bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of extended substrate specificity of the MALT1 as a strategy for the design of potent substrates and activity-based probes
Authors: Kasperkiewicz Paulina , Kołt Sonia , Janiszewski Tomasz , Groborz Katarzyna , Poręba Marcin , Snipas Scott J. , Salvesen Guy S. , Drąg Marcin
Published: October 2018

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) belongs to the CD clan of cysteine proteases. MALT1 is a unique enzyme among this clan because it recognizes the basic amino acid arginine in the P1 pocket. Previous studies carried out with natural amino acids revealed the substrate specificity of the P4-P1 pockets of MALT1 but have provided only limited information about the catalytic preferences of this enzyme. In this study, we exploited Hybrid Combinatorial Substrate Library and Internally Quenched Fluorescence substrate technologies to interrogate the extended substrate specificity profile of the S5-S2’ active site pockets using unnatural amino acids. This strategy resulted in the design of a peptide-based fluorogenic substrate, which exhibited significant activity toward MALT1. Subsequently, the substrate sequence was further utilized to develop potent, irreversible activity-based probes.
Origin of radiation resistance in multi-principal element alloys
Authors: Do Hyeon-Seok , Lee Byeong-Joo
Published: October 2018

Using molecular dynamics simulations, we characterized the generation and evolution of radiation-induced point defects in the CoCrFeMnNi high-entropy alloy (HEA), to compare it with pure Ni and pure Fe. The generation of primary point defects was investigated by a cascade simulation at 773 K and the evolution of point defect clusters by a defect evolution simulation using 1 at% defect-containing samples. The numbers of residual defects after cascade and surviving defects after evolution in the CoCrFeMnNi HEA are smaller than those in pure Ni and pure Fe. The defect clusters appearing in the CoCrFeMnNi HEA after the defect evolution are unstable because of the alloy complexity. The origin of the slower radiation damage accumulation and the higher radiation damage tolerance in the CoCrFeMnNi HEA is discussed.
Associations between Antibiotics for Non-tuberculous Mycobacterial Infection and Incident Sjögren’s Syndrome: A Nationwide, Population-based Case-control Study
Authors: Chao Wen-Cheng , Lin Ching-Heng , Chen Yi-Ming , Hsu Chiann-Yi , Chen Jun-Peng , Chen Hsin-Hua
Published: October 2018

This study aimed to address the association between the usage of antibiotics to treat nontuberculous mycobacteria (NTM) infection and the risk of Sjögren’s syndrome (SS). We identified 5,553 patients with newly diagnosed SS between 2002 and 2013 using Taiwan’s National Health Insurance Research Database and compared them with 83,295 non-SS controls matched (1:15) for age, sex, and the year of their first SS diagnosis. An increased risk of SS was found in patients receiving new macrolides (adjusted odds ratios (aOR) 1.95, 95% confidence intervals (CI) 1.80–2.11), fluoroquinolones (aOR 1.52, 95% CI 1.41–1.64), and tetracyclines (aOR 1.69, 95% CI 1.59–1.79) compared with non-SS controls after adjusting for the Charlson comorbidity index, bronchiectasis and Helicobacter pylori infection. Notably, the association was consistent among each antibiotic in these three groups of antibiotics. In contrast to these three groups of antibiotics, the use of amikacin tended to have a negative association with incident SS (aOR 0.68, 95% CI 0.53–0.87). In conclusion, new macrolides, fluoroquinolones and tetracyclines were associated with a higher incidence of SS. These findings indicate the need for vigilance of SS in prescribing these antibiotics and warrant further mechanistic studies.
Metabotropic glutamate receptor-1 regulates inflammation in triple negative breast cancer
Authors: Sexton Rachel E. , Hachem Ali H. , Assi Ali A. , Bukhsh Miriam A. , Gorski David H. , Speyer Cecilia L.
Published: October 2018

Breast cancer remains a major cause of death among women. 15% of these cancers are triple negative breast cancer (TNBC), an aggressive subtype of breast cancer for which no current effective targeted therapy exists. We have previously demonstrated a role for mGluR1 in mediating tumor cell growth, endothelial cell proliferation, and tumor-induced angiogenesis in TNBC. In this study, we explore a role for mGluR1 in regulating inflammation in TNBC. GRM1 expression was silenced in MDA-MB-231 cells to study changes in expression of inflammatory genes regulated by mGluR1. Results were confirmed by ELISA using GRM1-silenced and overexpressed cells and mGluR1 inhibitors. A functional role for these differentially expressed genes was determined in vitro and in vivo. 131 genes were differentially expressed in GRM1-silenced MDA-MB-231 cells, with some of these falling into four major canonical pathways associated with acute inflammation, specifically leukocyte migration/chemotaxis. Upregulation of three of these genes (CXCL1, IL6, IL8) and their corresponding protein was confirmed by qPCR analysis and ELISA in GRM1-manipulated TNBC cells. Upregulation of these cytokines enhanced endothelial adhesion and transmigration of neutrophils in co-culture assays and in 4T1 mouse tumors. Our results suggest mGluR1 may serve as a novel endogenous regulator of inflammation in TNBC.
The influence of electrically conductive and non-conductive nanocomposite scaffolds on the maturation and excitability of engineered cardiac tissues
Authors: Navaei Ali , Rahmani Eliato Kiarash , Ros Robert , Migrino Raymond Q. , Willis Brigham C. , Nikkhah Mehdi
Published: October 2018

