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19 pages, 4269 KiB

Open AccessArticle

Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures

by Joon Han, Chul-Moon Lee and Chul-Hwan Kim

Energies 2021, 14(5), 1311; https://doi.org/10.3390/en14051311 - 28 Feb 2021

Cited by 4 | Viewed by 1627

This paper presents an advanced adaptive single-pole auto-reclosing (ASPAR) scheme based on harmonic characteristics of the secondary arc voltage. For analysis of the harmonics, short-time Fourier transform (STFT), which is a universal signal processing tool for transforming a signal from the time domain [...] Read more.

This paper presents an advanced adaptive single-pole auto-reclosing (ASPAR) scheme based on harmonic characteristics of the secondary arc voltage. For analysis of the harmonics, short-time Fourier transform (STFT), which is a universal signal processing tool for transforming a signal from the time domain to the frequency domain, is utilized. STFT is applied to extract the abnormal harmonic signature from the voltage waveform of a faulted phase when a transient or permanent fault occurs on a power transmission line. The proposed scheme uses the total harmonic distortion (THD) factor to determine the fault type based on the variation and distortion characteristics of the harmonics. Harmonic components in the order of odd/even are also utilized to detect the secondary arc extinction time and guide the reclosing operation. Based on these factors, two coordinated algorithms are proposed to reduce the unnecessary dead time in conventional auto-reclosing methods and enable an optimal reclosing operation in the event of a single-pole to ground fault. The proposed ASPAR scheme is implemented using the electromagnetic transient program (EMTP), and various simulations are conducted for actual 345 and 765 kV Korean study systems. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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19 pages, 10949 KiB

Open AccessArticle

Design of Microgrid Protection Schemes Using PSCAD/EMTDC and ETAP Programs

by Hyun Shin, Sang Heon Chae and Eel-Hwan Kim

Energies 2020, 13(21), 5784; https://doi.org/10.3390/en13215784 - 04 Nov 2020

Cited by 9 | Viewed by 5407

Abstract

Steady-state, harmonics, and transient analysis of a power system by using a detailed simulation model is essential to microgrid operation before the installation of new power facilities, because the microgrid, which is a small-scale independent power grid consisting of distributed resources and an [...] Read more.

Steady-state, harmonics, and transient analysis of a power system by using a detailed simulation model is essential to microgrid operation before the installation of new power facilities, because the microgrid, which is a small-scale independent power grid consisting of distributed resources and an energy storage system, has no choice but to include many inverters consisting of switching devices. Accordingly, in the case of an accident in a microgrid system, various power system simulation tools must be used to calculate the fault current for grid protection components. Specifically, Modelling using Power System Computer Aided Design (PSCAD)/Electro-Magnetic Transient Design and Control (EMTDC) can perform detailed modeling of switching devices into each inverter, and Electrical Transient Analyzer Program (ETAP) can design protection relays. From this perspective, this study designed whole protection components in a microgrid system, including the capacity of switching devices for fault ride through a protective relay and the capacity of the circuit breaker. The parameters of an actual microgrid on the San Cristobal Island, Galapagos, were used to make a detailed simulation model in both PSCAD/EMTDC and ETAP. The capacities of the switching devices were estimated by using PSCAD/EMTDC. Additionally, the rated breaking capacities and the setting values of the protective relay were also calculated from the result of an ETAP simulation. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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12 pages, 2531 KiB

Open AccessArticle

A Study on an Out-of-Step Detection Algorithm Using the Time Variation of Complex Power: Part I, Mathematical Modeling

by You-Jin Lee, Jeong-Yong Heo, O-Sang Kwon and Chul-Hwan Kim

Energies 2020, 13(16), 4065; https://doi.org/10.3390/en13164065 - 06 Aug 2020

Cited by 1 | Viewed by 1343

Abstract

Power quality and stability have become the most important issues in power system operations, Micro Grids, and Smart Grids. Sensitive equipment can be seriously damaged when exposed to unstable power swing conditions. An unstable system may cause serious damage to Micro Grid System [...] Read more.

