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Renewable Electric Energy Systems
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Renewable Electric Energy Systems

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Power Electronics".

Deadline for manuscript submissions: closed (15 December 2018) | Viewed by 176534

Special Issue Editor

Prof. Dr. Kyo-Beum Lee

E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, Ajou University, World cup-row 206, Yeongtong-gu, Suwon 16499, Korea
Interests: power electronics; electric machine drives; wind and solar energy systems; electric vehicle applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Electric power generated from renewable energy sources is either intermittent and time-varying by nature or is unable to follow the fast variations that are in demand. System performance can be enhanced to maximize economic benefits by incorporating an appropriate electric energy control scheme. This allows for peak power tracking, continuous, and dispatchable power generation (in grid-connected mode), and successful load following (in stand-alone mode). This Special Issue focuses on the analysis, design, and implementation of electric energy control schemes for renewable energy, based on wind, solar, fuel cell, etc.

The topics of interest include, but are not limited to:

  • Control of wind turbines and wind farms
  • Control of PV power generators and plants
  • Power conversion systems for renewable electric energy systems
  • Reliability of renewable energy systems
  • Reliability of power conversion systems
  • Control of grid-connected converters under faults
  • MPPT algorithms

Prof. Dr. Kyo-Beum Lee
Guest Editor

Manuscript Submission Information

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18 pages, 528 KiB  
Article
Data-Driven Control Techniques for Renewable Energy Conversion Systems: Wind Turbine and Hydroelectric Plants
by Silvio Simani, Stefano Alvisi and Mauro Venturini
Electronics 2019, 8(2), 237; https://doi.org/10.3390/electronics8020237 - 20 Feb 2019
Cited by 3 | Viewed by 4154
Abstract
The interest in the use of renewable energy resources is increasing, especially towards wind and hydro powers, which should be efficiently converted into electric energy via suitable technology tools. To this end, data-driven control techniques represent viable strategies that can be employed for [...] Read more.
The interest in the use of renewable energy resources is increasing, especially towards wind and hydro powers, which should be efficiently converted into electric energy via suitable technology tools. To this end, data-driven control techniques represent viable strategies that can be employed for this purpose, due to the features of these nonlinear dynamic processes of working over a wide range of operating conditions, driven by stochastic inputs, excitations and disturbances. Therefore, the paper aims at providing some guidelines on the design and the application of different data-driven control strategies to a wind turbine benchmark and a hydroelectric simulator. They rely on self-tuning PID, fuzzy logic, adaptive and model predictive control methodologies. Some of the considered methods, such as fuzzy and adaptive controllers, were successfully verified on wind turbine systems, and similar advantages may thus derive from their appropriate implementation and application to hydroelectric plants. These issues represent the key features of the work, which provides some details of the implementation of the proposed control strategies to these energy conversion systems. The simulations will highlight that the fuzzy regulators are able to provide good tracking capabilities, which are outperformed by adaptive and model predictive control schemes. The working conditions of the considered processes will be also taken into account in order to highlight the reliability and robustness characteristics of the developed control strategies, especially interesting for remote and relatively inaccessible location of many plants. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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40 pages, 1139 KiB  
Article
A Weighted-Sum PSO Algorithm for HEMS: A New Approach for the Design and Diversified Performance Analysis
by Bilal Hussain, Asif Khan, Nadeem Javaid, Qadeer Ul Hasan, Shahzad A. Malik, Omar Ahmad, Amir Hanif Dar and Ahmad Kazmi
Electronics 2019, 8(2), 180; https://doi.org/10.3390/electronics8020180 - 04 Feb 2019
Cited by 15 | Viewed by 4172
Abstract
This research focuses on a decomposed-weighted-sum particle swarm optimization (DWS-PSO) approach that is proposed for optimal operations of price-driven demand response (PDDR) and PDDR-synergized with the renewable and energy storage dispatch (PDDR-RED) based home energy management systems (HEMSs). The algorithm for PDDR-RED-based HEMS [...] Read more.
This research focuses on a decomposed-weighted-sum particle swarm optimization (DWS-PSO) approach that is proposed for optimal operations of price-driven demand response (PDDR) and PDDR-synergized with the renewable and energy storage dispatch (PDDR-RED) based home energy management systems (HEMSs). The algorithm for PDDR-RED-based HEMS is developed by combining a DWS-PSO-based PDDR scheme for load shifting with the dispatch strategy for the photovoltaic (PV), storage battery (SB), and power grid systems. Shiftable home appliances (SHAs) are modeled for mixed scheduling (MS). The MS includes advanced as well as delayed scheduling (AS/DS) of SHAs to maximize the reduction in the net cost of energy ( C E ). A set of weighting vectors is deployed while implementing algorithms and a multi-objective-optimization (MOO) problem is decomposed into single-objective sub-problems that are optimized simultaneously in a single run. Furthermore, an innovative method to carry out the diversified performance analysis (DPA) of the proposed algorithms is also proposed. The method comprises the construction of a diversified set of test problems (TPs), defining of performance metrics, and computation of the metrics. The TPs are constructed for a set of standardized dynamic pricing signal and for scheduling models for MS and DS. The simulation results show the gradient of the tradeoff line for the reduction in C E and related discomfort for DPA. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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14 pages, 5810 KiB  
Article
A Current Reconstruction at Parallel Three Phase Inverters Using Two Current Sensors
by Jeongwoo Kim, Yu Han, Shanshan Wang, Yihe Wang and Younghoon Cho
Electronics 2019, 8(2), 179; https://doi.org/10.3390/electronics8020179 - 04 Feb 2019
Cited by 1 | Viewed by 3298
Abstract
In this paper, a current restoration method which can be applied to three phase parallel interleaved inverters (TPPII) using two current sensors has been proposed. In the proposed current reconstruction method, the branch current and the phase current of the two phases of [...] Read more.
In this paper, a current restoration method which can be applied to three phase parallel interleaved inverters (TPPII) using two current sensors has been proposed. In the proposed current reconstruction method, the branch current and the phase current of the two phases of the TPPII are sampled concurrently at the peak and valley of the pulse width modulation (PWM) carrier using two hall-effect sensors. Then, the phase current of each inverter is reconstructed by analyzing the sensed current with the current conduction path information according to the switch state in the peak and valley of the PWM carrier. This paper additionally analyzes the characteristics of the offset occurring in the detection process of two current sensors and it proposes a compensation method to reduce the offset on-line. In order to at once reduce the offset of the three-phase recovery current caused by the DC offset of the sensor, a coordinate conversion method and a low pass are used. To verify the performance of the proposed current recovery method and real-time offset compensation method, a simulation using PSIM software was performed, and experiments were conducted using a three phase parallel inverter composed of insulated gate bipolar transistor (IGBT) modules. In particular, the AC offset that occurred in the sampling process during the experiment was analyzed and modeled, and it was reduced by simple calculation. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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12 pages, 2811 KiB  
Article
An Optimized Methodology for a Hybrid Photo-Voltaic and Energy Storage System Connected to a Low-Voltage Grid
by Sarvar Hussain Nengroo, Muhammad Umair Ali, Amad Zafar, Sadam Hussain, Tahir Murtaza, Muhammad Junaid Alvi, K.V.G. Raghavendra and Hee Jee Kim
Electronics 2019, 8(2), 176; https://doi.org/10.3390/electronics8020176 - 02 Feb 2019
Cited by 27 | Viewed by 4165
Abstract
The growing human population and the increasing energy needs have produced a serious energy crisis, which has stimulated researchers to look for alternative energy sources. The diffusion of small-scale renewable distributed generations (DG) with micro-grids can be a promising solution to meet the [...] Read more.
