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4 pages, 171 KiB

Open AccessEditorial

Emerging Technologies in Power Systems

by Kun-Yik Jo, Truong-Duy Duong and Joon-Ho Choi

Electronics 2022, 11(1), 71; https://doi.org/10.3390/electronics11010071 - 27 Dec 2021

Cited by 5 | Viewed by 2546

Abstract

Recently, renewable energy resources have been connected to the power system to reduce carbon emissions worldwide [...] Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

Research

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19 pages, 7746 KiB

Open AccessArticle

Real Time-Based under Frequency Control and Energy Management of Microgrids

by Muhammed Y. Worku, Mohamed A. Hassan and Mohamed A. Abido

Electronics 2020, 9(9), 1487; https://doi.org/10.3390/electronics9091487 - 10 Sep 2020

Cited by 15 | Viewed by 3169

Abstract

In this paper, an efficient under frequency control and the energy management of a distributed energy resources (DERs)-based microgrid is presented. The microgrid is composed of a photovoltaic (PV), double-fed induction generator (DFIG)-based wind and diesel generator with critical and non-critical loads. The [...] Read more.

In this paper, an efficient under frequency control and the energy management of a distributed energy resources (DERs)-based microgrid is presented. The microgrid is composed of a photovoltaic (PV), double-fed induction generator (DFIG)-based wind and diesel generator with critical and non-critical loads. The system model and the control strategy are developed in a real time digital simulator (RTDS). The coordination and power management of the DERs in both grid-connected and islanded operation modes are implemented. During power imbalances and frequency fluctuations caused by fault or islanding, an advanced automatic load shedding control is implemented to regulate and maintain the microgrid frequency at its rated value. One distinct feature implemented for the load shedding operation is that highly unbalanced critical loads are connected to the microgrid. The diesel generator provides the required inertia in the islanded mode to maintain the microgrid rated frequency by operating in the isochronous mode. The International Council on Large Electric Systems (CIGRE) medium voltage (MV) test bench system is used to implement the DERs and their controller. The proposed control approach has potential applications for the complete operation of microgrids by properly controlling the power, voltage and frequency in both grid-connected and island modes. The real time digital simulator results verify the effectiveness and superiority of the proposed control scheme in grid connected, island and fault conditions. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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18 pages, 7155 KiB

Open AccessArticle

Study on the Capacity of an Active Phase Controller for Autonomous Grid Connection

by Da-Woom Jeong, Soo-Yeon Kim, Sung-Jun Park and Dong-Hee Kim

Electronics 2020, 9(8), 1252; https://doi.org/10.3390/electronics9081252 - 05 Aug 2020

Cited by 1 | Viewed by 1984

Abstract

For the efficient power allocation of the distribution line, several studies on intelligent distribution management systems that enable connection or separation between distribution networks are being conducted. However, in case the systems are linked together and if the voltage and phase of each [...] Read more.

For the efficient power allocation of the distribution line, several studies on intelligent distribution management systems that enable connection or separation between distribution networks are being conducted. However, in case the systems are linked together and if the voltage and phase of each distribution network are different, uncontrolled circulating current and inrush current flow into the line. To resolve this, we introduced the active phase controller (APC) as a solution and performed an analysis using the capacity calculation method for the APC connected to each distribution network. When connecting lines between distribution networks, the phase of each contact was ensured to be the same. Specifically, the phase value compensated by each APC is different because the amounts of active power and reactive power to be controlled are also different. In this study, we analyzed the APC capacity according to the impedance state of the distribution line and calculated the APC output voltage for the phase matching of each distribution network at the connection point. As a result, the minimum design capacity of APC was derived; moreover, simulation results were used to validate the analysis. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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24 pages, 9378 KiB

Open AccessFeature PaperArticle

Enhanced Control Scheme for a Three-Phase Grid-Connected PV Inverter under Unbalanced Fault Conditions

by Saeid Abbasi, Ali Asghar Ghadimi, Amir Hossein Abolmasoumi, Mohammad Reza Miveh and Francisco Jurado

Electronics 2020, 9(8), 1247; https://doi.org/10.3390/electronics9081247 - 03 Aug 2020

Cited by 12 | Viewed by 4880

Abstract

This paper presents an improved control strategy to cancel the double grid frequency oscillations in the active power, reactive power, and DC-link voltage of a three-phase grid-connected photovoltaic (PV) system under unbalanced grid condition. To achieve these goals, an enhanced positive–negative-sequence control (PNSC) [...] Read more.

