scholarly journals An Efficient Δ-Circuit approach for Online Short-Circuit Calculation in Large Islanded AC Microgrids

2022 ◽  
Author(s):  
Evangelos Pompodakis
Keyword(s):  
Short Circuit ◽  
Distribution Networks ◽  
Fault Analysis ◽  
Simple Extension ◽  
Current Form ◽  
Computational Performance ◽  
Short Circuit Calculation ◽  
Node Network ◽  
The Time Domain ◽  
Virtual Impedance

In this manuscript, a novel Δ-circuit approach is proposed, which enables the fast calculation of fault currents in large islanded AC microgrids (MGs), supplied by inverter-based distributed generators (IBDGs) with virtual impedance current limiters (VICLs). The concept of virtual impedance for limiting the fault current of IBDGs has gained the interest of research community in the recent years, due to the strong advantages it offers. Moreover, Δ-circuit is an efficient approach, which has been widely applied in the past, for the calculation of short?circuit currents of transmission and distribution networks. However, the traditional Δ-circuit, in its current form, is not applicable in islanded MGs, due to the particular characteristics of such networks, e.g., the absence of a slack bus. To overcome this issue, a novel Δ-circuit approach is proposed in this paper, with the following distinct features: a) precise simulation of islanded MGs, b) fast computational performance, c) generic applicability in all types of faults e.g., single-line, 2-line or 3-line faults, d) simple extension to other DG current limiting modes, e.g., latched limit strategy etc. The proposed approach is validated through the time-domain software of Matlab Simulink, in a 9-bus and 13-bus islanded MG. The computational performance of the proposed fault analysis method is further tested in a modified islanded version of the IEEE 8500-node network.

An Efficient Δ-Circuit approach for Online Short-Circuit Calculation in Large Islanded AC Microgrids

2022 ◽  
Author(s):  
Evangelos Pompodakis
Keyword(s):  
Short Circuit ◽  
Distribution Networks ◽  
Fault Analysis ◽  
Simple Extension ◽  
Current Form ◽  
Computational Performance ◽  
Short Circuit Calculation ◽  
Node Network ◽  
The Time Domain ◽  
Virtual Impedance

In this manuscript, a novel Δ-circuit approach is proposed, which enables the fast calculation of fault currents in large islanded AC microgrids (MGs), supplied by inverter-based distributed generators (IBDGs) with virtual impedance current limiters (VICLs). The concept of virtual impedance for limiting the fault current of IBDGs has gained the interest of research community in the recent years, due to the strong advantages it offers. Moreover, Δ-circuit is an efficient approach, which has been widely applied in the past, for the calculation of short?circuit currents of transmission and distribution networks. However, the traditional Δ-circuit, in its current form, is not applicable in islanded MGs, due to the particular characteristics of such networks, e.g., the absence of a slack bus. To overcome this issue, a novel Δ-circuit approach is proposed in this paper, with the following distinct features: a) precise simulation of islanded MGs, b) fast computational performance, c) generic applicability in all types of faults e.g., single-line, 2-line or 3-line faults, d) simple extension to other DG current limiting modes, e.g., latched limit strategy etc. The proposed approach is validated through the time-domain software of Matlab Simulink, in a 9-bus and 13-bus islanded MG. The computational performance of the proposed fault analysis method is further tested in a modified islanded version of the IEEE 8500-node network.

scholarly journals Short-Circuit Fault Analysis of the Sen Transformer Using Phase Coordinate Model

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5638
Author(s):  
Liang Bu ◽  
Song Han ◽  
Jinling Feng
Keyword(s):  
Power Flow ◽  
Short Circuit ◽  
Voltage Regulation ◽  
Fault Analysis ◽  
Power Flow Control ◽  
Fault Currents ◽  
Proposed Model ◽  
Three Phase ◽  
Coordinate Model ◽  
The Time Domain

The Sen Transformer (ST) provides an economical solution for power flow control and voltage regulation. However, fault analysis and evaluation of the performance of the transmission protection system in the presence of a ST have not been investigated. Hence, a short-circuit model of the ST using the phase coordinate method is proposed in this paper. Firstly, according to the coupled-circuit ST model, the nodal admittance matrix between the sending end and receiving end of the ST was deduced. Subsequently, a fully decoupled mathematical model was established that can reflect three characteristics, including its winding connection structure, electrical parameters, and ground impedance. Thus, with the help of the phase-coordinate-based solving methodology, a short-circuit ST model may be built for various short-circuit faults. The MATLAB and PSCAD/EMTDC software were employed to carry out simulated analyses for an equivalent two-bus system. The short-circuit currents obtained from the time-domain simulation and the analytic calculation utilizing the proposed model reached an acceptable agreement, confirming the simulation’s effectiveness. Moreover, the variation of the fault currents with the variation of the compensating voltage after single-phase-to-ground and three-phase short-circuit faults was demonstrated and used to analyze the effect of the ST on the fault currents.