Power quality and stability have become the most important issues in power system operations, Micro Grids, and Smart Grids. Sensitive equipment can be seriously damaged when exposed to unstable power swing conditions. An unstable system may cause serious damage to Micro Grid System elements such as generators, transformers, transmission lines, and so forth. Therefore, out-of-step detection is essential for the safe operation of a Micro Grid system. In general, Equal Area Criterion (EAC) is a method for evaluating the stability of Smart Grid systems. However, EAC can be performed only if it is possible to analyze the active power and generator angle. This paper presents an analysis of the trajectory of complex power using a mathematical model. The variation of complex power is analyzed using a mathematical method, and then the relationship between complex power and EAC is presented, and a simulation performed. Later, in part II, a novel out-of-step detection algorithm based on part I will be presented and tested. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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15 pages, 2875 KiB

Open AccessArticle

Cost-Effective Placement of Phasor Measurement Units to Defend against False Data Injection Attacks on Power Grid

by Junhyung Bae

Energies 2020, 13(15), 3862; https://doi.org/10.3390/en13153862 - 28 Jul 2020

Cited by 8 | Viewed by 1939

Abstract

This study presents the phasor measurement unit (PMU) placement strategy in the presence of false data injection attacks which is one of the most serious security threats against power grid. It is focused on applications related to supervisory control and data acquisition (SCADA) [...] Read more.

This study presents the phasor measurement unit (PMU) placement strategy in the presence of false data injection attacks which is one of the most serious security threats against power grid. It is focused on applications related to supervisory control and data acquisition (SCADA) systems where measurement data can be easily corrupted by adversaries without getting caught by the system. To safeguard power grids against malicious attacks, procedures have been proposed to facilitate the placement of secure PMUs to defend against false data injection attacks in a highly cost-effective way. It has formulated a method of identifying measurements that are vulnerable to false data injection attacks. It was discovered that a weak power grid can be transformed into a robust power grid by adding a few PMUs at vulnerable locations. Simulations on the IEEE standard test systems demonstrate the benefits of the proposed procedure. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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12 pages, 2278 KiB

Open AccessArticle

Ground Fault Detection Using Hybrid Method in IT System LVDC Microgrid

by Kyung-Min Lee and Chul-Won Park

Energies 2020, 13(10), 2606; https://doi.org/10.3390/en13102606 - 20 May 2020

Cited by 6 | Viewed by 2891

Abstract

Low voltage direct current (LVDC) microgrid systems have many advantages over low voltage alternating current (LVAC) systems. Furthermore, LVDC microgrids are growing in use because they are easy to link to distributed energy resources (DER) and energy storage systems (ESS), etc. Currently, IT [...] Read more.

Low voltage direct current (LVDC) microgrid systems have many advantages over low voltage alternating current (LVAC) systems. Furthermore, LVDC microgrids are growing in use because they are easy to link to distributed energy resources (DER) and energy storage systems (ESS), etc. Currently, IT system LVDC microgrids are widely used in direct current (DC) railways, hospitals, photovoltaic (PV) systems, and so on. When a ground fault occurs in an IT system LVDC microgrid, the ground fault may not be detected because the fault current is very small and there is no current path. In this paper, ground fault detection is proposed using a hybrid method that comprises pulsation signal generator injection and detailed coefficients of discrete wavelet transform (DWT). The LVDC microgrid was modeled and simulated using power systems computer-aided design (PSCAD). In addition, the proposed hybrid method was implemented using MATLAB’s wave menu, a script m-file, and the PSCAD library. The proper threshold was selected and tested by fault resistance change and load variation. In order to verify the superiority of the proposed hybrid method, a comparative study with the conventional method was performed. The results of various simulations show that the proposed hybrid detection method has normal operation and accurately and rapidly detects ground faults. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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13 pages, 7502 KiB

Open AccessArticle

Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method

by Shazia Baloch, Saeed Zaman Jamali, Khawaja Khalid Mehmood, Syed Basit Ali Bukhari, Muhammad Saeed Uz Zaman, Arif Hussain and Chul-Hwan Kim

Energies 2020, 13(9), 2350; https://doi.org/10.3390/en13092350 - 08 May 2020

Cited by 13 | Viewed by 2313

Abstract

To resolve the protection issues caused by high penetration of distributed energy resources, this paper proposes an efficient protection scheme for microgrids based on the autocorrelation of three-phase current envelopes. The proposed strategy uses a squaring and low-pass filtering approach for evaluating the [...] Read more.

