Reliability evaluation of repairable systems using various fuzzy-based methods – A substation automation case study

This paper focuses on material that is required for the practical application of fuzzy reliability; impacts of repair and data uncertainty. For this purpose, a holistic solution is presented to measure and manage the degree of uncertainty in the reliability indices of repairable systems. First, a flexible form of Markov Processes (MPs) namely Equivalent Transition Rate (ETR) is introduced in order to obtain an analytical formalism. Second, we delve deeply into the issues of fuzzy arithmetic by providing an intuitive, methodic and computational discussion of feasible approaches; Standard Fuzzy Arithmetic (SFA), Intermediate Variables (IMVs) and Taylor Series (TS). Specific emphasis is then placed upon Fuzzy Transformation Method (FTM). Third, we evaluate the performance of proposed techniques in case of a reliability problem involving fuzzy complexity. Consequently, the reader is given useful insights into the nature of fuzzy computations and practical impediments when measuring uncertain data. Given materials and methods, current paper provides a broad perspective by evaluating the reliability characteristics of a repairable Substation Automation System (SAS) that is one of the fundamental elements in Smart Grids (SGs). In this regard, quantitative results and diagrammatic outputs are supported by a detailed analysis under different assumptions. Our findings demonstrate that fuzzy outputs are computationally tractable and properly estimated. Besides, this investigation shows how the objective SAS can respond to the variations in reliability data. The framework proposed here encourages the continuation of the work towards more applications in electric power components and systems. As far as we know, there are no studies on these techniques, results and remarks.     

Novel economic modelling of a peer-to-peer electricity market with the inclusion of distributed energy storage—The possible case of a more robust and better electricity grid

Current electricity distribution systems allow prosumers to sell their surplus electricity back to the Distributed Network Operator (DNO). The export tariffs at which these sell-backs take place are considerably lower than the feed-in tariffs, offering little incentive to prosumers to sell their surplus energy. A peer-to-peer (P2P) electricity market where consumers and prosumers can interact by selling and buying energy between them at a premium rate that is lower than the standard feed-in tariffs but higher than the export tariffs is proposed. Such a system was modelled to process transactions every 20 s, and a simulation tool was created to obtain the total daily money flows between a consumer-prosumer pair. The inclusion of a Distributed Storage System (DSS) is also considered in the modelled system and simulation. The simulation results showed that the inclusion of a DSS is always beneficial for all parties in economic terms: consumers could save up to 6.4 % on the cost of their electricity while prosumers could save up to 49.1 %. A DSS could generate an income flow for the DNO of up to 6.9p/day per each consumer-prosumer pair.     

Creation and Development of Turbo-generators with Water-Cooled Stator and Rotor Windings in Shanghai Electrical Machinery Mfg Works

1. An Overview of Manufacture and Operation A turbine generator utilizing a new technology of electrical machinery industry, i.e. the windings of its stator and rotor all being inner water-cooled, was first successfully created in China and was known afterwards as a turbine generator with watercooled stator and rotor windings (Abbrev, TGWSR). The teachers from Zhejiang University came to Shanghai between April     

How can energy prices and subsidies accelerate the integration of electric vehicles in Brazil? An economic analysis

A sensitivity analysis indicates that the variables that most influence the payback period on purchases of battery electric vehicles are gasoline prices and financial incentives granted in the form of an exemption from the annual tax payment. Currently, the arithmetic mean value of the payback period for the purchase of BEVs is 24.23 years in 27 analyzed state capitals, suggesting broad-based adoption remains years away.     

Introduction to Puerto Rico’s energy transformation: An analysis of key documents and plans towards the reconstruction of the electric system

Puerto Rico’s electric system transformation depends on the execution of the current energy policy. However, key documents, such as the PREPA Fiscal Plan, do not detail how these transformations are going to be financed, and no analysis is provided for expected economic impacts that should arise from increasing electricity tariff rates to electricity consumers. This paper analyzes the three main documents developed as part of the planning for the Puerto Rico electric system transformation and reconstruction, including potential flaws and its effect on the electric utility. It also links to further studies and analyses developed toward the effect of such plans on Puerto Rico’s economy and on the electric utility.     

