Optimization of Jumper Design for Tension Towers of ± 800 kV UHV DC Transmission Line

现有±800 kV特高压直流输电线路耐张塔采用双“V”型“笼式”或”管式”硬跳线,具有限制串偏、减少跳线摆动的优点,然而其结构复杂,运输、安装不便,并且价格昂贵.对特高压直流耐张塔跳线采用单/双串、Ⅰ/Ⅴ串、软/硬跳线等多种方案进行了风偏计算、塔头设计与综合技术经济比较,探讨了特高压直流耐张塔多种跳线方案的优劣性和适用条件,为后续±800 kV直流耐张塔设计提供了参考.     

AC 500kV Substation Design in China

1.IntroductionTheresearchanddesignof500kVsubstahonsinChinawerestartedin1977,andthefirstsubstahonwasputintooperahonin1981.Fromthatbine,becauseoftherapiddevelopmentofelectriciansdemandinChina,designandconstrUchonof500kVsubstahonshaveagreatdevelopmentEspeciallyinrecentyears,duetOtheincreaseofcapitalinvestmentforpowersystemconstrUchonfromtheStateGovernment,500kVPowersystemhasdevelopedevenfaster.Till1998about55substahons(500kV)werealreadyputintooperahon,inwhich217transformerswereinsaned,andthe…     

New Research on AC–AC Converters without Intermediate Storage and Their Applications in Power-Electronic Transformers and AC Drives

AC-AC converters (e.g. matrix converters) are mostly semiconductor solutions for applications where intermediate energy storage is eliminated. This paper summarizes the research done and being carried out at the University of Minnesota for applications in motor drives and power-electronic transformers with advanced features. This paper presents a carrier-based modulation method for matrix converters and its application during for both input unbalance and output over-modulation. Various topologies of matrix converter are described for both drives and power-electronic transformers. These topologies have some inherent benefits like common-mode voltage elimination across the bearings of the motor/generator and controllable power factor at the input side. Some of the described technologies require open-ended machines as load and thereby some advantages like enhanced output voltage (1.5 times the output of normal three terminal load) are achieved. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

On the Use of Fractional-Order Controllers for Performance Improvements in AC Drives

Abstract—The control performance of AC electric drives is sensitive to and often degrades with parametric variations. This article proposes the use of fractional-order controllers to combat parameter variations. The speed control of an AC induction motor drive achieved through indirect field-oriented control is considered for illustration. The performance of the proposed controller is compared with a well-tuned proportional-integral controller when critical motor parameters are subject to parametric variations about their nominal values. Dynamic simulations in MATLAB/Simulink (The Math Works, Natick, Massachusetts, USA) are conducted to assess control performance.     

Practice and Prospect of AC/DC Hybrid Power Grid in Southern China

China Southern Power Grid is a unique EHV AC/DC hybrid transmission network that operates in China. In its service area, the distribution of energy resources and the development of economy are extremely unbalanced, so long-distance and bulk power transmission are needed; besides, the geography and climate conditions are serious, rains, fogs, lightning and typhoon as well as high temperature are common all the year round. Facing these challenges, the power grid enhanced stability control, improved the equipment and strengthen the network structure. In the future, the power grid plans to optimize the disposition of power sources and build digitalized power system.     

Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part I?Harmonic Elimination

This paper considers the theoretical problem of eliminating harmonics in inverter-output waveforms. Generalized methods are developed for eliminating a fixed number of harmonics in the half-bridge and full-bridge inverter-output waveforms, and solutions are presented for eliminating up to five harmonics. Numerical techniques are applied to solve the nonlinear equations of the problem on the computer. The uneliminated higher order harmonics can be easily attenuated by using filter circuits in the output stage of the inverter. The results show the feasibility of obtaining practically sinusoidal output waveforms, which are highly desirable in most inverter applications.     

