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  • 1.
    Alvarez, Manuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Distribution Network Planning Considering Capacity Mechanisms and Flexibility2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing penetration of distributed energy resources (DERs) has posed challenges to the distribution system operator (DSO) from the operation and regulatory point of view. High penetration of DERs could have negative impacts on the performance of the distribution grid, and depending on the regulatory framework, the DSO's remuneration as well. In liberalized electrical systems, the focus on promoting eciency has led to the implementation of an incentive-based regulation that exerts additional pressure on the DSOs to reduce costs. Additionally, the European Parliament Directive 2009/72/EC establishes a regulatory unbundling among the distribution, production, and retailing activities within the same vertically integrated electric utility.

    A way of helping the DSO to cope with the posed challenges is by providing it with exibility. This exibility can be acquired from the planning stage, and later be used during the system operation. This exibility can stem from the DSO's ability to exert control on the demand and the supply side to balance the system and correct its operational state.

    Based on the European DSOs' current situation at facing the increasing penetration of DERs, this thesis investigates in non-wired exible grid tools to solve the distribution network expansion problem. The investigation focuses on exibility providers, in particular on energy storage systems and hydropower, and also on capacity mechanisms to translate the capacity from DERs into the grid's capacity for planning purposes.

    Given that the share of renewable sources among the DERs is increasing, and considering the importance of energy storage systems in providing exibility to balance renewable energy production, the eort has been turned on to developing a hydropower model and a generic storage model that t both planning and operational studies.

    Given the need for gearing the DERs' behavior into the DSO's decision making process during the planning and operational timescales, the design and implementation of a distribution capacity mechanism have been developed. The design of the capacity mechanism has been conceived considering its integration within the distribution network expansion problem.

    The outcomes of this thesis can be synthesized as follows: 1) A generic hydraulic/storage model provided with an equivalent marginal cost that aids in considering the impact of present decisions in the future costs. 2) A market oriented distribution capacity mechanism that gears DERs and the DSOs to benefit mutually. 3) A distribution network expansion planning formulation that integrates the capacity resource from DERs through the distribution capacity mechanism.

  • 2.
    Alvarez, Manuel
    et al.
    Universidad Simón Bolívar, Caracas.
    Bermúdez, Juan
    Universidad Simón Bolívar, Caracas.
    Marginal pricing via penalty factors in the Venezuelan hydrothermal system2006In: 2006 IEEE PES Transmission and Distribution Conference and Exposition: Latin America, TDC'06, Piscataway, NJ: IEEE Communications Society, 2006, article id 4104756Conference paper (Refereed)
    Abstract [en]

    The work shown next deals with the definition of nodal marginal prices, in the context of an economic dispatch solution with transmission losses. The losses are incorporated through penalty factors obtained from line distribution factors, using a linearization process. This study is applied to the hydrothermal venezuelan system, considering plants with regulation capability and run-of-river dams. The objective function to be minimized includes present and future thermal costs. In addition, a discussion is given about the correct location of the slack node, in order to get similar results to these associated to an OPF solution. © 2006 IEEE.

  • 3.
    Alvarez, Manuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Gil-de-Castro, Aurora
    University of Cordoba, Electronics and Electronic Technology Area, University of Cordoba.
    A Smart Distribution Toolbox for Distribution System Planning2015Conference paper (Refereed)
    Abstract [en]

    The distribution system planner should be able to coordinate smart grid solutions in order to find cost effective expansions plans. These plans should be able to deal with new added system uncertainties from renewable production and consumers while guaranteeing power quality and availability of supply. This paper proposes a structure for distribution systems planning oriented to help the planner in deciding how to make use of smart solutions for achieving the described task. Here, the concept of a system planning toolbox is introduced and supported with a review of relevant works implementing smart solutions. These are colligated in a way that the system planner can foresee what to expect with their combined implementation. Future developments in this subject should attempt to theorize a practical algorithm in an optimization and decision making context.