The growing human population and the increasing energy needs have produced a serious energy crisis, which has stimulated researchers to look for alternative energy sources. The diffusion of small-scale renewable distributed generations (DG) with micro-grids can be a promising solution to meet the environmental obligations. The uncertainty and sporadic nature of renewable energy sources (RES) is the main obstacle to their use as autonomous energy sources. In order to overcome this, a storage system is required. This paper proposes an optimized strategy for a hybrid photovoltaic (PV) and battery storage system (BSS) connected to a low-voltage grid. In this study, a cost function is formulated to minimize the net cost of electricity purchased from the grid. The charging and discharging of the battery are operated optimally to minimize the defined cost function. Half-hourly electricity consumer load data and solar irradiance data collected from the United Kingdom (UK) for a whole year are utilized in the proposed methodology. Five cases are discussed for a comparative cost analysis of the electricity imported and exported. The proposed scheme provides a techno-economic analysis of the combination of a BSS with a low-voltage grid, benefitting from the feed-in tariff (FIT) scheme. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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13 pages, 5802 KiB  
Article
DC-Link Capacitor Voltage Imbalance Compensation Method Based Injecting Harmonic Voltage for Cascaded Multi-Module Neutral Point Clamped Inverter
by Kyoung-Pil Kang, Younghoon Cho, Ho-Sung Kim and Ju-won Baek
Electronics 2019, 8(2), 155; https://doi.org/10.3390/electronics8020155 - 01 Feb 2019
Cited by 4 | Viewed by 3807
Abstract
In a three-level (NPC) converter, the voltage imbalance problem in the DC-link capacitors is major issue. This paper proposes the DC-link capacitor voltage imbalance compensation method, where a common offset voltage is injected for a multi-module NPC inverter. The offset voltage consists of [...] Read more.
In a three-level (NPC) converter, the voltage imbalance problem in the DC-link capacitors is major issue. This paper proposes the DC-link capacitor voltage imbalance compensation method, where a common offset voltage is injected for a multi-module NPC inverter. The offset voltage consists of a harmonic voltage and a voltage difference between the upper and lower capacitors. The proposed method does not require any hardware modification, so that it is easily implemented. In order to show the effectiveness of the proposed balancing method, theoretical analysis is provided to balance the voltages, and both the simulations and the experiments were carried out to show that the voltage difference of the DC-link was decreased by the proposed method. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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27 pages, 14689 KiB  
Article
DC-Microgrid System Design, Control, and Analysis
by Adel El-Shahat and Sharaf Sumaiya
Electronics 2019, 8(2), 124; https://doi.org/10.3390/electronics8020124 - 24 Jan 2019
Cited by 51 | Viewed by 17437
Abstract
Recently direct current (DC) microgrids have drawn more consideration because of the expanding use of direct current (DC) energy sources, energy storages, and loads in power systems. Design and analysis of a standalone solar photovoltaic (PV) system with DC microgrid has been proposed [...] Read more.
Recently direct current (DC) microgrids have drawn more consideration because of the expanding use of direct current (DC) energy sources, energy storages, and loads in power systems. Design and analysis of a standalone solar photovoltaic (PV) system with DC microgrid has been proposed to supply power for both DC and alternating current (AC) loads. The proposed system comprises of a solar PV system with boost DC/DC converter, Incremental conductance (IncCond) maximum power point tracking (MPPT), bi-directional DC/DC converter (BDC), DC-AC inverter and batteries. The proposed bi-directional DC/DC converter (BDC) lessens the component losses and upsurges the efficiency of the complete system after many trials for its components’ selection. Additionally, the IncCond MPPT is replaced by Perturb & Observe (P&O) MPPT, and a particle swarm optimization (PSO) one. The three proposed techniques’ comparison shows the ranking of the best choice in terms of the achieved maximum power and fast—dynamic response. Furthermore, a stability analysis of the DC microgrid system is investigated with a boost converter and a bidirectional DC-DC converter with the Lyapunov function for the system has been proposed. The complete system is designed and executed in a MATLAB/SIMULINK environment and validated utilizing an OPAL real-time simulator. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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15 pages, 3936 KiB  
Article
Three-Phase Three-Level Flying Capacitor PV Generation System with an Embedded Ripple Correlation Control MPPT Algorithm
by Manel Hammami, Mattia Ricco, Alex Ruderman and Gabriele Grandi
Electronics 2019, 8(2), 118; https://doi.org/10.3390/electronics8020118 - 22 Jan 2019
Cited by 8 | Viewed by 4479
Abstract
This paper presents the implementation of a maximum power point tracking (MPPT) algorithm in a multilevel three-phase photovoltaic (PV) system using the ripple correlation control (RCC) method. Basically, RCC adopts the inherent oscillations of PV current and voltage as perturbation, and it has [...] Read more.
This paper presents the implementation of a maximum power point tracking (MPPT) algorithm in a multilevel three-phase photovoltaic (PV) system using the ripple correlation control (RCC) method. Basically, RCC adopts the inherent oscillations of PV current and voltage as perturbation, and it has been predominantly used for single-phase configurations, where the oscillations correspond to the 2nd order harmonics. The implementation of an RCC-MPPT algorithm in a three-phase system has not been presented yet in the literature. In this paper, the considered three-phase three-level converter is a three-level flying capacitor (FC) inverter. The proffered RCC method uses the 3rd harmonic components of PV current and voltage for the estimation of the voltage derivative of the power dPpv/dVpv (or current, dIpv/dVpv), compelling the PV array to operate at or very close to the maximum power point. The analysis and calculation of the low-frequency PV current and voltage ripple harmonic components in the three-phase flying capacitor inverter is presented first, with reference to centered carrier-based three-level PWM. The whole grid-connected PV generation scheme has been implemented by MATLAB/Simulink, and detailed numerical simulations verified the effectiveness of the control method in both steady-state and dynamic conditions, emulating different sun irradiance transients. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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19 pages, 8892 KiB  
Article
Research on an Auto-Optimized Capacitor Voltage Balancing Control Strategy of MMC SM for Renewable Energy HVDC Transmission System
by Jianfei Zhao, Changjiu Kong, Tingzhang Liu and Ruihua Li
Electronics 2019, 8(1), 104; https://doi.org/10.3390/electronics8010104 - 18 Jan 2019
Cited by 2 | Viewed by 3516
Abstract
The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but [...] Read more.
