bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal economic–emission power scheduling of RERs in MGs with uncertainty
Authors: Elsakaan Asmaa A. , El‐Sehiemy Ragab A. , Kaddah Sahar S. , Elsaid Mohammed I.
Published: October 2019

This study proposes a framework for economic–emission dispatch problem (EEDP) in microgrids (MGs). The problem of EEDP aims at finding the optimal scheduling of renewable energy resources (RERs) in isolated and grid‐connected MGs. The EEDP is formulated as a non‐linear constrained multi‐objective optimisation problem. It minimises the total cost and emission simultaneously. Simulation results in nine different cases are conducted to emulate the complexity of the EEDP. Also, the proposed scheduling procedure is tested under abnormal operation of MGs considering unexpected increase in power demand, shortage of battery storage and partial shedding of photovoltaic units. These cases reveal the capability of the proposed method. A multi‐objective function is employed to increase the economic benefits and minimise emission issues. In this line, the simulation results are obtained using an enhanced moth‐flame optimisation (EMFO) algorithm. The obtained results verified the effectiveness, robustness and global convergence for minimising emission and generation costs. These results are compared with several well‐known techniques in the literature. Notable economic and environmental benefits are achieved using the EMFO that lead to flexible scheduling of RERs for MG operation under uncertainty.
Frequency response reserves sharing across asynchronous grids through MTDC system
Authors: Sun Kaiqi , Xiao Huangqing , Sundaresh Lakshmi , Pan Jiuping , Li Ke‐Jun , Liu Yilu
Published: October 2019

Voltage source converter‐based multi‐terminal HVDC (VSC‐MTDC) system has been considered for interconnecting asynchronous power grids for improved system operation efficiency and reliability. In this study, a frequency response control strategy is proposed for the VSC‐MTDC systems that can enable operating reserves sharing among the interconnected asynchronous grids. The proposed control strategy consists of three frequency control components: MTDC primary frequency control, corrective frequency control, and MTDC secondary frequency control. The MTDC primary frequency control could keep the frequency of a disturbed power grid stable and avoid the frequency dropping into an unacceptable level when a sudden power imbalance event occurs. The corrective frequency control strives to guarantee the settled frequency can be within the predefined secure frequency range. The MTDC secondary frequency control provides a novel optimal allocation strategy for considering the participation of MTDC system for restoring system frequency back to the nominal frequency with the lowest cost. The simulation results, based on a modified IEEE New England 39‐bus system modelled in PSCAD/EMTDC, show the effectiveness of the proposed frequency response control strategies.
Statistical analysis of switching overvoltages in UHV transmission lines with a controlled switching
Authors: Zhang Fan , Duan Xiongying , Liao Minfu , Zou Jiyan , Liu Zhiheng
Published: October 2019

The objective of this work is to present a more precisely controlled switching strategy to reduce overvoltages due to ultra‐high voltage (UHV) transmission line closing. Essentially the switching strategy is to find a suitable circuit breaker (CB) optimal instant of closing. The electric field variation in the arc‐extinguish chamber has great effect on rate of decrease of dielectric strength (RDDS), when calculating optimal instant of closing with pre‐breakdown between the contacts. The relative value k of a CB is defined as the ratio of RDDS to the rate of voltage approaching the zero cross. In this calculation, the electric field E should be as a variation due to the uneven medium of SF6. Consequently equations were derived from calculating the pre‐breakdown instants. The ATP model of controlled closing UHV transmission line was built for switching overvoltage simulations considering RDDS and mechanical dispersion. The simulation results show that switching overvoltages are more accurate and closer to reality when regarding the electric field E as a variation. Contrarily, assuming E as a constant will increase the risk of failure via controlled switching. Furthermore, the simulation results demonstrate that k value can change the effect of the mechanical dispersion on switching overvoltages.
Low‐rank tensor completion for visual data recovery via the tensor train rank‐1 decomposition
Authors: Liu Xiaohua , Jing Xiao‐Yuan , Tang Guijin , Wu Fei , Dong Xiwei
Published: October 2019

In this study, the authors study the problem of tensor completion, in particular for three‐dimensional arrays such as visual data. Previous works have shown that the low‐rank constraint can produce impressive performances for tensor completion. These works are often solved by means of Tucker rank. However, Tucker rank does not capture the intrinsic correlation of the tensor entries. Therefore, the authors propose a new proximal operator for the approximation of tensor nuclear norms based on tensor‐train rank‐1 decomposition via the singular value decomposition. The proximal operator will perform a soft‐thresholding operation on tensor singular values. In addition, the low‐rank constraint can capture the global structure of data well, but it does not exploit local smooth of visual data. Therefore, they integrate total variation as a regularisation term into low‐rank tensor completion. Finally, they use a primal–dual splitting to achieve optimisation. Experimental results have shown that the proposed method, can preserve the multi‐dimensional nature inherent in the data, and thus provide superior results over many state‐of‐the‐art tensor completion techniques.
Higher precision range estimation for context‐based adaptive binary arithmetic coding
Authors: Im Sio‐Kei , Chan Ka‐Hou
Published: October 2019

