920 resultados para Distributed Control Problems


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Työn tavoitteena oli kokonaisnäkemyksen luominen Helsingin seudun liikenteenhallinnan tilasta ja kehitysnäkymistä sekä seuraavien tärkeimpien kehittämispolkujen tunnistaminen ja konkretisointi toimenpiteiksi. Työssä keskityttiin seuraaviin painopistealueisiin 1. Liityntäpysäköinnin informaation ja maksujärjestelmien kehittäminen 2. Liikenteenhallintakeskuksen toiminnan kehittäminen ja laajentaminen 3. Liikennejärjestelmän reaaliaikainen tilannekuva ja lyhyen aikavälin ennusteet 4. Pääkaupunkiseudun pääväylien ruuhkien ja häiriöiden hallinta 5. Joukkoliikenteen ajantasaisen matkustajainformaation kehittäminen. Työssä laadittiin katsaus kullakin painopistealueella jo tapahtuneeseen sekä käynnissä olevaan kehitystyöhön, kuvattiin esiin nousseita ongelmia ja laadittiin esitys vuoteen 2020 ulottuvasta toiminnallisesta tavoitetilasta sekä konkreettisista kehittämistoimista. Työssä järjestettiin myös tulevaisuustyöpaja, johon pyydettiin alustuksia valikoiduilta viranomaistahoilta, tutkijoilta ja palveluntuottajilta. Näiden keskustelujen kautta kirkastettiin seudun toimijoiden näkemystä älyliikenteen toimialan kehitysnäkymistä ja –tarpeista. Työn lopputuloksena syntyneeseen toimenpideohjelmaan kirjattiin yhteensä 30 hanketta. Näistä viisi hanketta valittiin työpajatyöskentelyn kautta varsinaisiksi kärkihankkeiksi, joiden toteutus on kriittistä liikkujien ja viranomaistyön palvelutason kannalta ja joka edellyttää usean toimijan yhteistyötä. Lisäksi tunnistettiin joukko seurattavia hankkeita. Valitut kärkihankkeet, käynnistämisen vastuutaho sekä tavoitteellinen käynnistysvuosi ovat seuraavat: 1. Liityntäpysäköinnin dynaamisen informaatiojärjestelmän pilotointi Hämeenlinnanväylän käytävässä Kehäradan asemilla (HSL 2012) 2. HSL:n alueen joukkoliikenteen häiriönhallinnan uudelleenorganisointi (HSL, Liikennevirasto 2012) 3. Seudullisen liikenteenhallintasuunnitelman laadinta verkollisen operoinnin kehittämiseksi häiriötilanteissa (ELY-keskus, Liikennevirasto 2013) 4. Reaaliaikaisen sujuvuustiedon tuottaminen ruuhkautuvalta pääkatu- ja alempiasteiselta maantieverkolta (Liikennevirasto, kunnat 2012) 5. Liikenteen vaihtuvan ohjauksen ja tiedottamisen hyödyntäminen pääväylien ruuhkautumisen ja häiriöiden hallinnassa. (ELY-keskus 2012) Kärkihankkeisiin ei liity sellaisia riippuvuuksia, että niitä ei voitaisi käynnistää ennen päätöksentekoa jostakin muusta investoinnista. Merkittävimmät riippuvuudet liittyvät LIJ2014-järjestelmän ajoneuvojen paikannuksen ja muiden työkalujen valmistumiseen. Johtoryhmän linjauksen mukaan kärkihankkeissa ja muissakin toimijoiden omissa hankkeissa syntyvien tietojärjestelmien rajapinnat avataan soveltuvasti kaupallisten toimijoiden käyttöön, jolloin syntyvien kaupallisten loppukäyttäjäpalveluiden kautta voidaan parantaa tietopalvelujen tavoittavuutta. Kärkihankkeiden valinta ja sisältö on rakennettu pitkälti sen lähtökohdan varaan, että liikenteen tietopalveluissa julkistoimijoiden roolina on pääasiassa lähtötietojen tuottaminen ja jakaminen varsinaisille palveluntuottajille. Vuoteen 2016 mennessä uusien rajapintojen kautta jaettavien tietojen määrä on nykyiseen verrattuna huomattavasti laajempi, ja odotukset uusien ja innovatiivisten palvelujen syntymiselle ovat korkeat. HLH-johtoryhmä nimeää jokaisen kärkihankkeen läpiviennistä vastaavan työryhmän, joiden työskentelyä ohjataan nykyisen kaltaisessa johtoryhmätyössä. Johtoryhmätyön organisointi on todettu toimivaksi, sillä ryhmä koostuu seudun 14 kunnan alueen keskeisistä julkisista toimijoista ja sen kautta on olemassa vahvat kytkennät sekä seudun liikennejärjestelmätyöhön (HLJ) että valtakunnalliseen älyliikenteen kehitystyöhön.