  • 4.
    Alvarez, Manuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Jabr, Rabih
    American University of Beirut.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Frías, Pablo
    Universidad Pontificia de Comillas.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Capacity Mechanisms for Distribution Network Expansion Planning2019In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208Article in journal (Refereed)
  • 5.
    Alvarez, Manuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Frías, Pablo
    Comillas Pontifical University, Madrid, Spain.
    Cossent, Rafael
    Comillas Pontifical University, Madrid, Spain.
    Jabr, Rabih
    American University of Beirut, Beirut, Lebanon.
    Zhong, Jin
    The University of Hong Kong, Hong Kong, China.
    A Capacity Mechanism Design for Distribution Network Expansion Planning2018In: 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2018, article id 8493874Conference paper (Refereed)
    Abstract [en]

    Capacity remuneration mechanisms have been originally oriented to ensure availability and continuity of supply on the power generation pool. Equivalent generation-based capacity mechanisms could be implemented to enhance and prolong the usability of the distribution grid. In particular, such capacity mechanisms would provide an alternative to traditional expansion options leading to investment deferral. In this work, a distribution capacity mechanism to fit within a distribution network planning methodology will be proposed and discussed. The capacity mechanism will be outlined following similar guidelines as for the design of capacity mechanisms used in the energy only market. The result of the design is a volume based capacity auction for a capacity-constrained system, oriented to both the active and the reactive power provision.

  • 6.
    Alvarez Perez, Manuel Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Stochastic Planning of Smart Electricity Distribution Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The penetration of intermittent Distributed Generation (DG) brought additional uncertainty to the system operation and planning. To cope with uncertainties the Distribution System Operator (DSO) could implement several strategies. These strategies range from the inclusion of smart technologies which will increment system’s flexibility and resiliency, to improvements in forecasting, modeling, and regulatory pledge that will facilitate the planning activity. Regardless of the nature of the solutions, they could be collected in a sort of toolbox. The planner will access the toolbox to conform cost effective plans, better able to deal with any uncertainty. The present work will address the problem of distribution system planning under uncertainties, considering smart solutions along with traditional reinforcements, in the short-term lead time up to 3 years ahead. The work will be focused on three aspects that are the cornerstones of this work:

     • A planning facilitating strategy: Distribution Capacity Contracts (DCCs).

     • A flexibility enabler technology: Energy Storage.

     • A binding methodology: Multistage Stochastic Programming. Stochastic dual dynamic programming (SDDP). 

    Under the present directive of the European Parliament concerning common rules for the internal market in electricity, distribution companies are not allowed to own DG but entitled to include it as a planning option to differ investment in traditional grid reinforcements. An evaluation of the regulatory context will lead this work to consider DCCs as a planning alternative available in the toolbox. The impact of this type of contract on the remuneration of the DG owner will be assessed in order to provide insight on its willingness to participate. The DCCs might aid the DSO to defer grid i ii investments during planning stages and to control the network flows during operation. 

    Given that storage solutions help to match in time production from intermittent sources with load consumption, they will play a major role in dealing with uncertainties. A generic storage model (GSM) based on a future cost piecewise approximation will be developed. This model inspired by hydro-reservoirs will help assessing the impact of storage in planning decisions. This model will be tested by implementing it in short-term hydro scheduling and unit commitment studies. 

    To trace a path towards the future of this research work, a discussion on the planning problem formulation, under consideration of the lead time, the expansion options, the smart strategies, and the regulatory framework will be presented. Special focus will be given to multistage stochastic programming methods and in particular to the SDDP approach.

  • 7.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. The University of Hong Kong.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    A Generic Storage Model Based on a Future Cost Piecewise-Linear Approximation2019In: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 10, no 1, p. 878-888Article in journal (Refereed)
    Abstract [en]

    This work presents a generic storage model (GSM) inspired by the scheduling of hydraulic reservoirs. The model for steady state short-term (ST) operational studies interlaces with the long-term (LT) energy scheduling through a piecewise-linear Future Cost Function (FCF). Under the assumption that a Stochastic Dual Dynamic Programming (SDDP) approach has been used to solve the energy schedule for the LT, the FCF output from that study will be processed to obtain an equivalent marginal opportunity cost for the storage unit. The linear characteristic of a segment of the future cost function (FCF) will allow a linear modeling of the storage unit production cost. This formulation will help to coordinate the renewable resource along with storage facilities in order to find the optimal operation cost while meeting end-point conditions for the long-term plan of the energy storage. The generic model will be implemented to represent a battery storage and a pumped-hydro storage. A stochastic unit commitment (SUC) with the GSM will be formulated and tested to assess the day-ahead scheduling strategy of a Virtual Power Plant (VPP) facing uncertainties from production, consumption, and market prices.