The Lagrangian rate distortion optimisation is widely employed in modern video encoders, such as high‐efficiency video coding (H.265/HEVC). In this work, the authors propose a more accurate context‐based adaptive binary arithmetic coding look‐up table that can enhance compression quality and provide substantially better accuracy of range estimation, by employing one‐more bit with 64 probability states. For the hardware implementation, they propose a higher precision look‐up table instead of the HEVC Test Model (HM) standard table. The authors also define a new finite‐state machine to handle the probability changing in real‐time. The significant BD‐RATE gain of the proposed context modelling is up to 6.0% for all‐intra mode and 13.0% for inter mode. This finite state machine offers no divergence from the H.265/HEVC standards and can be used in the current systems.
Applying maximally stable extremal regions and local binary patterns for guide‐wire detecting in percutaneous coronary intervention
Authors: Pusit Prasong , Xie Xiao‐Liang , Hou Zeng‐Guang
Published: October 2019

Intervention surgery strongly requires information on the guide‐wire position under the monitoring of X‐ray video. Hence, the related researches such as guide‐wire detecting or tracking have become widespread. However, most of the existing methods require a lot of resources for computing or large data for training since the X‐ray videos have internal physicals such as anatomical skeleton contours and organs that are quite similar to a guide‐wire. This work presents a practical method that only requires a moderate number of training data for detecting a guide‐wire tip in an X‐ray video sequence during the percutaneous coronary intervention surgery. The method applies maximally stable extremal regions (MSER) combine with modified multi‐filters (region area range filter and stroke width variation filter) for region detection and local binary patterns (LBP) for guide‐wire recognition. The motivation for applying MSER and LBP are the robust efficacy and the low requirement of resources. The approach evaluated 20 different sequences of X‐ray videos, a total of 1295 frames. 50 selected frames were used as training templates and others to experiment. The method was successfully performed to the detecting guide‐wires with p‐value < 0.01 compared with conventional MSER methods, 93.7% average detection accuracy, and 21 fps average speed.
Learning mean progressive scattering using binomial truncated loss for image dehazing
Authors: Qiu Bin , Liang Xiwen , Su Zhuo , Wang Ruomei , Zhou Fan
Published: October 2019

In this study, the authors propose a novel progressive dehazing network to address the single image haze removal problem based on a new mean progressive scattering model. Different from methods that learn atmosphere light and transmission maps with different networks, these two variables are optimised in a unified network. Following the methodology of traditional prior‐based methods that estimate a coarse transmission map first, a progressive refinement branch in the decoder has been designed to restore the fine‐scale transmission map. To improve the prediction accuracy of the transmission map, a novel binomial truncated loss that assigns weights to error values according to the probabilities of error occurrences has been proposed. An ablation study is conducted to verify the effectiveness of the components in the proposed method. Experiments in the synthetic datasets and real images demonstrate that the proposed method outperforms other state‐of‐the‐art methods.
Regularised IHS‐based pan‐sharpening approach using spectral consistency constraint and total variation
Authors: Khateri Mohammad , Shabanzade Fahim , Mirzapour Fardin
Published: October 2019

In this study, the authors address the fusion of low‐resolution multi‐spectral image with the corresponding high‐resolution panchromatic image to provide high‐resolution multi‐spectral (HRM) one, i.e. pan sharpening. The intensity–hue–saturation (IHS)‐based pan‐sharpening methods are popular because they are simple, efficient, and of high‐spatial quality. However, their frameworks are unavoidably subject to spectral distortion. To reduce the inevitable spectral distortion of IHS‐based pan‐sharpening approaches, the spectral consistency constraint is used in the proposed method. Moreover, to stabilise fusion results obtained from the ill‐posed pan‐sharpening problem and to keep the smoothness of the HRM image, a total variation regularisation term is considered. These considerations are formulated in a non‐quadratic optimisation problem. To solve this problem, a kind of variable splitting method, known as half‐quadratic approximation is utilised, and also an alternating optimisation procedure is used to reconstruct HRM image. To gain convenient control on the local spectral and the spatial information, and also to reduce the required memory, in the optimisation stage, the patch‐based strategy is employed. The proposed method was tested on two datasets acquired by GeoEye‐1 and Pleiades satellites. To evaluate the proposed method, visual assessment, as well as quantitative comparison with different pan‐sharpening methods, was carried out.
Training approach using the shallow model and hard triplet mining for person re‐identification
Authors: Choi Hyunguk , Yow Kin Choong , Jeon Moongu
Published: October 2019

