Economic criteria for optimizing the number and load factor of mining transformers

Purpose. This article discusses how to choose the optimal number and load factor, respectively the economic power in the first year of mining power transformers operation. The analysis is carried out based on technical-economic criteria. In this regard, two economic criteria are proposed for a detailed analysis, namely the minimum updated total expenses criterion and the minimum power and energy losses criterion. Methods. For determining the number and the optimal load factor, the paper presents mathematical models for the two eco-nomic criteria used. The results obtained by the presented methods are simulated using Matlab for several series of under-ground mining transformers. Also, it is assumed that the load remains constant over the year. Findings. The article confirms the possibility of using the analyzed economic criteria for establishing the optimal number of mining transformers as well as the optimal load factor, respectively the optimal power for the first year of operation. The difficulty of the research is related to the loss time assessment. Also, the paper presents the performed comparative analysis of the two implications. Originality. This research provides a novel approach, by the detailed presentation of the two criteria used for describing the objective functions which have to be minimized in order to gain the optimum, referring strictly to mining transformers, which represents a novelty for power engineering in mining. Practical implications. The methods described in the article can be successfully used in the case of new mining power networks which are going to be designed, and in the case of those currently in operation. Economic criteria analysed also provide results for the economical regime of mining transformers which corresponds to minimum energy loss. Therefore, this case also results in significant energy savings, i.e. lower economic criteria used.Мета. У статті обговорюється проблема вибору оптимального числа шахтних трансформаторів, визначення коефіцієнта їх навантаження і рентабельності протягом першого року експлуатації. Методика. Для визначення кількості трансформаторів і оптимального коефіцієнта їх навантаження запропонована математична модель на базі двох використаних економічних критеріїв: мінімальні скориговані загальні витрати та мінімальні втрати потужності й енергії. Отримані результати лягли в основу моделі, побудованої за допомогою Matlab для декількох серій підземних шахтних трансформаторів. Прийнято, що навантаження зберігається постійним протягом року. Результати. У статті підтверджена можливість використання аналізованих економічних критеріїв для визначення оптимального числа шахтних трансформаторів і оптимального коефіцієнта їх навантаження а, отже, оптимальної потужності протягом першого року їх експлуатації. Складність дослідження полягала в оцінці часових втрат. Крім того, у статті були представлені результати та порівняльний аналіз двох використаних економічних критеріїв. Встановлено, що оптимальним рішенням є використання трансформатора з номінальною потужністю, найближчою до теоретичного значення, отриманого в результаті розрахунків SNTmax. Результати, отримані при моделюванні, показують, що значення факторів навантаження, відповідно, оптимальної потужності шахтних трансформаторів, вище, ніж у поверхових, оскільки відношення втрат вище. Наукова новизна. Дослідження засноване на інноваційному підході, при якому детальне представлення двох критеріїв використано для опису об’єктивних функцій, що підлягають мінімізації, з метою отримання оптимальних рішень для шахтних трансформаторів. Даний підхід є принципово новим у галузі гірничої електроенергетики. Практична значимість. Методи, запропоновані в статті, можуть бути успішно застосовані як у разі проектування нових шахтних електричних мереж, так і для мереж, які вже перебувають в експлуатації. Аналізовані економічні критерії дозволяють встановити найбільш економічний режим експлуатації шахтних трансформаторів, при якому втрати енергії будуть мінімальні, що, в свою чергу, призведе до її суттєвої економії.Цель. В статье обсуждается проблема выбора оптимального числа шахтных трансформаторов, определения коэффициента их нагрузки и рентабельности в течение первого года эксплуатации. Методика. Для определения количества трансформаторов и оптимального коэффициента их нагрузки предложена математическая модель на базе двух использованных экономических критериях: минимальные скорректированные общие издержки и минимальные потери мощности и энергии. Полученные результаты легли в основу модели, построенной с помощью Matlab для нескольких серий подземных шахтных трансформаторов. Принято, что нагрузка сохраняется постоянной в течение года. Результаты. В статье подтверждена возможность использования анализируемых экономических критериев для определения оптимального числа шахтных трансформаторов и оптимального коэффициента их нагрузки и, следовательно, оптимальной мощности в течение первого года их эксплуатации. Сложность исследования заключалась в оценке временных потерь. Кроме того, в статье были представлены результаты и сравнительный анализ двух использованных экономических критериев. Установлено, что оптимальным решением является использование трансформатора с номинальной мощностью, ближайшей к теоретическому значению, полученному в результате расчетов SNTmax. Результаты, полученные при моделировании, показывают, что значения факторов нагрузки, соответственно, оптимальной мощности шахтных трансформаторов, выше, чем у поверхностных, поскольку отношение потерь выше. Научная новизна. Исследование основано на инновационном подходе, при котором детальное представление двух критериев использовано для описания объективных функций, подлежащих минимизации с целью получения оптимальных решений для шахтных трансформаторов. Данный подход является принципиально новым в области горной электроэнергетики Практическая значимость. Методы, предложенные в статье, могут быть успешно применены как в случае проектирования новых шахтных электрических сетей, так и для сетей, уже находящихся в эксплуатации. Анализируемые экономические критерии позволяют установить наиболее экономичный режим эксплуатации шахтных трансформаторов, при котором потери энергии будут минимальны, что, в свою очередь, приведет к ее существенной экономии.The authors state that this research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors

