Control and systems concepts in the innovation process

Allan Kjaer is an electrical engineer who arned master‘s and Ph.D.degrees in control nd system identification. He then began work n control, information, and production processes in the steel industry. Leading a team of evelopers at the Danish Steel Company, Dr. Kjaer applied systems thinking to the wider issues of process and information integration to achieve a tightly integrated production and business process. His article is important because it directly shows how control-systems     

Congestion management in power systems – A review

In the past few decades, restructuring has overtaken all possible domains including the electric supply industry. Restructuring has brought about considerable changes by the virtue of which electricity is now a commodity and has converted into deregulated one. Such a competitive market has paved way for innumerable participants. This has led to overloading and congestion of transmission lines. Moreover, open access transmission network has ingenerated a more intensified problem of congestion. Thus, congestion management in power systems is germane and of central importance to the power industry. In this paper a review work is carried out to unite all the publications in congestion management.     

Multiscale simulation of MOS systems based on high-κ oxides

We report on a multiscale simulation approach that includes both macroscopic drift-diffusion current model and quantum tunneling model. The models are solved together in a self-consistent way inside a single simulation package. As an example, we study the subthreshold transfer characteristics of MOS transistors based on high-κ oxides. We compare the high-κ gates based on HfO₂ and ZrO₂ with a SiO₂ gate of the same equivalent thickness and show the effect of the tunneling current on transistor performance.     

Current status and challenges in PEMFC stacks, systems and commercialization

Polymer electrolyte membrane fuel cells(PEMFCs)operate atlowtemperatures(60~80℃),offer a fast start-up and shut downti me(few minutes),fast response to changing electric loads,andcan sustain unli mited thermal cycles·They are ideally suited fortransport…     

Analysis of trends in the development of cities’ heat supply systems

New challenges—including the modern urban development policy, formation of the market of energy efficient technologies and different types of equipment of a broad power capacity range, tightening requirements to reliability, quality, and economic accessibility of heat supply—enhance the competitiveness of decentralized heat supply. In addition, its spontaneous growth and not always reasonable implementation lead to unjustified expenses, low efficiency, and ecological inconsistency. This proves the relevance of solving the problems of dividing an urban territory into zones of centralized heating (CH) and decentralized heating (DCH) along with their planning and justification, as well as determining a reasonable level of heat supply centralization and concentration of heat sources' power capacity. Solving these problems using the suggested method will allow optimizing the application areas for various types of heat supply and heat sources, justifying the degree of heat power capacity concentration and the extent of the systems as early as at the phase of a detailed urban planning project and then refining them during the design of urban heat supply systems. This will dramatically improve the reasonability of the decisions made and will simplify the procedure of their implementation. For criteria of limiting the extent (radius) of heat supply systems and defining their type, we suggest using standard values—the density of heat load per unit length of the pipeline and per unit area of urban territory. Standard values must be differentiated across the territory of Russia taking into account regional climatic and economic conditions and unique characteristics of heat supply development in cities and towns. The present article continues and develops the statements made in the previous articles created within the framework of the Theory of Hydraulic Circuits and takes into account the current situation and emerging trends in heat supply.     

On the synthesis of passive–adaptive systems for electric drive control

A new approach to synthesis of passive–adaptive electromechanical control systems is proposed. Decomposition of a control system structure into two subsystems, which solve a uniform problem of finite control, but have various functions, is a feature of the presented approach. The first subsystem is a control system of an electric drive, and it carries out the task of finite control that is invariant to the reference signals in the traditional statement of linear discrete–continuous systems. The second subsystem is an adaptive reference model that forms a criterion that is optimal in terms of performance and accuracy of the phase coordinate vector of an electric drive with restriction of them to acceptable levels. A discrete–continuous system of electric drive control and a functional structure of a passive–adaptive electromechanical system are set up in the MexBIOS Development Studio simulating the modeling environment. The results of simulation showed that there is an acceptable quality of system operation in both linear and nonlinear areas of operation when working out additive increments of setting the position of the drive shaft changing at random points of time. The synthesized system has low sensitivity to changes in the parameters of the object of electromechanical control.     

