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Impact of renewable energies on the operation and economic situation of coal fired power stations: Actual

Hans-Joachim KRAUTZ, Alexander LISK, Joachim POSSELT, Christian KATZER

《能源前沿（英文）》 2017年 第11卷 第2期   页码 119-125 doi: 10.1007/s11708-017-0468-4

摘要： Due to the fluctuating character of the renewable energy sources the demand of conventional power plants for flexibility is increasing. In the recent years, in Germany there has been a fast rise of production capacity of renewable energies, especially from wind turbines, photovoltaic installations, and biomass plants. The installed nominal power of wind turbines is actually (December 2016) 42 GW and of photovoltaic installations 40?GW. The renewable electric energy production in Germany is about 190?TWh/a, which represents a share of 33% of the yearly demand. The increased need for flexibility affects both the power gradients as well as the minimum load of conventional power plants. Due to this flexibility behaviour, conventional power plants are faced with problems concerning the durability of power plant components, corrosion, more maintenance effort and consequently the overall life expectancy. Another consequence of the increasing share of renewable energies is the decreasing full load operating hours, especially of coal fired and gas power plants. Along with decreasing revenues from the energy exchange market, coal fired power plants are faced with new economically challenges.

关键词： flexible load operation     minimal load     power gradients     power plant maintenance     corrosion     life expectancy    

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A new technique for islanding operation of distribution network connected with mini hydro

J. A. LAGHARI,H. MOKHLIS,M. KARIMI,A. H. A. BAKAR,Hasmaini MOHAMAD

《信息与电子工程前沿（英文）》 2015年 第16卷 第5期   页码 418-427 doi: 10.1631/FITEE.1400309

摘要： An islanding operation of a distribution network is a topic of interest due to the significant penetration of distributed generation (DG) in a power system network. However, controlling the frequency of an islanded distribution system remains an unresolved issue, especially when the load exceeds the generation. This paper presents a new technique for a successful islanding operation of a distribution network connected with multiple mini hydro based DGs. The proposed technique is based on three main parts. The first part uses an islanding detection technique to detect the islanding event correctly. The second part consists of a power imbalance estimation module (PIEM), which determines the power imbalance between the generation and load demand. The third part consists of a load shedding controller, which receives the power imbalance value and performs load shedding according to load priority. The proposed technique is validated on an 11 kV existing Malaysia distribution network. The simulation results show that the proposed technique is effective in performing a successful islanding operation by shedding a significant number of loads.

关键词： Islanding operation     Mini hydro     Distributed generation (DG)     Islanding detection     Load shedding    

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Large eddy simulation of a 660 MW utility boiler under variable load conditions

Haoshu SHEN, Yuxin WU, Minmin ZHOU, Hai ZHANG, Guangxi YUE, Junfu LYU

《能源前沿（英文）》 2021年 第15卷 第1期   页码 124-131 doi: 10.1007/s11708-020-0659-2

摘要： Large eddy simulation (LES) has become a promising tool for pulverized coal combustion with the development of computational fluid dynamics (CFD) technologies in recent years. LES can better capture the unsteady features and turbulent structures of coal jet flame than Reynolds averaged Navier Stokes (RANS). The coal-fired power plants in China are now required to be operated in a wide load range and quickly respond to the electric grid. The boiler performance of variable loads should be evaluated in terms of flow, heat transfer, and combustion processes. In this paper, LES was applied to simulate a 660 MW ultra-supercritical boiler under BMCR (boiler maximum continue rate), 75%THA-100, and 50%THA-100 conditions. The predicted gas velocities agree well with the thermal calculation and the temperature error is less than 130 K. The simulation results show that the operation load has significant effects on the boiler performance. It is also proved that LES can provide guidance for the design and operation of advanced coal-fired boilers.

