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One of the crucial challenges of the distribution network is the unintentionally isolated section of electricity from the power network, called unintentional islanding. Unintentional islanding detection is severed when the local generation is equal to or closely matches the load requirement. In this paper, both ensemble learning and canonical methods are implemented for the islanding detection technique of synchronous machine-based distributed generation. The ensemble learning models for this study are random forest (RF) and Ada boost, while the canonical methods are multi-layer perceptron (MLP), decision tree (DT), and support vector machine (SVM). The training and testing parameters for this technique are the total harmonic distortion (THD) of both current and voltage signals. THD is the most important parameter of power quality monitoring under islanding scenarios. The parameter and data extraction from the test system is executed in a MATLAB/Simulink environment, whereas the training and testing of the presented techniques are implemented in Python. Performance indices such as accuracy, precision, recall, and F 1 score are used for evaluation, and both ensemble learning models and canonical models demonstrate good performance. Ada-boost shows the highest accuracy among all the five models with original data, while RF is robust and gives the best results with noisy data (20 and 30 dB) because of its ensemble nature.
Arif Hussain; Chul‐Hwan Kim; Samuel Admasie. An intelligent islanding detection of distribution networks with synchronous machine DG using ensemble learning and canonical methods. IET Generation, Transmission & Distribution 2021, 1 .
AMA StyleArif Hussain, Chul‐Hwan Kim, Samuel Admasie. An intelligent islanding detection of distribution networks with synchronous machine DG using ensemble learning and canonical methods. IET Generation, Transmission & Distribution. 2021; ():1.
Chicago/Turabian StyleArif Hussain; Chul‐Hwan Kim; Samuel Admasie. 2021. "An intelligent islanding detection of distribution networks with synchronous machine DG using ensemble learning and canonical methods." IET Generation, Transmission & Distribution , no. : 1.
In this study, we describe the development of a plug-in type of switchgear that can control bidirectional power flow. This switchgear system can connect distributed generations such as photovoltaic and wind turbine generation, and AC and DC loads. The proposed switchgear system consists of an inverter for connecting distributed generations and DC load, a static transfer switch (STS) that can control and interrupt the bidirectional power flow, and an intelligent electronic device (IED) that can control each facility using a communication system. Since the topology inside the switchgear is composed of DC bus, it can be operated as a plug-in type of system that can be used by simply connecting the converters of various distributed generations to the inverter in the developed switchgear system. In this study, we describe the overall structure of the proposed switchgear system and the operation of the components. In addition, prototypes of each facility are developed and the results of building a small testbed are presented. Finally, we verify the operation of the inverter by performing an experiment on the testbed and show that throughout a test sequence the proposed switchgear system works normally. The contributions of this study are the development of a plug-in type of switchgear for AC/DC and the actual test results presented through prototype development and testbed configuration.
Keon-Woo Park; Chul-Hwan Kim. Bi-Directional Power Flow in Switchgear with Static Transfer Switch Applied at Various Renewable Energies. Energies 2021, 14, 3187 .
AMA StyleKeon-Woo Park, Chul-Hwan Kim. Bi-Directional Power Flow in Switchgear with Static Transfer Switch Applied at Various Renewable Energies. Energies. 2021; 14 (11):3187.
Chicago/Turabian StyleKeon-Woo Park; Chul-Hwan Kim. 2021. "Bi-Directional Power Flow in Switchgear with Static Transfer Switch Applied at Various Renewable Energies." Energies 14, no. 11: 3187.