The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but it would cause relatively high switching frequency and power loss. Aiming at the problem that the sub-module (SM) capacitor voltage sorting algorithm has a large switching loss due to the high switching frequency of the device, this paper proposes an auto-optimized capacitor voltage balancing control strategy. Firstly, the topology and operation principle of MMC are analyzed. Secondly, a SM capacitor voltage control method based on the dynamic deviation threshold is proposed. Considering the switch switching state of the SM and the difference between the voltages of each SM, the algorithm can obtain the dynamic deviation valve using the closed-loop control. The method can avoid the unnecessary repeated switching of the Insulated Gate Bipolar Transistor (IGBT) under the premise of ensuring that the capacitance voltages of the SMs are basically the same, which effectively result in reducing the switching frequency of the MMC SM and reducing the switching loss, thereby improving the operating efficiency of the system. Finally aiming at the proposed control strategy, the simulation and experimental verification are carried out which shows that the proposed algorithm can better control the system voltage deviation, reduce the switching loss of the system and improve the stability of the system. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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29 pages, 15316 KiB  
Article
Novel Dead-Time Compensation Strategy for Wide Current Range in a Three-Phase Inverter
by Jeong-Woo Lim, Hanyoung Bu and Younghoon Cho
Electronics 2019, 8(1), 92; https://doi.org/10.3390/electronics8010092 - 15 Jan 2019
Cited by 8 | Viewed by 7559
Abstract
This paper proposes a novel three-phase voltage source inverter dead-time compensation strategy for accurate compensation in wide current regions of the inverter. In particular, an analysis of the output voltage distortion of the inverter, which appears as parasitic components of the switches, was [...] Read more.
This paper proposes a novel three-phase voltage source inverter dead-time compensation strategy for accurate compensation in wide current regions of the inverter. In particular, an analysis of the output voltage distortion of the inverter, which appears as parasitic components of the switches, was conducted for proper voltage compensation in the low current region, and an on-line compensation voltage controller was proposed. Additionally, a new trapezoidal compensation voltage implementation method using the current phase was proposed to simplify realizing the trapezoidal shape of the three-phase compensation voltages. Finally, when the proposed dead-time compensation strategy was applied, the maximum phase voltage magnitude in the linear modulation voltage regions was defined to achieve smooth operation even at high modulation index. Simulations and experiments were conducted to verify the performance of the proposed dead-time compensation scheme. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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21 pages, 11749 KiB  
Article
Hybrid PWM Strategy for Power Efficiency Improvement of 5-Level TNPC Inverter and Current Distortion Compensation Method
by Taeyeong Lee, Hanyoung Bu and Younghoon Cho
Electronics 2019, 8(1), 76; https://doi.org/10.3390/electronics8010076 - 10 Jan 2019
Cited by 2 | Viewed by 4753
Abstract
This paper proposes a pulse width modulation (PWM) strategy for improving the efficiency of a 5-level H-bridge T-type neutral point clamped (TNPC) inverter. In the case of the proposed PWM strategy, unlike the conventional PWM strategy in which both of the switching legs [...] Read more.
This paper proposes a pulse width modulation (PWM) strategy for improving the efficiency of a 5-level H-bridge T-type neutral point clamped (TNPC) inverter. In the case of the proposed PWM strategy, unlike the conventional PWM strategy in which both of the switching legs of the H-bridge inverter operate at a high frequency, one switching leg of the inverter operates at a low frequency. As the switching frequency is lowered, the switching loss is reduced, this improving the efficiency of the system. The duty references for the switching legs and the operating principle of the inverter are described in detail. The proposed PWM strategy, however, causes distortion of the output filter inductor current. The cause of the distortion has been analyzed and a compensation method is proposed to mitigate the distortion of the current. The effect of the proposed PWM strategy can be predicted through the loss calculation of the inverter for each modulation strategy. Furthermore, current distortion mitigation obtained by compensation method is confirmed through the simulation. In order to verify the effectiveness of the proposed strategy, a 2 kW H-bridge TNPC inverter prototype is implemented and tested. The simulation and experimental results show that the efficiency of the inverter is improved when the proposed PWM strategy is applied. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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23 pages, 7661 KiB  
Article
Lyapunov Based Reference Model of Tension Control in a Continuous Strip Processing Line with Multi-Motor Drive
by Daniela Perduková, Pavol Fedor, Viliam Fedák and Sanjeevikumar Padmanaban
Electronics 2019, 8(1), 60; https://doi.org/10.3390/electronics8010060 - 04 Jan 2019
Cited by 11 | Viewed by 3955
Abstract
The article describes design and experimental verification of a new control structure with reference model for a multi-motor drive of a continuous technological line in which the motors are mutually mechanically coupled through processed material. Its principle consists in creating an additional information [...] Read more.
The article describes design and experimental verification of a new control structure with reference model for a multi-motor drive of a continuous technological line in which the motors are mutually mechanically coupled through processed material. Its principle consists in creating an additional information by introducing a new suitable state variable into the system. This helps to achieve a zero steady-state control deviation of the tension in the strip. Afterwards, the tension controller is designed to ensure asymptotic stability of the extended system by applying the second Lyapunov method. The realized experimental measurements performed on a continuous line laboratory model confirm the advantages and correctness of the proposed control structure: it is simple, stable, robust against changes of parameters, invariant to operating disturbances and ensures a high-quality dynamics of the controlled system prescribed by the reference model. To demonstrate effectiveness of the design, the performance of the controller was compared with properties of a standard Proportional Integral Derivative/Proportional Integral (PID/PI) controller designed in frequency domain. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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19 pages, 11948 KiB  
Article
Performance and Life Degradation Characteristics Analysis of NCM LIB for BESS
by Soon-Jong Kwon, Sung-Eun Lee, Ji-Hun Lim, Jinhyeok Choi and Jonghoon Kim
Electronics 2018, 7(12), 406; https://doi.org/10.3390/electronics7120406 - 07 Dec 2018
Cited by 28 | Viewed by 9346
Abstract
The battery energy storage system (BESS) market is growing rapidly around the world. Lithium Nickel Cobalt Manganese Oxide (LiNiCoMnO2) is attracting attention due to its excellent energy density, high output power, and fast response characteristics. It is being extensively researched and [...] Read more.