  • 8.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    A Hydro-Reservoir Generic Storage Model for Short-Term Hydrothermal Coordination2017In: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980882Conference paper (Refereed)
    Abstract [en]

    This work presents a linear solution for the short-term hydro-thermal scheduling problem linked to long-term conditions through a piecewise-linear Future Cost Function (FCF). Given end-point conditions to conform long-term water releases, and given actual reservoir conditions, a segment of a pre-built piecewise future cost function will be chosen. The linear characteristic of the FCF segment will allow a linear modeling of the hydro-power plant, in a similar fashion as a thermal unit with an equivalent marginal opportunity cost. A short-term hydro thermal coordination problem will be formulated considering parallel and cascaded hydro-reservoirs. Three study cases involving different reservoir configurations and scenarios will be computed to test the model. The results of this model mimics coherently the future-cost hydro-thermal coordination problem for the different configurations tested. Given similarities with other forms of energy storage, a new theoretical model for generic storage will be proposed and discussed.

  • 9.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bermúdez, Juan
    Department of Energy Conversion and Transport, Simón Bolívar University.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Reservoir-Type Hydropower Equivalent Model Based on a Future Cost Piecewise Approximation2018In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 155, p. 184-195Article in journal (Refereed)
    Abstract [en]

    The long-term (LT) scheduling of reservoir-type hydropower plants is a multistage stochastic dynamic problem that has been traditionally solved using the stochastic dual dynamic programming (SDDP) approach. This LT schedule of releases should be met through short-term (ST) scheduling decisions obtained from a hydro-thermal scheduling that considers uncertainties. Both time scales can be linked if the ST problem considers as input the future cost function (FCF) obtained from LT studies. Known the piecewise-linear FCF, the hydro-scheduling can be solved as a one-stage problem. Under certain considerations a single segment of the FCF can be used to solve the schedule. From this formulation an equivalent model for the hydropower plant can be derived and used in ST studies. This model behaves accordingly to LT conditions to be met, and provides a marginal cost for dispatching the plant. A generation company (GENCO) owning a mix of hydro, wind, and thermal power will be the subject of study where the model will be implemented. The GENCO faces the problem of scheduling the hydraulic resource under uncertainties from e.g. wind and load while determining the market bids that maximize its profit under uncertainties from market prices. A two-stage stochastic unit commitment (SUC) for the ST scheduling implementing the equivalent hydro model will be solved.

  • 10.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Regulatory Matters Affecting Distribution Planning With Distributed Generation2017In: CIRED - Open Access Proceedings Journal, E-ISSN 2515-0855, Vol. 2017, no 1, p. 2869-2873Article in journal (Refereed)
    Abstract [en]

    Under the present European directive concerning common rules for the internal market in electricity, distribution companies are not allowed to own distributed generation (DG) but encouraged to include it as a planning option to defer investment in traditional grid reinforcements. Distribution system operators (DSOs) have used the provision of capacity contracted to DG as a viable alternative under current regulatory arrangements. Here, the topics bonding DSOs and DG owners under the present regulation will be explored and a planning structure that considers distribution capacity contracts as a planning option will be proposed. This will serve as a road map for DSOs to implement its preferred planning tools in an optimisation context, considering costs of investment, reliability, operation, and capacity provision while complying with current regulation.

  • 11.
    Alvarez Perez, Manuel Alejandro
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Rönnberg, Sarah
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Cossent, Rafael
    Universidad Pontificia de Comillas.
    Zhong, Jin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Remuneration Assessment of a VPP Providing Distribution Capacity Services2017In: IEEE PES PowerTech Manchester 2017: towards and beyond sustainable energy systems, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980881Conference paper (Refereed)
    Abstract [en]

    A Distribution System Operator (DSO) might consider a capacity contract as a planning alternative to defer grid investments. A Virtual Power Plant (VPP) might be able to provide such capacity and change its production as requested by the DSO. This article presents an assessment of the impact of this type of distribution capacity contract (DCC) on VPP's remuneration. This assessment is done by comparing the optimal production / bidding strategy which maximize its profit, under presence or absence of these contracts. The impact of intermittent generation and storage while evaluating these scenarios will be investigated as well. A stochastic unit commitment will be used to determine the VPP's strategy under uncertainties from wind power, load, market prices, and the requested power by the DSO. The model showed that the VPP involvement in distribution capacity contracts can improve its remuneration when certain types of Distributed Energy Resources (DER) are used to provide the service.