关键词： large eddy simulation     ultra-supercritical boiler     operation load    

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Applications of thermostatically controlled loads for demand response with the proliferation of variable renewable energy

Meng SONG, Wei SUN

《能源前沿（英文）》 2022年 第16卷 第1期   页码 64-73 doi: 10.1007/s11708-021-0732-5

摘要： More flexibility is desirable with the proliferation of variable renewable resources for balancing supply and demand in power systems. Thermostatically controlled loads (TCLs) attract tremendous attentions because of their specific thermal inertia capability in demand response (DR) programs. To effectively manage numerous and distributed TCLs, intermediate coordinators, e.g., aggregators, as a bridge between end users and dispatch operators are required to model and control TCLs for serving the grid. Specifically, intermediate coordinators get the access to fundamental models and response modes of TCLs, make control strategies, and distribute control signals to TCLs according the requirements of dispatch operators. On the other hand, intermediate coordinators also provide dispatch models that characterize the external characteristics of TCLs to dispatch operators for scheduling different resources. In this paper, the bottom-up key technologies of TCLs in DR programs based on the current research have been reviewed and compared, including fundamental models, response modes, control strategies, dispatch models and dispatch strategies of TCLs, as well as challenges and opportunities in future work.

关键词： thermostatically controlled load     demand response     renewable energy     power system operation    

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Neural Operation Management: A New Avenue for Productive and Military Operations

Qing-guo Ma

《工程管理前沿（英文）》 2014年 第1卷 第3期   页码 304-307 doi: 10.15302/J-FEM-2014039

摘要： An important effect of technological progress is the increasing replacement of manual labor by mental labor in productive and military operations. The variation of the operator’s capabilities in cognition, judgment and decision-making has drawn much attention from operation management researchers. Monitoring and evaluation of these capabilities is especially significant in conditions such as long-time operation, operation with special properties and operation under special circumstances. The military power and economic power are both the key concerns for a nation. The military power depends not only on the weapon system, but also the operators’ capabilities of manipulating the system. Similarly, the economic power is not only dependent on advanced machine system, but also the operational capability of the operators. Thus it has become a hot field of research and practice to monitor and assess the operator’s physiological and psychological states online based on neural measurement technology, and then to give real time intervention, so as to reduce the occurrence of accidents and increase the operation performance.

关键词： operation management     productive operation     military operation     neural operation management     neuromanagement    

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Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

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Calculation method of load distribution on pipe threaded connections under tension load

Shoujun CHEN, Lianxin GAO, Qi AN

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 241-248 doi: 10.1007/s11465-011-0219-x

摘要：

This paper presents a new calculation method that can calculate the load distribution on pipe threaded connections under tension load. On the basis of elastic mechanics, the new method was developed by analyzing each thread tooth, and a new deformation and covariant equation by making a mechanics analysis on each thread tooth was obtained. Compared with the traditional method proposed by the previous references, the new deformation and covariant equation could be used to describe the relation between the previous and the next thread tooth. By applying the new method on the sample of P-110S pipe threaded connection, the obtained results show that the load on thread tooth mainly concentrates on the four or five threads engaged and the middle teeth were not utilized well to bear the loads. The model offers a new way to calculate the loads carried on the thread teeth under tension load.

关键词： load distribution     calculation method     pipe threaded connections     tension load    

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Comparison of optimal capacitor placement methods in radial distribution system with load growth andZIP load model

Veera Venkata Satya Naryana MURTY, Ashwani KUMAR

《能源前沿（英文）》 2013年 第7卷 第2期   页码 197-213 doi: 10.1007/s11708-013-0249-7

摘要： In this paper, a combined power loss sensitivity (PLS) index-based approach is proposed to determine the optimal location of the capacitors in the radial distribution system (RDS) based on the real and reactive combined loss sensitivity index, as capacitor placement not only reduces real power loss with voltage profile improvement but also reduces reactive power loss due to the reactive power compensation in the network. The results have been obtained with the existing methods of power loss index (PLI) and index vector (IV) method for comparison. Besides, the optimal placement has been obtained with the proposed method as well as existing methods and the total kVar support has been obtained. In addition, the results of net cost savings for the 10-, 34-, and 69-bus systems are obtained for comparison. Moreover, the results have been obtained for a large system of 85 buses to validate the results with combined sensitivity based approach. Furthermore, the load growth factor has been considered in the study which is essential for the planning and expansion of the existing systems, whereas the impact of the realistic load model as ZIP load model has been considered for the study of all the systems.