The battery energy storage system (BESS) market is growing rapidly around the world. Lithium Nickel Cobalt Manganese Oxide (LiNiCoMnO2) is attracting attention due to its excellent energy density, high output power, and fast response characteristics. It is being extensively researched and is finding use in many applications, such as in electric vehicles (EV) and energy storage systems (ESS). The performance and lifetime characteristics of a battery change for varying Ni contents. The consideration of these characteristics of a battery allow for a more reliable battery management system (BMS) design. In this study, various experiments and analyses were carried out using a lithium-ion battery (NCM LIB) with differing Ni contents. In particular, the following two combinations were studied: LiNi0.5Co0.2Mn0.3O2(NCM523) and LiNi0.6Co0.2Mn0.2O2 (NCM622). Various analyses were performed, such as C-rate (C-rate is the charge-discharge rate of a battery relative to nominal capacity) performance tests, hybrid pulse power characterization (HPPC), accelerated deterioration experiments, electrochemical impedance spectroscopy (EIS), parameter estimations of battery equivalent circuits through alternating current (AC) and direct current (DC) impedance, and comparative analyses of battery modeling. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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14 pages, 6251 KiB  
Article
A Novel Screening Method Based on a Partially Discharging Curve Using a Genetic Algorithm and Back-Propagation Model for the Cascade Utilization of Retired Lithium-Ion Batteries
by Xin Lai, Dongdong Qiao, Yuejiu Zheng and Wei Yi
Electronics 2018, 7(12), 399; https://doi.org/10.3390/electronics7120399 - 06 Dec 2018
Cited by 27 | Viewed by 3610
Abstract
Reusing the retired lithium-ion batteries from electric vehicles can generate considerable economic benefits. In this paper, a novel screening method based on partial discharge curves using a genetic algorithm and back-propagation (GA-BP) neural network for the retired cells is proposed. First, the discharge [...] Read more.
Reusing the retired lithium-ion batteries from electric vehicles can generate considerable economic benefits. In this paper, a novel screening method based on partial discharge curves using a genetic algorithm and back-propagation (GA-BP) neural network for the retired cells is proposed. First, the discharge curves of the retired cells with different aging degrees were investigated. Based on this, the calculation method of internal resistance of retired cells was developed. Second, a novel capacity screening model based on a partially discharging process using a GA-BP model was proposed. In this model, the capacity and discharge characteristic data of a small number of sample cells were selected to train the capacity model using GA-BP, and the capacity of a large number of the remaining unsampled cells was estimated using the trained capacity model. Third, the screening simulation model with 108 retired cells was established, and the simulation results showed the effectiveness and rapidity of our proposed method. Finally, experimental verification was performed on the 20 retired cells with different aging degrees. The results showed that our proposed method is feasible, and the maximum error of capacity estimation was 2.951%. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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20 pages, 6279 KiB  
Article
A Bidirectional Double Uneven Power Converter Based DC–DC Converter for Solid-State Transformers
by Kiwoo Park and Kyo-Beum Lee
Electronics 2018, 7(11), 334; https://doi.org/10.3390/electronics7110334 - 19 Nov 2018
Cited by 4 | Viewed by 3739
Abstract
This paper presents a novel bidirectional double uneven power (BiDUP) based dc-dc converter and its design and control methods. The proposed converter utilizes two dual active bridge (DAB) converters with different power ratings in a special way to realize zero current switching (ZCS), [...] Read more.
This paper presents a novel bidirectional double uneven power (BiDUP) based dc-dc converter and its design and control methods. The proposed converter utilizes two dual active bridge (DAB) converters with different power ratings in a special way to realize zero current switching (ZCS), where both turn-on and turn-off switchings occur under the zero-current condition. A design example of the proposed BiDUP converter is presented for medium voltage (MV) and high-power solid-state transformer (SST) systems where both voltage transformation and bidirectional power flow are required. The main features of the proposed converter are to reduce both the switching losses in power semiconductor devices and the filter inductance requirement simultaneously. To verify the feasibility of the proposed converter, a simulation study on the BiDUP converter based SST in a distribution system is presented. Furthermore, to validate the operational principle of the proposed converter, an experimental study using a small-scale prototype is also presented. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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17 pages, 6725 KiB  
Article
Improved Voltage Drop Compensation Method for Hybrid Fuel Cell Battery System
by Tae-Ho Eom, Jin-Wook Kang, Jintae Kim, Min-Ho Shin, Jung-Hyo Lee and Chung-Yuen Won
Electronics 2018, 7(11), 331; https://doi.org/10.3390/electronics7110331 - 17 Nov 2018
Cited by 6 | Viewed by 5307
Abstract
In this paper, a voltage drop compensation method for hybrid hydrogen fuel cell battery system, with a hydrogen recirculation powering a forklift, is studied. During recirculating hydrogen fuel to recycle hydrogen that has not reacted enough at the system, impurities can be mixed [...] Read more.
In this paper, a voltage drop compensation method for hybrid hydrogen fuel cell battery system, with a hydrogen recirculation powering a forklift, is studied. During recirculating hydrogen fuel to recycle hydrogen that has not reacted enough at the system, impurities can be mixed with the hydrogen fuel. This leads to low hydrogen concentration and a drop in the output voltage of the fuel cell system. In excessive voltage drop, the fuel cell system can be shutdown. This paper proposes a voltage drop compensation method using an electrical control algorithm to prevent system shutdown by reducing voltage drop. Technically, voltage drop is typically caused by three kinds of factors: (1) The amount of pure hydrogen supply; (2) the temperature of fuel cell stacks; and (3) the current density to catalysts of the fuel cell. The proposed compensation method detects voltage drop caused by those factors, and generates compensation signals for a controller of a DC–DC converter connecting to the output of the fuel cell stack; thus, the voltage drop is reduced by decreasing output current. At the time, insufficient output current to a load is supplied from the batteries. In this paper, voltage drop caused by the abovementioned three factors is analyzed, and the operating principle of the proposed compensation method is specified. To verify this operation and the feasibility of the proposed method, experiments are conducted by applying it to a 10 kW hybrid fuel cell battery system for a forklift. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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29 pages, 24638 KiB  
Article
A Novel Ten Check Maximum Power Point Tracking Algorithm for a Standalone Solar Photovoltaic System
by Muhammad Mateen Afzal Awan and Tahir Mahmood
Electronics 2018, 7(11), 327; https://doi.org/10.3390/electronics7110327 - 16 Nov 2018
Cited by 22 | Viewed by 4444
Abstract
Optimal energy extraction under partial shading conditions from a photovoltaic (PV) array is particularly challenging. Conventional techniques fail to achieve the global maximum power point (GMPP) under such conditions, while soft computing techniques have provided better results. The main contribution of this paper [...] Read more.