The integration of distributed generators has changed the paradigm of modern power transmission systems. To cope with energy demands, electrical networks emphasize the efficient utilization of power transmission. Thus, high-voltage DC (HVDC) and hybrid (AC/DC) transmission systems are also getting attention owing to their high efficiency in addition to the widely adopted high-voltage AC (HVAC) systems. Most faults in the bulk of transmission lines are temporary or intermittent. Auto-reclosing schemes can be used to prevent these faults. However, conventional auto-reclosing schemes based on constant dead time cannot recognize the fault nature within the assigned duration. Consequently, the accuracy of power grids can be compromised. Therefore, adaptive auto-reclosing schemes are convenient for overcoming the issues caused by the rapid restoration of faulty power lines. This can enhance system reliability and avoid power failures and blackouts. This study is based on a systematic, detailed, and thorough research review of the existing auto-reclosing schemes in all three power transmission lines, i.e., AC, DC, and hybrid (AC/DC). Subsequently, a critical analysis has been performed to assess the pros and cons of each existing adaptive auto-reclosing scheme. Finally, future recommendations are presented to improve adaptive auto-reclosing schemes in each medium.
Arif Mehdi; Chul-Hwan Kim; Arif Hussain; Ji-Soo Kim; S. Jarjees Ul Hassan. A Comprehensive Review of Auto-Reclosing Schemes in AC, DC, and Hybrid (AC/DC) Transmission Lines. IEEE Access 2021, 9, 74325 -74342.
AMA StyleArif Mehdi, Chul-Hwan Kim, Arif Hussain, Ji-Soo Kim, S. Jarjees Ul Hassan. A Comprehensive Review of Auto-Reclosing Schemes in AC, DC, and Hybrid (AC/DC) Transmission Lines. IEEE Access. 2021; 9 (99):74325-74342.
Chicago/Turabian StyleArif Mehdi; Chul-Hwan Kim; Arif Hussain; Ji-Soo Kim; S. Jarjees Ul Hassan. 2021. "A Comprehensive Review of Auto-Reclosing Schemes in AC, DC, and Hybrid (AC/DC) Transmission Lines." IEEE Access 9, no. 99: 74325-74342.
In this study, an optimal reactive power (Volt/VAr) control of smart inverters for photo-voltaic (PV) and battery energy storage systems (BESSs) to improve the PV hosting capacity (PVHC) of distribution networks is proposed. The primary objective of the proposed method is to improve the PVHC of a distribution network by determining the optimal oversize, dispatch, and control setting of the Volt/VAr functions of the smart inverters for both PVs and BESSs. Concurrently, the optimal locations of the PVs and BESSs are determined. The problem is formulated as a multi-objective mixed-integer nonlinear optimization to maximize the PVHC and minimize the voltage deviation simultaneously. A bio-inspired metaheuristic optimization method, i.e., the slime mould algorithm (SMA), is employed to solve the optimization problem. To assess the efficacy of the proposed PVHC improvement method, extensive simulations are conducted on an IEEE 33-node system using MATLAB software. The simulation results verify that the proposed method improves the PVHC of the distribution network compared to different cases and the default Volt/VAr control settings of the smart inverters. Furthermore, the SMA optimization method provides superior performance in finding the optimal PVHC of a distribution network compared to the conventional metaheuristic optimization methods.
Teke Gush; Chul-Hwan Kim; Samuel Admasie; Ji-Soo Kim; Jin-Sol Song. Optimal Smart Inverter Control for PV and BESS to Improve PV Hosting Capacity of Distribution Networks Using Slime Mould Algorithm. IEEE Access 2021, 9, 52164 -52176.
AMA StyleTeke Gush, Chul-Hwan Kim, Samuel Admasie, Ji-Soo Kim, Jin-Sol Song. Optimal Smart Inverter Control for PV and BESS to Improve PV Hosting Capacity of Distribution Networks Using Slime Mould Algorithm. IEEE Access. 2021; 9 (99):52164-52176.
Chicago/Turabian StyleTeke Gush; Chul-Hwan Kim; Samuel Admasie; Ji-Soo Kim; Jin-Sol Song. 2021. "Optimal Smart Inverter Control for PV and BESS to Improve PV Hosting Capacity of Distribution Networks Using Slime Mould Algorithm." IEEE Access 9, no. 99: 52164-52176.
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.
Joon Han; Chul-Moon Lee; Chul-Hwan Kim. Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures. Energies 2021, 14, 1311 .