We developed different classes of hydrogels, with conductive and non-conductive nanomaterials, to study cardiac tissue maturation and excitability.
A highly efficient magnetically confined ion source for real time on-line monitoring of trace compounds in ambient air
Authors: Tang Jie , Ding Xuelu , Zhang Pei , Lei Bingying , Zhao Zhongjun , Duan Yixiang
Published: October 2018

A magnetically confined ambient ion source enables a great improvement in the MS signal intensity and detection sensitivity.
Light-induced desorption of trivalent chromium from adsorbents: one step closer to sustainability
Authors: Guan Xiaoyu , Yan Sunxian , Chang Jinming , Yang Gaofu , Fan Haojun
Published: October 2018

Trivalent chromium can be repelled from surface-bound merocyanine upon visible light irradiation, avoiding any chemical desorbent, and thus secondary contamination, to restore the adsorption capacity of the exhausted adsorbents.
Facile surface functionalization of upconversion nanoparticles with phosphoryl pillar[5]arenes for controlled cargo release and cell imaging
Authors: Wang Xu , Yang Jie , Sun Xiujuan , Yu Hongliang , Yan Fei , Meguellati Kamel , Cheng Ziyong , Zhang Haiyuan , Yang Ying-Wei
Published: October 2018

A new organic–inorganic hybrid material based on upconversion nanoparticles and pillarenes is constructed for cargo controlled delivery and cell imaging.
Aryne-based strategy in the total synthesis of naturally occurring polycyclic compounds
Authors: Takikawa Hiroshi , Nishii Arata , Sakai Takahiro , Suzuki Keisuke
Published: October 2018

This review has outlined the strategies and tactics of using arynes in the total syntheses of polycyclic natural products.
Upconversion core/shell nanoparticles with lowered surface quenching for fluorescence detection of Hg2+ ions
Authors: Shi Lichun , Hu Junshan , Wu Xiaofeng , Zhan Shiping , Hu Shigang , Tang Zhijun , Chen Mingshu , Liu Yunxin
Published: October 2018

In this study, we reported a fluorescent nanoprobe assembled with upconversion core/shell nanoparticles and a chromophore ruthenium complex (N719@UCNPs).
Flush with a flash: natural three-component antimicrobial combinations based on S-nitrosothiols, controlled superoxide formation and “domino” reactions leading to peroxynitrite
Authors: Alhasan Rama , Kharma Ammar , Nasim Muhammad Jawad , Abdin Ahmad Yaman , Bonetti Justine , Giummelly Philippe , Ejike Chukwunonso E. C. C. , Leroy Pierre , Gaucher Caroline , Jacob Claus
Published: October 2018

Controlled O2˙− production promotes the decomposition of S-nitrosothiols, forming highly aggressive ONOO−.
Supramolecular nanofibrillar hydrogels as highly stretchable, elastic and sensitive ionic sensors
Authors: Zhang Xiaohui , Sheng Nannan , Wang Linan , Tan Yeqiang , Liu Chunzhao , Xia Yanzhi , Nie Zhihong , Sui Kunyan
Published: October 2018

Nature-inspired ionic conductors based on supramolecular nanofibril are developed for flexible and stretchable strain/pressure sensors.
Metal-catalyzed 1,3-dipolar cycloaddition reactions of nitrile oxides
Authors: Roscales Silvia , Plumet Joaquín
Published: October 2018

In this review recent advances in the metal-catalyzed 1,3-dipolar cycloaddition reactions of nitrile oxides are highlighted, covering references from the period 2000 until August 2018.
Understanding coordination equilibria in solution and gel-phase [2]rotaxanes
Authors: Hewson Sean W. , Mullen Kathleen M.
Published: October 2018

An active-metal template approach has been use to synthesise solution and surface bound addressable [2]rotaxanes giving unique insights into thermodynamic equilibria in interlocked structures.
Total synthesis of (±)-chondrosterin I using a desymmetric aldol reaction
Authors: Kawamoto Yuichiro , Ozone Daiki , Kobayashi Toyoharu , Ito Hisanaka
Published: October 2018

The first total synthesis of racemic chondrosterin I was accomplished featuring a desymmetric intramolecular aldol reaction of the meso diketoester compound.
New photoluminescent iodoargentates with bisimidazole derivatives as countercations
Authors: Wang Rong-Yan , Zhang Xiao , Yu Jie-Hui , Xu Ji-Qing
Published: October 2018

Three bisimidazole-based chained iodoargentates were solvothermally synthesized, and their photoluminescent behaviors at different temperatures were investigated. Of those, 3 has been found to possess photochromic luminescence properties.
Molecular species fingerprinting and quantitative analysis of saffron (Crocus sativusL.) for quality control by MALDI mass spectrometry
Authors: Aiello Donatella , Siciliano Carlo , Mazzotti Fabio , Di Donna Leonardo , Athanassopoulos Constantinos M. , Napoli Anna
Published: October 2018

Herein we describe a rapid, simple, and reliable method for the quantitative analysis and molecular species fingerprinting of saffron (Crocus sativusL.) by direct MS and MS/MS analysis.
Removal of Au3+ and Ag+ from aqueous media with magnetic nanoparticles functionalized with squaramide derivatives
Authors: Duel Paulino , Gutiérrez M. Susana , Rodríguez Paulina , León Alberto , López Kenia A. , Morey Jeroni , Piña M. Nieves
Published: October 2018

