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Transmission and Distribution Conference and Exposition: Latin America (T&D-LA), 2010 IEEE/PES

Date 8-10 Nov. 2010

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Displaying Results 1 - 25 of 140
  • [Title page]

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  • 2010 IEEE/PES Transmission and Distribution Conference and Exposition: Latin America (T&D-LA) [Copyright notice]

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  • Table of content

    Page(s): 1 - 18
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  • Commitees

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  • Authors index

    Page(s): 1 - 10
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  • Device to limit Transient Recovery Voltage

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    This paper summarizes the main results about design and evaluation of a device to reduce Transient Recovery Voltage (TRV) magnitude in medium voltage switching equipments. Zinc Oxide (ZnO) devices are modeled in an Electromagnetic Transients Program (EMTP), being applied as an alternative to limit TRV peaks in circuit breakers and reclosers of 15 kV and 72.5 kV voltage class. The assessment of device effectiveness in elimination of three-phase ungrounded and kilometric faults is performed with the purpose of providing information for testing and future deployment. Laboratory conditions are reproduced digitally describing the absorved energy by the device as a function of fault current and TRV frequency. The most severe cases allow the use of ZnO varistors commercially available, giving feasibility to achieve limiter devices. Results obtained in studies presented good agreement, showing that operations preliminarily qualified as unsafe can become permissive. Financial support usually used to replace equipment by another with higher voltage class can be reduced. View full abstract»

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  • Microgrid systems: Current status and challenges

    Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    The objective of this paper is to present the current status and state-of-the-art of microgrid systems as well as the barriers that are being encountered for their integration to the network. The expectation about the microgrid performance is high, thus, issues related to the microgrid standards, autonomous operation, control strategies, regulatory barriers as well as its protection and islanding operation, among other aspects, will be discussed herein. Some examples of practical installations worldwide will also be presented. View full abstract»

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  • Study on the influence of TCSC structure and control on SSR damping using an improved s-domain model

    Page(s): 13 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1133 KB) |  | HTML iconHTML  

    This paper investigates the influence of basic TCSC main circuit structure and control on subsynchronous torsional damping of a nearby turbine-generator. An improved s-domain model based on dynamic phasor approach was used to obtain the results presented in the paper. The study is conducted on the System-1 of the IEEE Second Benchmark Model. Detailed eigenvalue analyses are carried out in order to evaluate the effect of the proportion of TCSC to FSC, Boost Factor and size of TCSC reactor on subsynchronous damping. The influence of constant current controller and synchronization system (PLL) parameters is also investigated. Finally, a simple Subsynchronous Damping Controller (SSDC) is added to the TCSC main control in order to demonstrate that the SSR damping capability of TCSC may be enhanced by proper modulation of firing angle. The results obtained in the time domain simulations are validated through PSCAD/EMTDC simulations. View full abstract»

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  • Failure analysis of three 230kV XLPE cables

    Page(s): 22 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (897 KB) |  | HTML iconHTML  

    This paper presents a case study on the failures of three 230 kV XLPE cables. These cables failed after only 4 years of service. It was found that the copper woven fibre glass (CWFG) tape and the water swellable tape had many burnt stains. The causes of these stains were analysed. It was proved from theoretical analysis and experimental investigations that there was a problem of bad contact between the outer semi-conductive screen and the aluminum sheath. During operation, the charging current from system ac voltage damaged the semi-conductive layer and caused the insulation breakdown. The lessons learnt from these failures are also discussed in the paper. View full abstract»

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  • Experience in the evaluation of polymeric insulators for distribution systems in medium voltage through a natural laboratory

    Page(s): 26 - 31
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (671 KB) |  | HTML iconHTML  