Optimal energy extraction under partial shading conditions from a photovoltaic (PV) array is particularly challenging. Conventional techniques fail to achieve the global maximum power point (GMPP) under such conditions, while soft computing techniques have provided better results. The main contribution of this paper is to devise an algorithm to track the GMPP accurately and efficiently. For this purpose, a ten check (TC) algorithm was proposed. The effectiveness of this algorithm was tested with different shading patterns. Results were compared with the top conventional algorithm perturb and observe (P&O) and the best soft computing technique flower pollination algorithm (FPA). It was found that the proposed algorithm outperformed them. Analysis demonstrated that the devised algorithm achieved the GMPP efficiently and accurately as compared to the P&O and the FPA algorithms. Simulations were performed in MATLAB/Simulink. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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19 pages, 4865 KiB  
Article
A Hybrid Moth-Flame Fuzzy Logic Controller Based Integrated Cuk Converter Fed Brushless DC Motor for Power Factor Correction
by Kuditi Kamalapathi, Neeraj Priyadarshi, Sanjeevikumar Padmanaban, Jens Bo Holm-Nielsen, Farooque Azam, Chandrahasan Umayal and Vigna K. Ramachandaramurthy
Electronics 2018, 7(11), 288; https://doi.org/10.3390/electronics7110288 - 01 Nov 2018
Cited by 36 | Viewed by 5291
Abstract
This research work deals with a hybrid control system based integrated Cuk converter fed brushless DC motor (BLDCM) for power factor correction. In this work, moth-flame optimization (MFO) and a fuzzy logic controller (FLC) have been combined and a moth-flame fuzzy logic controller [...] Read more.
This research work deals with a hybrid control system based integrated Cuk converter fed brushless DC motor (BLDCM) for power factor correction. In this work, moth-flame optimization (MFO) and a fuzzy logic controller (FLC) have been combined and a moth-flame fuzzy logic controller (MFOFLC) has been proposed. Firstly, the BLDC motor modeling is composed with the power factor correction (PFC) based integrated Cuk converter and BLDC speed is regulated using variable DC-Link inverter voltage which results in a low switching operation with fewer switched losses. Here, with the use of a switched inductor, the task and execution of the proposed converter is redesigned. The DBR (diode bridge rectifier) trailed by a proposed PFC based integrated Cuk converter operates in discontinuous inductor conduction mode (DICM) for achievement of better power factor. MFO is exhibited for gathering of a dataset from the input voltage signal. At that point, separated datasets are sent to the FLC to improve the updating function and minimization of torque ripple. However, our main objective is to assess adequacy of the proposed method, but the power factor broke down. The execution of the proposed control methodology is executed in the MATLAB/Simulink working platform and the display is assessed with the existing techniques. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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18 pages, 5941 KiB  
Article
Single-Phase Bidirectional On-Board Charger Using Starter Generator System in Hybrid Electric Vehicles
by Seok-Min Kim, Ho-Sung Kang and Kyo-Beum Lee
Electronics 2018, 7(11), 287; https://doi.org/10.3390/electronics7110287 - 01 Nov 2018
Cited by 4 | Viewed by 4337
Abstract
This paper presents the design and control methods of a single-phase bidirectional on-board charger (OBC) using a hybrid starter generator (HSG) and an inverter in a hybrid electric vehicle (HEV). In an HEV, there are a number of components, including the combustion engine, [...] Read more.
This paper presents the design and control methods of a single-phase bidirectional on-board charger (OBC) using a hybrid starter generator (HSG) and an inverter in a hybrid electric vehicle (HEV). In an HEV, there are a number of components, including the combustion engine, transmission, traction motor, motor controller, OBC, and HSG system. The proposed design reconfigures the HSG system to provide battery-charging capability instead of a conventional OBC based on the use of additional power relays. As a result, the number of power converters is effectively reduced through the replacement of the conventional OBC, and, thus, the power density is increased. This paper also proposes a control method for enabling not only battery charging but also a reactive power support depending on the grid command. Compared with a conventional reactive power compensation method, the proposed method has an advantage because it is located near the principal reactive power source. The simulation and experimental results verify the validity and feasibility of the proposed bidirectional OBC design and its control methods. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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14 pages, 1969 KiB  
Article
Reliability of Variable Speed Pumped-Storage Plant
by Anto Joseph, Thanga Raj Chelliah, Sze Sing Lee and Kyo-Beum Lee
Electronics 2018, 7(10), 265; https://doi.org/10.3390/electronics7100265 - 22 Oct 2018
Cited by 10 | Viewed by 4900
Abstract
The multi-channel (MC) back-to-back voltage source inverter (VSI)-fed doubly fed induction machine (DFIM) is emerging as a highly interesting topic in large-rated variable speed pumped-storage power plants (PSPP) in view of cost, optimal efficiency, and space requirements. Although the VSI is the fundamental [...] Read more.
The multi-channel (MC) back-to-back voltage source inverter (VSI)-fed doubly fed induction machine (DFIM) is emerging as a highly interesting topic in large-rated variable speed pumped-storage power plants (PSPP) in view of cost, optimal efficiency, and space requirements. Although the VSI is the fundamental part of the drive controlling the active/reactive power of the plant, redundancy is presently not adopted in practice causing the unit as a whole to shut down upon a failure in the converter and control circuit. This paper evaluates a large-rated (250 MW) DFIM-fed variable-speed unit of a PSPP in terms of its reliability and availability. A Markov model is developed to assess the reliability of the drive based on a number of factors including survivability and annual failure rate (FIT). Further, the Markov model is applied to different PSPPs for comparison of reliability among them. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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15 pages, 5655 KiB  
Article
Economical Evaluation and Optimal Energy Management of a Stand-Alone Hybrid Energy System Handling in Genetic Algorithm Strategies
by Omar Hazem Mohammed, Yassine Amirat and Mohamed Benbouzid
Electronics 2018, 7(10), 233; https://doi.org/10.3390/electronics7100233 - 04 Oct 2018
Cited by 57 | Viewed by 4363
Abstract
Hybrid renewable energy systems are a promising technology for clean and sustainable development. In this paper, an intelligent algorithm, based on a genetic algorithm (GA), was developed and used to optimize the energy management and design of wind/PV/tidal/ storage battery model for a [...] Read more.
Hybrid renewable energy systems are a promising technology for clean and sustainable development. In this paper, an intelligent algorithm, based on a genetic algorithm (GA), was developed and used to optimize the energy management and design of wind/PV/tidal/ storage battery model for a stand-alone hybrid system located in Brittany, France. This proposed optimization focuses on the economic analysis to reduce the total cost of hybrid system model. It suggests supplying the load demand under different climate condition during a 25-years interval, for different possible cases and solutions respecting many constraints. The proposed GA-based optimization approach achieved results clear highlight its practicality and applicability to any hybrid power system model, including optimal energy management, cost constraint, and high reliability. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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17 pages, 11009 KiB  
Article
Synchronous Reference Frame Repetitive Control of a Single-Phase Three-Level Dual-Buck Photovoltaic Inverter
by Jung-Yong Lee and Younghoon Cho
Electronics 2018, 7(10), 226; https://doi.org/10.3390/electronics7100226 - 02 Oct 2018
Cited by 4 | Viewed by 3722
Abstract
This paper proposes a synchronous reference frame (SRF) control strategy for a single-phase, three-level, dual-buck photovoltaic (PV) inverter. The concept of virtual d-q transformation is adapted to the current control of the inverter, and the repetitive controller is implemented in the SRF. With [...] Read more.