An efficient methodology, based on squaramide-coated magnetite nanoparticles, for the removal of Au3+ and Ag+ by magneto filtration from water.
A statistical approach dealing with multicollinearity among predictors in microfluidic reactor operation to control liquid-phase oxidation selectivity
Authors: Siddiquee Muhammad N. , Sivaramakrishnan Kaushik , Wu Yucheng , de Klerk Arno , Nazemifard Neda
Published: October 2018

Chemometric tools to monitor the tetralin oxidation process and identify key parameters that influence product selectivity have not been investigated before.
Active particles under confinement and effective force generation among surfaces
Authors: Caprini Lorenzo , Marini Bettolo Marconi Umberto
Published: October 2018

We consider the effect of geometric confinement on the steady-state properties of a one-dimensional active suspension subject to thermal noise.
Near-surface microrheology reveals dynamics and viscoelasticity of soft matter
Authors: Liu Wei , Gong Xiangjun , Ngai To , Wu Chi
Published: October 2018

We report the development of a microrheology technique that incorporates a magnetic-field-induced simulator on total internal reflection microscopy (TIRM) to probe the near-surface dynamics and viscoelastic behaviors of soft matter like polymer solution/gels and colloidal dispersions.
Hyaluronic acid grafted nanoparticles of a platinum(ii)–silicon(iv) phthalocyanine conjugate for tumor and mitochondria-targeted photodynamic therapy in red light
Authors: Mitra Koushambi , Samsó Montserrat , Lyons Charles E. , Hartman Matthew C. T.
Published: October 2018

Hyaluronic acid nanoparticles containing a platinum(ii)–silicon(iv) phthalocyanine conjugate exhibited selective uptake by cancer cells and potent mitochondria-targeted PDT and chemotherapy.
A three-lncRNA expression signature predicts survival in head and neck squamous cell carcinoma (HNSCC)
Authors: Wang Peng , Jin Meng , Sun Chuan-hui , Yang Like , Li Yu-shan , Wang Xin , Sun Ya-nan , Tian Lin-li , Liu Ming
Published: October 2018

Increasing evidence has shown that long non-coding RNAs (lncRNAs) have important biological functions and can be used as a prognostic biomarker in human cancers. However, investigation of the prognostic value of lncRNAs in head and neck squamous cell carcinoma (HNSCC) is in infancy. In the present study, we analyzed the lncRNA expression data in a large number of HNSCC patients (n=425) derived from The Cancer Genome Atlas (TCGA) to identify an lncRNA expression signature for improving the prognosis of HNSCC. Three lncRNAs are identified to be significantly associated with survival in the training dataset using Cox regression analysis. Three lncRNAs were integrated to construct an lncRNA expression signature that could stratify patients of training dataset into the high-risk group and low-risk group with significantly different survival time (median survival 1.85 years vs. 5.48 years; P=0.0018, log-rank test). The prognostic value of this three-lncRNA signature was confirmed in the testing and entire datasets, respectively. Further analysis revealed that the prognostic power of three-lncRNA signature was independent of clinical features by multivariate Cox regression and stratified analysis. These three lncRNAs were significantly associated with known genetic and epigenetic events by means of functional enrichment analysis. Therefore, our results indicated that the three-lncRNA expression signature can predict HNSCC patients’ survival.
High selective microstrip bandpass filter and diplexer with common magnetic coupling
Authors: Xiao Jian‐Kang , Zhang Min , Ma Jian‐Guo
Published: October 2018

A new common magnetic coupling structure has been proposed. A high selective microstrip bandpass filter and a diplexer with the common magnetic coupling and 0° feeding have been developed. A pair of transmission zeros can be generated by 0° feeding, while an additional transmission zero can be produced by the common magnetic coupling structure and can be controlled/adjusted by the electric/magnetic couplings. The proposed diplexer has been fabricated and measured, and the measurement shows a channel insertion loss of <1.3 dB, and an isolation of not <34 dB. The measured results agree with the prediction.
Wideband and high‐gain circularly polarised microstrip antenna design using sandwiched metasurfaces and partially reflecting surface
Authors: Srivastava Kunal , Kumar Ashwani , Chaudhary Prashant , Kanaujia Binod K. , Dwari Santanu , Verma Anand K. , Esselle Karu P. , Mittra Raj
Published: October 2018

In this study, the authors propose a new type of metasurface, namely a sandwiched anisotropic metasurface, for converting a linearly polarised elliptical patch antenna into a wideband circularly polarised antenna. A partially reflecting surface (PRS) as a superstrate is further used to enhance the gain of the antenna. The design rules of the antenna are also presented. The combined metasurface and the PRS‐based patch antenna is designed on a low‐cost substrate FR‐4. The realised 3 dB axial ratio bandwidth (ARBW) of the antenna is 1.01 GHz (3.55–4.56 GHz), its impedance matching bandwidth is 1.33 GHz (3.08–4.41 GHz), and its peak gain varies from 7 to 7.84 dB within the band. By placing the PRS superstrate above the antenna, gain further improves to 9.32 dBi without degrading the performance of the antenna. Measured results are presented to validate the antenna performance and results are compared against a large number of similarly available antenna.
Dual‐band transmission‐type circular polariser based on frequency selective surfaces
Authors: Zeng Qingyun , Ren Wu , Zhao He , Xue Zhenghui , Li Weiming
Published: October 2018