Multi‐target tracking in a non‐overlapping camera network is an active research field, and one of the important problems in it is the person re‐identification problem. In this study, the authors propose an approach to improve the performance of the backbone model in the person re‐identification. Their approach focuses on training a fusion model with a shallow model and making hard triplets with relationship matrices quickly and efficiently. The proposed approach is simple, but it improves the performance of the backbone. In addition, the hard triplet mining in their process is much faster than the conventional approach. Experimental evaluation shows that the proposed approach can improve the performances of the backbone model. The proposed approach improves rank‐1 and mean average precision (mAP) performance by more than 12.54 and 15.44%, respectively, over the backbone models in the Market1501 and DukeMTMC‐reID dataset. The approach also achieves competitive performances compared with state‐of‐the‐art approaches.
Image encryption algorithm based on image hashing, improved chaotic mapping and DNA coding
Authors: Zhang Qiuyu , Han Jitian , Ye Yutong
Published: October 2019

In order to improve the problems of security and robustness for existing image encryption algorithms and to reduce the security risks of encryption algorithms against statistical analysis, differential attacks, exhaustive attacks, cropping and noise attacks etc., a novel image encryption algorithm based on image hashing, improved chaotic mapping and DNA coding is proposed. Firstly, extracting the image features and evenly block after pre‐processing the original image and fingerprint image. Secondly, the features are generated to be a binary hash sequence through the image hash algorithm, and the generated hash sequence is iterated as the initial parameter of the improved chaotic map and Chen's chaotic system. Finally, Chen's chaotic system is used to generate a random sequence, and the matrix generated by the improved chaotic map and the original image is subjected to DNA calculation and encoding operations to obtain an encrypted image. Experimental results show that the proposed algorithm has better performance on security, larger key space and higher key sensitivity, the pixel correlation coefficient close to 0, the information entropy close to 8, unified average changing intensity and number of pixels change rate values are close to ideal values, and it has better robustness on noise and cropping attacks.
Performance analysis of a novel hybrid FSO/RF communication system
Authors: Ali Amirabadi Mohammad , Tabataba Vakili Vahid
Published: October 2019

In this paper, a novel dual‐hop relay‐assisted hybrid Free Space Optical / Radio Frequency (FSO / RF) communication system is presented. In this structure an access point connects users within the building to the Base Station via a hybrid parallel FSO / RF link, this link is proposed firstly. The parallel combination of FSO and RF links and use of an access point will increase capacity, reliability and data rate of the system. It is the first time that the effect of the number of users on the performance of a dual‐hop relay‐assisted hybrid parallel FSO / RF system is investigated. FSO link is considered in Gamma‐Gamma atmospheric turbulence with the effect of pointing error and RF link is considered in Rayleigh fading. For the first time, closed‐form expressions are derived for Bit Error Rate (BER) and Outage Probability of the proposed system. Derived expressions are verified through MATLAB simulations. It is shown that performance of the proposed system is almost independent of atmospheric turbulence intensity, thereby when atmospheric turbulence strengthens, low power consumption is required for performance maintenance. Hence the proposed structure is suitable for mobile systems in which a small battery supplies transmitter power.
Improved powered bus communication technique based on PD‐TDMT for distributed power system (DPS)
Authors: Wu Jiande , Wang Ruichi , Chen Jinghui , He Xiangning
Published: October 2019

For many distributed power systems (DPSs) such as light‐emitting diode lighting and battery management, communication is essential. This study presents an improved method of integrating power transfer and communication through a common bus by applying the concept of power/data time division multiplexing transmission (PD‐TDMT). The proposed method employs power electronic topologies as the basic circuits to create the power transfer system and utilises the power transmission intervals for communication. Compared with conventional communication techniques in DPS, the proposed method has the advantages of simple implementation, enhanced noise immunity and higher output power capacity. The general structure of PD‐TDMT systems is presented, which includes power sourcing equipment (PSE) and powered devices (PDs). A series of PSE and PD circuits are derived based on dc–dc topologies. The timing sequence of power transfer and communication is given. To suppress the common‐mode interferences under the high‐power condition, a balanced power transmission system is also proposed. Besides, the termination circuits are discussed in detail under the long‐distance transmission condition. Finally, the proposed method and theoretical analysis are verified by experiment.
Experimental study of a novel filter structure designed for MEMS‐based sensors in electric vehicles
Authors: Linani Messaoud , Mokhtari Bachir , Cheknane Ali , Hilal Hikmat S.
Published: October 2019

This work describes a comparative study between Kalman filter, a complementary filter and a combination of both, for use in electrical vehicles. Combining the benefits offered by each filter to obtain an optimised filter combination is targeted. Three different combinations: The Kalman‐complementary filter (KCF), complementary‐Kalman filter (CKF) and 2KCFs are examined here. The filters are used to improve signals obtained via two sensors (gyroscope and accelerometer) integrated into the sensor IMU‐MPU6050, with internal DMP. The sensor data are filtered to guarantee the movement quality of electrical vehicles. The KCF combination shows higher performance than the CKF combination. Moreover, the experimental results show that the 2KCF combination yields best performance with minimal noise levels and more accurate angle measurement. The optimal combination is strongly recommended for future electrical vehicle development.
Output voltage tracking controller embedding auto‐tuning algorithm for DC/DC boost converters
Authors: Choi Kyunghwan , Kim Yonghun , Kim Kyung‐Soo , Kim Seok‐Kyoon
Published: October 2019