AMA StyleJoon Han, Chul-Moon Lee, Chul-Hwan Kim. Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures. Energies. 2021; 14 (5):1311.
Chicago/Turabian StyleJoon Han; Chul-Moon Lee; Chul-Hwan Kim. 2021. "Adaptive Single-Pole Auto-Reclosing Scheme Based on Secondary Arc Voltage Harmonic Signatures." Energies 14, no. 5: 1311.
As a large number of distributed generations are connected to the distribution system, research on the hosting capacity is actively being conducted. In particular, various methods, such as smart inverter functionality, co-located energy storage systems (ESS), and the use of on-load tap changers (OLTC), have been proposed to improve the hosting capacity. In this paper, a method to improve the hosting capacity by utilizing a solid-state transformer (SST) and its unique control capability is proposed. Lastly, the proposed method is verified in the distribution system of the Republic of Korea using the OpenDSS program.
Jin-Sol Song; Ji-Soo Kim; Barry Mather; Chul-Hwan Kim. Hosting Capacity Improvement Method Using MV–MV Solid-State-Transformer. Energies 2021, 14, 622 .
AMA StyleJin-Sol Song, Ji-Soo Kim, Barry Mather, Chul-Hwan Kim. Hosting Capacity Improvement Method Using MV–MV Solid-State-Transformer. Energies. 2021; 14 (3):622.
Chicago/Turabian StyleJin-Sol Song; Ji-Soo Kim; Barry Mather; Chul-Hwan Kim. 2021. "Hosting Capacity Improvement Method Using MV–MV Solid-State-Transformer." Energies 14, no. 3: 622.
Power loss and voltage instability are major problems in distribution systems. However, these problems are typically mitigated by efficient network reconfiguration, including the integration of distributed generation (DG) units in the distribution network. In this regard, the optimal placement and sizing of DGs are crucial. Otherwise, the network performance will be degraded. This study is conducted to optimally locate and sizing of DGs into a radial distribution network before and after reconfiguration. A multi-objective particle swarm optimization algorithm is utilized to determine the optimal placement and sizing of the DGs before and after reconfiguration of the radial network. An optimal network configuration with DG coordination in an active distribution network overcomes power losses, uplifts voltage profiles, and improves the system stability, reliability, and efficiency. For considering the actual power system scenarios, a penalty factor is also considered, this penalty factor plays a crucial role in the minimization of total power loss and voltage profile enhancement. The simulation results showed a significant improvement in the percentage power loss reduction (32% and 68.05% before and after reconfiguration, respectively) with the inclusion of DG units in the test system. Similarly, the minimum bus voltage of the system is improved by 4.9% and 6.53% before and after reconfiguration, respectively. The comparative study is performed, and the results showed the effectiveness of the proposed method in reducing the voltage deviation and power loss of the distribution system. The proposed algorithm is evaluated on the IEEE-33 bus radial distribution system, using MATLAB software.
Waseem Haider; S Jarjees Ul Hassan; Arif Mehdi; Arif Hussain; Gerardo Ondo Micha Adjayeng; Chul-Hwan Kim. Voltage Profile Enhancement and Loss Minimization Using Optimal Placement and Sizing of Distributed Generation in Reconfigured Network. Machines 2021, 9, 20 .
AMA StyleWaseem Haider, S Jarjees Ul Hassan, Arif Mehdi, Arif Hussain, Gerardo Ondo Micha Adjayeng, Chul-Hwan Kim. Voltage Profile Enhancement and Loss Minimization Using Optimal Placement and Sizing of Distributed Generation in Reconfigured Network. Machines. 2021; 9 (1):20.
Chicago/Turabian StyleWaseem Haider; S Jarjees Ul Hassan; Arif Mehdi; Arif Hussain; Gerardo Ondo Micha Adjayeng; Chul-Hwan Kim. 2021. "Voltage Profile Enhancement and Loss Minimization Using Optimal Placement and Sizing of Distributed Generation in Reconfigured Network." Machines 9, no. 1: 20.