This paper presents an improved control strategy to cancel the double grid frequency oscillations in the active power, reactive power, and DC-link voltage of a three-phase grid-connected photovoltaic (PV) system under unbalanced grid condition. To achieve these goals, an enhanced positive–negative-sequence control (PNSC) to remove oscillations of active power and an instantaneous active–reactive control (IARC) to mitigate the fluctuations of active and reactive power, simultaneously, are suggested. These methods are also effective to reduce the oscillations of the DC-link voltage. To track the desired unbalanced or harmonic reference currents, improved proportional resonant (PR) current controllers have been designed using the Bode frequency analysis. Simulation studies are carried out via Matlab/Simulink^® software to verify the effectiveness of the suggested control strategies. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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23 pages, 2674 KiB

Open AccessArticle

Generation Expansion Planning in the Presence of Wind Power Plants Using a Genetic Algorithm Model

by Ali Sahragard, Hamid Falaghi, Mahdi Farhadi, Amir Mosavi and Abouzar Estebsari

Electronics 2020, 9(7), 1143; https://doi.org/10.3390/electronics9071143 - 14 Jul 2020

Cited by 15 | Viewed by 2901

Abstract

One of the essential aspects of power system planning is generation expansion planning (GEP). The purpose of GEP is to enhance construction planning and reduce the costs of installing different types of power plants. This paper proposes a method based on a genetic [...] Read more.

One of the essential aspects of power system planning is generation expansion planning (GEP). The purpose of GEP is to enhance construction planning and reduce the costs of installing different types of power plants. This paper proposes a method based on a genetic algorithm (GA) for GEP in the presence of wind power plants. Since it is desirable to integrate the maximum possible wind power production in GEP, the constraints for incorporating different levels of wind energy in power generation are investigated comprehensively. This will allow the maximum reasonable amount of wind penetration in the network to be obtained. Besides, due to the existence of different wind regimes, the penetration of strong and weak wind on GEP is assessed. The results show that the maximum utilization of wind power generation capacity could increase the exploitation of more robust wind regimes. Considering the growth of the wind farm industry and the cost reduction for building wind power plants, the sensitivity of GEP to the variations of this cost is investigated. The results further indicate that for a 10% reduction in the initial investment cost of wind power plants, the proposed model estimates that the overall cost will be minimized. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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18 pages, 6868 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Optimal Power Flow Incorporating FACTS Devices and Stochastic Wind Power Generation Using Krill Herd Algorithm

by Arsalan Abdollahi, Ali Asghar Ghadimi, Mohammad Reza Miveh, Fazel Mohammadi and Francisco Jurado

Electronics 2020, 9(6), 1043; https://doi.org/10.3390/electronics9061043 - 24 Jun 2020

Cited by 34 | Viewed by 2935

Abstract

This paper deals with investigating the Optimal Power Flow (OPF) solution of power systems considering Flexible AC Transmission Systems (FACTS) devices and wind power generation under uncertainty. The Krill Herd Algorithm (KHA), as a new meta-heuristic approach, is employed to cope with the [...] Read more.

This paper deals with investigating the Optimal Power Flow (OPF) solution of power systems considering Flexible AC Transmission Systems (FACTS) devices and wind power generation under uncertainty. The Krill Herd Algorithm (KHA), as a new meta-heuristic approach, is employed to cope with the OPF problem of power systems, incorporating FACTS devices and stochastic wind power generation. The wind power uncertainty is included in the optimization problem using Weibull probability density function modeling to determine the optimal values of decision variables. Various objective functions, including minimization of fuel cost, active power losses across transmission lines, emission, and Combined Economic and Environmental Costs (CEEC), are separately formulated to solve the OPF considering FACTS devices and stochastic wind power generation. The effectiveness of the KHA approach is investigated on modified IEEE-30 bus and IEEE-57 bus test systems and compared with other conventional methods available in the literature. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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22 pages, 2970 KiB