To resolve the protection issues caused by high penetration of distributed energy resources, this paper proposes an efficient protection scheme for microgrids based on the autocorrelation of three-phase current envelopes. The proposed strategy uses a squaring and low-pass filtering approach for evaluating the envelope of the current signal. Then, the variance of the autocorrelation function is used to extract the hidden information of the distorted envelope to detect the fault signatures in the microgrid. Furthermore, the reactive power is used for determining the fault direction. The performance of the proposed protection scheme was verified on a standard medium-voltage microgrid by performing simulations in the MATLAB/Simulink environment (Version: R2017b). The proposed scheme was shown to be easy to implement and have good performance under looped and radial configuration for both grid-connected and islanded operation modes. The simulation results showed that the scheme could not only detect, locate, classify, and isolate various types of short-circuit faults effectively but also provide backup protection in case of primary protection failure. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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15 pages, 4424 KiB

Open AccessArticle

A Study on the Out-of-Step Detection Algorithm Using Time Variation of Complex Power-Part II: Out-of-Step Detection Algorithm and Simulation Results

by You-Jin Lee, O-Sang Kwon, Jeong-Yong Heo and Chul-Hwan Kim

Energies 2020, 13(7), 1833; https://doi.org/10.3390/en13071833 - 10 Apr 2020

Cited by 3 | Viewed by 1990

Abstract

One of the established unstable power swing (out-of-step) detection algorithms in micro grid/smart grid power systems uses a trajectory of apparent impedance in the R-X plane. However, this algorithm is not suitable for fast out-of-step conditions and it is hard to detect out-of-step [...] Read more.

One of the established unstable power swing (out-of-step) detection algorithms in micro grid/smart grid power systems uses a trajectory of apparent impedance in the R-X plane. However, this algorithm is not suitable for fast out-of-step conditions and it is hard to detect out-of-step conditions exactly. Another algorithm for out-of-step detection is using phasor measurement units (PMUs). However, PMUs need extra equipment. This paper presents the out-of-step detection algorithm using the trajectory of complex power. The trajectory of complex power and generator mechanical power is used to identify out-of-step conditions. A second order low pass digital filter is used to extract the generator mechanical power from the complex power. Variations of complex power are used to identify equilibrium points between stable and unstable conditions. The proposed out-of-step algorithm is based on the modification of assessment of a transient stability using equal area criterion (EAC). The proposed out-of-step algorithm is verified and tested by using alternative transient program/electromagnetic transient program (ATP/EMTP) MODELS. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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Graphical abstract

19 pages, 10300 KiB

Open AccessArticle

New Protection Scheme Based on Coordination with Tie Switch in an Open-Loop Microgrid

by Hun-Chul Seo

Energies 2019, 12(24), 4756; https://doi.org/10.3390/en12244756 - 13 Dec 2019

Cited by 9 | Viewed by 2211

Abstract

Owing to the increase in renewable energy, microgrids (MGs) are increasing. A MG has a small loop-type grid configuration. In the loop MG, challenges in protection such as maloperation of protection relay may occur owing to bidirectional current flow. Herein, we propose a [...] Read more.

Owing to the increase in renewable energy, microgrids (MGs) are increasing. A MG has a small loop-type grid configuration. In the loop MG, challenges in protection such as maloperation of protection relay may occur owing to bidirectional current flow. Herein, we propose a new protection scheme in the loop MG. Considerations for protection in loop MG and fault characteristics are analyzed. Based on these, a new index to solve the considerations for MG protection are proposed using a wavelet transform. Furthermore, the new protection scheme based on the coordination with tie switch using the proposed new index is proposed. To verify the proposed scheme, the MG and the proposed scheme are modeled using the electromagnetic transients program and MATLAB. Various simulations according to the fault location and the success/failure of fault section separation are performed. Simulation results indicate that the power supply on the original feeder can be maintained by proposed method. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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22 pages, 12048 KiB

Open AccessArticle

An Innovative Operation Strategy of ESS for Capacity Expansion of Renewable Energy and Customer Load with Electric Vehicle Chargers in Low Voltage Distribution Systems

by Kyung-Sang Ryu, Dae-Jin Kim, Yang-Hyun Nam, Heesang Ko, Byungki Kim and Ho-Chan Kim

Energies 2019, 12(24), 4668; https://doi.org/10.3390/en12244668 - 09 Dec 2019

Cited by 3 | Viewed by 2730

Abstract

This paper proposes an innovative operation strategy to extend the acceptance of EVC (Electric Vehicle Charger) and RES (Renewable Energy Resource) in LVDS (Low Voltage Distribution System) by introducing an ESS (Energy Storage System). In conventional LVDS, the load and RES capacity are [...] Read more.