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The target of the thesis is to improve product profitability control in continuous IT-services. Accurate product cost accounting and correctly allocated revenues are a necessity for good product profitability control. The focus of the study is on costs and revenues that are not traced directly to services. The thesis is focused on revenue allocations as revenue allocation methods have not been used in the case company before. In order to achieve the target revenue allocation methods, which improve the product profitability accounting and control, are presented. The research methods used in the thesis are literature review and empirical case study. The research approach is constructive. The theoretical part is composed of literature and articles that create a base for the empirical part. Internal interviews describe the current situation in the company and based on it development actions are planned. The part of the empirical case study is seen mostly in the limitations as the research is limited to concern only one department in the company. Problems in the revenue tracing are caused by customer specific services and lack of service definitions because of which the revenues are not traced correctly. Methods to allocate revenues are presented in the thesis and stand-alone revenue allocation method is the most suitable one because it is fair and it can be modified. Approximate product profitability analysis is done in the thesis and the results of it indicate that some services are profitable and some unprofitable.

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Rapid ongoing evolution of multiprocessors will lead to systems with hundreds of processing cores integrated in a single chip. An emerging challenge is the implementation of reliable and efficient interconnection between these cores as well as other components in the systems. Network-on-Chip is an interconnection approach which is intended to solve the performance bottleneck caused by traditional, poorly scalable communication structures such as buses. However, a large on-chip network involves issues related to congestion problems and system control, for instance. Additionally, faults can cause problems in multiprocessor systems. These faults can be transient faults, permanent manufacturing faults, or they can appear due to aging. To solve the emerging traffic management, controllability issues and to maintain system operation regardless of faults a monitoring system is needed. The monitoring system should be dynamically applicable to various purposes and it should fully cover the system under observation. In a large multiprocessor the distances between components can be relatively long. Therefore, the system should be designed so that the amount of energy-inefficient long-distance communication is minimized. This thesis presents a dynamically clustered distributed monitoring structure. The monitoring is distributed so that no centralized control is required for basic tasks such as traffic management and task mapping. To enable extensive analysis of different Network-on-Chip architectures, an in-house SystemC based simulation environment was implemented. It allows transaction level analysis without time consuming circuit level implementations during early design phases of novel architectures and features. The presented analysis shows that the dynamically clustered monitoring structure can be efficiently utilized for traffic management in faulty and congested Network-on-Chip-based multiprocessor systems. The monitoring structure can be also successfully applied for task mapping purposes. Furthermore, the analysis shows that the presented in-house simulation environment is flexible and practical tool for extensive Network-on-Chip architecture analysis.