Power system decarbonisation with Global Energy Interconnection——a case study on the economic viability of international transmission network in Australasia

The electric energy system in Indonesia is undergoing with the challenges of fast-increasing electricity demand,carbon constraints,and rising costs.Using our model of the Australian and Indonesian electrical grids(either separately or interconnected)that incorporates operational flexibility in capacity expansion planning,we first show that meeting the projected demand for Java and Bali—the main Indonesian grid,with 100%locally integrated renewables by 2050 would be challenging.However,a submarine high-voltage DC(HVDC)link connecting Indonesia’s Java-Bali power grid to the Australian National Electricity Market(NEM)grid through the Northern Territory would help alleviate this situation,given Australia’s abundant renewable energy resources.Then,our model reveals that the Australian NEM could also profit from additional renewables if connected to the Northern Territory through a ground HVDC transmission line to gather intermittent wind and solar generation,which would be curtailed otherwise if unused by Indonesia through the submarine link.Despite the expensiveness of long HVDC links,the wholesale electricity cost of the integrated 100%renewable Australasia power system could be reduced by over 16%,from$AUD177/MWh with only local renewables to$AUD148/MWh with integrated HVDC transmission.The model retrieved the optimal international HVDC link with capacity of 43.8 GW,and the optimal regional HVDC transmission line with a capacity of 5.5 GW.To the best of our knowledge,this is the first detailed model on power system decarbonisation planning for both Australian NEM and Indonesian Java-Bali power grid considering HVDC interconnections.     

Diagnosis and Forecast of Chinese Power Industry——An interview with Mr. Song Yonghua, Academician of Royal Academy of Engineering and expert of China power reform under UN Development Program

Fundamental changes will arise in world en- ergy structure in 21st century Journalist of China Electric Power (referred as Journalist below for short): Being a world famous scholar, would you please explain the world energy focus briefly with a globalism …     

Energy systems planning and GHG-emission control under uncertainty in the province of Liaoning,China – A dynamic inexact energy systems optimization model

In this study, a dynamic interval-parameter optimization model (DIP-REM) has been developed for supporting long-term energy systems planning in association with GHG mitigation in the region of Liaoning province. The model can describe Liaoning province energy planning systems as networks of a series of energy flows, transferring extracted/imported energy resources to end users through a variety of conversion and transmission technologies over a number of periods and address the problem of GHG-emission reduction within a general energy planning systems framework under uncertainty. Two scenarios (including a reference case) are considered corresponding to different GHG-emission mitigation levels for in-depth analysis of interactions existing among energy, socio-economy and environment in the Liaoning province. Useful solutions for Liaoning province energy planning systems have been generated, reflecting trade-offs among energy-related, environmental and economic considerations. The results can not only provide optimal energy resource/service allocation and capacity-expansion plans, but also help decision-makers identify desired policies for GHG mitigation with a cost-effective manner in the region of Liaoning province. Thus, it can be used by decision makers as an effective technique in examining and visualizing impacts of energy and environmental policies, regional development strategies and emission reduction measures within an integrated and dynamic framework.     

FP-LAPW study of energy bands and optical properties of the filled skutterudite $$\hbox {CeRu}_{4}\hbox {As}_{12}$$ with spin–orbit coupling

The density functional theory (DFT)-based fully relativistic version of the full-potential linearized augmented plane wave method with spin–orbit coupling (SOC) has been used to study the electronic and optical properties of the filled skutterudite \(\hbox {CeRu}_{4}\hbox {As}_{12}\). The exchange and correlation potential has been treated with the local density approximation (LDA). The analysis of the density of states and energy bands in the vicinity of the Fermi energy level suggests the semiconducting nature of the material with narrow indirect energy band gap of 0.11 eV; however, the gap value increases to 0.17 eV for without SOC calculation. Additionally, the modified Becke–Johnson (mBJ) potential has been utilized along with the LDA approach to estimate the precise value of the energy band gap of the material. The mBJ treatment enhances the energy band gap to ?0.2 eV. In order to understand the structural and mechanical properties of the sample material, the elastic constants are also estimated at ambient conditions. The analysis of the elastic constants suggests the brittle nature of the material whose stiffness is comparable with that of \(\hbox {CeOs}_{4}\hbox {Sb}_{12}\) and the covalent contribution is expected in the bonding. The optical response of the material has been studied from the energy bands, which reflects the metallic behavior of the material in the infrared region of frequency radiation and turns to act as opaque material with superluminal behavior at ultraviolet frequency radiation. The inclusion of the hybrid functional in the calculation suggests the metallic nature of the material.     

Analysis and Design of a Series–Parallel Uninterruptible Power Supply with an Improved Control Strategy for Seamless Transition

In this paper, a high-performance control structure is designed, implemented, and applied to a three-phase series–parallel uninterruptible power supply (UPS). This kind of UPS system provides input power factor correction, output voltage conditioning, and high efficiency. The control strategy proposed in this paper is based on voltage control of the parallel converter and current control of the series converter. It is shown that this strategy improves the system operation, specifically resulting in a smoother and more seamless transition between UPS operating modes. The controller in the proposed strategy is based on combination of two control methods with different characteristics and is therefore called a hybrid structure. To enhance the steady-state performance of the UPS and reach fast error convergence, a repetitive controller is used. In addition, to reach a fast transient response required for control of output voltage, a fast deadbeat is used. The stability of this hybrid controller is discussed, and the design procedure for a typical converter is given. For validation and verification of the theoretical analysis, both experimental and simulation results are shown.     