In this paper, a coordination method of multiple electric vehicle (EV) aggregators has been devised to flatten the system load profile. The proposed scheme tends to reduce the peak demand by discharging EVs and fills the valley gap through EV charging in the off-peak period. Upper level fair proportional power distribution to the EV aggregators is exercised by the system operator which provides coordination among the aggregators based on their aggregated energy demand or capacity. The lower level min max objective function is implemented at each aggregator to distribute power to the EVs. Each aggregator ensures that the EV customers’ driving requirements are not relinquished in spite of their employment to support the grid. The scheme has been tested on IEEE 13-node distribution system and an actual distribution system situated in Seoul, Republic of Korea whilst utilizing actual EV mobility data. The results show that the system load profile is smoothed by the coordination of aggregators under peak shaving and valley filling goals. Also, the EVs are fully charged before departure while maintaining a minimum energy for emergency travel.
Saad Ullah Khan; Khawaja Khalid Mehmood; Zunaib Maqsood Haider; Muhammad Kashif Rafique; Muhammad Omer Khan; Chul-Hwan Kim. Coordination of Multiple Electric Vehicle Aggregators for Peak Shaving and Valley Filling in Distribution Feeders. Energies 2021, 14, 352 .
AMA StyleSaad Ullah Khan, Khawaja Khalid Mehmood, Zunaib Maqsood Haider, Muhammad Kashif Rafique, Muhammad Omer Khan, Chul-Hwan Kim. Coordination of Multiple Electric Vehicle Aggregators for Peak Shaving and Valley Filling in Distribution Feeders. Energies. 2021; 14 (2):352.
Chicago/Turabian StyleSaad Ullah Khan; Khawaja Khalid Mehmood; Zunaib Maqsood Haider; Muhammad Kashif Rafique; Muhammad Omer Khan; Chul-Hwan Kim. 2021. "Coordination of Multiple Electric Vehicle Aggregators for Peak Shaving and Valley Filling in Distribution Feeders." Energies 14, no. 2: 352.
Distribution planning refers to the act of estimating the risks of distribution systems that may arise in the future and establishing investment plans to cope with them. Forecasted loads are one of the most typical variables used to analyze the risk of the distribution system, thus the efficiency of distribution planning may vary depending on its accuracy. For these reasons, a lot of studies are also being conducted to perform load prediction by incorporating the latest methods, such as machine learning (ML). However, the unchangeable fact is that no matter what prediction method is used, the accuracy and reliability of the predicted load can vary depending on the reliability of the data used. In particular, the detection of temporary load increases, due to load transfer that can occur frequently in the distribution system are essential for securing high-quality data. Therefore, in this study, a LSTM (Long Short-Term Memory) based load transfer detection model was proposed, and the appropriateness and reliability of the proposed method were analyzed by comparing actual planned load transfer data with the estimated load transfer results from the proposed model. It was also shown that the proposed model can improve the efficiency and reliability of the distribution planning by reasonably removing load variations, due to load transfer.
Jun-Hyeok Kim; Byung-Sung Lee; Chul-Hwan Kim. A Study on the Development of Machine-Learning Based Load Transfer Detection Algorithm for Distribution Planning. Energies 2020, 13, 4358 .
AMA StyleJun-Hyeok Kim, Byung-Sung Lee, Chul-Hwan Kim. A Study on the Development of Machine-Learning Based Load Transfer Detection Algorithm for Distribution Planning. Energies. 2020; 13 (17):4358.
Chicago/Turabian StyleJun-Hyeok Kim; Byung-Sung Lee; Chul-Hwan Kim. 2020. "A Study on the Development of Machine-Learning Based Load Transfer Detection Algorithm for Distribution Planning." Energies 13, no. 17: 4358.
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.