A design of dual‐band transmission‐type linear‐to‐circular polarisation converter based on frequency selective surfaces (FSSs) has been presented in this study. The proposed converter is implemented by cascading a two‐dimensional periodic array of split‐ring resonators bisected by metal strips and an array of rectangular patches surrounded by rectangular microstrip rings. The structure composed of metal layers and dielectric layers is designed to behave differently for field components of the two orthogonal polarisations and transmit a circularly polarised wave once illuminated by a linearly polarised plane wave within two frequency bands. Using the equivalent circuit models of the FSSs, the operating principle of the converter is presented and discussed in detail. Also, as an illustrating example, a prototype of the proposed polarisation converter operating in two frequency bands of 6.4–8.8 GHz and 12.1–13.9 GHz is simulated, fabricated and experimentally characterised. The measurement results demonstrate that the dual‐band polarisation converter operates <3 dB axial ratio in a field view of ±25° with fractional bandwidths of 31.6 and 13.8%.
Passive SAR imaging using DVB‐T illumination for airborne applications
Authors: Gromek Damian , Radecki Krzysztof , Drozdowicz Jędrzej , Samczyński Piotr , Szabatin Jerzy
Published: October 2018

This study presents recent research results obtained by the Warsaw University of Technology, Poland in airborne passive synthetic aperture radar (SAR) imaging using digital video broadcasting‐terrestrial illumination. The main goal of the research was to prove the possibility of passive SAR imaging and its usage for airborne applications. In the study, different signal processing techniques used for passive SAR image creation are discussed in detail, together with an analysis of their computational requirements and implementation possibilities on the computing platforms available on the market. Also, a real measurement campaign is presented showing passive SAR images obtained. Finally, challenges in airborne passive SAR image creation are discussed, showing potential directions of the future development in this field.
Development of a ±660 kV DC transmission line arrester
Authors: Gu Shanqiang , Cao Wei , Wan Shuai , Chen Jiahong , Tan Jin , Wang Jian , Lv Jun
Published: October 2018

In order to improve the lightning withstand level of ±660 kV DC transmission line in China, the authors had begun to develop the ±660 kV DC line arrester since 2014, which was developed successfully in 2016. The structure, technical parameters, protection performance, and installation of line arrester are analysed in detail. The arrester adopts the structure of polymer housing with an external series air gap and a four‐section body. The technical parameters and protection performance are designed and calculated according to the relevant standards. The results show that the arrester has good electrical and mechanical performances, and it meets the requirement of insulation coordination. Pillar insulator supporting installation is used in the arrester application. Up to now, the ±660 kV DC line arrester has been used in the ±660 kV DC transmission line in China, which works safely and reliably over a long time. The successful operation can accumulate operating experience and provide a basis for the large‐scale application of the line arrester on the ±660 kV DC transmission line in the future.
Sub‐synchronous resonance mitigation by a STATCOM in doubly fed induction generator‐based wind farm connected to a series‐compensated transmission network
Authors: Gao Benfeng , Hu Yunting
Published: October 2018

With the fast development of wind power generation, large‐scale wind farms are connected to an electrical network which is series compensated to increase transmission capacity. However, a series‐compensated power system may encounter with a sub‐synchronous resonance (SSR) problem. Flexible AC transmission systems controllers are widely applied to mitigate SSR and improve the transient stability of the power system. A static synchronous compensator (STATCOM) with an SSR damping controller is proposed to mitigate the potential of SSR in a series‐compensated doubly fed induction generator‐based wind farm. The local signal is used as the input of the damping controller, which is feasible to be implemented in a practical project. Taking account of different series compensation levels and operating conditions, extensive transient simulations have been carried out using power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) to demonstrate the capability of STATCOM in damping SSR. It is shown that the SSR is successfully alleviated by STATCOM, which also verifies the effectiveness of the proposed STATCOM controller in improving the stability of the transmission system.
Detailed modelling and simulations of an all‐DC PMSG‐based offshore wind farm
Authors: Shi Tianyu , Shi Libao , Yao Liangzhong
Published: October 2018

A detailed modelling method and corresponding simulations for an all‐DC offshore wind farm equipped with a permanent magnet synchronous generator (PMSG) are elaborately discussed and conducted. This all‐DC wind farm is designed in series‐connected topology with an offshore DC substation and a voltage‐sourced converter−high‐voltage direct current (VSC‐HVDC) transmission system. Some major components including wind turbine, synchronous generator, VSC, and isolated full bridge converter are all modelled based on the complete electrical models and engineering parameter settings. Containing the start process of the system, the simulations under various wind speed conditions and the specific faults analysis under different situations are carried out in the MATLAB/SimulinkTM environment. Simulation results reveal the comprehensive operating characteristics of this all‐DC offshore wind farm and its system response to faults.
Exploration of a structural model of EIDN
Authors: Zhao Shanshan , Song Xiaohui , Li Yajie , Gao Fei , Li Jianfang , Zhang Yu
Published: October 2018