scholarly journals Short-Circuit Calculation in Distribution Networks with Distributed Induction Generators

Energies ◽  
2016 ◽  
Vol 9 (4) ◽  
pp. 277 ◽  
Author(s):  
Niancheng Zhou ◽  
Fan Ye ◽  
Qianggang Wang ◽  
Xiaoxuan Lou ◽  
Yuxiang Zhang
Keyword(s):  
Short Circuit ◽  
Distribution Networks ◽  
Induction Generators ◽  
Short Circuit Calculation

scholarly journals Thermal and Arc Flash Analysis of Electric Motor Drives in Distribution Networks

2017 ◽  
Vol 8 (2) ◽  
pp. 47-57
Author(s):  
Srete Nikolovski ◽  
Dragan Mlakić ◽  
Emir Alibašić
Keyword(s):  
Electric Motor ◽  
Short Circuit ◽  
Flow Analysis ◽  
Distribution Networks ◽  
Motor Drives ◽  
Fault Analysis ◽  
Electrical Network ◽  
Electric Motor Drives ◽  
Arc Flash ◽  
Energy Computation

The paper presents thermal analysis and arc flash analysis taking care of protection relays coordination settings for electric motor drives connected to the electrical network. Power flow analysis is performed to check if there are any voltage and loading violation conditions in the system. Fault analysis is performed to check the short circuit values and compute arc flash energy dissipated at industrial busbars to eliminate damage to electrical equipment and electrical shocks and hazard to personnel. Computers enable the use of smart algorithms used by electrical engineers in providing accuracy of these actions. A fast and accurate procedure for proper incident arc flash energy computation and overcurrent relays coordination in distribution networks is presented. The paper presents the use of the Arc Flash module for arc flash energy computation during the short circuit on LV and HV busbars with soft motor starters. A sample case of one real network is presented which uses soft motor starters as well as the influence on arc flash energy in one transformer station supplying the industrial network in Bosnia and Herzegovina.

Influence of distributed power supply in distributed power distribution network

2021 ◽  
pp. 1-8
Author(s):  
Xin Shen ◽  
Hongchun Shu ◽  
Min Cao ◽  
Nan Pan ◽  
Junbin Qian
Keyword(s):  
Power Supply ◽  
Power Distribution ◽  
Short Circuit ◽  
Power Grid ◽  
Distribution Network ◽  
Distribution Networks ◽  
Power Supplies ◽  
Power Distribution Network ◽  
Power Sources ◽  
Distributed Power

In distribution networks with distributed power supplies, distributed power supplies can also be used as backup power sources to support the grid. If a distribution network contains multiple distributed power sources, the distribution network becomes a complex power grid with multiple power supplies. When a short-circuit fault occurs at a certain point on the power distribution network, the size, direction and duration of the short-circuit current are no longer single due to the existence of distributed power, and will vary with the location and capacity of the distributed power supply system. The change, in turn, affects the current in the grid, resulting in the generation and propagation of additional current. This power grid of power electronics will cause problems such as excessive standard mis-operation, abnormal heating of the converter and component burnout, and communication system failure. It is of great and practical significance to study the influence of distributed power in distributed power distribution networks.

Teaching Short - Circuit Calculation with Off - Nominal Turns Ratio Transformers

TEM Journal ◽  
2021 ◽  
pp. 1525-1533
Author(s):  
Allen A. Castillo ◽  
M. Natalia Galván Osuna ◽  
Norma A. Barboza Tello ◽  
Alejandra J. Vega
Keyword(s):  
Case Studies ◽  
Short Circuit ◽  
Circuit Analysis ◽  
Industrial System ◽  
Software Simulation ◽  
Three Phase ◽  
Short Circuit Calculation ◽  
The Subject ◽  
Ieee Standards ◽  
Short Circuit Analysis

Teaching short-circuit analysis is conducted primarily through case studies; however, there are not many validated short-circuit studies available on the subject, especially when considering off-nominal turns ratio transformers. In order to improve the teaching of short-circuit analysis, a three phase short-circuit study in an industrial system according to ANSI/IEEE standards by means of Zmatrix method is presented; two case studies are considered: the industrial system with nominal and offnominal turns ratio transformers, in both cases the step by step solution is given in an explicit manner and the analytical results are validated through software simulation.

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