You-Jin Lee; Jeong-Yong Heo; O-Sang Kwon; Chul-Hwan Kim. A Study on an Out-of-Step Detection Algorithm Using the Time Variation of Complex Power: Part I, Mathematical Modeling. Energies 2020, 13, 4065 .
AMA StyleYou-Jin Lee, Jeong-Yong Heo, O-Sang Kwon, Chul-Hwan Kim. A Study on an Out-of-Step Detection Algorithm Using the Time Variation of Complex Power: Part I, Mathematical Modeling. Energies. 2020; 13 (16):4065.
Chicago/Turabian StyleYou-Jin Lee; Jeong-Yong Heo; O-Sang Kwon; Chul-Hwan Kim. 2020. "A Study on an Out-of-Step Detection Algorithm Using the Time Variation of Complex Power: Part I, Mathematical Modeling." Energies 13, no. 16: 4065.
The Scott transformer is used in substations of the Korean AC electric railway system to convert a three-phase source to a single-phase source. The Scott transformer consists of two single-phase transformers and protects the M-phase and T-phase transformers with a single-phase protective relay. Percentage differential and overcurrent relays are used to provide primary and back-up protection to the Scott transformer. In this study, an overcurrent relay is used, and the protective relay is modeled using the Power System Computer Aided Design/Electromagnetic Transients program including DC (PSCAD/EMTDC). The inverse-time overcurrent relay present in the existing PSCAD/EMTDC will only change the coefficients in a given equation or use limited specifications with the default model. Unlike the existing element, which is limited when configuring the protection operating time, it is possible to obtain the operating time using a specific desired equation and coefficients through the modeled overcurrent relay. This overcurrent relay can be used to model the actual Korean AC electric railway system, and it is verified that the modeling approach that generates a fault in the feeding system is set based on comparison with numerical calculation. Based on this study, we developed a new modeling methodology for the overcurrent relay and for the Korean AC electric railway feeding system. In addition, no national or international standards exist that govern the protection standards for Scott transformers. Therefore, this study is expected to contribute considerably to the design and establishment of protection regulations for Scott transformers.
Min-Sung Kim; Gyu-Jung Cho; Chul-Hwan Kim; Jong-Seo Chai. New protective relay modeling scheme and analysis for AC electric railway feeding systems with Scott transformer. International Journal of Electrical Power & Energy Systems 2020, 123, 106226 .
AMA StyleMin-Sung Kim, Gyu-Jung Cho, Chul-Hwan Kim, Jong-Seo Chai. New protective relay modeling scheme and analysis for AC electric railway feeding systems with Scott transformer. International Journal of Electrical Power & Energy Systems. 2020; 123 ():106226.
Chicago/Turabian StyleMin-Sung Kim; Gyu-Jung Cho; Chul-Hwan Kim; Jong-Seo Chai. 2020. "New protective relay modeling scheme and analysis for AC electric railway feeding systems with Scott transformer." International Journal of Electrical Power & Energy Systems 123, no. : 106226.
Microgrid (MG) has emerged as an effective way of distributed generations (DGs) integration. MGs can be operated as a grid-connected or islanded mode. During the fault situation, fault current magnitudes will vary depending on the MG operating mode. Consequently, protecting the MG using conventional methods is a challenging problem. Also, the Fault Ride Through (FRT) concept has not been introduced in the Korean distribution system. FRT is a grid code to maintain the connection of the DG for a while and to support the distribution system by injecting a reactive power when the fault occurs in the power system. Therefore, in this paper, the relay setting values of the MG connected to the DG is proposed considering the FRT. Moreover, using the Hilbert-Transform (HT) of operation mode about the energy of power flow, and adaptive dual setting method is proposed. Finally, the proposed method is validated using the Electro-Magnetic Transients Program (EMTP).
Woo-Sik Lee; Ji-Soo Kim; Jin-Sol Song; Gwang-Su Shin; Chul-Hwan Kim. A Study on the Adaptive Dual Setting Method of the Microgrid Protective Devices Considering FRT. The Transactions of The Korean Institute of Electrical Engineers 2020, 69, 657 -663.
