Short-Circuit Analysis of DER-Based Microgrids in Connected and Islanded Modes of Operation

Since microgrids should be able to smoothly operate in two distinct modes—grid-connected and islanded, their fault currents can widely fluctuate depending on the operational mode. When the microgrid is connected to the grid, the highest fault current, by far, is supplied by the utility grid. In this mode, the fault current contribution from distributed energy resources (DERs) is less than 20%. However, when the microgrid switches to the islanded mode, the fault current contribution from the utility grid is lost and DERs are the sole fault current sources. Thus, the overall fault current in the islanded mode is multiple times lower when compared to the grid connected mode. Moreover, most of the DERs are inverter-based, with limited fault currents, which further reduces the overall fault current in the islanded mode. With the rapid rise of the microgrid penetration around the globe, this phenomenon can adversely influence the relay protection, and thus the microgrid fault current needs to be precisely analyzed. Therefore, the main purpose of this paper is to thoroughly analyze the fault current differences in two distinct operation modes of a microgrid, and to consequently derive conclusions regarding the required improvements in fault calculations and relay protection analysis in emerging microgrids. A representative microgrid test bed is developed and modelled using the in-house developed software as well as in a state-of-the-art hardware-in-the-loop environment. Several different short-circuit faults were simulated and analyzed in both grid-connected and islanded modes. The results show that the fault currents significantly differ depending on the operating mode, and thus highly influence the protection system. Moreover, test results show that the fault calculation algorithms aimed at radial distribution grids, mostly used for microgrid fault calculations in the available literature, need to be further improved to provide precise and time-efficient results when the emerging microgrids are considered. These results provide a valuable insight into the current state of the microgrids’ fault calculation and protection and reveal several important directions for future research.

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Fault Current Limitation (FCL) and Voltage Dip Improvement Thanks to Distributed Static Series Compensator (DSSC)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.260-261.525 ◽

2012 ◽

Vol 260-261 ◽

pp. 525-531 ◽

Cited By ~ 1

Author(s):

Salman Badkubi

Keyword(s):

Power Systems ◽

Power Flow ◽

Short Circuit ◽

Short Circuit Current ◽

Fault Current ◽

Additional Function ◽

Power Flow Control ◽

Current Limitation ◽

Fault Currents ◽

Voltage Dip

This paper presents the comprehensive implementation of Distributed Static Series Compensator (DSSC) to limit the fault currents in power systems. This is the first time that the limitation of fault currents with D-FACTS devices is addressed. DSSC is one of the D-FACTS families whichoperate in a similar manner as Static Synchronous Series Compensator (SSSC) but in smaller size, lower price and more capability. The effectiveness of the DSSC in fault current limitation is investigated through the series voltage effect upon the line. The short circuit current limitation strategy presented here exhibited that besides of the power flow control which is carried out by DSSC; it can also perform this additional function. In the following the potency of the DSSC in reduction of instantaneous voltage dip range during fault current limiting mode is clarified. Furthermore, it is disclosed that with performing more DSSC in the power system, the entire system voltage dip will be improved. In order to validate the claims, computer simulations using PSCAD/EMTDC are exploited.

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First Superconducting Fault Current Limiter in Russian Power Grid

Elektrichestvo ◽

10.24160/0013-5380-2021-4-4-16 ◽

2021 ◽

Vol 4 (4) ◽

pp. 4-16

Author(s):

Michael E. MOZAH ◽

◽

Sergey V. SAMOYLENKOV ◽

Andrey P. VAVILOV ◽

Evgeny P. PROKHOROV ◽

...

Keyword(s):

Power System ◽

High Voltage ◽

Short Circuit ◽

Relay Protection ◽

Short Circuit Current ◽

Fault Current ◽

Fault Current Limiter ◽

Superconducting Fault Current Limiter ◽

Current Limiter ◽

Technical Solutions

Superconducting fault current limiter (SFCL) is an innovative method for reducing the level of short-circuit currents in high-voltage electrical networks. This reduces the number of points of separation of the electrical network in conditions of short-circuit current limitation and thereby increases the network capacity and reliability of power supply to consumers. At the same time, the development of such devices poses new challenges for power engineers related to the integration of this equipment into the existing power system. The article discusses the process of implementation and pilot operation of the SFCT 220 kV pilot project (produced by CJSC “SuperOx”) at the 220/20 kV “Mnevniki” high-voltage substation in Moscow. The project required an extensive set of scientific studies and tests to confirm the characteristics of new devices and the possibility of their use in Russian power systems, the use of digital modeling technologies to test the operability of relay protection devices, as well as the development of new methodological documents for calculating the short-circuit current and relay protection parameters. As a result of the work, SFCT was switched on at the 220/20 kV “Mnevniki” substation at the end of 2019. The subsequent operation of the SFCT in 2019-2020 fully confirmed the declared characteristics of the device and the correctness of the selected technical solutions. The article is devoted to the features of the process of integrating a new device into the existing power system, the main technical solutions, the results of testing and operation of the device, as well as possible prospects for the development of SFCT technology.