Development of Design for Circulating Water Intake Structure in Thermal Power Plant

SummaryThispaperintroducesthedesigndevelopmentinthefields0fcirculatingwater(C.W.)intakestructuredesignedbyEastChinaElectricPowerDesignInstitute(ECEPDI).Therearemanymethodssuchascaissonmeth0d,sinkingwellmethod,floatingcaiss0nmeth0d,andexterior-protectedconstructionfoundationmethodetc.f0rC.W.pumph0usedesign.Therearejackingsteelpipetunnel,jackingR.C.pipetunnel,shieIdtunnelandfl0atingpipetunneletc.f0rdesignofdiversionpipe.Thefl0atingcaiss0nc0nstructionofC.W.pumphouseisfirstusedinChina.1.…     

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.     

Design Technology for Bracing of Deep Foundation Pit

1,PrefaceWiththerapiddevelopmentofreformandopeninChina,moreandmorecivilworkshavebeenputintoconstructionsincel980's.Fortheundergroundpartofth0secivilworks,theircharacteristicsisoflargescope,ofgreatdifficultyandofnewtechnology.Fortunately,muchnewachievementshavebeenmadeindesign,constructi0nandresearchareaofbracingofdeepf0undationpit.Therefore,theDTBDFPlevelhasbeenimprovedobvi0uslyinrecentyearsinChina.Bracing0fDeepFoundati0nPit(BDFP)consistsofexteri0r-pr0tectstructure,bracing(orgr0undanch0…     

Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part II?Voltage Control Techniques

Theoretical techniques of voltage control for the half-bridge and full-bridge inverters are derived based on the results in [1]. Detailed analytical results for the symmetrical pulsewidth modulation method of voltage control are also presented. Voltage control techniques are derived whereby harmonic elimination is possible in variable-frequency variable-voltage three-phase inverter circuits. The technique for the half-bridge inverter is optimized subject to the constraint of switching frequency of the SCR's, using the concepts of modern control theory. Variable-frequency variable-voltage sinusoidal output in three-phase inverters is possible by employing the techniques developed. The methods show great promise in application to variable-speed ac motor drive systems.     

Stability improvement of power system by simultaneous AC–DC power transmission

This paper presents a concept of improving the transient stability of power system by simultaneous AC–DC power transmission through a transmission line. A double circuit long transmission line is converted to simultaneous AC–DC line for feasibility study. Loss of synchronism is prevented by quickly producing sufficient decelerating energy to counteract accelerating energy gained during fault and subsequently due to loss of line after clearing the fault. Fast controllability and modulation of DC component is utilized to achieve this feature. The system under consideration is found to remain stable under transient condition up to transmission angle of 80°. Simulation study on PSCAD/EMTDC is carried out to validate the concept.     

Design and Construction of the Power Plant Multi-flue Chimneys in East China Area

1.TheGeneralSituationofConstructionWiththerapiddevelopmentoftheec0nomicconstruction,theunitcapacityofthermalpowerplantisgettingIargerandlarger.ThestructuraltypeofthepowerplantchimneysinEastChinaareahasbeenresearchedandimprovedfr0mthebeginningofthe90s.Onesleevetype(single-flue)chimneyper600MWunitisforBeilungangPowerPlant(thisp0werplantwasconnectedint0electricnetworkinl99l),onedouble-fluechimneypertw06O0MWunitsf0rShidongkouSec0ndPowerPlant,andonefour-fluechimneyperfour300MWunitsisforWaig…     

Artificial Neural Network for monitoring the asymmetric half bridge DC–DC converter

This paper investigates the effectiveness of an Artificial Neural Network (ANN) while training as an asymmetric half bridge DC–DC converter circuit used in sensitive applications. The ANN is trained to form a mapping between the inputs and outputs of converter circuit using back propagation algorithm. After training the Artificial Neural Network monitor the asymmetric half bridge converter in order to detect the performance deviations. The ultimate objective of the designed Neural network is to perform like the trained converter circuit when the circuit is changed from its original conditions. Such information can be valuable for many sensitive power electronic applications. Typical simulation results are provided that indicates the effectiveness of the proposed scheme.     