关键词： load growth     load models     reactive power compensation     radial distribution system     power loss index (PLI)     power loss sensitivity (PLS)     index vector (IV)    

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A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 877-894 doi: 10.1007/s11709-021-0756-2

摘要： Many bridge design specifications consider multi-lane factors (MLFs) a critical component of the traffic load model. Measured multi-lane traffic data generally exhibit significant lane disparities in traffic loads over multiple lanes. However, these disparities are not considered in current specifications. To address this drawback, a multi-coefficient MLF model was developed based on an improved probabilistic statistical approach that considers the presence of multiple trucks. The proposed MLF model and approach were calibrated and demonstrated through an example site. The model sensitivity analysis demonstrated the significant influence of lane disparity of truck traffic volume and truck weight distribution on the MLF. Using the proposed approach, the experimental site study yielded MLFs comparable with those directly calculated using traffic load effects. The exclusion of overloaded trucks caused the proposed approach, existing design specifications, and conventional approach of ignoring lane load disparity to generate comparable MLFs, while the MLFs based on the proposed approach were the most comprehensive. The inclusion of overloaded trucks caused the conventional approach and design specifications to overestimate the MLFs significantly. Finally, the benefits of the research results to bridge practitioners were discussed.

关键词： bridges     multi-lane factor     traffic load     lane load disparity     multi-truck presence     weigh-in-motion data    

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CORRECTION to: Energy-saving operation approaches for urban rail transit systems

Ziyou GAO, Lixing YANG

《工程管理前沿（英文）》   页码 698-698 doi: 10.1007/s42524-019-0047-y

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Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 852-862 doi: 10.1007/s11709-019-0522-x

摘要： Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词： arch dam     shape optimization     robust optimization     load uncertainty     approximation model    

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Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 374-386 doi: 10.1007/s11709-019-0600-0

摘要： Modeling and prediction of bed loads is an important but difficult issue in river engineering. The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data. In this paper, three different artificial neural networks (ANNs) including multilayer percepterons, radial based function (RBF), and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed. The optimum models were found through 102 data sets of flow discharge, flow velocity, water surface slopes, flow depth, and mean grain size. The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data. The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models. The accuracy performance of all models was evaluated and interpreted using different statistical error criteria, analytical graphs and confusion matrixes. Although the ANN models predicted compatible outputs but the RBF with 79% correct classification rate corresponding to 0.191 network error was outperform than others.

关键词： bed load prediction     artificial neural network     modeling     empirical equations    

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Application of a vertex chain operation algorithm on topological analysis of three-dimensional fractured

Zixin ZHANG, Jia WU, Xin HUANG

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 187-208 doi: 10.1007/s11709-017-0391-0

摘要： Identifying the morphology of rock blocks is vital to accurate modelling of rock mass structures. This paper applies the concepts of directed edges and vertex chain operations which are typical for block tracing approach to block assembling approach to construct the structure of three-dimensional fractured rock masses. Polygon subtraction and union algorithms that rely merely on vertex chain operation are proposed, which allow a fast and convenient construction of complex faces/loops. Apart from its robustness in dealing with finite discontinuities and complex geometries, the advantages of the current methodology in tackling some challenging issues associated with the morphological analysis of rock blocks are addressed. In particular, the identification of complex blocks with interior voids such as cavity, pit and torus can be readily achieved based on the number and the type of loops. The improved morphology visualization approach can benefit the pre-processing stage when analyzing the stability of rock masses subject to various engineering impacts using the block theory and the discrete element method.

