khand, Madad Ali Shah, Lukasz Staszewski, Veer Bhan, Abdul Majeed, Shoaib Shaikh and Leonowicz Zbigniew

Electronics 2021, 10(18), 2312; https://doi.org/10.3390/electronics10182312 - 20 Sep 2021

Cited by 6 | Viewed by 3611

Abstract

Distribution networks are inherently radial and passive owing to the ease of operation and unidirectional power flow. Proper installation of Distributed Generators, on the one hand, makes the utility network active and mitigates certain power quality issues e.g., voltage dips, frequency deviations, losses, etc., but on the other hand, it disturbs the optimal coordination among existing protection devices e.g., over-current relays. In order to maintain the desired selectivity level, such that the primary and backup relays are synchronized against different contingencies, it necessitates design of intelligent and promising protection schemes to distinguish between the upstream and downstream power flows. This research proposes exploiting phase angle jump, an overlooked voltage sag parameter, to add directional element to digital over-current relays with inverse time characteristics. The decision on the direction of current is made on the basis of polarity of phase angle jump together with the impedance angle of the system. The proposed scheme at first is evaluated on a test system in a simulated environment under symmetrical and unsymmetrical faults and, secondly, as a proof of the concept, it is verified in real-time on a laboratory setup using a Power Hardware-in-loop (PHIL) system. Moreover, a comparative analysis is made with other state-of-the-art techniques to evaluate the performance and robustness of the proposed approach. Full article

(This article belongs to the Special Issue Environment and Electrical Engineering-Edition 2021)

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12 pages, 2085 KB

Open AccessArticle

Enhancing LVRT of DFIG by Using a Superconducting Current Limiter on Rotor Circuit

by Flávio Oliveira, Arthur Amorim, Lucas Encarnação, Jussara Fardin, Marcos Orlando, Selênio Silva and Domingos Simonetti

Energies 2016, 9(1), 16; https://doi.org/10.3390/en9010016 - 25 Dec 2015

Cited by 18 | Viewed by 6338

Abstract

This paper have studied the dynamic of a 2.0 MW Doubly Fed Induction Generator (DFIG) during a severe voltage sag. Using the dynamic model of a DFIG, it was possible to determine the current, Electromagnetic Force and flux behavior during three-phase symmetrical voltage dip. Among the technologies of wind turbines the DFIG is widely employed; however, this machine is extremely susceptible to disturbances from the grid. In order to improve DFIG Low Voltage Ride-Through (LVRT), it is proposed a novel solution, using Superconducting Current Limiter (SCL) in two arrangements: one, the SCL is placed between the machine rotor and the rotor side converter (RSC), and another placed in the RSC DC-link. The proposal is validated through simulation using PSCAD™/EMTDC™ and according to requirements of specific regulations. The analysis ensure that both SCL arrangements behave likewise, and are effective in decrement the rotor currents during the disturbance. Full article

(This article belongs to the Special Issue Wind Turbine 2015)

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