Optimization strategy for aggregating electric vehicles through VPP to participate in the carbon market北大核心

Virtual power plant (VPP) is an important solution for distributed energy management of power grid. VPP's participation in carbon emission trading can give full play to its environmental benefits and improve the overall income of VPP. Based on the demand for electric vehicles to participate in the certification and emission reduction market, a coordinated scheduling optimization strategy for aggregating electric vehicles through VPP to participate in the carbon market is proposed. Firstly.design a scheme for VPP to represent electric vehicles in the certification and emission reduction market, and increase VPP revenue by charging service fees. Then, analyze the carbon emission characteristics of different aggregated resources in VPP and evaluate the volatility of new energy output by scenario generation method. Finally. with the goal of maximizing VPP revenue.design an optimization model for VPP participation in the carbon market. The aggregation of electric vehicles as controllable loads and energy storage devices can increase the stability of VPP operation. Example analysis shows that aggregating multiple types of resources including electric vehicles through VPP and participating in carbon market can not only incentivize VPP to reduce the power generation of traditional thermal power units and reduce carbon emissions generated during VPP operation, but also improve the stability of VPP operation.increase VPP revenue and social benefits through the use of electric vehicles. © 2023, Editorial Department of Electric Power Engineering Technology. All rights reserved.     

Design and Implementation of a Class of Robust H ∞ Control for Stability Enhancement in Power Systems

The paper presents a method of designing a class of robust H X generator excitation controller in a power system. The proposed controller is utilized to damp inter-area oscillations and enhance power system stability. The robust controller design procedure for a linear composite system is presented in terms of positive definite solutions to modified algebraic inequalities. The resulting controller guarantees closed-loop stability and an H X -norm bound on disturbance attenuation. The effectiveness of the H X controller is demonstrated through digital simulation studies on a two-machine system. The digital simulation studies are conducted using a PSCAD/EMTDC software package. The simulation results show that the controller contributes significantly to the damping of inter-area oscillations and the enhancement of power system stability during disturbances.     

Will you be there for me the whole time? On the importance of obligation periods in design of capacity markets

This paper discusses the importance of length of capacity products traded in wholesale capacity markets when there is seasonal variation in both the electricity load and the electricity generation. We first discuss how investments and bidding behavior are affected by the length of the capacity product traded in the market. Then, we explain the potential welfare consequences of procuring subannual capacity product in addition to annual capacity product.     

What is the state of development of retail electricity markets in the EU?

For our research, which aims to provide a thorough approach to assessing the development of the retail electricity market in the EU, we tested the hypotheses that the number of suppliers in the retail markets of EU member states has increased significantly over the past decade, and that in the same period, the number of suppliers entering the retail markets of EU member states increased significantly with market liberalisation. We also collected data on the number of electricity suppliers to end-consumers in EU member states between 2010 and 2017, and used the Kruskal-Wallis test for verification, which was also used to establish the ratio between electricity consumers and suppliers between 2010 and 2017. A thorough overview of current scientific findings led us to contemplate a possible combination to measure the dynamics and assess the energy market development, since several authors indicate that no method has been fully accepted as standardised for a thorough assessment of the energy market development. Therefore, a combination of indicators to measure the dynamics and assess the energy market development is proposed in the conclusion of this article, which brings important implications for science and specifically for politics and experts.     

Optimization of the range of asynchronous motors with the dimensions 100–132 with combined windings

The theoretical foundations for creation of a new type of intelligent energy-saving asynchronous electric motor with combined windings are described. The results of theoretical studies and computer modeling, as well as a method of manufacturing a range of such motors, are given.     

The Study on theDevelopment of Main Power Building Structure Design of Thermal Power Plants in China

Thecivilstructuredesignlevelofathermalpowerplantismostlyreflectedbythestructuredesignofitsmainpowerbuilding.Thispaperistoreviewanddiscussthedesignofthemainpowerbuildinginthermalpowerplants:I.ReviewontheCivilStructllreofThermalPowerPlantsThecategoriesofpowerhousecivilstructUreinChinacanbedividedintothree:reinforcedconcrete,steelstrUctUreandsteelplusconcretestructures.Ofthethreetypesofstructures,thereinforcedconcreteisthemostfrequentlyused.Theconstructiontechnologyofthereinforcedconcretestr…