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18 pages, 5482 KB

Open AccessArticle

Time-Domain Fault Detection and Location Scheme for Flexible DC Distribution Networks

by Yafei Li, Jie Li, Kejun Qian, Xiuyong Yu and Xinsong Zhang

Energies 2024, 17(20), 5128; https://doi.org/10.3390/en17205128 - 15 Oct 2024

Cited by 1 | Viewed by 1416

Accurately detecting and locating the fault point of the DC line is significant for eliminating the fault and restoring the power supply of the flexible DC distribution network as soon as possible. Firstly, a direction pilot protection scheme for a complex DC distribution network is proposed based on the integral of the current superposition to identify the fault direction. Then, an online time-domain fault location method based on the least square (LS) method to solve the overdetermined equations is proposed by analyzing the fault loop circuit after the DC line fault. The proposed location scheme utilizes fault data at both ends of the line to eliminate the theoretical impact of fault resistance, and the calculation of the current difference method is discussed to reduce the location error of whether the fault current-limiting reactor (CLR) exists. Finally, various simulations by PSCAD/EMTDC V4.5 demonstrate that the proposed scheme has high protection reliability and location results after different fault positions and resistances. The proposed scheme has low requirements for the sampling rate, fault data length, and implementation costs, which can meet practical application requirements. Full article

(This article belongs to the Section F: Electrical Engineering)

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14 pages, 5503 KB

Open AccessArticle

Analysis on DC Fault Current Limiting Operation of Twice-Quench Trigger Type SFCL Using Transformer Considering Magnetizing Current and Current Limiting Reactor

by Sung-Hun Lim, Min-Ki Park, Sung-Hoon Park and Jae-Woo Chung

Energies 2023, 16(17), 6299; https://doi.org/10.3390/en16176299 - 30 Aug 2023

Cited by 2 | Viewed by 1508

Abstract

As the penetration of distributed energy resources (DER) has increased, research on direct current (DC) power transmission and distribution has been actively performed. The DC system has the advantage of high-power transmission efficiency. However, it has a very large and rapid increase in fault current in the DC system directly after a fault occurs. As one of the countermeasures, studies on the application of the superconducting fault current limiter (SFCL) into the DC system have been conducted to protect major facilities from DC fault current, which is expected to alleviate the power burden on the DC circuit breaker through its quench operation. Among the studied DC SFCLs, the trigger-type DC SFCL using a transformer, which can achieve the peak DC fault current-limiting operation, has been suggested. However, the DC fault current-limiting operation, in the case of the DC SFCL with a current-limiting reactor (CLR), was analyzed to not be effectively executed in the steady state since the transient state directly follows the fault occurrence. In this paper, the DC fault current-limiting operation of a twice-quench trigger type SFCL using a transformer considering magnetizing current and its CLR was analyzed. Through DC fault current-limiting experiments according to the inductance of its current-limiting reactor (CLR), the effective current-limiting design of twice-quench trigger type SFCL using a transformer was described. Full article

(This article belongs to the Special Issue Fault Current Limiters: Technologies, Applications and Field Experience)

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13 pages, 5809 KB

Open AccessArticle

Analysis of the DC Fault Current Limiting Characteristics of a DC Superconducting Fault Current Limiter Using a Transformer

by Kang-Cheol Cho, Min-Ki Park and Sung-Hun Lim

Energies 2020, 13(16), 4210; https://doi.org/10.3390/en13164210 - 14 Aug 2020

Cited by 4 | Viewed by 2366

Abstract

Recently, a lot of interesting research has been conducted to solve the fault current problem of the DC system. In long-distance transmission, DC transmission is more economical than AC transmission. The connection of power grids with a DC system can also better control the power flow and provide high stability. However, the control of the fault current in a DC system is more difficult to handle than in an AC system because the DC system does not make a zero point, unlike the AC system. In addition, there is a disadvantage, in that an arc occurs when a circuit breaker operates. In this paper, a new type of DC superconducting fault current limiter (SFCL) is proposed. This new type of SFCL is composed of two superconducting elements, a current limiting resistor/reactor (CLR), and a transformer. With the proposed SFCL, the DC fault current limiting experiments were performed and the DC fault current limiting characteristics of this SFCL due to the component of the CLR were analyzed. Full article

(This article belongs to the Section A1: Smart Grids and Microgrids)

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19 pages, 3572 KB

Open AccessArticle

Efficient Production of Clean Power and Hydrogen Through Synergistic Integration of Chemical Looping Combustion and Reforming

by Mohammed N. Khan, Schalk Cloete and Shahriar Amini

Energies 2020, 13(13), 3443; https://doi.org/10.3390/en13133443 - 3 Jul 2020

Cited by 10 | Viewed by 3174

Abstract

Chemical looping combustion (CLC) technology generates power while capturing CO₂ inherently with no direct energy penalty. However, previous studies have shown significant energy penalties due to low turbine inlet temperature (TIT) relative to a standard natural gas combined cycle plant. The low TIT is limited by the oxygen carrier material used in the CLC process. Therefore, in the current study, an additional combustor is included downstream of the CLC air reactor to raise the TIT. The efficient production of clean hydrogen for firing the added combustor is key to the success of this strategy. Therefore, the highly efficient membrane-assisted chemical looping reforming (MA-CLR) technology was selected. Five different integrations between CLC and MA-CLR were investigated, capitalizing on the steam in the CLC fuel reactor outlet stream to achieve highly efficient reforming in MA-CLR. This integration reduced the energy penalty as low as 3.6%-points for power production only (case 2) and 1.9%-points for power and hydrogen co-production (case 4)—a large improvement over the 8%-point energy penalty typically imposed by post-combustion CO₂ capture or CLC without added firing. Full article

(This article belongs to the Section A5: Hydrogen Energy)

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