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In this doctoral thesis, a power conversion unit for a 10 kWsolid oxide fuel cell is modeled, and a suitable control system is designed. The need for research was identified based on an observation that there was no information available about the characteristics of the solid oxide fuel cell from the perspective of power electronics and the control system, and suitable control methods had not previously been studied in the literature. In addition, because of the digital implementation of the control system, the inherent characteristics of the digital system had to be taken into account in the characteristics of the solid oxide fuel cell (SOFC). The characteristics of the solid oxide fuel cell as well the methods for the modeling and control of the DC/DC converter and the grid converter are studied by a literature survey. Based on the survey, the characteristics of the SOFC as an electrical power source are identified, and a solution to the interfacing of the SOFC in distributed generation is proposed. A mathematical model of the power conversion unit is provided, and the control design for the DC/DC converter and the grid converter is made based on the proposed interfacing solution. The limit cycling phenomenon is identified as a source of low-frequency current ripple, which is found to be insignificant when connected to a grid-tied converter. A method to mitigate a second harmonic originating from the grid interface is proposed, and practical considerations of the operation with the solid oxide fuel cell plant are presented. At the theoretical level, the thesis discusses and summarizes the methods to successfully derive a model for a DC/DC converter, a grid converter, and a power conversion unit. The results of this doctoral thesis can also be used in other applications, and the models and methods can be adopted to similar applications such as photovoltaic systems. When comparing the results with the objectives of the doctoral thesis, we may conclude that the objectives set for the work are met. In this doctoral thesis, theoretical and practical guidelines are presented for the successful control design to connect a SOFC-based distributed generation plant to the utility grid.

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Parasite related problems are considered one of the major health problems for sheep breeding, causing considerable economic losses to commercial husbandry. The aim of this study was to determine the technological level and the level of knowledge of farmers regarding management practices to control gastrointestinal parasites in sheep in Minas Gerais state, southeastern Brazil. The analysis was based on 213 questionnaires applied by official veterinarians of the State Government Agency for Animal Health (Instituto Mineiro de Agropecuária, IMA), covering 16.6% of all counties. From two hundred and thirteen sheep farms sampled, 117 farms had their technological level determined. From the samples, 0.9% were characterized as high level, 45.3% as medium, and 53.0% as low technological level. The flock size ranged from 2 to 1843 with an average of 80.5 sheep per farm. The majority of the sheep production systems was extensive/semi-extensive (74.5%). The management practices adopted by the farmers to reduce parasitism were: split young and adult animals (5.6%), change pasture after deworm the animals (5.2%), use quarantine for incoming animals (2.3%), deworm newly arrived sheep (1.5%), and have regular technical assistance (31.9%). Although 76.5% of the farmers medicate the animals, treatments were performed without any major technical criteria, with an average interval of 4.6 months. The most commonly used drug families were macrocyclic lactones (38.5%) and benzimidazoles (24.9%). The management practices adopted in Minas Gerais are based on old recommendations and may not return in a good set of strategies to prevent parasite infections. Field observations reinforce the finding where farmers have obtained unsatisfactory results in maintaining the health and productivity level of their enterprises.

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Pulse Response Based Control (PRBC) is a recently developed minimum time control method for flexible structures. The flexible behavior of the structure is represented through a set of discrete time sequences, which are the responses of the structure due to rectangular force pulses. The rectangular force pulses are given by the actuators that control the structure. The set of pulse responses, desired outputs, and force bounds form a numerical optimization problem. The solution of the optimization problem is a minimum time piecewise constant control sequence for driving the system to a desired final state. The method was developed for driving positive semi-definite systems. In case the system is positive definite, some final states of the system may not be reachable. Necessary conditions for reachability of the final states are derived for systems with a finite number of degrees of freedom. Numerical results are presented that confirm the derived analytical conditions. Numerical simulations of maneuvers of distributed parameter systems have shown a relationship between the error in the estimated minimum control time and sampling interval

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The dynamics of flexible systems, such as robot manipulators , mechanical chains or multibody systems in general, is becoming increasingly important in engineering. This article deals with some nonlinearities that arise in the study of dynamics and control of multibody systems in connection to large rotations. Specifically, a numerical scheme that adresses the conservation of fundamental constants is presented in order to analyse the control-structure interaction problems.