    In order to identify possible shortcomings at design and manufacturing level, polymeric insulators are subjected to various tests at the laboratory established in ANSI C29.13-2000 and IEC 61109-1995 norms. One of these are environmental, which is done via simulations in laboratories, but these never become so severe and demanding as the present conditions of operation in the field. Therefore, this research develops a methodology to evaluate different designs of polymeric insulators (silicone rubber) suspension type with galvanized steel hardware, aluminum and polymer coated in a natural environment. For this, a specific area was available where environmental conditions are the most severe on the west coast of Zulia State, located north of the Venezuela Guajira, and establishing it as a Natural Laboratory. As a result recommendations were established for the characteristics of polymeric insulators to be used in the distribution network in the Zulia region, in order to obtain the highest reliability through the useful life. View full abstract»

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  • Ancillary services definitions, markets and practices in the world

    Page(s): 32 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    Ancillary services are some operational reserved services procured by the Transmission System Operator (TSO) for keeping a balance between supply and demand, stabilizing the transmission system and maintaining the power quality on an economical basis in any competitive electricity market environment. This paper discusses different types of ancillary services and their characteristics and challenges in the power market in order to find an efficient combination of ancillary services with the least reservation cost that secures reliable transmission system operation. An overview of practical experiences regarding performance of ancillary services in several competitive markets in the Europe, Australia and New Zealand will be discussed. Further, wind power as a disputable ancillary service will be presented in brief. In addition, some efficient proposals for revising the design and implementation of those markets will be mentioned in conclusions. View full abstract»

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  • Optimal Phasor Measurement Units Placement for fault location on overhead electric power distribution feeders

    Page(s): 37 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (531 KB) |  | HTML iconHTML  

    This paper proposes a new approach for optimal phasor measurement units placement for fault location on electric power distribution systems using Greedy Randomized Adaptive Search Procedure metaheuristic and Monte Carlo simulation. The optimized placement model herein proposed is a general methodology that can be used to place devices aiming to record the voltage sag magnitudes for any fault location algorithm that uses voltage information measured at a limited set of nodes along the feeder. An overhead, three-phase, three-wire, 13.8 kV, 134-node, real-life feeder model is used to evaluate the algorithm. Tests show that the results of the fault location methodology were improved thanks to the new optimized allocation of the meters pinpointed using this methodology. View full abstract»

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  • Automatic reestablishment of power supply in distribution systems using Smart Grid concepts

    Page(s): 44 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (886 KB) |  | HTML iconHTML  

    The continuity of electric energy supply to consumers is a permanent objective of the power utilities, pursuing the development of technological solutions to improve the performance of the power re-establishment in contingency conditions. The main purpose is to minimize the impact on the number of consumers affected and reduce the time required to re-establish the energy supply. In this way, the power utilities have been employing efforts for the automation of distribution networks in order to reestablish power in a more agile way, resulting in better indexes of continuity and increase consumer satisfaction. Therefore, the purpose of this paper is to develop a methodology to reestablish the electric energy supply by using remote-controlled switches, regarding the validation of the technical viability for distribution networks reconfiguration in real time by means of computational simulations, applying the Smart Grid concepts. The best option for the load transfer using remote-controlled switches, after contingencies, will be defined based on multicriteria decision making. The effectiveness of the proposed algorithm is demonstrated with case studies involving actual systems. View full abstract»

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  • Representation of transmission lines in modal domain using analytical transformation matrices

    Page(s): 50 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1270 KB) |  | HTML iconHTML  

    The phases of a transmission line are tightly coupled due to mutual impedances and admittances of the line. One way to accomplish the calculations of currents and voltages in multi-phase lines consists in representing them in modal domain, where its n coupled phases are represented by their n propagation modes. The separation line in their modes of propagation is through the use of a modal transformation matrix whose columns are eigenvectors associated with the parameters of the line. Usually, this matrix is achieved through numerical methods which does not allow the achievement of an analytical model for line developed directly in the phases domain. This work will show the modal transformation matrix of a hypothetical two-phase obtained with numerical and analytical procedures. It will be shown currents and voltage s at terminals of the line taking into account the use of modal transformation matrices obtained by using numerical and analytical procedures. View full abstract»

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  • Transmission lines using aluminium cable steel reinforced ground wires nearby power substations