  • 12.
    Bermúdez, Juan
    et al.
    Universidad Simón Bolívar.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Inclusion of ancillary services in a cost-based centralized economic dispatch solution for hydrothermal systems2007In: LESCOPE'07: 2007 Large Engineering Systems Conference on Power Engineering : conference proceedings : the Delta Centre-Ville Hotel, Montreal, Quebec, Canada, October 10-12, 2007, Piscataway, NJ: IEEE Communications Society, 2007, p. 131-136, article id 4437366Conference paper (Refereed)
    Abstract [en]

    In this paper a centralized economic dispatch is developed, where some services are included, associated to frequency control and generation outages. The study can consider thermal machines but hydro turbines as well, both of the run-of-river or regulation type, in whose case the objective function is the present and future thermal cost in the context of the stochastic dual dynamic programming (SDDP), simplified for academic purposes [8][6]. In this study the immediate plus future thermal cost is minimized, taking into account the primary reserves requirement in each unit (speed governor primary action), plus the AGC reserve, besides the (tertiary) reserves, associated to the outage of any turbine (n-1 criterion). The problem proposed was resolved using a linear programming commercial package. For the sake of clarifying the results, some didactical cases are solved, where comparisons are discussed between the traditional energy-only dispatch and the model herein proposed. This paper extends in a very simple manner the results of a traditional cost-based centralized economic dispatch, of the hydrothermal case, to include the AGC restrictions and spinning reserves requirements. © 2007 IEEE.

  • 13.
    Bermúdez, Juan
    et al.
    Universidad Simón Bolívar.
    Alvarez, Manuel
    Universidad Simón Bolívar.
    Villasana, R.
    Universidad Simón Bolívar.
    Khodr, H. M.
    GECAD–Knowledge Engineering and Decision-Support Research Group of the Electrical Engineering Institute of Porto.
    Una metodologia para combinar los manteniminentos forzados y preventivos en etapas de panficacion2009Conference paper (Refereed)
    Abstract [en]

    El Mantenimiento Correctivo (MC) o forzado es clásicamente un evento de naturaleza aleatoria,pero el Mantenimiento Preventivo (MP) o programado puede ser considerado un eventodeterminístico. Ahora bien, estrictamente hablando es imposible predecir cuándo exactamente unequipo será parado por efectos de MP, ni cuánto tiempo durará en ese estado. Por ende, a pesar decualquier programación que pueda realizarse, el MP es en realidad un evento aleatorio, cuyostiempos de permanencia en cada uno de sus vertientes (equipo operativo / equipo no operativo),pueden considerarse exponencialmente distribuidos, si el equipo está dentro de su periodo de deVida Útil. De ser así, la teoría de Markov puede ser utilizada para definir una forma de combinarlos dos procesos aleatorios, a nivel de la tasa de fallas y la duración de las paradas para cadaequipo, para posteriormente extender la aplicación a sistemas complejos, con generación ytransmisión considerados simultáneamente.En este trabajo se desarrolla tal esquema, el cual una vez formulado es aplicado a cálculostradicionales de confiabilidad en sistemas de potencia, tales como LOLE, ELOL, Elementos enSerie/Paralelo y Conjuntos de Corte. Se hacen comparaciones con las consideracionesdeterminísticas tradicionales, que sirvan para ilustrar las bondades de la metodología propuesta.Obviamente esta metodología se adapta perfectamente a las modernas simulaciones de MonteCarlo.

