Limitation of cross country fault currents in MV distribution networks by current limiting reactors connected between cable screens and primary substation earth electrode

2022 ◽  
Vol 205 ◽  
pp. 107720
Author(s):  
A. Cerretti ◽  
L. D'Orazio ◽  
F.M. Gatta ◽  
A. Geri ◽  
S. Lauria ◽  
...  
Keyword(s):  
Distribution Networks ◽  
Fault Currents ◽  
Current Limiting ◽  
Cross Country ◽  
Earth Electrode

scholarly journals An Equivalent Circuit for the Evaluation of Cross-Country Fault Currents in Medium Voltage (MV) Distribution Networks

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1929 ◽  
Author(s):  
Fabio Gatta ◽  
Alberto Geri ◽  
Stefano Lauria ◽  
Marco Maccioni
Keyword(s):  
Distribution Networks ◽  
General Purpose ◽  
Simultaneous Occurrence ◽  
Medium Voltage ◽  
Electromagnetic Transient ◽  
High Impedance ◽  
Fault Currents ◽  
Cross Country ◽  
Return Path

A Cross-Country Fault (CCF) is the simultaneous occurrence of a couple of Line-to-Ground Faults (LGFs), affecting different phases of same feeder or of two distinct ones, at different fault locations. CCFs are not uncommon in medium voltage (MV) public distribution networks operated with ungrounded or high-impedance neutral: despite the relatively small value of LGF current that is typical of such networks, CCF currents can be comparable to those that are found in Phase-To-Phase Faults, if the affected feeder(s) consists of cables. This occurs because the faulted cables’ sheaths/screens provide a continuous, relatively low-impedance metallic return path to the fault currents. An accurate evaluation is in order, since the resulting current magnitudes can overheat sheaths/screens, endangering cable joints and other plastic sheaths. Such evaluation, however, requires the modeling of the whole MV network in the phase domain, simulating cable screens and their connections to the primary and secondary substation earth electrodes by suitable computer programs, such as ATP (which is the acronym for alternative transient program) or EMTP (the acronym for electromagnetic transient program), with substantial input data being involved. This paper presents a simplified yet accurate circuit model of the faulted MV network, taking into account the CCF currents’ return path (cable sheaths/screens, ground conductors, and earthing resistances of secondary substations). The proposed CCF model can be implemented in a general-purpose simulation program, and it yields accurate fault currents estimates: for a 20 kV network case study, the comparison with accurate ATP simulations evidences mismatches mostly smaller than 2%, and never exceeding 5%.

Zero-sequence admittance used to protect distribution networks with low earth fault currents

2011 ◽  
Vol 82 (1) ◽  
pp. 32-37 ◽  
Author(s):  
A. Valroos ◽  
A. A. Navolochnyi ◽  
O. A. Onisova ◽  
I. S. Solonina
Keyword(s):  
Distribution Networks ◽  
Earth Fault ◽  
Fault Currents ◽  
Zero Sequence

scholarly journals A Method Based on Only Currents for Determining Fault Direction in Radial Distribution Networks Integrated with Distributed Generations

2021 ◽  
Vol 20 ◽  
pp. 01-11
Author(s):  
Ngo Minh Khoa ◽  
Tran Xuan Khoa
Keyword(s):  
Phase Angle ◽  
Radial Distribution ◽  
Phase Distribution ◽  
Distribution Network ◽  
Distribution Networks ◽  
Positive Sequence ◽  
Voltage Measurement ◽  
Distributed Generations ◽  
Fault Currents ◽  
Three Phase

Nowadays, more distributed generations (DGs) are connected to a radial distribution network, so conventional overcurrent relays cannot operate correctly when a fault occurs in the network. This study proposes a method to determine the fault direction in a three-phase distribution network integrated with DGs. The obtained pre-fault and fault currents are utilized to extract their phasors by the fast Fourier transform, and the phase angle difference between the positive-sequence components of the pre-fault and fault currents is used. Moreover, the method only uses the local current measurement to calculate and identify the phase angle change of the fault current without using the voltage measurement. Matlab/Simulink software is used to simulate the three-phase distribution network integrated with DGs. The faults with different resistances are assumed to occur at backward and forward fault locations. The simulation results show that the proposed method correctly determines the fault direction.

scholarly journals A Fast DC Fault Detection Method for Multi-Terminal AC/DC Hybrid Distribution Network Based on Voltage Change Rate of DC Current-Limiting Inductor

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1828 ◽  
Author(s):  
Xiaomin Qi ◽  
Wei Pei ◽  
Luyang Li ◽  
Li Kong
Keyword(s):  
Fault Detection ◽  
Detection Method ◽  
Distribution Network ◽  
Distribution Networks ◽  
Change Rate ◽  
Fault Type ◽  
Dc Fault ◽  
Voltage Change ◽  
Current Limiting ◽  
Hybrid Distribution

The rapid detection of direct current (DC) faults is one of the key technologies for the development of multi-terminal alternating current (AC)/DC hybrid distribution networks. The DC fault current rises quickly and affects the whole network. Therefore, DC faults must be detected much faster than AC faults. This paper proposes a fast DC fault detection method based on the voltage change rate of the current-limiting inductor (CLI) for the multi-terminal AC/DC hybrid distribution network. Firstly, the characteristics of the fault voltages and currents and of the CLIs are studied in detail, and the feasibility of using the voltage change rate of the CLI to detect DC fault is analyzed. Based on this, a primary fault detection method is proposed to identify the faulty line, determine the fault type and the fault poles using the amplitudes of the single-ended CLI voltage change rates. For high-resistance DC faults, a backup detection method using the directions and amplitudes of the voltage change rates of the double-ended CLIs is proposed. Finally, the proposed method is verified by MATLAB simulations. The simulation results show that the proposed method can detect all DC faults accurately, and the faulty line, fault type and fault poles can be determined quickly. The proposed method is not affected by the fault location, current-limiting inductance, power reversal of the converters, AC fault and communication delay.

scholarly journals Fault Current Tracing and Identification via Machine Learning Considering Distributed Energy Resources in Distribution Networks

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4333 ◽  
Author(s):  
Wanghao Fei ◽  
Paul Moses
Keyword(s):  
Feature Space ◽  
Distribution Networks ◽  
Power Line ◽  
Support Vector ◽  
Fault Current ◽  
Distributed Energy ◽  
System Protection ◽  
Fault Currents ◽  
First Time ◽  
Current Detection

The growth of intermittent distributed energy sources (DERs) in distribution grids is raising many new operational challenges for utilities. One major problem is the back feed power flows from DERs that complicate state estimation for practical problems, such as detection of lower level fault currents, that cause the poor accuracy of fault current identification for power system protection. Existing artificial intelligence (AI)-based methods, such as support vector machine (SVM), are unable to detect lower level faults especially from inverter-based DERs that offer limited fault currents. To solve this problem, a current tracing method (CTM) has been proposed to model the single distribution feeder as several independent parallel connected virtual lines that traces the detailed contribution of different current sources to the power line current. Moreover, for the first time, the enhanced current information is used as the expanded feature space of SVM to significantly improve fault current detection on the power line. The proposed method is shown to be sensitive to very low level fault currents which is validated through simulations.

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