    Page(s): 57 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    This article shows the advantages of using transmission lines with ACSR (Aluminium Cable Steel Reinforced) ground wires in the neighbourhood of high voltage power substations. The concept of selfneutralized current is reminded in order to explain why the utilization of a double ACSR ground wire 7-20 km from the transmission line terminal substations is able to reduce up to 65% the value of the terminal substation ground mat current. It is also shown that, for power cables with metallic shielding grounded in both terminal substation ground mats, the reduction of mat current can be as large as 99.5%. The article reminds that these procedures are already successfully used in several high voltage power substations now in operation. Some equivalent circuits are presented in order to allow a simple calculation of the value of the mat current (IM), using ACSR ground wires close to the terminal substations. It is also reminded that Steinmetz Circuit Theory has several advantages over the direct utilization of Maxwell Equations when computing A.C. transmission metallic circuits. View full abstract»

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  • Corrective effects of cable shielding with single or double grounding points-calculations and measurements

    Page(s): 65 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (755 KB) |  | HTML iconHTML  

    This article reports measurements carried out at Lactec high voltage laboratory. It also shows how to use Steinmetz Circuit Theory to obtain computed results very similar to measured values. The article also comments how difficult it is to obtain the same results using Shelkunoff Transfer Impedance Theory. The article also recalls basic principles of cable shielding technique. View full abstract»

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  • Basic design procedures to control electromagnetic interferences at power and telecommunication installations

    Page(s): 72 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    This article presents a summary of the standard design procedures successfully used by several Brazilian utilities to control electromagnetic interferences in power plants, substations and telecommunication installations. Those users stated in articles and conferences that the reported procedures controlled very well the interference problems in their facilities. The article shows that usual cable shielding is able to control basically the noises caused by periodic disturbances such as short circuits and harmonics. The article comments also a set of design procedures that are necessary to control the effects of the aperiodic disturbances, such as discharges, switching and circuit braker operation. View full abstract»

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  • Location of linghtning arresters at digitalized installations - A critical review

    Page(s): 79 - 85
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    This article presents a critical analysis of the 3 different methodologies to determine the suitable location of lightning arresters that are simultaneously accepted by some Brazilian and international standards. View full abstract»

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  • Distribution system restoration in a DG environment using a heuristic constructive multi-start algorithm

    Page(s): 86 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB) |  | HTML iconHTML  

    This paper proposes a heuristic constructive multi-start algorithm (HCMA) to distribution system restoration in real time considering distributed generators installed in the system. The problem is modeled as nonlinear mixed integer and considers the two main goals of the restoration of distribution networks: minimizing the number of consumers without power and the number of switching. The proposed algorithm is implemented in C++ programming language and tested using a large real-life distribution system. The results show that the proposed algorithm is able to provide a set of feasible and good quality solutions in a suitable time for the problem. View full abstract»

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  • Multi-area decentralized optimal VAr planning using the Dantzig-Wolfe decomposition principle

    Page(s): 92 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    This paper presents a new methodology for solving the optimal VAr planning problem in multi-area electric power systems, using the Dantzig-Wolfe decomposition. The original multi-area problem is decomposed into subproblems (one for each area) and a master problem (coordinator). The solution of the VAr planning problem in each area is based on the application of successive linear programming, and the coordination scheme is based on the reactive power marginal costs in the border bus. The aim of the model is to provide coordinated mechanisms to carry out the VAr planning studies maximizing autonomy and confidentiality for each area, assuring global economy to the whole system. Using the mathematical model and computational implementation of the proposed methodology, numerical results are presented for two interconnected systems, each of them composed of three equal subsystems formed by IEEE30 and IEEE118 test systems. View full abstract»

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  • Technical solutions for harmonic resonance at MV: Relocatable capacitor bank technique

    Page(s): 99 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1146 KB) |  | HTML iconHTML  