This paper proposes a synchronous reference frame (SRF) control strategy for a single-phase, three-level, dual-buck photovoltaic (PV) inverter. The concept of virtual d-q transformation is adapted to the current control of the inverter, and the repetitive controller is implemented in the SRF. With the proposed control strategy, the memory allocation quantity for the repetitive controller is decreased and the capability of the current reference tracking is maximized. Thus, the proposed method significantly reduces the total harmonic distortion (THD) of the output current in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In addition, the distortion of the output current is mostly composed of odd harmonics. Odd harmonic expressed to the even harmonic in SRF can be calculated using Park’s transformation. Therefore, a repetitive controller can improve dynamics by considering only even harmonic components in SRF rather than including all harmonics. The simulation and the experimental results verify the effectiveness of the proposed control strategy. The proposed method not only reduces the THD of the output current in both the CCM operation and the DCM operation, but also improves the dynamics of the current controller. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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22 pages, 6895 KiB  
Article
A Control Strategy for Bidirectional Isolated 3-Phase Current-Fed Dual Active Bridge Converter
by Dong-Min Lee, Seung-Wook Hyun, Jin-Wook Kang, Yong-Su Noh and Chung-Yuen Won
Electronics 2018, 7(10), 214; https://doi.org/10.3390/electronics7100214 - 23 Sep 2018
Cited by 4 | Viewed by 4299
Abstract
This paper examines the characteristics of the zero voltage switching (ZVS) and zero voltage transition (ZVT) soft-switching applied in the 3-phase current fed dual active bridge (3P-CFDAB) converter, which combines the advantages of the dual active bridge (DAB) converter and current-fed full bridge [...] Read more.
This paper examines the characteristics of the zero voltage switching (ZVS) and zero voltage transition (ZVT) soft-switching applied in the 3-phase current fed dual active bridge (3P-CFDAB) converter, which combines the advantages of the dual active bridge (DAB) converter and current-fed full bridge (CFFB) converter. When an active clamp circuit is added to the CFFB converter, the circuit configuration of the DAB converter is shown in part of the entire circuit. This allows the use of pulse width modulation (PWM) techniques which combine the PWM techniques of both the DAB converter and CFFB converter. The proposed converter performs both duty and phase control at the same time in order to reduce the circulating current and ripple current of the output capacitor, which are the disadvantages of the CFFB converter and DAB converter. In addition, the ZVS and ZVT soft switching areas were analyzed by means of the phase current and leakage inductor current in each transformers. To verify the principle and feasibility of the proposed operation techniques, a simulation and experiment were implemented with the 3P-CFDAB. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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16 pages, 6880 KiB  
Article
Optimized Modeling and Control Strategy of the Single-Phase Photovoltaic Grid-Connected Cascaded H-bridge Multilevel Inverter
by Seongjun Lee and Jonghoon Kim
Electronics 2018, 7(9), 207; https://doi.org/10.3390/electronics7090207 - 18 Sep 2018
Cited by 9 | Viewed by 4188
Abstract
This paper presents the modeling and control-loop design method with an inverted decoupling scheme of a single-phase photovoltaic grid-connected five-level cascaded H-bridge multilevel inverter. For the unity power factor, the proportional and integral current controller with a duty ratio feed-forward compensation is used. [...] Read more.
This paper presents the modeling and control-loop design method with an inverted decoupling scheme of a single-phase photovoltaic grid-connected five-level cascaded H-bridge multilevel inverter. For the unity power factor, the proportional and integral current controller with a duty ratio feed-forward compensation is used. In addition, in order to achieve the maximum power point tracking of each photovoltaic array, when the stacked modules are in the partial shading condition, each direct current (DC) voltage is stably controlled to their maximum power points (MPP) by dedicated voltage controllers of each H-bridge module. This paper also presents a control method that minimizes the effect of the loop-interaction in the design of an individual DC-link voltage control loop in a two-input two-output system. The proposed control methods of the cascaded H-bridge multilevel inverter are validated through the simulation and experimental results of the 2-kW prototype hardware. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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19 pages, 5677 KiB  
Article
Decentralized Power Management for Electrical Power Systems in More Electric Aircrafts
by Myungchin Kim, Sung Gu Lee and Sungwoo Bae
Electronics 2018, 7(9), 187; https://doi.org/10.3390/electronics7090187 - 10 Sep 2018
Cited by 14 | Viewed by 4931
Abstract
In order to implement reliable and flexible power management among energy sources, a decentralized power management approach for electrical power systems (EPSs) in the more electric aircraft (MEA) is studied. Considering the increased use of electrical power for various functions, the performance of [...] Read more.
In order to implement reliable and flexible power management among energy sources, a decentralized power management approach for electrical power systems (EPSs) in the more electric aircraft (MEA) is studied. Considering the increased use of electrical power for various functions, the performance of MEA would be determined by the design and operation of the EPS. By using a virtual impedance that includes both a resistive term and an inductive term, autonomous power sharing is realized. Because of the frequency dependence in the virtual impedance, different power sharing ratios between steady state and transient state can be considered. Not only the operation of various power sources is coordinated without supervision of a centralized controller, but also the operation profile of each source can be adjusted to meet output characteristics of each source. To demonstrate the effectiveness of the proposed approach, a series of simulations that consider various virtual impedance configurations were conducted. The proposed approach contributes to a higher level of operational flexibility, while enabling reliable and cost-effective management of MEAs. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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25 pages, 16117 KiB  
Article
Improved Neutral-Point Voltage-Shifting Strategy for Power Balancing in Cascaded NPC/H-Bridge Inverter
by Jin-Wook Kang, Seung-Wook Hyun, Jae-Ok Ha and Chung-Yuen Won
Electronics 2018, 7(9), 167; https://doi.org/10.3390/electronics7090167 - 29 Aug 2018
Cited by 10 | Viewed by 4833
Abstract
This paper investigates the fault-tolerance control of a multilevel cascaded NPC/H-bridge (CNHB) inverter. The fault-tolerance control method has been widely used for multilevel inverters, such as the neutral-point voltage-shifting control, which can operate for a certain period of time by compensating for the [...] Read more.
This paper investigates the fault-tolerance control of a multilevel cascaded NPC/H-bridge (CNHB) inverter. The fault-tolerance control method has been widely used for multilevel inverters, such as the neutral-point voltage-shifting control, which can operate for a certain period of time by compensating for the phase voltage of a faulty stack even if one stack is broken. Even though the three-phase equilibrium is maintained in the case of failure by using the conventional neutral-point voltage-shifting control, an imbalance in the output power occurs between each stack, which causes problems for maintenance and lifetime. Therefore, this paper proposes a fault-tolerance control that can maintain three-phase equilibrium in a case of stack failures and minimize power imbalances between the stacks. The problem of the conventional neutral-point voltage-shifting control is presented based on the output power. In addition, the power imbalance is improved by performing selective neutral-point voltage-shifting control according to the reference voltage range. To verify the principle and feasibility of the proposed neutral-point voltage-shifting control method, a simulation and an experiment are implemented with the CNHB inverter. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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15 pages, 32502 KiB  
Article
Optimal Control of a Compact Converter in an AC Microgrid
by Issam A. Smadi, Saher Albatran and Mohammad A. Alsyouf
Electronics 2018, 7(7), 102; https://doi.org/10.3390/electronics7070102 - 27 Jun 2018
Cited by 6 | Viewed by 3698
Abstract
This paper presents an optimal control method for a compact reduced switch count AC/AC converter in an AC microgrid. The AC/AC converter is adopted to interconnect dual three-phase renewable energy sources (RESs) and a three-phase permanent magnet synchronous motor (PMSM) to the grid [...] Read more.