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Video transcoding refers to the process of converting a digital video from one format into another format. It is a compute-intensive operation. Therefore, transcoding of a large number of simultaneous video streams requires a large amount of computing resources. Moreover, to handle di erent load conditions in a cost-e cient manner, the video transcoding service should be dynamically scalable. Infrastructure as a Service Clouds currently offer computing resources, such as virtual machines, under the pay-per-use business model. Thus the IaaS Clouds can be leveraged to provide a coste cient, dynamically scalable video transcoding service. To use computing resources e ciently in a cloud computing environment, cost-e cient virtual machine provisioning is required to avoid overutilization and under-utilization of virtual machines. This thesis presents proactive virtual machine resource allocation and de-allocation algorithms for video transcoding in cloud computing. Since users' requests for videos may change at di erent times, a check is required to see if the current computing resources are adequate for the video requests. Therefore, the work on admission control is also provided. In addition to admission control, temporal resolution reduction is used to avoid jitters in a video. Furthermore, in a cloud computing environment such as Amazon EC2, the computing resources are more expensive as compared with the storage resources. Therefore, to avoid repetition of transcoding operations, a transcoded video needs to be stored for a certain time. To store all videos for the same amount of time is also not cost-e cient because popular transcoded videos have high access rate while unpopular transcoded videos are rarely accessed. This thesis provides a cost-e cient computation and storage trade-o strategy, which stores videos in the video repository as long as it is cost-e cient to store them. This thesis also proposes video segmentation strategies for bit rate reduction and spatial resolution reduction video transcoding. The evaluation of proposed strategies is performed using a message passing interface based video transcoder, which uses a coarse-grain parallel processing approach where video is segmented at group of pictures level.

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Reduced use of herbicides that cause environmental pollution problems is of great interest in modern agriculture. Soil mulching with gliricidia (Gliricidia sepium) branches does not have an allelopathic effect on corn, but decreases weed populations. The objective of this study was to evaluate the effects of gliricidia planting density, when grown as an intercrop, on weed control and corn yield parameters. A randomized block design with split-plots and ten replicates was adopted. Corn cultivars AG 1051 and BM 3061 were grown without hoeing, with two hoes (at 24 and 44 days after planting), and intercropped with gliricidia (planted simultaneously with corn, between crop rows, using two seedlings/pit, spaced at 30, 40, or 50 cm). Twenty-one weed species were found in the experimental area. Increased gliricidia planting density reduced weed biomass, but no difference was found between weed biomass in the intercrop and weed biomass in non-hoed corn. Gliricidia intercropped with corn, planted at a row spacing of 30 cm, did not significantly differ from hoed corn in most characteristics considered to evaluate green corn yield, although mean values were smaller. As to the number and weight of marketable green ears, reductions of 5% and 13%, respectively, were observed. Intercropping caused a 17% reduction in grain yield, reducing the losses (36%) observed in non-hoed corn by more than 50%. The highest green ear yield and grain yield values were obtained with two hoeings, while the lowest values were observed for non-hoed corn. The cultivars did not differ regarding green ear yield and grain yield.

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There has been interest in reducing the use of herbicides for weed control in order to decrease environmental degradation problems. The objective of this study was to evaluate the effects of gliricidia planting density sown by broadcasting and intercopping on green ear and corn grain yield as well as on weed control. A randomized block design with split-plots and five replicates were adopted. Cultivars AG 1051, BM 2022, and BM 3061, assigned to plots, were submitted to the following treatments: no hoeing, two hoeings (at 20 and 40 days after sowing), and intercropped with gliricidia sown at densities of 10 and 20 seeds m-2. Thirty weed species occurred in the experiment area, with Cucumis anguria as the most frequent ones. Cultivar BM 2022 was the best for the total number of ears (TNE) and number (NMHE) and weight of marketable husked ears. Together with cultivar AG 1051, this cultivar had the highest total weight and marketable unhusked ear weight (MUEW). However, the cultivars did not differ with respect to grain yield (GY). The highest green ear and corn grain yield and weed control percentages were obtained with two hoeings; in MUEW, NMHE and GY, intercropping provided intermediate means in comparison with those obtained in hoed and non-hoed plots, indicating that gliricidia was partially beneficial to corn. Increased gliricidia seeding density heightened the benefits to corn (TNE and MUEW). The lack of hoeing produced the poorest green ear and grain yields.