Active actuator fault-tolerant control of a wind turbine benchmark model

This paper describes the design of an active fault-tolerant control scheme that is applied to the actuator of a wind turbine benchmark. The methodology is based on adaptive filters obtained via the nonlinear geometric approach, which allows to obtain interesting decoupling property with respect to uncertainty affecting the wind turbine system. The controller accommodation scheme exploits the on-line estimate of the actuator fault signal generated by the adaptive filters. The nonlinearity of the wind turbine model is described by the mapping to the power conversion ratio from tip-speed ratio and blade pitch angles. This mapping represents the aerodynamic uncertainty, and usually is not known in analytical form, but in general represented by approximated two-dimensional maps (i.e. look-up tables). Therefore, this paper suggests a scheme to estimate this power conversion ratio in an analytical form by means of a two-dimensional polynomial, which is subsequently used for designing the active fault-tolerant control scheme. The wind turbine power generating unit of a grid is considered as a benchmark to show the design procedure, including the aspects of the nonlinear disturbance decoupling method, as well as the viability of the proposed approach. Extensive simulations of the benchmark process are practical tools for assessing experimentally the features of the developed actuator fault-tolerant control scheme, in the presence of modelling and measurement errors. Comparisons with different fault-tolerant schemes serve to highlight the advantages and drawbacks of the proposed methodology

A Generic Framework for Real-Time Multi-Channel Neuronal Signal Analysis, Telemetry Control, and Sub-Millisecond Latency Feedback Generation

Distinct modules of the neural circuitry interact with each other and (through the motor-sensory loop) with the environment, forming a complex dynamic system. Neuro-prosthetic devices seeking to modulate or restore CNS function need to interact with the information flow at the level of neural modules electrically, bi-directionally and in real-time. A set of freely available generic tools is presented that allow computationally demanding multi-channel short-latency bi-directional interactions to be realized in in vivo and in vitro preparations using standard PC data acquisition and processing hardware and software (Mathworks Matlab and Simulink). A commercially available 60-channel extracellular multi-electrode recording and stimulation set-up connected to an ex vivo developing cortical neuronal culture is used as a model system to validate the method. We demonstrate how complex high-bandwidth (>10 MBit/s) neural recording data can be analyzed in real-time while simultaneously generating specific complex electrical stimulation feedback with deterministically timed responses at sub-millisecond resolution