To meet the new demand of extensive interconnection, open and interactive, complementation and sharing, clean and efficient utilisation of various energy resources, the energy−Internet distribution network (EIDN) will lead the future development direction of the AC/DC distribution network. Firstly, the basic connotation and the technical features of EIDN are presented. Secondly, the structural characteristics of EIDN are analysed further. Moreover, a new structural model of EIDN is proposed in the AC/DC distribution network. Then the study proposes a method which can establish the new EIDN structural model. Finally, the application of the proposed EIDN structural model is simulated. The simulation results show that compared with the traditional network structural model, the new EIDN structural model can not only realise optimal allocation and connection sharing of various energy resources but also greatly enlarge the maximum allowable penetration of distributed energy resources and keep energy utilisation effective, secure, and sustainable. Therefore, it can have reference significance to the development of the future AC/DC distribution network
Voltage pole‐wave protection scheme for multi‐terminal DC grid
Authors: Xie Zhongrun , Zou Guibin , Gao Lei , Zhang Jie , Gao Houlei
Published: October 2018

With the rapid development of flexible DC transmission and multi‐terminal high voltage direct current transmission (HVDC) (MTDC) grid, the protection schemes of flexible DC transmission lines are still the traditional methods, which do not achieve the properties of fast and selective operation in the DC grid. In this study, using Zhangbei MTDC grid as the research object, the fast protection of DC transmission lines of MTDC grid has been studied. First, the voltage response characteristics of fault line and non‐fault line at the boundary of DC lines are analysed. On the basis of this, using wavelet transform to extract the characteristic value of voltage pole‐wave, this study put forward a high‐speed non‐unit protection criterion to identify the internal and external faults. In addition, two auxiliary criteria are constructed to identify lightning disturbance and faulted pole, respectively. Finally, a simulation model of Zhangbei MTDC grid is constructed, and the effectiveness of the proposed protection scheme is verified by extensive simulation results.
Design and implementation of the integrated experiment cabinet for micro‐transmission lines
Authors: Li Hao , Lu Yi , Zhang Hengxu , Zheng Zewen
Published: October 2018

Micro‐transmission lines are the physical model elements that own the same physical properties as the real transmission lines in power system, which are the significant components of a micro‐dynamic simulation laboratory. This study presents an integrated experiment cabinet for micro‐transmission lines (IECMTL). IECMTL integrates 20 micro‐emulating transmission lines units, four micro‐bus units and two light‐synchronised phasor measurement units (PMU Lights). Benefitting from the same size and interface, researchers can change the position and wiring of any two transmission lines units according to the needs of the simulation experiment. PMU Lights are employed to get the operating status of micro‐emulating transmission lines, including three‐phase frequency, voltage phasor and current phasor. Appropriate software was developed on server to communicate with IECMTL in a two‐way manner through the internet. Real‐time monitoring and control features of IECMTL provide a flexible physical platform not only for innovative research ideas but also for education engineering of the power system. An example test‐bed consisting of two IECMTLs was presented to simulate the power grids containing three generators and nine buses.
Steady‐state control strategy of VSC‐HVDC transmission system based on full‐order terminal sliding mode control method
Authors: Zheng Xuemei , Li Yangman , Liu Zhuang , Wang Chao
Published: October 2018

High‐voltage direct current (HVDC) techniques play an important role in the power transmission, especially for the distance district. For the HVDC, control system is necessary to the operation of flexible transmission system, so it is significant to research its control strategy. Normally, the traditional control method is proportional integral (PI) control under the dq frame system, but if the grid voltage is unbalanced, the traditional control method cannot reach the required aim. So the article proposed the full‐order terminal sliding mode (TSM) control under the frame system. In the proposed control strategy, the cross‐coupled term of current in two‐phase stationary reference frame is avoided; thus, the feed‐forward decoupling is not needed and the whole control system becomes simple. At last, the proposed control strategy is simulated in PSCAD/EMEDC, and simulation results show that the proposed control strategy is correct and effective.
Optimal approach in the EMS of microgrids based on online forecasts
Authors: Die Wang , Gui‐quan Han , Su‐min Pang , Ming‐fei Wang , Guo‐hui Han , Xu‐dong Hao , Hang Song , Jun Liu
Published: October 2018

Energy management system (EMS) is able to coordinate the generation and load to ensure economic and reliable operation and improve performance metrics of microgrids (MGs). However, most the previous studies have focused mainly on the optimal dispatch of the gas turbines and/or energy storage systems inside a normal MG. Very few works have been carried out to address the potential power outage in MGs. In this study, a novel optimal approach in the EMS based on online forecasts is proposed to minimise the system‐wide outages of MG, specifically through pre‐emptive load shedding. Online distributed generations' output forecasts are updated to predict the state of system and characterise potential upcoming outages. Proper control strategies based on receding horizon methods are introduced in this study. Outage mitigation actions using pre‐emptive load shedding are then performed to avoid power outages or minimise the duration of unavoidable outages. The effectiveness of proposed approach can be demonstrated in the presence of various fluctuations, which can be easily integrated in the EMS for both islanded and grid‐connected MGs.
Input‐parallel–output‐series control strategy for three‐level medium‐voltage DC grid‐type converter
Authors: Mehmood Shah Faisal , Xie Wenqiang , Yan Wen Li , Li Rui , Minxiao Han , Teshager Bitew Girmaw
Published: October 2018