关键词： morphology     block assembling     vertex operation     discontinuities    

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Reliability evaluation of future photovoltaic systems with smart operation strategy

Amir AHADI,Hosein HAYATI,Seyed Mohsen MIRYOUSEFI AVAL

《能源前沿（英文）》 2016年 第10卷 第2期   页码 125-135 doi: 10.1007/s11708-015-0392-4

摘要： This paper investigates a new operation strategy for photovoltaic (PV) systems, which improves the overall reliability of the system as a result of the improvement in the reliability of the critical components. First, a mathematical model is proposed using the fault tree analysis (FTA) to estimate the reliability of the PV systems in order to find the suitable maintenance strategies. The implementations demonstrate that it is essential to employ smart maintenance plans and monitor the identified most critical components of PV systems. Then, an innovative analytical method based on the Markov process is presented to model smart operation plans in PV systems. The impact of smart operation strategy on the PV systems is then evaluated. The objective of this paper is to develop plans for improving the reliability of PV systems. A series of case studies have been conducted to demonstrate the importance of smart operation strategies for PV systems as well as the applicability and feasibility of the proposed method.

关键词： smart operation strategy     renewable energy     fault tree analysis (FTA)     Markov model    

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A method to predict cooling load of large commercial buildings based on weather forecast and internal

Junbao JIA,Jincheng XING,Jihong LING,Ren PENG

《能源前沿（英文）》 2016年 第10卷 第4期   页码 459-465 doi: 10.1007/s11708-016-0424-8

摘要： Considering the fact that customers of large commercial buildings have the characteristics of the higher density and randomness, this paper presented an air-conditioning cooling load prediction method based on weather forecast and internal occupancy density. The multiple linear feedback regression model was applied to predict, with precision, the air conditioning cooling load. Case analysis showed that the largest mean relative error of hourly and the daily predicting cooling load maximum were 18.1% and 5.14%, respectively.

关键词： commercial building     load prediction     multiple linear regression    

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标题 作者 时间 类型 操作

Impact of renewable energies on the operation and economic situation of coal fired power stations: Actual

Hans-Joachim KRAUTZ, Alexander LISK, Joachim POSSELT, Christian KATZER

期刊论文

A new technique for islanding operation of distribution network connected with mini hydro

J. A. LAGHARI,H. MOKHLIS,M. KARIMI,A. H. A. BAKAR,Hasmaini MOHAMAD

期刊论文

Large eddy simulation of a 660 MW utility boiler under variable load conditions

Haoshu SHEN, Yuxin WU, Minmin ZHOU, Hai ZHANG, Guangxi YUE, Junfu LYU

期刊论文

Applications of thermostatically controlled loads for demand response with the proliferation of variable renewable energy

Meng SONG, Wei SUN

期刊论文

Neural Operation Management: A New Avenue for Productive and Military Operations

Qing-guo Ma

期刊论文

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Calculation method of load distribution on pipe threaded connections under tension load

Shoujun CHEN, Lianxin GAO, Qi AN

期刊论文

Comparison of optimal capacitor placement methods in radial distribution system with load growth andZIP load model

Veera Venkata Satya Naryana MURTY, Ashwani KUMAR

期刊论文

A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

期刊论文

CORRECTION to: Energy-saving operation approaches for urban rail transit systems

Ziyou GAO, Lixing YANG

期刊论文

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

期刊论文

Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

期刊论文

Application of a vertex chain operation algorithm on topological analysis of three-dimensional fractured

Zixin ZHANG, Jia WU, Xin HUANG

期刊论文

Reliability evaluation of future photovoltaic systems with smart operation strategy

Amir AHADI,Hosein HAYATI,Seyed Mohsen MIRYOUSEFI AVAL

期刊论文

A method to predict cooling load of large commercial buildings based on weather forecast and internal

Junbao JIA,Jincheng XING,Jihong LING,Ren PENG

期刊论文