This study suggests a non‐linear output voltage tracking controller for DC/DC boost converters in the form of a classical cascade control structure. Non‐linearities in the converter dynamics as well as parameter uncertainties and load variations are considered. The first contribution of this study is the design of an auto‐tuner, which automatically adjusts the control gain according to the output voltage error to enhance transient performance. The second contribution involves proving that the closed‐loop system ensures the performance recovery without any steady‐state errors in the presence of parameter and load variations. The effectiveness of the proposed algorithm was verified through experimental investigations using a 5 kW prototype DC/DC boost converter.
Modified single‐switch bridgeless PFC SEPIC structure by eliminating circulating current and power quality improvement
Authors: Romai Noor Mohamad Kamil , Ponniran Asmarashid , Abdul Rashid Munirah Az Zahra , Jumadril J.N. , Yatim Mohd Hafizie , Kasiran Mohd Amirul Naim , Bakar Afarulrazi Abu , Shah Shaharil Mohd , Muhammad Khairul Safuan , Itoh Jun‐ichi
Published: October 2019

In this study, a modified single‐switch bridgeless power factor correction (PFC) single‐ended primary‐inductor converter (SEPIC) structure is proposed. The major practical drawbacks of the existing structure are the presence of circulating current and high maximum current stress at the input capacitor and line diodes. Therefore, to overcome these problems, the existing structure is restructured by repositioning the line diodes in series with input inductors. Besides, the principle of design parameters optimisation is used based on the balancing energy compensation between input capacitors and output inductor. This structure is designed to operate in discontinuous conduction mode in order to achieve almost a unity power factor. The operation principle and design consideration of the modified structure is introduced in details. The experimental results demonstrate that the total harmonic distortion current is reduced from 56.3 to 4.9% after the optimisation process is performed, and at the same time the dead zones are inherently eliminated. Furthermore, it is shown that the output voltage ripple frequency is always double from the input line frequency of 50 Hz and the output voltage ripple is constantly lower than the maximum input voltage ripple. Thus, the designed parameters of the experimental converter are verified with ∼160 W of the converter output power.
Stochastic methods for prediction of charging and discharging power of electric vehicles in vehicle‐to‐grid environment
Authors: Haque Ahteshamul , Kurukuru Varaha Satya Bharath , Khan Mohammed Ali
Published: October 2019

As the penetration rate of the electric vehicles (EVs) increases, their uncontrolled charging could cause undervoltage and network congestion in the electric network. To mitigate these impacts, the controlled charging of the EVs has been investigated by earlier publications. However, controlled charging cannot be easily implemented as it involves multiple customers having individual interests. To overcome these drawbacks, the power prediction of charging and discharging of EVs plays a major role. A new realistic power prediction algorithm that accounts for the requirements of different patterns and consumers is developed in this study. The main objective of the study is to develop a charging and discharging coordination algorithm that effectively addresses the problem of power demand during peak time. Stochastic methods were used to develop the charging‐discharging models and estimate the EV usage. The proposed algorithm aims to manage high power demands at peak times using vehicle‐to‐grid technologies. Intensive computer simulations are performed to test and estimate the power demand by adapting the proposed algorithm. The developed algorithm shows a significant improvement in the comprehensive index with a value of 0.649 which is very high compared with conventional charging strategies. The results depicted an efficient scheduling and power distribution without affecting the performance of the EV or the flexibility of EV owner's trip schedule.
Fault‐tolerant compensation control for T‐type three‐level inverter with zero‐sequence voltage injection
Authors: Zhang Jianzhong , Hu Lucai , Xu Shuai , Deng Fujin
Published: October 2019

This study proposes a carrier‐based PWM strategy with zero‐sequence voltage injection for T‐type three‐level inverter to a tolerant open‐circuit fault. The half‐bridge and NP bridge open‐circuit faults are analysed. The faulty switch can be identified by the average phase current and the deviation of neutral‐point (NP) voltage. In the case of half‐bridge failure, the fault‐tolerant control reduces the distortion of phase current and the amplitude of line‐to‐line voltage is decreased. In the case of NP failure, the faulty pole voltage becomes two‐level instead of three‐level and the phase voltage is not reduced. By using the novel zero‐sequence voltage injection, the NP voltage is balanced in both half‐bridge and NP bridge failures, which do not require additional hardware and complex calculations. The effectiveness of the proposed fault‐tolerant PWM strategy and injection of zero‐sequence voltage is validated by the simulation and experiment results.
SiC‐based active quasi‐Z‐source inverter with improved PWM control strategy
Authors: Duong Truong‐Duy , Nguyen Minh‐Khai , Lim Young‐Cheol , Choi Joon‐Ho , Vilathgamuwa D. Mahinda
Published: October 2019