A control topology input‐parallel–output‐series converter system is investigated, which is suitable for high‐voltage and high‐output power applications. In this control method input current sharing (ICS) and output current sharing (OVS) taken into account. As observed, ICS is automatically attained as OVS sharing is controlled. In this design, two modules are connected in series, Module 1 provided variable voltage but in Module 2 by using three‐level neutral‐point‐clamped converter and designing a comprehensive control feedback system, which regulates the DC voltages at the constant magnitude and constant frequency, helps to provide constant output voltages in the event of uncertain disturbance and load variation, A feedback double closed‐loop control topology (inner current loop control and outer voltage loop control) with the combination of sliding mode control and a proportional–integral control method. A simulation model is built, by using MATLAB/Simulink, and the simulation results show excellent performance and feasibility of this system. This will be beneficial for research and improvement for the grid‐connected converter.
Improved hybrid modular multilevel converters with dc short‐circuit fault ride‐through capacity
Authors: Lei Yuhang , Si Gangquan , Zhu Jianwei , Zhang Yanbing
Published: October 2018

Modular multilevel converter (MMC) has become a promising converter alternative for transmission voltage‐source converter high‐voltage direct current applications. The main issue and challenge of MMC is how to handle the dc short‐circuit fault. Based on the half‐bridge MMC, this study proposed an improved hybrid MMC topology which has the dc faults ride‐through capability and requires less switching devices contrast with the present hybrid topology. The improved hybrid topology consists of m half‐bridge submodules and n modified half‐bridge sub‐modules (e‐RBSM) which consists of an insulated gate bipolar transistor (IGBT), two reverse blocking IGBTs (RB‐IGBTs), two diodes and a resistance. The required number of e‐RBSM n is deduced according to the dc short‐circuit fault ride‐through requirement. Moreover, the analysis of the fault current blocking mechanism and electrical stress of the power switches is made in detail. Furthermore, the improved topology allows all RB‐IGBTs not to conduct simultaneously by employing the parallel circuit including a diode and a resistance, therefore, it reduces the requirement of trigger pules operation. Simulation results on PSCAD/EMTDC verify the efficiency of the proposed topology and strategy.
Harmonic compensation method using single‐phase cascaded H‐bridge converters
Authors: Wang Ruiqi , Xu Wei , Shi Xin , Li Sun , Wang Chao , Lyu Weilong , Liang Jian , Du Liyang
Published: October 2018

In this study, a cascaded single‐phase converter topology is proposed for single‐phase microgrid integrated into high‐voltage power distribution systems. In this system, the lower single‐phase converter works in voltage controlled mode to reduce the harmonic distortions of supply voltage to local critical load. At the same time, the upper single‐phase converter is placed in between the main grid and the output of the lower single‐phase converter. Alternatively, the upper power cell works in current controlled mode to block the harmonic current pollutions from the local non‐linear load. Through collaborative control of the cascaded upper and lower converter, the proposed system can provide active harmonic filtering to both single‐phase supply voltage and single‐phase grid current, but without any harmonic extractions in the entire process.
Influence of solid oxide fuel cell on power system transient stability
Authors: Liu Jun , Su Can , Wang Chao , Zhu Longyang , He Jian
Published: October 2018

Due to its modular, efficient and non‐polluting characteristics, solid oxide fuel cell (SOFC) is promising to be widely utilised in the area of distributed generation. Previous studies mainly focused on dynamic modelling of SOFC to analyse its load following behaviour, however, the influence of SOFC on power system transient stability is not yet clear and needs further discussion. In this study, a system‐level electromechanical transient mathematical model for SOFC is proposed, based on the circuit structure of SOFC, DC/DC step‐up converter and DC/AC converter. Then, a double closed‐loop control scheme is designed for the control of SOFC. Finally, the effect of SOFC on the power system's transient stability is discussed through simulations based on IEEE 3‐machine 9‐bus standard system. Results show that, under real and reactive power coordinated control strategy, cell current can be adjusted. Therefore, the output power of SOFC can be modulated to help with voltage recovery and power angle stability. The authors’ work reveals the feasibility of using SOFC to enhance power system transient stability.
Backward travelling wave‐variation‐based protection for the transmission line of a hybrid HVDC system
Authors: Wang Yanting , Zhang Baohui
Published: October 2018

The hybrid high‐voltage direct current (HVDC) transmission system comprising a line‐commutated converter (LCC) on the rectifier side and a voltage source converter (VSC) on the inverter side combines the advantages of both LCC and VSC. It has broad prospects in many application fields. However, at the VSC‐based inverter side of the hybrid system, there is no dc filters, and the inductance of the smoothing reactor is much smaller than that of the LCC station. Therefore, it is hard to distinguish line internal and external faults at the VSC side for the conventional protections based on the attenuation characteristic of the line boundary. In order to solve this problem, this study proposes a non‐unit protection for hybrid HVDC transmission lines. The protection judges the fault section based on the differences of the backward travelling waveforms under internal and external fault conditions. Simulation results show that the proposed protection is able to distinguish internal faults from external ones, identify the faulty pole exactly, and has enough sensitivity under large resistance faults.
General active stabiliser for coordinated control of low voltage multi‐terminal AC/DC hybrid system
Authors: Deng Wei , Pei Wei , Li Luyang , Kong Li
Published: October 2018