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The assembly and maintenance of the International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is highly challenging since the tasks performed by the robot involve welding, material handling, and machine cutting from inside the VV. The VV is made of stainless steel, which has poor machinability and tends to work harden very rapidly, and all the machining operations need to be carried out from inside of the ITER VV. A general industrial robot cannot be used due to its poor stiffness in the heavy duty machining process, and this will cause many problems, such as poor surface quality, tool damage, low accuracy. Therefore, one of the most suitable options should be a light weight mobile robot which is able to move around inside of the VV and perform different machining tasks by replacing different cutting tools. Reducing the mass of the robot manipulators offers many advantages: reduced material costs, reduced power consumption, the possibility of using smaller actuators, and a higher payload-to-robot weight ratio. Offsetting these advantages, the lighter weight robot is more flexible, which makes it more difficult to control. To achieve good machining surface quality, the tracking of the end effector must be accurate, and an accurate model for a more flexible robot must be constructed. This thesis studies the dynamics and control of a 10 degree-of-freedom (DOF) redundant hybrid robot (4-DOF serial mechanism and 6-DOF 6-UPS hexapod parallel mechanisms) hydraulically driven with flexible rods under the influence of machining forces. Firstly, the flexibility of the bodies is described using the floating frame of reference method (FFRF). A finite element model (FEM) provided the Craig-Bampton (CB) modes needed for the FFRF. A dynamic model of the system of six closed loop mechanisms was assembled using the constrained Lagrange equations and the Lagrange multiplier method. Subsequently, the reaction forces between the parallel and serial parts were used to study the dynamics of the serial robot. A PID control based on position predictions was implemented independently to control the hydraulic cylinders of the robot. Secondly, in machining, to achieve greater end effector trajectory tracking accuracy for surface quality, a robust control of the actuators for the flexible link has to be deduced. This thesis investigates the intelligent control of a hydraulically driven parallel robot part based on the dynamic model and two schemes of intelligent control for a hydraulically driven parallel mechanism based on the dynamic model: (1) a fuzzy-PID self-tuning controller composed of the conventional PID control and with fuzzy logic, and (2) adaptive neuro-fuzzy inference system-PID (ANFIS-PID) self-tuning of the gains of the PID controller, which are implemented independently to control each hydraulic cylinder of the parallel mechanism based on rod length predictions. The serial component of the hybrid robot can be analyzed using the equilibrium of reaction forces at the universal joint connections of the hexa-element. To achieve precise positional control of the end effector for maximum precision machining, the hydraulic cylinder should be controlled to hold the hexa-element. Thirdly, a finite element approach of multibody systems using the Special Euclidean group SE(3) framework is presented for a parallel mechanism with flexible piston rods under the influence of machining forces. The flexibility of the bodies is described using the nonlinear interpolation method with an exponential map. The equations of motion take the form of a differential algebraic equation on a Lie group, which is solved using a Lie group time integration scheme. The method relies on the local description of motions, so that it provides a singularity-free formulation, and no parameterization of the nodal variables needs to be introduced. The flexible slider constraint is formulated using a Lie group and used for modeling a flexible rod sliding inside a cylinder. The dynamic model of the system of six closed loop mechanisms was assembled using Hamilton’s principle and the Lagrange multiplier method. A linearized hydraulic control system based on rod length predictions was implemented independently to control the hydraulic cylinders. Consequently, the results of the simulations demonstrating the behavior of the robot machine are presented for each case study. In conclusion, this thesis studies the dynamic analysis of a special hybrid (serialparallel) robot for the above-mentioned special task involving the ITER and investigates different control algorithms that can significantly improve machining performance. These analyses and results provide valuable insight into the design and control of the parallel robot with flexible rods.