In this study, an improved pulse width modulation (PWM) scheme was proposed for an active quasi‐Z source inverter (AqZSI). Compared to the quasi‐Z‐source inverter (qZSI), the AqZSI with improved PWM strategy can operate in a wide range of input voltage with higher efficiency. Furthermore, the AqZSI can operate with a higher modulation index, a lower inductor current stress, and a reduced shoot‐through current. A procedure flowchart is presented for the optimal selection of the shoot‐through duty cycle, the switching ratio of the additional switch, and the modulation index for AqZSI. Moreover, some comparative results between the AqZSI, qZSI and conventional two‐stage inverter with a boost DC–DC converter are shown in detail. Finally, 1.2 kVA SiC‐based three‐phase inverter prototypes are built to verify the agreement between theory and measurement.
Wavelet entropy analysis and machine learning classification model of DC serial arc fault in electric vehicle power system
Authors: Xia Kun , Liu Bangzheng , Fu Xiale , Guo Haotian , He Sheng , Yu Wei , Xu Jingjun , Dong Hui
Published: October 2019

Electric vehicle (EV) power system is flammable and explosive when the direct current (DC) arc occurs at elevated temperature. Thus, DC serial arc real‐time monitoring is an insurance to keep away from disaster. In this study, the detection algorithm of DC serial arc is proposed. The wavelet entropy algorithm, the classification model based on support vector machine and logistic regression are analysed separately. The above algorithms are combined to identify the DC serial arc faults effectively under different types of loads in EV power system. The results show that the combined algorithm has a good performance of DC serial arc detection with high accuracy and robustness compared with a simple approach. Meanwhile, the false detection rate of the detection algorithm is close to zero, which could ensure the safety and stable operation of the system.
Geometrical visualisation of indirect space vector modulation for matrix converters operating with abnormal supplies
Authors: Guan Quanxue , Wheeler Pat , Simon Olaf , Guan Quansheng , Clare Jon
Published: October 2019

Matrix converters can be sensitive to abnormal supply conditions due to the absence of energy storage elements. This sensitivity can get worse when the matrix converters are modulated by a traditional indirect space vector modulation that assumes the input variables are sinusoidal and balanced. Therefore, this study proposes a methodology for the modulation of matrix converters without requiring any assumption of the input voltages. The method uses a geometric representation based on the singular value decomposition of the switch states to synthesise the rotating vectors of the target duty‐cycle matrix. Furthermore, this study mathematically highlights the factors that regulate the amplitude of the output voltages and utilise them to compensate the adverse effect of the abnormal input voltages. Experimental results presented in this study validate that the proposed method can provide sinusoidal and balanced output currents in the presence of abnormal supply conditions.
Regenerative switched‐inductor/capacitor type DC–DC converter with large voltage gain for PV applications
Authors: Karthikeyan Venkitusamy , Sundaramoorthy Kumaravel , Guru Kumar Gangavarapu , Babaei Ebrahim
Published: October 2019

In grid‐connected PV applications, the presence of a transformer not only increases the cost, size and weight, but also decreases the whole system efficiency, especially, under poor irradiation conditions. To eliminate the transformer and to meet DC link voltage, a regenerative switched‐inductor/capacitor type DC–DC converter with large voltage gain is proposed in this study. In traditional boost type and derived converters, the voltage gain ratio is limited due to voltage stress on the semiconductor devices and low efficiency because of more components count and large duty cycle operation. The proposed converter recycles the energy in lossless passive components and increases the step‐up voltage gain, which improves the efficiency. In addition, the converter possesses fewer ripples and smooth continuous current, which reduces the power loss, elongates lifespan of the input source and restricts electromagnetic interference issues. This study presents detailed operating waveforms, modes of operation and performance characteristics of the proposed converter. In order to validate the operation, 500 W experimental prototype is developed and verified with measured results. The proposed converter yields the peak efficiency of 95.20% for the output power of 440 W.
Synchronous drive circuit with current limitation for solid‐state pulsed power modulators
Authors: Rao Junfeng , Zeng Tong , Jiang Song , Xia Kun , Li Zi
Published: October 2019

Recently, solid‐state pulsed power modulators (SSPPMs) are widely used in pulsed power applications. Due to the relatively low rated voltage and rated current of semiconductor switches, a single SSPPM usually consists of hundreds of power switches which work at different voltage potentials. Therefore, the synchronous and isolated driving of so many switches is a very challenging task in the design of SSPPMs. Here, a very simple but powerful synchronous drive circuit with current limitation is proposed for a solid‐state Marx generator. It spares the use of isolated power supply for drives, and the negative bias voltage enhances the electromagnetic compatibility. Moreover, the proposed circuit can flexibly change the value of clamped current according to practical requirements. This drive circuit can be utilised in other types of SSPPMs. The operation principle i.e. the design concept of the pulsed power system is given in detail and the feasibility is verified experimentally.
Temperature‐dependent dynamic RDS,ON under different operating conditions in enhancement‐mode GaN HEMTs
Authors: Li Yuan , Zhao Yuanfu , Huang Alex Q. , Zhang Liqi , Huang Qingyun , Yu Ruiyang , Sen Soumik , Ma Qingxuan , He Yunlong
Published: October 2019