It is known that if AC/DC converter power exceeds limit it may lead to instability of DC network, especially DC voltage, and further affects the whole system. Concerning the instability risk in coordinated control, this study proposes a stabilisation method allowing large signal stability to stabilise a low voltage multi‐terminal AC/DC hybrid system. The equivalent model of electric system is studied firstly. Then, an active stabiliser based on Lyapunov theory, and the stabilising feedback law, are proposed. Finally, a study case is built using MATLAB/Simulink, and the feasibility is verified.
Construction of an example system for AC/DC hybrid power grid with high‐proportion renewable energy
Authors: Zhao Dawei , Ma Jin , Qian Minhui , Zhu Lingzhi , Yao Liangzhong , Ding Kun , Han Hualing
Published: October 2018

Large‐scale wind and solar power generations have got rapid development in recent years in China and abroad. They always connect to load centres through high‐voltage direct current (HVDC) transmission or ultra HVDC (UHVDC) transmission lines. Such systems are so large and it is necessary to make appropriate equivalence according to the purpose of different research. At present, the analysis model of this kind of real system is few, and simplified single‐machine infinite‐bus system or IEEE example system is adopted most of the time, which may affect the accuracy of analysis results. Here, the UHVDC project from a practical renewable energy base to load centres in China is chosen as an example, the actual structure and parameters are used to establish a typical example system for AC/DC hybrid power grid with high‐proportion renewable energy. The new‐generation synchronous condenser with large capacity and the supporting synchronous generators are all considered. First, the installed power generation, power grid structure, and load configuration of example system are introduced. Then the load flow distribution and transient stability characteristics are analysed by using DIgSILENT PowerFactory software. Finally, the feasibility of the proposed example system is shown by simulation results.
Study on characteristics and impacting factors of oscillation of wind farms integration via an MMC‐based HVDC system
Authors: Wang Xiao , Hu Xiaobao , Liu Hui , Lan Haibo , Sheng Siqing , Wu Linlin
Published: October 2018

Modular multilevel converter (MMC)‐based high‐voltage DC (HVDC) transmission technology has become an ideal solution for large and remote wind farms integration. Oscillation or instability phenomena might occur due to the rapid control of power electronic converters in both wind farms and MMC‐based HVDC system. In order to reveal oscillation characteristics of wind farms and MMC‐based HVDC interconnected system, the system equivalent damping stability criterion is deduced theoretically, and a system damping analysis platform is built in this study. On this base, the impact on 1–1000 Hz oscillation characteristics from many factors including controller parameters of wind turbines and MMC‐based HVDC, wind turbines power and wind turbines number is analysed, and mechanism of instability under different conditions is explained physically in terms of system damping characteristics. Time‐domain simulations in RT‐LAB are presented to validate the stability study.
Electromagnetic transient parallel simulation optimisation based on GPU
Authors: Yao Shujun , Zhang Shuo , Guo Wanhua
Published: October 2018

The development of smart grid and the increasing scale of power system bring much pressure to the electromagnetic transient simulation of a power system. The graphic processing unit (GPU), which features the massive concurrent threads and excellent floating point performance, brings a new chance to the area of power system simulation. This study introduces a parallel lower triangular and upper triangular decomposition algorithm and calculation strategy of electromagnetic transient simulation based on GPU. In this scheme, the GPU is mainly used to do the computationally intensive part of the simulation in parallel on its built‐in multiple processing cores, and the CPU is assigned for updating history terms and flow control of the simulation. By comparing with the results simulating by the CPU‐only implementations, the validity and efficiency of the proposed method are verified.
Frequency regulation participation of offshore wind farm integrated by diode‐rectifer HVDC system
Authors: Xie Lijun , Yao Liangzhong , Li Yan , Xu Lie , Wang Zhibing , Wei Chunxia , Fan Chen
Published: October 2018

Large‐scale wind farms integrated with multi‐terminal direct current (MTDC) system decouples the frequency between the wind farms and the receiving end, resulting in weakened frequency regulation ability of the onshore AC grid. Recently a new topology is proposed, called diode rectifier based HVDC, which recouples the wind farm and onshore AC system due to its characteristics, where offshore AC voltage changes with the DC voltage of HVDC system. A coordinated power control strategy for frequency regulation participation is proposed in this paper for offshore wind farms connected with diode‐rectifier based high voltage direct current (HVDC) system. Considering the primary frequency and inertia response control, variable power supplementary control is implemented in wind turbines, and a telecommunication‐less method of frequency event detection via detection of offshore AC voltage is proposed, avoiding communication delay and communication failure. Simulations using EMTDC/PSCAD show that frequency dip can be accurately detected by the AC voltage of offshore wind farm, and wind farm can quickly compensate active power.
Fault distance estimation‐based protection scheme for DC microgrids
Authors: Zhang Lin , Tai Nengling , Huang Wentao , Wang Yanhong
Published: October 2018

The DC microgrid has become a typical distribution network due to its excellent performances. However, a well‐designed protection scheme still remains to be a challenge for DC microgrids. This paper proposes a fault distance estimation‐based protection scheme for DC loop‐type microgrids relying on two‐terminal electrical quantities. Different from the traditional methods, a small inductor is implemented at each head of the line instead of obtaining the derivative of fault current using current difference value. Thus, the derivative of currents can be calculated accurately with the measured voltages on the small inductors during faults. The presented protection method is able to realise fault location and fault isolation quickly and accurately. Furthermore, it is immune to fault resistances. The presented protection scheme has been tested and verified through PSCAD/EMTDC simulations. The results prove that the new protection scheme possesses the excellent performance.
Hierarchical control of parallel voltage source inverters in AC microgrids
Authors: Li Zhongwen , Cheng Zhiping , Xu Yali , Wang Yifan , Liang Jing , Gao Jinfeng
Published: October 2018