  • 14.
    Bermúdez, Juan
    et al.
    Universidad Simón Bolívar.
    Leanez, F.
    Pontificia Universidad Católica de Chile.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Khodr, H. M.
    GECAD - Knowledge Engineering and Decision-Support Research Center.
    A generalized methodology based on symmetrical components for multiple-fault calculation in power systems2009In: Electric power components and systems, ISSN 1532-5008, E-ISSN 1532-5016, Vol. 37, no 10, p. 1081-1101Article in journal (Refereed)
    Abstract [en]

    This article presents an efficient computational method to solve the problem of simultaneous multiple faults in power systems, using a conventional symmetrical component formulation. The methodology made possible the development of a programming routine, which takes into account a generic set of boundary conditions for almost any type of fault or combination of faults that can occur simultaneously, involving any number of phases. The program was tested with IEEE 14-, 57-, 118-, and 300-busbar benchmark systems facing up to ten simultaneous series and shunt faults. The results were satisfactorily tested against classical three-phase formulation solutions.

  • 15.
    Castro, Guillermo
    et al.
    Inelectra, Caracas.
    Bermúdez, Juan
    Universidad Simón Bolívar, Caracas.
    Jimenez, Manuel
    Universidad Simón Bolívar, Caracas.
    Alvarez, Manuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Arreaza, Alex
    Derwick Associates of Venezuela.
    AVRs and PSSs Revisited2015In: 2015 9th International Conference on Electrical and Electronics Engineering: ELECO 2015, Bursa, Turkey, 26 - 28 November 2015, Piscataway, NJ: IEEE Communications Society, 2015, p. 1006-1010, article id 7394473Conference paper (Refereed)
    Abstract [en]

    In this paper a conceptual analysis on the effect ofAutomatic Voltage Regulators (AVR) and Power SystemStabilizers (PSS) for small signal stability (SSS) of powersystems is developed. A modal formulation approachincluding the use of the Participation Matrix is used. TheModal Formulation is performed considering synchronousgenerator (SG) equations for both the Electromotive Forces(EMF) model and the Flux Linkages (FL) model as well asAVR and PSS equations. Then, a selected study case isevaluated to study the effect of the AVR and PSS on thesmall signal stability. For pedagogical purposes acomparison between the basic RLC circuit and asynchronous generator connected to an infinite bus, toclarify the concepts of synchronizing torque and dampingtorque, is presented.1. Introduction

  • 16.
    Jesus, P. M. De Oliveira-De
    et al.
    Energy Institute and Department of Conversion and Energy Delivery, Simon Bolivar University, Caracas.
    Alvarez, Manuel
    Energy Institute and Department of Conversion and Energy Delivery, Simon Bolivar University, Caracas.
    Yusta, J. M.
    Department of Electrical Engineering, University of Zaragoza.
    Distribution power flow method based on a real quasi-symmetric matrix2013In: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 95, p. 148-159Article in journal (Refereed)
    Abstract [en]

    This paper presents a new load flow formulation to solve active and passive electric distribution networks. The fundamental idea discussed here is how to obtain the power flow solution by using the elements of a unique quasi-symmetric matrix called TRX in the iterative process. The method is formulated for single-phase balanced and three-phase unbalanced radially operated networks. It works with real variables as opposed to complex variables used in previous backward/forward sweep algorithms discussed in literature. The proposed TRX matrix constitutes a complete database by including information of network topology structure as well as branch impedances of the distribution feeder. Data arrangement is suitable to be exchanged under standard Common Information Model (CIM) under Distribution Management Systems (DMS) environment allowing an efficient computation of the state of the system for on-line and off-line study applications. The proposed methodology was applied on a group of IEEE test systems and a real distribution system of 49,000 nodes. © 2012 Elsevier B.V. All rights reserved.

  • 17. Jesus, P.M. De Oliveira-De
    et al.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Leao, MT Ponce de
    Yusta, J. M.
    University of Zaragoza.
    Uncertainty Assessment of Incremental Transmission Loss Factors2008In: Power systems and power technology: proceedings of the 8th WSEAS International Conference on Power Systems (PS 2008) ; Santander, Cantabria, Spain, September 23 - 25, 2008 / [ed] José Ma. Zamanillo Sáinz de la Maza, WSEAS Press , 2008, p. 195-200Conference paper (Refereed)
  • 18.
    Jesus, PM De Oliveira-De
    et al.
    Universidad Simón Bolívar.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Leao, MT Ponce de
    DEEC-FEUP Oporto.
    Yusta, JM
    Universidad de Zaragoza.
    A Novel Approach to Evaluate Incremental Transmission Losses2009In: WSEAS Transactions on Power Systems, Vol. 4, no 1, p. 12-21Article in journal (Refereed)
    Abstract [en]