Open AccessArticle

Transmission Grid Expansion Planning of a High Proportion Renewable Energy Power System Based on Flexibility and Economy

by Zhanpeng Chen, Yan Hu, Nengling Tai, Xiangying Tang and Guangzeng You

Electronics 2020, 9(6), 966; https://doi.org/10.3390/electronics9060966 - 10 Jun 2020

Cited by 11 | Viewed by 2382

Abstract

The large-scale grid connection of renewable energy causes great uncertainty in power system planning and operation. The power system flexibility index can quantify the system’s ability to adjust to uncertain events such as renewable energy, load fluctuations, and faults. Compared with traditional planning [...] Read more.

The large-scale grid connection of renewable energy causes great uncertainty in power system planning and operation. The power system flexibility index can quantify the system’s ability to adjust to uncertain events such as renewable energy, load fluctuations, and faults. Compared with traditional planning methods, the flexibility planning method can accurately evaluate the impact of various uncertain events on the system during the planning process, thus effectively ensuring the safe and economic operation of renewable energy systems. First, from the perspective of power transmission and safe operation, the flexibility index of the transmission line is defined. On this basis, considering the system’s economic operation strategy, aiming at the optimization of flexibility, investment cost, operation cost, and renewable energy consumption, a multi-objective transmission grid planning model based on flexibility and economy is proposed. The NSGAII optimization algorithm is used to solve the model. Finally, the simulation is performed in the modified Garver-6 and IEEE RTS-24 node systems to analyze the effectiveness of the proposed model. The results show that the planning model can meet the needs of flexibility and economy, improve the transmission capacity of power grids, reduce the probability of renewable energy abandonment or exceeding power flow, as well as enhance the flexibility, economy, and reliability of power systems. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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12 pages, 5437 KiB

Open AccessArticle

A Stationary Reference Frame Current Control Algorithm for Improvement of Transient Dynamics of a Single Phase Grid Connected Inverter

by Horyeong Jeong and Jae Suk Lee

Electronics 2020, 9(5), 722; https://doi.org/10.3390/electronics9050722 - 27 Apr 2020

Cited by 5 | Viewed by 3073

Abstract

This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied [...] Read more.

This paper proposes a stationary reference frame current control algorithm for a single-phase grid-connected inverter (GCI) for improvement of transient dynamic performance. Disturbance, i.e., grid voltage in a target system, is estimated using a stator current observer, and the estimated disturbance is applied to a current controller for implementation of disturbance rejection control (DRC). In the proposed current control algorithm, the disturbance rejection control algorithm is applied to reduce the overcurrent occurring in the single-phase grid-connected inverter when grid faults happen. In this paper, the AC phase current of a single-phase inverter is controlled, instead of the current vector, which is a DC signal. To compensate for the drawbacks of controlling the AC phase current, such as phase lag and steady-state error, command feedforward control is also applied in the proposed control system. The proposed control algorithm is mathematically derived and represented in transfer functions and implemented via simulation and experiment. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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25 pages, 12491 KiB

Open AccessArticle

Flexibility Evaluation Method of Power Systems with High Proportion Renewable Energy Based on Typical Operation Scenarios

by Xiangying Tang, Yan Hu, Zhanpeng Chen and Guangzeng You

Electronics 2020, 9(4), 627; https://doi.org/10.3390/electronics9040627 - 10 Apr 2020

Cited by 12 | Viewed by 3179

Abstract

The development of renewable energy represented by wind, photovoltaic and hydropower has increased the uncertainty of power systems. In order to ensure the flexible operation of power systems with a high proportion of renewable energy, it is necessary to establish a multi-scenario power [...] Read more.