Here, a distributed hierarchical control strategy is proposed for the parallel operating of voltage source inverters (VSIs) in AC microgrids (MGs). For the output voltage control of a VSI, conventional double‐loop proportional‐integral (PI) control method has deteriorative performance under disturbance parameters conditions and has a narrow range of stable operation. Here, the sliding mode control (SMC)‐based inner‐loop current control (level0) and mixed H 2 /H ∞ ‐based outer‐loop voltage control (level1) are proposed for the output voltage control of a VSI, which combines the advantages of robustness and fast transient response. The droop control (level2) is applied to avoid circulating currents among the VSIs without using any critical communication between them. The multi‐agent system (MAS)‐based distributed economic automatic generation control (EAGC) and distributed automatic voltage control (AVC) (level3) are proposed to restore the voltage magnitude and frequency deviations caused by droop controller and achieve optimal active power dispatch at the same time.
Design and research on a power distribution system for airborne radar
Authors: Ding Ke , Wu Fang , Li Shanqing , Li Bing , He Yiyang , Zhang Yingying
Published: October 2018

With the rapid progress of electronic and computer technology, as well as the application requirements under complicated conditions, modern airborne radars are developing to multifunction, highly integrated, digital and modular. As a ‘heart’ component of the radar, the performance and reliability of the distribution system is one of the decisive factors for its development. In this work, the design and research of an airborne radar power distribution system was introduced. The distribution system adopts the layered and fused power supply architecture of ‘centralized rectification, decentralized voltage stabilization’. Further, according to the actual application requirements, the input under‐voltage and over‐voltage protection, health management and other functional modules were added. The detailed composition, design and the corresponding implementation scheme of the distribution system were carefully investigated. The test results show that the system is controllable, stable and reliable, and the performance index meets the requirements of the radar system for the power supply characteristics. The distribution system is feasible, and has important reference significance for the design of power supply and distribution system of other radars.
Wireless power transmission for remote‐relay‐nodes‐aided smart metering
Authors: Wang Qing , Dai Yanjie , Du Yan , Li Xiao , Li Fucun , Wang Lingyin
Published: October 2018

Wireless power transmission is a promising technique to provide continuous power supply for the limited capacitance of smart meters (SMs) with short distance communication. In this study, the authors propose a remote‐relay‐nodes (RRNs)‐aided wireless SM system, where several geographically separated RRNs are connected to a concentrator or an acquire terminal via radio‐over‐fibre. A RRN selection scheme is employed in the wireless power transfer phase. With the energy harvested, the SM can report special or urgent events in the wireless information transfer phase. The asymptotic reporting probability and reliability of smart metering are derived in terms of close form over fading channels. Numerical results are provided to verify the theoretical analysis. The optimal deployment of RRNs can be also efficiently obtained by averaging the locations of a SM in the network.
TCM considering EIZs' integration
Authors: Liu Yangyang , Lian Hongbo , Tang Xiaowei , Shen Zhongqi , Li Jiarui , Liu Lian
Published: October 2018

Transmission congestion threatens the reliability and economy of power systems. It becomes more severe with the increase of load demands and peak−valley differences. In recent years, energy internet zones (EIZs) have attracted wide attention, and many demonstration projects have been developed. EIZs connect the supply and consumption of multi‐energy like electricity, gas, heat, and cooling. Thus, EIZs’ electricity load demands can be flexibly adjusted by controlling their multi‐energy flows. The controlling method should consider not only demand response but also heat, cooling, and gas energy balance. The integration of EIZs provides a new solution for transmission congestion management (TCM). First, an EIZ's optimal controlling strategy considering its multi‐energy flow requirements was proposed. Then, the optimal re‐dispatch problem for TCM was studied, taking into account EIZs' and traditional generators' adjustment costs. Re‐dispatch determines the output adjustment schedules and compensation prices, while the EIZ's controlling strategy controls multi‐energies' supply and consumption. A simplified Songjiang transmission system in Shanghai was adopted to illustrate the proposed methods. It was proven that the EIZs' integration could reduce the re‐dispatch costs in TCM and increase EIZs' profits.
Independent‐phase current control of a three‐phase VSC under unbalanced operating conditions
Authors: Shi Xianghua , Filizadeh Shaahin
Published: October 2018

This study presents an independent phase‐current‐control architecture for a three‐phase voltage source converter. It comprises three independent single‐phase phase locked loops (PLLs), and a dual‐loop scheme including an outer loop (responsible for active power and ac voltage control) and three similar inner current control loops. To obtain reliable phase‐tracking, an enhanced second‐order generalised integrator‐based PLL is developed. The phase‐tracking angle is strategically selected from the three PLLs to minimise the impact of imbalance‐induced distortions. To validate the proposed control scheme, extensive simulations are conducted for a 101‐level, 500‐MW, 500‐kV (dc) half‐bridge modular multi‐level converter in PSCAD/EMTDC. The simulation results prove that the proposed scheme enables the system to ride through unbalanced conditions effectively and reliably.