High‐voltage enhancement‐mode (E‐mode) gallium nitride (GaN) high electron mobility transistor (HEMT) is a superior candidate to enable higher efficiency and higher power density when compared with silicon power devices in power converter applications. However, the dynamic problem affects the conduction loss of the converter and remains one of the major issues that must be resolved. In this study, a comprehensive experimental evaluation and analysis method of the temperature‐dependent dynamic of GaN HEMT in a circuit level is proposed. A commercial E‐mode GaN HEMT (GS66508T) is used as a sample to study the temperature‐dependent dynamic using a double‐pulse‐tester. The temperature‐dependent dynamic under different DC‐link voltages and different load currents are studied and the results show a non‐monotonic temperature‐dependence of the dynamic . It is concluded that the temperature dependence of the buffer‐induced trapping and de‐trapping effect, and the temperature dependence of electron mobility together influence the dynamic of E‐mode GaN HEMT device during operation. This finding is important since in converter applications the devices are typically operating at elevated temperatures. The proposed comprehensive experimental method can be used to estimate and analyse the dynamic characteristics of other GaN devices.
Two‐phase high efficiency interleaved buck converter with improved step‐down conversion ratio and low voltage stress
Authors: Biswas Mriganka , Majhi Somanath , Nemade Harshal
Published: October 2019

A two‐phase interleaved buck converter (IBC) providing a high step‐down conversion ratio is proposed in this study. The proposed IBC uses a switch‐capacitor cell to achieve a high step‐down conversion ratio compared to the conventional IBC. The cell consists of two parallel switches and two crossly placed identical capacitors. These identical capacitors are charged in series and discharged in parallel by producing a lower output voltage compared to the conventional IBC at the same duty ratio. The proposed converter provides less voltage and current stresses. The operation principle, the ripple and the average current through the inductors are described in continuous conduction mode. The boundary load condition is also determined. By describing the charging and discharging of the two identical capacitors of the cell, the capacitance value is determined. The losses and efficiency are analysed, and 96.33% efficiency is achieved. Finally, the proposed converter is implemented and experimental results are provided.
Single‐switch high step‐up boost converter based on a novel voltage multiplier
Authors: Zhu Binxin , Wang Han , Vilathgamuwa Don Mahinda
Published: October 2019

A single‐switch high step‐up boost converter based on a novel voltage multiplier (VM) has been proposed in this study. Compared to traditional boost converter, not only the voltage conversion ratio has been increased, but also voltage stress across semiconductor devices has been decreased. Moreover, the voltage conversion ratio and voltage stress of switch of the proposed converter can be adjusted by the number of the VM cells. The control and drive circuits for the proposed converter is as simple as boost converter as there are no additional switches. Working principles and performance characteristics of the proposed converter have been analysed in detail. A 200 W experimental prototype with three VMs has been built to validate the theoretical analysis.
Comparative analysis on selection and synthesis of multiple input converters: a review
Authors: Hema Chander Allamsetty , Kumar Sahu Lalit , Ghosh Subhojit , Gupta Krishna Kumar
Published: October 2019

Power electronics converters for DC–DC conversion are extensively used in various applications. Further, with an increase in demand for integrating multiple sources with distinct I–V characteristics, a change over from single input DC–DC converters to multiple input converters (MICs) has been observed in the recent past. MICs are widely used for effective integration of energy sources in various applications ranging from milliwatt to megawatt power levels and millivolt to several kilovolts of voltage levels. The combination of sources with respective energy buffering units allow for a new configuration and topology, which are quite confusing and challenging to pick one for a specific application. MICs are categorised based on their characteristics, and each category has its pros and cons depending on the application. Further, this study categorises and comprehensively reviews the MICs based on their characteristics. In this regard, this study aims to provide a clear picture of MICs and the general rules and framework for the selection of MIC topology for a specific application. Also, the key features and limitations of a few recently proposed MICs, followed by the selection of MICs for different applications are discussed.
Dynamic performance of key components for hydraulic power take‐off of the wave energy converter
Authors: Qijuan Chen , Wen Jiang , Xuhui Yue , Dazhou Geng , Donglin Yan , Weiyu Wang
Published: October 2019