This paper proposes an innovative operation strategy to extend the acceptance of EVC (Electric Vehicle Charger) and RES (Renewable Energy Resource) in LVDS (Low Voltage Distribution System) by introducing an ESS (Energy Storage System). In conventional LVDS, the load and RES capacity are designed not to exceed the pole transformer capacity. However, when the ESS is connected to the end of LVDS and the bidirectional power flow becomes possible, the linkable capacity of the load and renewable energy can be improved up to twice the capacity of the pole transformer. In addition, even though the power consumption of the load and the power generation of RES exceed the pole transformer capacity, it is possible to maintain the feeder capacity and grid voltage within the allowable limit by the appropriate operation of the ESS. The simulations are performed in the environment of PSCAD/EMTDC, and the ability of the proposed strategy is assessed and discussed. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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16 pages, 9164 KiB

Open AccessArticle

Photovoltaic-Driven SiC MOSFET Circuit Breaker with Latching and Current Limiting Capability

by David Marroqui, Ausias Garrigos, Jose M. Blanes and Roberto Gutierrez

Energies 2019, 12(23), 4585; https://doi.org/10.3390/en12234585 - 02 Dec 2019

Cited by 3 | Viewed by 4031

Abstract

This paper introduces a Solid State Circuit Breaker with Latching and Current Limiting capabilities for DC distribution systems. The proposed circuit uses very few electronic parts and it is fully analog. A SiC N-MOSFET driven by a photovoltaic driver and a maximum current [...] Read more.

This paper introduces a Solid State Circuit Breaker with Latching and Current Limiting capabilities for DC distribution systems. The proposed circuit uses very few electronic parts and it is fully analog. A SiC N-MOSFET driven by a photovoltaic driver and a maximum current detector circuit are the core elements of the system. This work details circuit operation under different conditions and includes experimental validation at 1 kVdc. Wide versatility, highly configurable, and very fast response, less than 1 µs in the case of short-circuit, are the most remarkable outcomes. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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16 pages, 2217 KiB

Open AccessArticle

Intelligent Fault Classification and Location Identification Method for Microgrids Using Discrete Orthonormal Stockwell Transform-Based Optimized Multi-Kernel Extreme Learning Machine

by Teke Gush, Syed Basit Ali Bukhari, Khawaja Khalid Mehmood, Samuel Admasie, Ji-Soo Kim and Chul-Hwan Kim

Energies 2019, 12(23), 4504; https://doi.org/10.3390/en12234504 - 27 Nov 2019

Cited by 29 | Viewed by 4274

Abstract

This paper proposes an intelligent fault classification and location identification method for microgrids using discrete orthonormal Stockwell transform (DOST)-based optimized multi-kernel extreme learning machine (MKELM). The proposed method first extracts useful statistical features from one cycle of post-fault current signals retrieved from sending-end [...] Read more.

This paper proposes an intelligent fault classification and location identification method for microgrids using discrete orthonormal Stockwell transform (DOST)-based optimized multi-kernel extreme learning machine (MKELM). The proposed method first extracts useful statistical features from one cycle of post-fault current signals retrieved from sending-end relays of microgrids using DOST. Then, the extracted features are normalized and fed to the MKELM as an input. The MKELM, which consists of multiple kernels in the hidden nodes of an extreme learning machine, is used for the classification and location of faults in microgrids. A genetic algorithm is employed to determine the optimum parameters of the MKELM. The performance of the proposed method is tested on the standard IEC microgrid test system for various operating conditions and fault cases, including different fault locations, fault resistance, and fault inception angles using the MATLAB/Simulink software. The test results confirm the efficacy of the proposed method for classifying and locating any type of fault in a microgrid with high performance. Furthermore, the proposed method has higher performance and is more robust to measurement noise than existing intelligent methods. Full article

(This article belongs to the Special Issue Micro Grid Protection)

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