This paper presents an optimal control method for a compact reduced switch count AC/AC converter in an AC microgrid. The AC/AC converter is adopted to interconnect dual three-phase renewable energy sources (RESs) and a three-phase permanent magnet synchronous motor (PMSM) to the grid to form an example of a mixed grid-feeding-drive system. For the adopted converter, a generalized pulse width modulation (PWM) scheme employing the third harmonic injection and a control method are proposed. Moreover, to achieve reduced dc link voltage ripple, good reference tracking and disturbance rejection, the gains of the controllers are optimized by minimizing a weighted sum of different objective functions. Each objective function represents a specific aspect to be minimized and the optimization problem is solved employing particle swarm optimization (PSO) method, while ensuring that the total harmonic distortion (THD) of the current at the points of common coupling (PCC) are less than 5%. For this mixed grid-feeding-drive system, simulation results under fast transient are provided to demonstrate the applicability of the adopted converter in the AC microgrid, the effectiveness of the proposed PWM, and the proposed optimal control method. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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23 pages, 4623 KiB  
Article
Optimizing Generation Capacities Incorporating Renewable Energy with Storage Systems Using Genetic Algorithms
by Farukh Abbas, Salman Habib, Donghan Feng and Zheng Yan
Electronics 2018, 7(7), 100; https://doi.org/10.3390/electronics7070100 - 21 Jun 2018
Cited by 16 | Viewed by 4842
Abstract
In grid advancement, energy storage systems are playing an important role in lowering the cost, reducing infrastructural investment, ensuring reliability and increasing operational capability. The storage system can provide stabilization services and is pivotal for backup power for emergencies. With a continuous rise [...] Read more.
In grid advancement, energy storage systems are playing an important role in lowering the cost, reducing infrastructural investment, ensuring reliability and increasing operational capability. The storage system can provide stabilization services and is pivotal for backup power for emergencies. With a continuous rise in fuel prices and increasing environmental issues, the energy from renewable resources is gaining more popularity. The main drawbacks of some renewable sources are their intermittent energy generation and uncertain source availability, which has increased interest in energy storage systems (ESSs). This paper investigates the economic feasibility when ESSs are introduced in the electric grid with an expansion of a storage system as well as more percentage of the renewable energy integration and less percentage of fuel consumption by conventional power sources. The Artificial Neural Network is implemented to validate the forecasted load model. The uncertainties associated with the renewable energy system are handled by a chance-constrained model and solved by a genetic algorithm (GA) in MATLAB; selection criteria of GA for optimization process is also discussed in detail. The effectivity of the proposed methodology is verified by applying it to a case that lies in the western region of China. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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18 pages, 2107 KiB  
Article
Three Topologies of a Non-Isolated High Gain Switched-Inductor Switched-Capacitor Step-Up Cuk Converter for Renewable Energy Applications
by Yasser Almalaq and Mohammad Matin
Electronics 2018, 7(6), 94; https://doi.org/10.3390/electronics7060094 - 10 Jun 2018
Cited by 21 | Viewed by 6240
Abstract
This paper introduces three topologies of a non-isolated high gain step-up Cuk converter based on a switched-inductor (SL) and switched-capacitor (SC) techniques for renewable energy applications, such as photovoltaic and fuel cells. These kinds of Cuk converters provide a negative-to-positive step-up dc–dc voltage [...] Read more.
This paper introduces three topologies of a non-isolated high gain step-up Cuk converter based on a switched-inductor (SL) and switched-capacitor (SC) techniques for renewable energy applications, such as photovoltaic and fuel cells. These kinds of Cuk converters provide a negative-to-positive step-up dc–dc voltage conversion. The proposed three topologies SLSC Cuk converters increase the voltage boost ability significantly using the switched-inductor and switched-capacitor techniques compared with the classical Cuk and boost converters. The proposed Cuk converters are derived from the classical Cuk converter by replacing the single inductor at the input and output sides with a SL and the transferring energy capacitor by a SC. The main advantages of the proposed SLSC Cuk converters are achieving a high voltage conversion ratio and reducing the voltage stress across the main switch. Therefore, a switch with low voltage rating and thus, of low RDS-ON can be used, and that leads to a higher efficiency. For example, the third topology have the ability to boost the input voltage up to 13 times when D = 0.75, D is the duty cycle. The voltage gain and the voltage stress across the main switch in the three topologies have been compared with the classical Cuk and boost converter. The proposed three topologies avoid using a transformer, coupled inductors, or extreme duty cycles leading to less volume, loss, and cost. The proposed SLSC Cuk converters are analyzed in continuous conduction mode (CCM), and they have been designed for 12 V input supply voltage, 100 W rated power, 50 kHz switching frequency, and 75% duty cycle. A detailed theoretical analysis of the CCM is represented and all the equations have been derived and matched with the results. The proposed three topologies SLSC Cuk converters have been simulated in MATLAB/SIMULINK and results are discussed. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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19 pages, 4091 KiB  
Article
Implementation of a Single-Phase SST for the Interface between a 13.2 kV MVAC Network and a 750 V Bipolar DC Distribution
by Hyeok-Jin Yun, Dong-Keun Jeong, Ho-Sung Kim, Myoungho Kim, Ju-Won Baek, Ju-Yong Kim and Hee-Je Kim
Electronics 2018, 7(5), 62; https://doi.org/10.3390/electronics7050062 - 04 May 2018
Cited by 11 | Viewed by 5575
Abstract
This paper presents the implementation of a single-phase solid-state transformer (SST) for the interface between a 13.2 kV medium voltage alternative current (MVAC) network and a 750 V bipolar DC distribution. The SST has ten cascaded subunits in consideration of the device rating [...] Read more.