AMA StyleWoo-Sik Lee, Ji-Soo Kim, Jin-Sol Song, Gwang-Su Shin, Chul-Hwan Kim. A Study on the Adaptive Dual Setting Method of the Microgrid Protective Devices Considering FRT. The Transactions of The Korean Institute of Electrical Engineers. 2020; 69 (5):657-663.
Chicago/Turabian StyleWoo-Sik Lee; Ji-Soo Kim; Jin-Sol Song; Gwang-Su Shin; Chul-Hwan Kim. 2020. "A Study on the Adaptive Dual Setting Method of the Microgrid Protective Devices Considering FRT." The Transactions of The Korean Institute of Electrical Engineers 69, no. 5: 657-663.
Recently, the operation of a mixed transmission system has increased due to rapid urbanization and the purpose of a good view. Therefore, a proper protection scheme for a mixed transmission system is required. Generally, when a fault occurs on a transmission line, auto reclosing is performed for the purpose of improving the continuity of service by clearing the fault and restoring the power system. However, the auto reclosing scheme should be applied to a mixed transmission system carefully because the mixed transmission system involves underground cable sections. When a fault occurs in the underground cable section, it is mostly a permanent fault. If auto reclosing is performed on a permanent fault condition, it may cause excessive overcurrent and switching surge, which can generate a serious impact on the whole transmission system and even cause an explosion. Due to this, many utilities worldwide do not allow auto reclosing or only apply it very restrictively on a mixed transmission system based on their practice. However, there is no clear guidance or standard related to auto reclosing on a mixed transmission system. Therefore, in this paper, an application of a recloser operation algorithm is proposed. Based on the proposed algorithm, reclosers can work properly and protect the transmission system. To verify the proposed algorithm, simulations were conducted using the ElectroMagnetic Transient Program (EMTP).
Seung-Hyun Sohn; Gyu-Jung Cho; Chul-Hwan Kim. A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method. Energies 2020, 13, 2610 .
AMA StyleSeung-Hyun Sohn, Gyu-Jung Cho, Chul-Hwan Kim. A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method. Energies. 2020; 13 (10):2610.
Chicago/Turabian StyleSeung-Hyun Sohn; Gyu-Jung Cho; Chul-Hwan Kim. 2020. "A Study on Application of Recloser Operation Algorithm for Mixed Transmission System Based on Travelling Wave Method." Energies 13, no. 10: 2610.
The rapid integration of wind-power generation with existing power grids has caused reliability and stability concerns owing to the negative impact on the dynamic behaviors of power systems. During a fault, large electromotive force is induced in the rotor circuit of a doubly fed induction generator (DFIG) as the circuit is highly vulnerable to it. Such circumstances increase the importance of the low-voltage ride-through (LVRT) capability of a DFIG to ensure stability of the electric grid during transient conditions. Considering these factors, this study focuses on the mitigation of rotor overcurrents and DC-link voltage variations by modifying the control structure of the DFIG converter, thereby enhancing its LVRT capability. Additional voltage terms are injected into the rotor-voltage references to improve the transient behavior of the DFIG control system. In the proposed design, transient rotor currents and DC-link voltage variations are effectively suppressed. Because the voltage terms are introduced outside the current loops, there is no impact on their stability. Furthermore, electromagnetic torque oscillations during the faults are considerably suppressed. Finally, the validity of the proposed design during abnormal grid conditions is demonstrated via MATLAB/Simulink. The results confirm the feasibility and effectiveness of the improved converter control design to enhance the LVRT capability of a DFIG.
Muhammad Arif Sharafat Ali; Khawaja Khalid Mehmood; Shazia Baloch; Chul-Hwan Kim. Modified rotor-side converter control design for improving the LVRT capability of a DFIG-based WECS. Electric Power Systems Research 2020, 186, 106403 .