Modeling Guidelines for Code Generation in the Railway Signaling Context

Modeling guidelines constitute one of the fundamental cornerstones for Model Based Development. Their relevance is essential when dealing with code generation in the safety-critical domain. This article presents the experience of a railway signaling systems manufacturer on this issue. Introduction of Model-Based Development (MBD) and code generation in the industrial safety-critical sector created a crucial paradigm shift in the development process of dependable systems. While traditional software development focuses on the code, with MBD practices the focus shifts to model abstractions. The change has fundamental implications for safety-critical systems, which still need to guarantee a high degree of confidence also at code level. Usage of the Simulink/Stateflow platform for modeling, which is a de facto standard in control software development, does not ensure by itself production of high-quality dependable code. This issue has been addressed by companies through the definition of modeling rules imposing restrictions on the usage of design tools components, in order to enable production of qualified code. The MAAB Control Algorithm Modeling Guidelines (MathWorks Automotive Advisory Board)[3] is a well established set of publicly available rules for modeling with Simulink/Stateflow. This set of recommendations has been developed by a group of OEMs and suppliers of the automotive sector with the objective of enforcing and easing the usage of the MathWorks tools within the automotive industry. The guidelines have been published in 2001 and afterwords revisited in 2007 in order to integrate some additional rules developed by the Japanese division of MAAB [5]. The scope of the current edition of the guidelines ranges from model maintainability and readability to code generation issues. The rules are conceived as a reference baseline and therefore they need to be tailored to comply with the characteristics of each industrial context. Customization of these recommendations has been performed for the automotive control systems domain in order to enforce code generation [7]. The MAAB guidelines have been found profitable also in the aerospace/avionics sector [1] and they have been adopted by the MathWorks Aerospace Leadership Council (MALC). General Electric Transportation Systems (GETS) is a well known railway signaling systems manufacturer leading in Automatic Train Protection (ATP) systems technology. Inside an effort of adopting formal methods within its own development process, GETS decided to introduce system modeling by means of the MathWorks tools [2], and in 2008 chose to move to code generation. This article reports the experience performed by GETS in developing its own modeling standard through customizing the MAAB rules for the railway signaling domain and shows the result of this experience with a successful product development story

Projection-based hyper-reduced order modeling of stress and reaction fields, and application of static condensation for multibody problems

Computational Mechanics' problems are often solved using the Finite Element Method (FEM). The resulting systems of equations may lead to large data and therefore, the solution requires high memory and time to be computed. This situation can be surpassed by applying Reduced Order Modeling (ROM) techniques, allowing the user to capture the system's dominant effects to build a high-fidelity reduced model that gives the possibility to predict and analyze the behaviour of a complex model using low computational resources within a micro time-step. This paper aims to enrich the already implemented Kratos' Rom Application with a reconstruction of the reaction and 2nd Piola Kirkchhoff stress fields. The applied methodology is a projection-based strategy using the Proper Orthogonal Decomposition together with a Gappy Data reconstruction technique. The gappy data comes from building a hyper-reduced order model (HROM). A surrogate model application using static condensation and HROM techniques is proposed to show the possibility of solving multibody systems interfacing Kratos' ROM framework with Mathworks control capabilities in a fast and accurate way. The validation of the applied methodology is given by 3D complex models

Dynamics Simulation and Optimal Control of a Multiple-input and Multiple-output Balancing Cube

This thesis document outlines the development of a multibody dynamics simulation of an actively stabilized multiple-input, multiple-output, coupled, balancing cube and the process of verifying the results by implementing the control algorithm in hardware. A non-linear simulation of the system was created in Simscape and used to develop a Linear Quadratic Gaussian control algorithm. To implement this algorithm in actual hardware, the system was first designed, manufactured, and assembled. The structure of the cube and the reaction wheels were milled from aluminum. DC brushless motors were installed into the mechanical system. In terms of electronics, a processor, orientation sensor, motor drivers, analog to digital converters, and a pulse width modulation board were assembled into the cube. Upon completion, the software to control the cube was developed using Simulink and run on a Raspberry Pi computer within the mechanism