This paper presents the implementation of a single-phase solid-state transformer (SST) for the interface between a 13.2 kV medium voltage alternative current (MVAC) network and a 750 V bipolar DC distribution. The SST has ten cascaded subunits in consideration of the device rating and modulation index (MI). Each subunit consists of an AC/DC stage and a DC/DC stage with a high frequency isolated transformer (HFIT). The AC/DC stage consists of cascaded H-bridges (CHBs) to cope with the MVAC. The DC/DC stage employs a triple active bridge (TAB) converter for bipolar DC distribution. Topology analysis and controller design for this specific structure are discussed. In addition, the insulation of HFIT used in DC/DC converters is also discussed. A simple balancing controller at the AC/DC stage and a current sharing controller at the DC/DC stage are used to prevent DC-link voltage unbalance caused by the cascaded structure. The discussions are validated using a 150 kW single-phase 21-level SST prototype at the laboratory level. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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25 pages, 4576 KiB  
Article
Bagged Decision Trees Based Scheme of Microgrid Protection Using Windowed Fast Fourier and Wavelet Transforms
by Solomon Netsanet, Jianhua Zhang and Dehua Zheng
Electronics 2018, 7(5), 61; https://doi.org/10.3390/electronics7050061 - 03 May 2018
Cited by 27 | Viewed by 5437
Abstract
Microgrids of varying size and applications are regarded as a key feature of modernizing the power system. The protection of those systems, however, has become a major challenge and a popular research topic because it involves greater complexity than traditional distribution systems. This [...] Read more.
Microgrids of varying size and applications are regarded as a key feature of modernizing the power system. The protection of those systems, however, has become a major challenge and a popular research topic because it involves greater complexity than traditional distribution systems. This paper addresses this issue through a novel approach which utilizes detailed analysis of current and voltage waveforms through windowed fast Fourier and wavelet transforms. The fault detection scheme involves bagged decision trees which use input features extracted from the signal processing stage which are selected by correlation analysis. The technique was tested on a microgrid model developed using PSCAD/EMTDS, which is inspired from an operational microgrid in Goldwind Science Technology Co. Ltd., in Beijing, China. The results showed a great level of effectiveness to accurately identify faults from other non-fault disturbances, precisely locating the fault and trigger opening of the right circuit breaker/s under different operation modes, fault resistances, and other system disturbances. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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16 pages, 6102 KiB  
Article
Stand-Alone Microgrid Inverter Controller Design for Nonlinear, Unbalanced Load with Output Transformer
by Jae-Uk Lim, Hag-Won Kim, Kwan-Yuhl Cho and Joung-Hwan Bae
Electronics 2018, 7(4), 55; https://doi.org/10.3390/electronics7040055 - 23 Apr 2018
Cited by 7 | Viewed by 6392
Abstract
This paper proposes a technique that compensates for unbalance and nonlinearity in microgrid inverters with power transformers operating in stand-alone mode. When a microgrid inverter is operating in stand-alone mode, providing high-quality power is very important. When an unbalanced, nonlinear load is connected, [...] Read more.
This paper proposes a technique that compensates for unbalance and nonlinearity in microgrid inverters with power transformers operating in stand-alone mode. When a microgrid inverter is operating in stand-alone mode, providing high-quality power is very important. When an unbalanced, nonlinear load is connected, zero sequence current and negative sequence current occur, which leads to an unbalanced output voltage. This paper examines why the zero sequence component occurs differently depending on the structure of a three-phase transformer connected to the inverter output terminal, and it proposes a method for controlling the zero sequence component. It also uses a resonant controller to remove the harmonics that correspond to the negative sequence component and the nonlinear component. The proposed elements were verified by a Powersim (PSIM) simulation. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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13 pages, 937 KiB  
Article
Robust Offset-Free Speed Tracking Controller of Permanent Magnet Synchronous Generator for Wind Power Generation Applications
by Seok-Kyoon Kim and Kyo-Beum Lee
Electronics 2018, 7(4), 48; https://doi.org/10.3390/electronics7040048 - 04 Apr 2018
Cited by 3 | Viewed by 4744
Abstract
This article presents a robust speed tracking algorithm for a permanent magnet synchronous generator utilized for wind power generation systems, considering the machine parameter and load uncertainties. There are two major contributions: (a) a disturbance observer is designed to exponentially estimate disturbances from [...] Read more.
This article presents a robust speed tracking algorithm for a permanent magnet synchronous generator utilized for wind power generation systems, considering the machine parameter and load uncertainties. There are two major contributions: (a) a disturbance observer is designed to exponentially estimate disturbances from the model-plant mismatches and severe load torque variations, and (b) it is included in a nonlinear cascade-type proportional speed tracking controller to establish the performance recovery and offset-free properties without the use of tracking error integrators. A simulation result numerically verifies the effectiveness of the proposed technique, where the PowerSIM software emulates a wind power generation system. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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Review

Jump to: Research

13 pages, 1075 KiB  
Review
Meter Placement in Power System Network—A Comprehensive Review, Analysis and Methodology
by Ramesh Lekshmana, Sanjeevikumar Padmanaban, Sagar Bhaskar Mahajan, Vigna K. Ramachandaramurthy and Jens Bo Holm-Nielsen
Electronics 2018, 7(11), 329; https://doi.org/10.3390/electronics7110329 - 16 Nov 2018
Cited by 4 | Viewed by 3804
Abstract
The blackout in North India due to the failure of the central grid has led to the need for intelligent power system state estimation, where optimal location is necessary to understand. State estimation meter placement plays a major role in the smart operation [...] Read more.
The blackout in North India due to the failure of the central grid has led to the need for intelligent power system state estimation, where optimal location is necessary to understand. State estimation meter placement plays a major role in the smart operation of a modern distributed power system. A literature review of the different algorithms incorporated for the determination of minimal number of meters required for the measurement of real time measurements is presented for the power system and distribution system state estimation, including smart meter location. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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16 pages, 1139 KiB  
Review
Failure Modes, Mechanisms, Effects, and Criticality Analysis of Ceramic Anodes of Solid Oxide Fuel Cells
by Nripendra K. Patel, Sean R. Bishop, Robert G. Utter, Diganta Das and Michael Pecht
Electronics 2018, 7(11), 323; https://doi.org/10.3390/electronics7110323 - 15 Nov 2018
Cited by 5 | Viewed by 5778
Abstract
Solid oxide fuel cells (SOFCs) are a highly efficient chemical to electrical energy conversion devices that have potential in a global energy strategy. The wide adoption of SOFCs is currently limited by cost and concerns about cell durability. Improved understanding of their degradation [...] Read more.
Solid oxide fuel cells (SOFCs) are a highly efficient chemical to electrical energy conversion devices that have potential in a global energy strategy. The wide adoption of SOFCs is currently limited by cost and concerns about cell durability. Improved understanding of their degradation modes and mechanisms combined with reduction–oxidation stable anodes via all-ceramic-anode cell technology are expected to lead to durability improvements, while economies of scale for production will mitigate cost of commercialization. This paper presents an Ishikawa analysis and a failure modes, mechanisms, effects, and criticality analysis (FMMECA) for all-ceramic anode based SOFCs. FMMECA takes into account the life cycle conditions, multiple failure mechanisms, and their potential effects on fuel-cell health and safety. Full article
(This article belongs to the Special Issue Renewable Electric Energy Systems)
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