AMA StyleMuhammad Arif Sharafat Ali, Khawaja Khalid Mehmood, Shazia Baloch, Chul-Hwan Kim. Modified rotor-side converter control design for improving the LVRT capability of a DFIG-based WECS. Electric Power Systems Research. 2020; 186 ():106403.
Chicago/Turabian StyleMuhammad Arif Sharafat Ali; Khawaja Khalid Mehmood; Shazia Baloch; Chul-Hwan Kim. 2020. "Modified rotor-side converter control design for improving the LVRT capability of a DFIG-based WECS." Electric Power Systems Research 186, no. : 106403.
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.
Shazia Baloch; Saeed Zaman Jamali; Khawaja Khalid Mehmood; Syed Basit Ali Bukhari; Muhammad Saeed Uz Zaman; Arif Hussain; Chul-Hwan Kim. Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method. Energies 2020, 13, 2350 .
AMA StyleShazia Baloch, Saeed Zaman Jamali, Khawaja Khalid Mehmood, Syed Basit Ali Bukhari, Muhammad Saeed Uz Zaman, Arif Hussain, Chul-Hwan Kim. Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method. Energies. 2020; 13 (9):2350.
Chicago/Turabian StyleShazia Baloch; Saeed Zaman Jamali; Khawaja Khalid Mehmood; Syed Basit Ali Bukhari; Muhammad Saeed Uz Zaman; Arif Hussain; Chul-Hwan Kim. 2020. "Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method." Energies 13, no. 9: 2350.
In recent years, the application of renewable energy resources (RES) with DC output has increased, and RES integration as DC islanded microgrids (DC ImGs) has attracted the attention of many researchers. However, DC ImGs face many challenges, and voltage stability is extremely critical for efficient power distribution. This challenge becomes more prominent when exogenous disturbances, as well as time-delay, exist in the system mainly because of the communication network. In this study, we develop a mathematical model of the time-delay DC ImG. To compensate for the effect of the time-delay, three control strategies are introduced—stabilizing, robust, and robust-predictor. The controller’s stability is guaranteed based on the Lyapunov-Krasovskii theorem, whereas for the exogenous disturbance rejection, the L2-norm of the system is reduced. Furthermore, to obtain the proposed controllers’ gains, linear-matrix-inequality constraints are formulated. The performances of the controllers are investigated through numerous simulations, and a detailed analysis is presented.
Muhammad Mehdi; Chul-Hwan Kim; Muhammad Saad. Robust Centralized Control for DC Islanded Microgrid Considering Communication Network Delay. IEEE Access 2020, 8, 77765 -77778.
AMA StyleMuhammad Mehdi, Chul-Hwan Kim, Muhammad Saad. Robust Centralized Control for DC Islanded Microgrid Considering Communication Network Delay. IEEE Access. 2020; 8 (99):77765-77778.
Chicago/Turabian StyleMuhammad Mehdi; Chul-Hwan Kim; Muhammad Saad. 2020. "Robust Centralized Control for DC Islanded Microgrid Considering Communication Network Delay." IEEE Access 8, no. 99: 77765-77778.
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.
You-Jin Lee; O-Sang Kwon; Jeong-Yong Heo; Chul-Hwan Kim. 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. Energies 2020, 13, 1833 .
AMA StyleYou-Jin Lee, O-Sang Kwon, Jeong-Yong Heo, Chul-Hwan Kim. 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. Energies. 2020; 13 (7):1833.
Chicago/Turabian StyleYou-Jin Lee; O-Sang Kwon; Jeong-Yong Heo; Chul-Hwan Kim. 2020. "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." Energies 13, no. 7: 1833.