Definition of a Type System for Generic and Reflective Graph Transformations

This thesis presents the extension of the graph transformation language SDM (Story Driven Modeling) with generic and reflective features as well as the definition of type checking rules for this language. The generic and reflective features aim at improving the reusability and expressiveness of SDM, whereas the type checking rules will ensure the type-safety of graph transformations. This thesis starts with an explanation of the relevant concepts as well as a description of the context in order to provide the reader with a better understanding of our approach. The model driven development of software, today considered as the standard paradigm, is generally based on the use of domain-specific languages such as MATLAB Simulink and Stateflow. To increase the quality, the reliability,and the efficiency of models and the generated code, checking and elimination of detected guideline violations defined in huge catalogues has become an essential, but error-prone and time-consuming task in the development process. The MATE/MAJA projects, which are based on the use of the SDM language, aim at an automation of this task for MATLAB Simulink/Stateflow models. Modeling guidelines can be specified on a very high level of abstraction by means of graph transformations. Moreover, these specifications allow for the generation of guideline checking tools. Unfortunately, most graph transformation languages do not offer appropriate concepts for reuse of specification fragments - a MUST, when we deal with hundreds of guidelines. As a consequence we present an extension of the SDM language which supports the definition of generic rewrite rules and combines them with the reflective programming mechanisms of Java and the model repository interface standard JMI. Reusability and expressiveness are not the only aspects we want to improve. Another fundamental aspect of graph transformations must be ensured: their correctness in order to prevent type errors while executing the transformations. Checking and testing the graph transformations manually would ruin the benefit obtained by the automation of the guideline checking and by the generic and reflective features. Therefore, we propose in this work a type-checking method for graph transformations. We introduce a new notation for rules of inference and define a type system for SDM. We also proposed an algorithm to apply this type system. We illustrate and evaluate both contributions of our work by applying them on running examples. Proposals for other additional SDM features as well as for possible improvements of our type checking open new perspectives and future research to pursue our work

Light vehicle model for dynamic car simulator

Driving simulators have been becoming little by little a suitable tool oriented to improve the knowledge about the domain of driving research. The investigations that can be conducted with this type of tool concern the driver's behaviour, the design/control of vehicles, testing assistance systems for driving and the roadway infrastructure's impact. The benefits of simulation studies are many: lack of any real risk to users, reproducible situations, time savings and reduced testing costs. In addition, their flexibility allows to test situations that do not exist in reality or at least they rarely and randomly exist. The topic of the present work concerns the development of a brand new dynamic model for an existing car simulator owned by LEPSIS laboratory (Laboratoire d'Expliotation, Perception, Simulateurs et Silulations – Laboratory for Road Operations, Perception, Simulators and Simulations) belonging to COSYS (COmposants et SYStems), which is a department of IFSTTAR institute (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux – French Institute of Science and Technology for Transport, Spatial Planning, Development and Networks) site. Once uses and advantages of driving simulators are listed and described, imperfections and limitations of the existing driving vehicle model belonging to the two Degrees of Freedom (DoF) driving simulator of the laboratory are highlighted. Subsequently, structure of the brand new vehicle model, designed by means of Matlab Simulink software, are illustrated through the theoretical framework. Since the vehicle model must refer to a real one, an instrumented Peugeot 406 has been chosen because all its technical features are provided and inserted both on the present model and Prosper/Callas 4.9 by OKTAL software to create a highly sophisticated and accurate virtual version of the commercial car. The validation of this new vehicle model is performed, where the results returned by several different driving scenarios are compared with the ones provided by Prosper software. All the scenarios are simulated with both existing and new vehicle model uploaded in the driving simulator, and the outputs are subsequently compared with the ones returned by Prosper in order to demonstrate the improvements done. Finally, being the number of outputs provided by the new model definitively higher with respect to previous one, additional validations concerning the further results are accomplished