Since the input power of the real waves varies continuously and periodically, how to stabilise the operation and generation during wave energy utilisation has become an inevitable and significant topic. This study focuses on the wave energy converter of a hydraulic power take‐off (HPTO) connected to a pendulum and studies the influences of the key components, i.e. the high‐pressure accumulator, oil tank and flow control valve, on the operational stability of HPTO by simulations and experiments. Parameters of the high‐pressure accumulator are analysed and optimised. The dynamic performance of the HPTO with or without the oil tank is also investigated. Besides, the functions of the flow control valve in the cases of excessive input power and load shedding are given. Results show that the key components play very important roles in the operational stability of HPTO. Reasonable configurations of the high‐pressure accumulator and oil tank are significant to improve the quality of output power and stability. Appropriate actions of the flow control valve are beneficial to protection and stability. Therefore, these key components should be considered preferentially during the design of HPTO.
Zonotope‐based method for optimal allocation of wind capacity in microgrids considering generation uncertainty
Authors: Gao Jianing , Han Bei , Zhang Lijun , Xu Chenbo , Li Guojie , Feng Lin , Wang Keyou
Published: October 2019

The increasing wind capacity integration brings new challenges to power system planning and operation, due to the intermittency and uncertainty of its power generation. This study determines the optimal allocation of wind capacity in microgrids, with considerations of the impact of generation uncertainty on both static and dynamic performance of the system, for reducing the possible violations of operation limits caused by wind power fluctuations. The system performance under uncertainty is evaluated using a zonotope‐based set‐theoretic method. The uncertain variations of wind power are modelled by a zonotope, then the uncertainty sets of static and dynamic state variables, which capture all possible values of the system states, are further calculated by set operations and are embedded in the optimisation model as constraints for system performance. The proposed method is applied to a 33‐bus microgrid; the results prove the validity of the method and show that the system can be guaranteed to operate within acceptable security regions in all possible situations when subjected to certain level of uncertainty.
Experimental study of static and dynamic behaviours of cracked PV panels
Authors: Al‐Soeidat Mohammad , Cheng Tian , Lu Dylan Dah‐Chuan , Agelidis Vassilios G.
Published: October 2019

Solar cell power performance is greatly affected by two critical factors ageing and crack. In order to mitigate their negative effects on the solar system, these cells are to be substituted by new cells, thus, replacing the panels. This study presents an active crack detection method that detects the cracked cells within a solar string by using AC parameter characterisation without a need to have a physical inspection. The mathematical module of the solar cell shows that it constitutes of series and parallel resistors in addition to a parallel capacitor and that their values change by ageing and crack. In addition to studying the effects of the crack on the solar cell, it is verified by the experiment that the solar cells behave as a capacitive circuit, and their capacitance increases when the cell gets cracked, getting higher as the crack becomes more serious. The experiment is extended to investigate the effect of series and parallel PV strings, which are affected by cracked and partially shaded cells to evaluate their criticality levels. By monitoring the AC parameter of the solar cell and the change of the capacitance, it is easy to detect the crack when it occurs.
Power oscillation damping with virtual capacitance support from modular multilevel converters
Authors: Taffese Abel A. , Endegnanew Atsede G. , D'Arco Salvatore , Tedeschi Elisabetta
Published: October 2019

Power oscillation damping (POD) is one of the ancillary services expected from high‐voltage direct current (HVDC) converters. When providing POD to the ac side, converters draw power from the dc side, which can cause distortion to the dc voltage especially in the case of limited dc capacitance. In meshed/multi‐terminal HVDC grids, where dc voltage regulation is distributed using a dc voltage droop control strategy, the distortion due to the POD controller action is propagated to other connected ac grids because of the droop action. This propagation can be reduced by using the inherent energy storage capability of the modular multilevel converter (MMC), which is a common converter topology for HVDC. Different methods to utilise the energy stored in the MMC for the purpose of POD have been proposed in the literature. This study presents a detailed analysis and experimental validation of one of these methods, referred to as virtual capacitance support, which increases the effective dc grid capacitance by using the stored energy of multiple MMCs connected in the same grid. The experiments, which were carried out using power hardware in the loop setup, demonstrated the effectiveness of the method.
New hybrid‐microgrid topology using a bidirectional interleaved converter as a robust power interface operating in grid‐connected and islanded modes
Authors: Tricarico Thiago , Gontijo Gustavo F. , Aredes Mauricio , Dias Robson , Guerrero Josep M.
Published: October 2019

This study presents a new microgrid topology that uses a bidirectional interleaved converter performing a power interface between DC buses in a hybrid microgrid allowing for both grid‐connected and islanded modes. The authors propose a new control strategy and controllers' design method aiming at achieving a high‐performance dynamic response regarding the converter load and generation disturbance rejection capability. In the grid‐connected mode, the interleaved converter operates in the buck mode providing a high‐power‐quality DC microgrid voltage. In the islanded mode, the interleaved converter operates in the boost mode and it is responsible for regulating the DC link of the back‐to‐back converter that connects the main grid to the AC microgrid. A detailed mathematical model is presented to obtain a MIMO system that takes into account the system's disturbances to analyze both stability margins and disturbance‐rejection response. Simulations of the proposed topology are carried out in PSCAD/EMTDC in a microgrid operating in grid‐connected and islanded operation modes. Experimental results are provided in order to validate the proposed control tuning method.
Adaptive real‐time recursive radial distance‐time plane Hough transform track‐before‐detect algorithm for hypersonic target
Authors: Li Lin , Wang Guohong , Zhang Xiangyu , Yu Hongbo
Published: October 2019