State extension in adequacy evaluation of composite power systems—concept and algorithm

The number of possible system contingency states can be extremely large for practical composite generation and transmission systems. It is therefore not feasible or even possible to investigate all the contingencies in adequacy evaluation of composite power systems. Only those system states which are credible or usually given as up to certain contingency level are investigated in practical calculations. Although the probabilities of the ignored high level system contingency states are individually very small, the total value can be significant as the number of these high level system states is very large, especially for large size composite systems. This paper presents a state extension algorithm, which effectively includes the effects of high level contingencies without increasing the computational effort. The algorithm can, therefore, effectively and efficiently provide improved estimates of the adequacy indices. The accuracy improvement applies to the basic failure probability, frequency and duration (F&D) indices, determined for both the overall system and the individual load points. The technique also provides exact error estimates for the three adequacy indices. The concepts associated with the technique are developed and illustrated using simple networks. A numerical example is presented in the paper to illustrate the effectiveness of the proposed algorithm.     

Optical measuring systems and technologies for some urgent tasks in industry and science

Modern industry and science take novel optical measuring systems and laser technologies with high resolution and productivity for solving actual tasks,including safety problems for mining,oil,atomic and railway in-dustries.The TDI SIE's results in these trends are presented.     

Structural–acoustic modal analysis of cylindrical shells: application to MRI scanner systems

Object  

The acoustic noise in a magnetic resonance imaging (MRI) scanner bore is mainly introduced by the vibration of gradient coils. The interaction between acoustic modes in the scanner bore and structure modes in the coil structure leads to structural–acoustic coupling. In order to implement quiet MRI design, the structural–acoustic coupling mechanism in MRI machines needs to be fully investigated.     

Effects of electrified railways on quality of electric energy supply in urban power systems

IntroductionBeing of great value to railway transport and hence to nationaleconomy,electrification of railways has been carried out very rapidlyin China in the past 30 years.By the end of 1990,some 6941 km ofelectrified railways have been opened to traffic and about 16,000 kmor one fourth of the total railway length are expected to be electrified,accounting for 45% of the total railway freight volume.At present,Shaanxi Province ranks first with respect to total     

The power flow algorithm for balanced and unbalanced bipolar multiterminal ac–dc systems

Bipolar dc terminals are used for hvdc transmission in an ac–dc system. The sequential ac–dc power flow algorithm has been proposed for an ac–dc system consisting of balanced and unbalanced bipolar multiterminal in this paper. The algorithm has two superiority. Firstly, as dc system variables are not included in Jacobian matrix the convergence time of the algorithm and necessity of computer memory is little. Secondly, both this algorithm has been developed for (balanced and unbalanced) bipolar system (not only monopolar) and this algorithm also can be run with current controlled, voltage controlled and power controlled terminals without making any changes in proposed method.     

Static synchronous series compensator—a mean for dynamic power flow control in electric power systems

In this paper an attempt has been made to point out the basic differences between an `impedance based' controllable series compensation (CSC) and a static synchronous series compensator (SSSC), which is based on power electronic converters with GTO thyristors. First, basic theoretical considerations regarding power flow control in the transmission line using CSC and SSSC respectively, were studied, applying the mathematical model. Results clarified basic differences between CSC and SSSC regarding this question and showed that SSSC is superior to CSC in the area of low transmission angles (short lines or low-loaded lines). The time-domain simulation using a detailed SSSC simulation model confirmed theoretical considerations. For this purpose, a decoupled control structure with a predictive control loop based on the transformation of the three-phase system to the rotating reference frame was developed. On the test system, which may be found in various countries, the differences between CSC and SSSC regarding power oscillation damping were demonstrated. Results showed that under specific conditions, SSSC can be much more effective than CSC.     