The development of renewable energy represented by wind, photovoltaic and hydropower has increased the uncertainty of power systems. In order to ensure the flexible operation of power systems with a high proportion of renewable energy, it is necessary to establish a multi-scenario power system flexibility evaluation method. First, this study uses a modified k-means algorithm to cluster operating scenarios of renewable energy and load to obtain several typical scenarios. Then, flexibility evaluation indices are proposed from three perspectives, including supply and demand balance of the zone, power flow distribution of the zone and transmission capacity between zones. Next, to calculate the flexibility evaluation indices of each scenario—and according to the occurrence probability of each scenario—we multiplied the indices of each scenario by the scenario occurrence probability to obtain comprehensive evaluation indices of all scenarios. Based on the actual historical output data of renewable energy and load of a southern power system in China, a flexibility evaluation was performed on the modified IEEE 14 system and modified IEEE 39 system. The results show that the proposed clustering method and flexibility indices can effectively reflect the flexibility status of the power system. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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13 pages, 441 KiB

Open AccessArticle

Study on Operational Characteristics of Protection Relay with Fault Current Limiters in an LVDC System

by Hyeong-Jin Lee, Jin-Seok Kim, Jae-Chul Kim, Sang-Yun Yun and Sung-Min Cho

Electronics 2020, 9(2), 322; https://doi.org/10.3390/electronics9020322 - 12 Feb 2020

Cited by 8 | Viewed by 2973

Abstract

As the application of low-voltage-direct-current system increases, fault analysis in the low-voltage-direct-current system has essential because the fault response has different from the conventional AC distribution system. Especially, the fault current by the discharge current of the capacitor in the low-voltage-direct-current distribution system [...] Read more.

As the application of low-voltage-direct-current system increases, fault analysis in the low-voltage-direct-current system has essential because the fault response has different from the conventional AC distribution system. Especially, the fault current by the discharge current of the capacitor in the low-voltage-direct-current distribution system has very large compared with the conventional AC distribution system. Therefore, this paper proposed the application of the superconducting fault current limiter for limiting the fault current on the low-voltage-direct-current system. As one of the protected methods against fault current, the superconducting fault current limiter which could quickly limit the fault current has been noticed as an attractive method. However, the protection relay may malfunction such as over current relay, selective protection relay due to limiting fault current by applying superconducting fault current limiter. Therefore, in this paper proposed a solution to malfunction problem of the protection relay using the voltage components of the high temperature superconductivity. This paper verified the effect of the proposed method through test modelling and PSCAD/EMTDC. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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19 pages, 1186 KiB

Open AccessArticle

Energy Management of a Power System for Economic Load Dispatch Using the Artificial Intelligent Algorithm

by Chao Fu, Suqi Zhang and Kuei-Hsiang Chao

Electronics 2020, 9(1), 108; https://doi.org/10.3390/electronics9010108 - 07 Jan 2020

Cited by 20 | Viewed by 7280

Abstract

Economic Load Dispatch (ELD) is a key issue in power systems and its goal is to achieve minimum economic costs by allocating the output of generator units when satisfying the load demands and the operating constraints. As the dimension of the variables and [...] Read more.

Economic Load Dispatch (ELD) is a key issue in power systems and its goal is to achieve minimum economic costs by allocating the output of generator units when satisfying the load demands and the operating constraints. As the dimension of the variables and the constraints increase, the traditional mathematical method is gradually not suitable for the ELD. This paper proposes an Improved Bird Swarm Algorithm (IBSA) to solve the ELD problem of a power system. By introducing the nonlinear cognitive and social coefficients, the proportion of individual learning and social learning of birds can be dynamically adjusted. In addition, the Levy flight strategy is added to the group between producers and beggars to increase the randomness. The performance of IBSA is verified via two systems consisting of 6 and 15 units, respectively, that take into account generation limitation, ramp rate limit, and prohibited operating zones. From the simulation results, the IBSA has shown excellent performance and robustness, which can be considered as a reliable solution for the ELD. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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16 pages, 7870 KiB

Open AccessFeature PaperArticle

A Study on Input Power Factor Compensation Capability of Matrix Converters

by Huu-Nhan Nguyen, Minh-Khai Nguyen, Truong-Duy Duong, Tan-Tai Tran, Young-Cheol Lim and Joon-Ho Choi

Electronics 2020, 9(1), 82; https://doi.org/10.3390/electronics9010082 - 01 Jan 2020

Cited by 12 | Viewed by 3221

Abstract

In practice, the input filter is an important component in matrix converter (MC) systems for removing high harmonic components from input currents. Due to the input filter, the input power factor (IPF) at the main power supply does not always achieve unity. To [...] Read more.