Under the condition of low signal‐to‐noise ratio (SNR), the track‐before‐detect algorithm based on Hough transform (HT‐TBD) is an effective means to detect and track hypersonic targets. In view of the problem that the existing HT‐TBD algorithms cannot detect hypersonic multi‐target in real time and some targets may be missed, an adaptive real‐time recursive radial distance‐time plane HT‐TBD (RTHT‐TBD) algorithm for a hypersonic target is proposed in this study. Firstly, RTHT‐TBD technology is used to perform the non‐coherent integration detection of the first n frames measurement data, and the initial accumulation matrix and storage array are obtained. Then the data of 2∼n + 1, 3∼n + 2,… frames are processed recursively in turn. In order to solve the problem that the parameter space accumulation matrix cannot accumulate normally when the parameter space accumulation matrix changes in the recursive process, the adaptive technology is used to adjust the parameter space to realise the recursive detection at all times. The simulation results show that the proposed algorithm can realise real‐time detection and tracking of hypersonic multi‐target under low SNR, and effectively reduce the computational complexity.
Improved FBG interrogator considering FFP filter nonlinearity and investigation into performance limit
Authors: Jeong Seong‐Yong , Choi Sang‐Jin , Pan Jae‐Kyung
Published: October 2019

The authors propose and experimentally demonstrate a calibration process unit for mitigating the effects of nonlinearity and dependence on the ambient temperature for the fibre Fabry–Perot (FFP) filter. Additionally, the performance limits of the peak detection process unit based on the maximum detection algorithm according to the noise and the characteristics of the fibre Bragg grating (FBG) and FFP filter are presented. The experimental results obtained without and with the calibration process unit exhibited an average absolute error of <93.0 and 7.34 pm, respectively. The repeatability test results for the FBG interrogator showed an absolute error <2.19 pm. To investigate the performance limits of the peak detection process unit, the Bragg wavelength with variations in the noise of both the FBG reflection spectrum and the FFP filter transmission spectrum and with different characteristics of the FBG and the FFP filter were calculated. The calculated results for the given parameters show that the error of the mean value and the standard deviation increase with decreasing signal‐to‐noise ratios of both the FBG and FFP filter. Additionally, it was confirmed that the errors increase with the increase of the full‐widths at half‐maximum of both the FFP filter and the FBG and with the decrease of the Bragg wavelength intervals.
Estimation of switching surge flashover rate of point on wave switching over‐voltages along transmission line by adaptive neuro‐fuzzy inference system meta‐model
Authors: Hasanpour Mojtaba , Ghanbari Mahmood , Parvin‐Darabad Vahid
Published: October 2019

Limiting switching overvoltages (SOVs) and performing proper insulation coordination against stresses caused by them have great importance in UHV transmission lines (TLs). The point on wave switching (PWS) is the best strategy to limit SOV without needing any arrester. Although detailed electromagnetic transient studies are carried out in the design of transmission systems, such studies are not common in day‐to‐day operations. However, it is important for the power utility and/or operator to ensure that the peak value of SOVs is well within the safe limits. This study presents a new PWS strategy in the EMTP/ATP environment by considering line‐trapped charge to train an adaptive neuro‐fuzzy inference system meta‐model used to estimate the SOVs and to determine spots of critical failure risk caused by SOVs along TLs. The proposed meta‐model can be used by power utilities and/or design engineers for planning the proper insulation level without consuming time to meet a desirable value of risk. Moreover, the operators can decide on the energisation of lines in sequence, which is safe and leads to successful energisation. In order to reduce the training error, an intelligent method based on two‐stage data classification is introduced in which k‐means clustering method is used.
Electric spring average model development and dynamic analysis for demand‐side management
Authors: Areed Emad Fuad , Abido Mohamed A. , Al‐Awami Ali T. , Hussain Syed Asim
Published: October 2019

This study proposes a new averaged model for steady‐state and dynamic response analysis of the electric spring (ES). The accuracy of steady‐state and dynamic behaviour of the ES is demonstrated. Further, the dynamic behaviour of the proposed model is described as a function of the modulating signal. The developed model is used to design a controller for bus voltage regulation in a distribution system with an intermittent renewable energy source. The ES controller design problem is formulated as an optimization problem with a time domain‐based objective function to reduce the time‐weighted voltage deviations using particle swarm optimization method. Different disturbances have been applied to verify the developed ES model accuracy including sudden changes in renewable source current and load variations. An experimental analysis is also performed with the detailed non‐linear switching model of the ES to verify its behaviour with that of the proposed averaged model. The characteristics and performance of ES are thoroughly investigated. The effectiveness of the developed model and the proposed controller design approach is demonstrated in terms of a significant improvement in the dynamic performance of the distribution system