    During the past thirty years, the evaluation of incremental losses in transmission systems has beenwidespread around the world encompassing a fundamental task in order to solve the well-known economic dispatchproblem. Nowadays, incremental losses or computation of penalty factors has gained a new relevance allocatingtransmission losses among market participants being integrated in the spot pricing model. Nevertheless, vagueness in power injections from load demand and renewable resources has a fundamental influence on transmission incremental losses, and consequently affecting spot prices of the energy. This paper presents a new method to compute Incremental Transmission Loss (ITL) factors taking into account the effect of uncertainty on power injections due to measurement errors or future estimation. Fuzzy Set Theory is applied to deal with vagueness of information about power injections. The proposed technique provides a broad spectrum of feasibility of incremental losses in order to perform operational planning tasks by Transmission System Operators or network regulators. A 3-bus system is used to illustrate the proposed methodology.

  • 19.
    Piemonti, Carlos
    et al.
    Universidad Simón Bolívar, Caracas.
    Bermúdez, Juan
    Universidad Simón Bolívar.
    Khodr, H. M.
    Universidad Simón Bolívar, Caracas.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Optimal solutions for the Venezuelan unit commitment hydrothermal system2006In: 2006 IEEE PES Transmission and Distribution Conference and Exposition: Latin America, TDC'06, Piscataway, NJ: IEEE Communications Society, 2006, article id 4104749Conference paper (Refereed)
    Abstract [en]

    This work is about different optimal solutions for the unit commitment problem in the Venezuelan hydrothermal power system, disregarding the transmission system. The centralized cost-based maximum net social benefit solution, the oligopoly solution and the unregulated monopoly solution are formulated and analyzed. The oligopoly is studied via Nash-Cournot equilibrium, obtained iteratively considering both price-maker and price-taker firms. The price-demand curves are created using a price-demand elasticity parameter. The hydro plants can be of the run-of-river type or can have a regulation period, like in the case of Guri. In latter case the future profit is represented by a fixed volume of water to be turbined in the day ahead. Since integer variable are necessary to simulate the shut-down, start-up process a mixed integer commercial programming application is employed. © 2006 IEEE.

  • 20.
    Sorrentino, Elmer
    et al.
    Universidad Simón Bolívar, Caracas.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Análisis de la Curva de Daño de Transformadores para Varias Conexiones Usadas en Sistemas de Distribución2010Conference paper (Refereed)
    Abstract [en]

    Resumen—Se presenta un análisis de las curvas de daño de lostransformadores de distribución para las siguientes conexiones:a) monofásica, con toma central en el secundario; b) estrellaabierta-delta abierta, con o sin toma central en una rama de ladelta secundaria; c) delta abierta-delta abierta, con o sin tomacentral en una rama de la delta secundaria; d) estrella-delta,con toma central en una rama de la delta secundaria, con o sinpuesta a tierra del neutro de la estrella primaria; e) delta-delta,con toma central en una rama de la delta secundaria. Para cadauno de los casos se obtuvo el factor por el cual hay quemultiplicar las corrientes con el fin de trasladarhorizontalmente la curva de daño del transformador. Dichofactor es necesario para verificar si la protección primariaefectivamente protege al equipo. Además, se analizó el efecto deemplear transformadores monofásicos de distinta capacidad.

  • 21.
    Sorrentino, Elmer
    et al.
    Universidad Simón Bolívar, Caracas.
    Alvarez, Manuel
    Universidad Simón Bolívar, Caracas.
    Multipliers to shift the through-fault protection curve for various connections of distribution transformers2011In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 26, no 3, p. 2055-2057, article id 5725148Article in journal (Refereed)
    Abstract [en]

    This paper presents the multipliers to shift the through-fault protection curve for various connections of distribution transformers. Cases with a secondary center tap and with secondary open delta were analyzed as well as the effect of using single-phase units with different short-circuit impedances. © 2011 IEEE.

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