Nodal price volatility reduction and reliability enhancement of restructured power systems considering demand–price elasticity

With the development of restructured power systems, the conventional “same for all customers” electricity price is getting replaced by nodal prices. Electricity prices will fluctuate with time and nodes. In restructured power systems, electricity demands will interact mutually with prices. Customers may shift some of their electricity consumption from time slots of high electricity prices to those of low electricity prices if there is a commensurate price incentive. The demand side load shift will influence nodal prices in return. This interaction between demand and price can be depicted using demand–price elasticity. This paper proposes an evaluation technique incorporating the impact of the demand–price elasticity on nodal prices, system reliability and nodal reliabilities of restructured power systems. In this technique, demand and price correlations are represented using the demand–price elasticity matrix which consists of self/cross-elasticity coefficients. Nodal prices are determined using optimal power flow (OPF). The OPF and customer damage functions (CDFs) are combined in the proposed reliability evaluation technique to assess the reliability enhancement of restructured power systems considering demand–price elasticity. The IEEE reliability test system (RTS) is simulated to illustrate the developed techniques. The simulation results show that demand–price elasticity reduces the nodal price volatility and improves both the system reliability and nodal reliabilities of restructured power systems. Demand–price elasticity can therefore be utilized as a possible efficient tool to reduce price volatility and to enhance the reliability of restructured power systems.     

Physical and dielectric properties of BaTiO3–fluoride–glass systems for nitrogen-fireable embedded capacitors

BaTiO₃-based dielectrics containing the selective additive combinations from Pb-free glasses and fluoride compounds such as AlF₃, BaF₂, CaF₂, LiF and ZnF₂ were studied mainly for a potential N₂-fireable embedded capacitor in printed circuit board with Cu metallization. The physical and dielectric properties, such as dielectric constant (k), loss tangent (tanδ) and T _c, strongly depended on the choice of additive combination. A bismuth borosilicate glass was most promising in terms of the degree of densification and dielectric constant. The samples containing LiF and ZnF₂ and sintered at 950 °C looked most beneficial in that these additives produced high k of >1,200 and low tanδ of < 0.022 at room temperature regardless of sintering atmosphere. As an example, the 95BaTiO₃–2LiF–3(Bi borosilicate) sample exhibited k?~?1,340 and tanδ?~?0.022 at room temperature when fired at 950 °C in N₂.     

Strategies for improving resilience of regional integrated energy systems in the prevention–resistance phase of integration

he construction of integrated energy systems can help improve energy efciency and promote global energy transition. However, in recent years, the occurrence of extreme natural disasters has brought certain threats to the safe and stable operation of the integrated energy system. Thus, it is necessary to improve the ability of the integrated energy system to resist disasters, reduce disaster losses, and restore energy supply as soon as possible, i.e., improve its resilience. Considering the infuence of pre-disaster prevention measures and disaster-time operational measures on system disaster resilience and the correlation between the two, this paper proposes a system hardening strategy based on three-layer robust optimization. The upper layer formulates the optimal hardening strategy of the system before the disaster event occurs, the middle layer identifes the failed elements in the worst disaster situation, while the lower layer realizes the system operational optimization by coordinating the energy storage charging and discharging plan of each subsystem. The strategy can reduce the total supply shortage of the integrated energy system and improve the fexibility of the system in the pre-disaster prevention and disaster resistance integration stages.     

Mathematical advances and horizons for classical and quantum-perturbed drift-diffusion systems: solid state devices and beyond

The classical drift-diffusion model employed in semi-conductor simulation is now seen as part of a hierarchy of mathematical models designed to capture the intricate patterns of current flow in solid-state devices. These models include those incorporating quantum mechanical effects. Scientific computation has vastly outpaced our mathematical understanding of these models. This article is restricted in its focus, and describes mathematical understanding achieved during the last few decades primarily in terms of Gummel decomposition, as applied to drift-diffusion models and the closely related family of quantum corrected drift-diffusion models. Drift-diffusion models are being employed once again in organic devices, and in bio-chip devices, and a re-examination is now seen as timely, as such studies proceed beyond solid state devices.