In practice, the input filter is an important component in matrix converter (MC) systems for removing high harmonic components from input currents. Due to the input filter, the input power factor (IPF) at the main power supply does not always achieve unity. To investigate the behavior of the IPF, this paper analyzes the IPF compensation capacity of MCs with an LC input filter based on space vector theory and the conservation of energy law. The study shows that the range of voltage transfer ratio (VTR) to achieve unity IPF depends strongly on the quality factor, which is determined by the system parameters. If the quality factor is greater than 0.375, the MC can never achieve unity IPF for the whole range of VTR. If the quality factor is lower than 0.375, the MC can only achieve unity IPF for a certain range of VTR, except at a very low or very high VTR. Experimental results are provided to confirm the correctness of the study. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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14 pages, 7013 KiB

Open AccessArticle

CRM PFC Converter with New Valley Detection Method for Improving Power System Quality

by Kwang-Seung Cho, Byoung-Kuk Lee and Jong-Soo Kim

Electronics 2020, 9(1), 38; https://doi.org/10.3390/electronics9010038 - 27 Dec 2019

Cited by 5 | Viewed by 5342

Abstract

High efficiency and the power factor of power converters, are very important factors which can improve power system quality. In particular, research on improving low efficiency and the power factor at light-load conditions is essential. A boost power factor correction (PFC) is most [...] Read more.

High efficiency and the power factor of power converters, are very important factors which can improve power system quality. In particular, research on improving low efficiency and the power factor at light-load conditions is essential. A boost power factor correction (PFC) is most commonly used in home appliances, with several operations being at light-loads; the critical conduction mode (CRM) control, fixed ON-time control, and valley detection technique are mainly applied to PFC control. However, these control schemes have the following problems: (1) low efficiency, due to sudden increase in switching frequency at light-loads; and (2) low power factor, due to switching ON-time limitation. This paper presents a new valley detection method that can actively extend the fixed ON-time to overcome these problems. Furthermore, a new valley point detection circuit and an ON-time extension signal generation circuit are proposed and described in detail. The superiority of the proposed method is demonstrated via comparison with two existing CRM PFC control methods, namely fixed ON-time (conventional#1) and existing valley detection (conventional#2) methods. Experimental results at 20% load demonstrate that the proposed method shows an efficiency improvement of 2.1%, compared with the fixed ON-time strategy; and a power factor improvement of 34.9%, compared with the existing valley detection strategy. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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19 pages, 7165 KiB

Open AccessArticle

Transformerless High Step-Up DC-DC Converters with Switched-Capacitor Network

by Truong-Duy Duong, Minh-Khai Nguyen, Tan-Tai Tran, Young-Cheol Lim and Joon-Ho Choi

Electronics 2019, 8(12), 1420; https://doi.org/10.3390/electronics8121420 - 28 Nov 2019

Cited by 19 | Viewed by 4992

Abstract

High-voltage gain conversion is necessary for several applications, especially for low voltage renewable source applications. In order to achieve a high-voltage gain, the presented paper proposes a class of transformerless DC-DC converters based on three switched-capacitor networks. The proposed converters have the following [...] Read more.

High-voltage gain conversion is necessary for several applications, especially for low voltage renewable source applications. In order to achieve a high-voltage gain, the presented paper proposes a class of transformerless DC-DC converters based on three switched-capacitor networks. The proposed converters have the following characteristics: reduced voltage stress on the capacitors and power devices; obtained high voltage gain with small duty cycle; and reduced conduction losses in the power switches. To verify the operation principle of the proposed converters, the detailed analysis in different conditions of the proposed converters and a comparison considering existing topologies are also discussed in the paper. Moreover, the parameter selection and controller design for the converters are determined. Finally, to reconfirm the theoretical analysis, both the simulation and experimental results taken from a 400 W prototype operating at 60 kHz are given. Full article

(This article belongs to the Special Issue Emerging Technologies in Power Systems)

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