Efficient design and simulation of an expandable hybrid (wind–photovoltaic) power system with MPPT and inverter input voltage regulation features in compliance with electric grid requirements

In this paper an efficient design along with modeling and simulation of a transformer-less small-scale centralized DC—bus Grid Connected Hybrid (Wind–PV) power system for supplying electric power to a single phase of a three phase low voltage (LV) strong distribution grid are proposed and presented. The main components of the hybrid system are: a PV generator (PVG); and an array of horizontal-axis, fixed-pitch, small-size, variable-speed wind turbines (WTs) with direct-driven permanent magnet synchronous generator (PMSG) having an embedded uncontrolled bridge rectifier. An overview of the basic theory of such systems along with their modeling and simulation via Simulink/MATLAB software package are presented. An intelligent control method is applied to the proposed configuration to simultaneously achieve three desired goals: to extract maximum power from each hybrid power system component (PVG and WTs); to guarantee DC voltage regulation/stabilization at the input of the inverter; to transfer the total produced electric power to the electric grid, while fulfilling all necessary interconnection requirements. Finally, a practical case study is conducted for the purpose of fully evaluating a possible installation in a city site of Xanthi/Greece, and the practical results of the simulations are presented.     

Development of and experience using the Del’Tek computerized automation system for furnishing thermal power facilities with automated process control systems

Basic principles of constructing the Russian Del’Tek computerized automation system intended for development of modern process control systems for thermal power engineering facilities are considered. Informational-computation systems and full-scale process control systems built around the Del’Tek computerized automation system, as well as test results and experience gained from their operation, are described.     

Over hundred experts gathered in the academic activity on energy strategic study——Annual Session of Energy and Information Committee, CSEE held by the end of 1991

The 2nd Annual Session of Energyand Information Committee,CSEE, chaired by Mr. Sun Jiaping was held inBeijing on Dec. 17-20, 1991. Vice MinisterShi Dazhen, Chief Engineer Mr. LuYanchang of the Ministry of Energy, GeneralSecretary Mr. Du Xingyou of CSEE and someother leading staff attended the meeting.Vice Minister Shi Dazhen expressed sincerehope in his address to the session that scien-tific and technical staff in energy fieldshould launch macro policy study morewidely and deeply under the guideline of so-     

Computational study of transport properties of graphene upon adsorption of an amino acid: importance of including –$$\hbox {NH}_{2}$$ and –COOH groups

The effects of histidine and its imidazole ring adsorption on the electronic transport properties of graphene were investigated by first-principles calculations within a combination of density functional theory and non-equilibrium Greens functions. Firstly, we report adsorption energies, adsorption distances, and equilibrium geometrical configurations with no bias voltage applied. Secondly, we model a device for the transport properties study: a central scattering region consisting of a finite graphene sheet with the adsorbed molecule sandwiched between semi-infinite source (left) and drain (right) graphene electrode regions. The electronic density, electrical current, and electronic transmission were calculated as a function of an applied bias voltage. Studying the adsorption of the two systems, i.e., the histidine and its imidazole ring, allowed us to evaluate the importance of including the carboxyl (–COOH) and amine (–\(\hbox {NH}_{2}\)) groups. We found that the histidine and the imidazole ring affects differently the electronic transport through the graphene sheet, posing the possibility of graphene-based sensors with an interesting sensibility and specificity.     

A simulation study of short channel effects with a QET model based on Fermi–Dirac statistics and nonparabolicity for high-mobility MOSFETs

In this paper, the quantum confinement and short channel effects of Si, Ge, and \(\hbox {In}_{0.53}\hbox {Ga}_{0.47}\)As n-MOSFETs are evaluated. Both bulk and double-gate structures are simulated using a quantum energy transport model based on Fermi–Dirac statistics. Nonparabolic band effects are further considered. The QET model allows us to simulate carrier transport including quantum confinement and hot carrier effects. The charge control by the gate is reduced in the Ge and \(\hbox {In}_{0.53}\hbox {Ga}_{0.47}\)As bulk n-MOSFETs due to the low effective mass and high permittivity. This charge control reduction induces the degradation of short channel effects. In double-gate structures, different improvements of drain induced barrier lowering (DIBL) and subthreshold slope (SS) are seen. The double-gate structure is effective in the suppression of DIBL for all channel materials. The SS degradation depends on channel materials even in double-gate structure.