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Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

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Due to various advantages such as flexibility, scalability and updatability, software intensive systems are increasingly embedded in everyday life. The constantly growing number of functions executed by these systems requires a high level of performance from the underlying platform. The main approach to incrementing performance has been the increase of operating frequency of a chip. However, this has led to the problem of power dissipation, which has shifted the focus of research to parallel and distributed computing. Parallel many-core platforms can provide the required level of computational power along with low power consumption. On the one hand, this enables parallel execution of highly intensive applications. With their computational power, these platforms are likely to be used in various application domains: from home use electronics (e.g., video processing) to complex critical control systems. On the other hand, the utilization of the resources has to be efficient in terms of performance and power consumption. However, the high level of on-chip integration results in the increase of the probability of various faults and creation of hotspots leading to thermal problems. Additionally, radiation, which is frequent in space but becomes an issue also at the ground level, can cause transient faults. This can eventually induce a faulty execution of applications. Therefore, it is crucial to develop methods that enable efficient as well as resilient execution of applications. The main objective of the thesis is to propose an approach to design agentbased systems for many-core platforms in a rigorous manner. When designing such a system, we explore and integrate various dynamic reconfiguration mechanisms into agents functionality. The use of these mechanisms enhances resilience of the underlying platform whilst maintaining performance at an acceptable level. The design of the system proceeds according to a formal refinement approach which allows us to ensure correct behaviour of the system with respect to postulated properties. To enable analysis of the proposed system in terms of area overhead as well as performance, we explore an approach, where the developed rigorous models are transformed into a high-level implementation language. Specifically, we investigate methods for deriving fault-free implementations from these models into, e.g., a hardware description language, namely VHDL.

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The South American sea lion, Otaria flavescens, is widely distributed along the Pacific and Atlantic coasts of South America. However, along the Brazilian coast, there are only two nonbreeding sites for the species (Refúgio de Vida Silvestre da Ilha dos Lobos and Refúgio de Vida Silvestre do Molhe Leste da Barra do Rio Grande), both in Southern Brazil. In this region, the species is continuously under the effect of anthropic activities, mainly those related to environmental contamination with organic and inorganic chemicals and fishery interactions. This paper reports, for the first time, the genetic diversity of O. flavescens found along the Southern Brazilian coast. A 287-bp fragment of the mitochondrial DNA control region (D-loop) was analyzed. Seven novel haplotypes were found in 56 individuals (OFA1-OFA7), with OFA1 being the most frequent (47.54%). Nucleotide diversity was moderate (π = 0.62%) and haplotype diversity was relatively low (67%). Furthermore, the median joining network analysis indicated that Brazilian haplotypes formed a reciprocal monophyletic clade when compared to the haplotypes from the Peruvian population on the Pacific coast. These two populations do not share haplotypes and may have become isolated some time back. Further genetic studies covering the entire species distribution are necessary to better understand the biological implications of the results reported here for the management and conservation of South American sea lions.

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Liberalization of electricity markets has resulted in a competed Nordic electricity market, in which electricity retailers play a key role as electricity suppliers, market intermediaries, and service providers. Although these roles may remain unchanged in the near future, the retailers’ operation may change fundamentally as a result of the emerging smart grid environment. Especially the increasing amount of distributed energy resources (DER), and improving opportunities for their control, are reshaping the operating environment of the retailers. This requires that the retailers’ operation models are developed to match the operating environment, in which the active use of DER plays a major role. Electricity retailers have a clientele, and they operate actively in the electricity markets, which makes them a natural market party to offer new services for end-users aiming at an efficient and market-based use of DER. From the retailer’s point of view, the active use of DER can provide means to adapt the operation to meet the challenges posed by the smart grid environment, and to pursue the ultimate objective of the retailer, which is to maximize the profit of operation. This doctoral dissertation introduces a methodology for the comprehensive use of DER in an electricity retailer’s short-term profit optimization that covers operation in a variety of marketplaces including day-ahead, intra-day, and reserve markets. The analysis results provide data of the key profit-making opportunities and the risks associated with different types of DER use. Therefore, the methodology may serve as an efficient tool for an experienced operator in the planning of the optimal market-based DER use. The key contributions of this doctoral dissertation lie in the analysis and development of the model that allows the retailer to benefit from profit-making opportunities brought by the use of DER in different marketplaces, but also to manage the major risks involved in the active use of DER. In addition, the dissertation introduces an analysis of the economic potential of DER control actions in different marketplaces including the day-ahead Elspot market, balancing power market, and the hourly market of Frequency Containment Reserve for Disturbances (FCR-D).