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Fault current contribution and short circuit behaviour of a solar PV integrated distribution network

International Journal of Renewable Energy Technology ◽

10.1504/ijret.2018.10011082 ◽

2018 ◽

Vol 9 (1/2) ◽

pp. 208

Author(s):

Sudhir Y. Kumar ◽

Pramod Kumar Bhatt

Keyword(s):

Short Circuit ◽

Distribution Network ◽

Fault Current ◽

Solar Pv ◽

Current Contribution

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Analysis of the Impact of Distributed Generation on Distribution Network Protection

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.433-440.5924 ◽

2012 ◽

Vol 433-440 ◽

pp. 5924-5929 ◽

Cited By ~ 1

Author(s):

Jie Dong ◽

Ya Jun Rong ◽

Chun Jiang Zhang

Keyword(s):

Distributed Generation ◽

Theoretical Basis ◽

Short Circuit ◽

Distribution Network ◽

Relay Protection ◽

Fault Current ◽

Protection Scheme ◽

Network Protection ◽

The Impact ◽

Short Circuit Condition

With the connection of distributed generation (DG), structure of traditional distribution network changes and original relay protection scheme should be adjusted. On the basis of introducing the concept and advantages of distributed generation, this paper discusses the influence of distributed generation with different position or different capacity on current protection. The paper analyzes magnitude and distribution of fault current under short-circuit condition and change curves of fault current are given, which provides some theoretical basis for new relay protection scheme.

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A Type of Depth Fault Current Limiter Based on Fast Switch and its Experimental Research

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.521.213 ◽

2014 ◽

Vol 521 ◽

pp. 213-216

Author(s):

Li Jun Qin ◽

Xiao Teng Wu

Keyword(s):

Power System ◽

Energy Loss ◽

Short Circuit ◽

Circuit Breaker ◽

Short Circuit Current ◽

Current Level ◽

Fault Current ◽

Fault Current Limiter ◽

Fault Currents ◽

Current Limiter

Along with the expansion of power system, the rapid growth of load in power system and large capacity generators continuously going into operation, the increasing of short-circuit current level cause a serious threat to the security of the power system. The contradiction between high fault currents and limited circuit breaker interrupting capacity is prominent, in order to limit high short-circuit current, reduce the energy loss of traditional fault current limiter, and improve the limiting depth, this paper presents an new fault current limiter (FCL), and analysis its ability of limiting short current.

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Fault current contribution and short circuit behaviour of a solar PV integrated distribution network

International Journal of Renewable Energy Technology ◽

10.1504/ijret.2018.090120 ◽

2018 ◽

Vol 9 (1/2) ◽

pp. 208

Author(s):

Pramod Kumar Bhatt ◽

Sudhir Y. Kumar

Keyword(s):

Short Circuit ◽

Distribution Network ◽

Fault Current ◽

Solar Pv ◽

Current Contribution

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Control of high short-circuit fault currents and fault current limiters

Power Systems Modelling and Fault Analysis ◽

10.1016/b978-0-12-815117-4.00010-2 ◽

2019 ◽

pp. 743-781

Author(s):

Nasser Tleis

Keyword(s):

Short Circuit ◽

Fault Current ◽

Fault Currents ◽

Fault Current Limiters ◽

Short Circuit Fault

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Impact of Momentary Cessation Voltage Level in Inverter-Based Resources on Increasing the Short Circuit Current

Sustainability ◽

10.3390/su11041153 ◽

2019 ◽

Vol 11 (4) ◽

pp. 1153 ◽

Cited By ~ 3

Author(s):

Namki Choi ◽

Bohyun Park ◽

Hwanhee Cho ◽

Byongjun Lee

Keyword(s):

Power Systems ◽

Short Circuit ◽

Circuit Breaker ◽

Short Circuit Current ◽

Fault Current ◽

Test Results ◽

Voltage Level ◽

Fault Currents ◽

Current Calculation ◽

The Impact

This study analyzed the impact of varying the momentary cessation (MC) voltage level on the short circuit current of inverter-based resources (IBRs). To analyze the impact of the IBR MC function on the short circuit current, this paper proposes an advanced IBR model for fault current calculation to reflect its fault characteristics and a scheme for analyzing the influence of MC on the short circuit current. Based on the proposed methods, the authors conducted case studies using planning data from the Korea Electric Power Corporation (KEPCO). The influence of MC was investigated on the IBRs located at the southwest side of the KEPCO systems by screening the fault currents while varying the MC voltage. This paper demonstrates that the minimum MC voltage level needed for the fault current not to exceed the circuit breaker (CB) capacity can be proposed through analyzing the impact of MC voltage level on the short circuit current. The test results based on the proposed scheme showed that the short circuit current to power systems could not violate CB capacity if IBRs adjusted the MC voltage level higher than the lowest MC voltage level.

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