Microgrids experience significantly different fault currents in different operating scenarios, which make microgrid protection challenging. Existing intelligent protection schemes rely on the extraction of appropriate fault features using statistical parameters. The selection of these features is difficult in a microgrid because of its various operating scenarios. This study develops a convolutional neural network-based intelligent fault protection strategy (CNNBIPS) for microgrids that inherently integrates the feature extraction and classification process. The proposed strategy is directly applicable to three-phase (TP) current signals; thus, it does not require any separate feature extractor. In the proposed CNNBIPS, TP current signals sampled by the protective relays are used as an input to three different CNNs. The CNNs apply convolution and pooling operations to extract the features from the input signals. Then, fully connected layers of the CNNs employ the features to develop fault-type, phase, and location information. To analyse the efficacy of the proposed design, we execute exhaustive simulations on a standard microgrid test system. The results confirm the effectiveness of the proposed strategy in terms of detection accuracy, security, and dependability. Moreover, comparisons with previous methods show that the proposed approach outperforms the existing microgrid protection schemes.
Syed Basit Ali Bukhari; Chul‐Hwan Kim; Khawaja Khalid Mehmood; Raza Haider; Muhammad Saeed Uz Zaman. Convolutional Neural Network‐Based Intelligent Protection Strategy for Microgrids. IET Generation, Transmission & Distribution 2020, 14, 1177 -1185.
AMA StyleSyed Basit Ali Bukhari, Chul‐Hwan Kim, Khawaja Khalid Mehmood, Raza Haider, Muhammad Saeed Uz Zaman. Convolutional Neural Network‐Based Intelligent Protection Strategy for Microgrids. IET Generation, Transmission & Distribution. 2020; 14 (7):1177-1185.
Chicago/Turabian StyleSyed Basit Ali Bukhari; Chul‐Hwan Kim; Khawaja Khalid Mehmood; Raza Haider; Muhammad Saeed Uz Zaman. 2020. "Convolutional Neural Network‐Based Intelligent Protection Strategy for Microgrids." IET Generation, Transmission & Distribution 14, no. 7: 1177-1185.
The advantages of increased penetration of distributed generation are also accompanied by several challenges, low inertia being one of them, which threatens the grid stability. An emerging approach to confront this problem is the introduction of so-called virtual inertia (VI) provided by energy storage systems (ESS). In contrast to the already available literature which considers a conventional load frequency control (LFC) model, this work concentrates on a modified LFC model as the integration of a large portion of ESS changes the inertia constant ( H ) of a power system. A sensitivity function is derived that shows the effects of changes in H on the power system’s frequency response. With the help of the developed mathematical model and simulation results, it is shown that a difference in the actual and calculated values of H can deteriorate the system performance and economy. As one of the reasons for this difference is improper modeling of ESS in the LFC model, therefore, the study signifies the accurate calculation of H in the power systems having enlarged penetration of ESS.
Muhammad Saeed Uz Zaman; Muhammad Irfan; Muhammad Ahmad; Manuel Mazzara; Chul-Hwan Kim. Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis. Energies 2020, 13, 902 .
AMA StyleMuhammad Saeed Uz Zaman, Muhammad Irfan, Muhammad Ahmad, Manuel Mazzara, Chul-Hwan Kim. Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis. Energies. 2020; 13 (4):902.
Chicago/Turabian StyleMuhammad Saeed Uz Zaman; Muhammad Irfan; Muhammad Ahmad; Manuel Mazzara; Chul-Hwan Kim. 2020. "Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis." Energies 13, no. 4: 902.
Ji-Soo Kim; Chul-Hwan Kim; Yun-Sik Oh; Gyu-Jung Cho; Jin-Sol Song. An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method. IEEE Transactions on Sustainable Energy 2020, 11, 2722 -2731.
AMA StyleJi-Soo Kim, Chul-Hwan Kim, Yun-Sik Oh, Gyu-Jung Cho, Jin-Sol Song. An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method. IEEE Transactions on Sustainable Energy. 2020; 11 (4):2722-2731.
Chicago/Turabian StyleJi-Soo Kim; Chul-Hwan Kim; Yun-Sik Oh; Gyu-Jung Cho; Jin-Sol Song. 2020. "An Islanding Detection Method for Multi-RES Systems Using the Graph Search Method." IEEE Transactions on Sustainable Energy 11, no. 4: 2722-2731.