    Capacitor banks are installed to compensate the reactive energy demanded by the local loads or feeder reactance, in order to adequate the voltage and technical losses. Although those benefits of installing capacitor banks in feeders are incontestable, the engineers should consider the harmonic resonance effects and the possibility of this resonance to increase the voltage distortion to levels above of the acceptable limits. In fact, the problems related to harmonics are spreading on MV systems due to the increasing quantity of disturbing loads. This work presents one case under survey at CPFL Paulista, where a feeder supplies several non-linear loads in two plants and three automatic capacitor banks. On weekdays, the harmonic voltage distortion levels were lower than the limits, but on the weekends, the limits exceeded, when most of non-linear loads were disconnected. At first analysis, there was a possibility of the consumer loads are operating as passive filters to the feeder. However, after the analysis of measurements and of the capacitor banks operations, it was possible to conclude that the feeder has resonance conditions due to the power factor correction of the capacitor banks. The paper presents three different approaches for solving the harmonic resonance problems, using the ATPDraw as a tool of simulation, and then recommendations for practical applications. The first one is to replace the capacitor bank in the same feeder, with relocatable capacitor bank technique; second, to reconfigure existing capacitor banks with a detuned reactive power, and the last one is to switch off the capacitor bank on the weekend when the non-linear loads are out, by automatic controller. View full abstract»

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  • Reactive power support pricing of Distributed Generators with primary energy source uncertainty

    Page(s): 104 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1023 KB) |  | HTML iconHTML  

    In this paper, a novel methodology to price the reactive power support ancillary service of Distributed Generators (DGs) with primary energy source uncertainty is shown. The proposed methodology provides the service pricing based on the Loss of Opportunity Costs (LOC) calculation. An algorithm is proposed to reduce the uncertainty present in these generators using Multiobjective Power Flows (MOPFs) implemented in multiple probabilistic scenarios through Monte Carlo Simulations (MCS), and modeling the time series associated with the generation of active power from DGs through Markov Chains (MC). View full abstract»

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  • Effect of distributed generation capacity on the coordination of protection system of distribution network

    Page(s): 110 - 115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (451 KB) |  | HTML iconHTML  

    Conventional power distribution system is radial in nature, characterized by a single source feeding a network of downstream feeders. Protection scheme for distribution system, primarily consisting of fuses and reclosures and, in some cases, relays, has traditionally been designed assuming the system to be radial. In last year extra attention applied in use of distributed generator units in distribution networks. The integration of distributed sources into existing networks brings up several technical, economical and regulatory questions. The connection of distributed generators (DG) to distribution networks also influences the performance of the networks and the impact depends on the number, location and size of injected DG. The presence of distributed generators in the distribution network can cause the mis-coordination of the protection system. In order to overcome this problem, one can change the relay setting based on the number and location of DGs in the network. In this paper, another approach is selected in which, the capacity of DG at each node is determined in such a way, that the mis-coordination does not happen. The proposed method is explained in two cases. In the first case, just one DG at each node is considered, but in the second case existence of two or more DGs in separate nodes is taken into account. The simulation result are presented and discussed in a typical distribution network. View full abstract»

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  • Tap-off power from a transmission line shield wires to feed small loads

    Page(s): 116 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    In this article, the feasibility to obtain power from the shield wires of a transmission line, as a result of the electromagnetic induction effect, will be presented. The phase conductors of the considered transmission line are horizontally arranged each having a quadruple bundle configuration. The transmission line used during the study operates at 525 kV. The results obtained showed that this form of power generation can be a feasible and cost-effective alternative for feeding small loads along a transmission line when compared to other forms of electricity supply. In order to obtain the highest induced current some shield conductor configurations were analyzed. The simulation tool used for analyzing the electromagnetic induction was the Alternative Transients Program (ATP). View full abstract»

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  • Decentralized robust control for FACTS using hankel reduced order models

    Page(s): 122 - 126
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1090 KB) |  | HTML iconHTML  

    This paper presents a decentralized robust control scheme for two types of FACTS devices: SVC and TCSC, to enhance the voltage and angular stability in a power system. The robust control scheme is based on reduced order models, which are computed using the Hankel reduction theory. After that, computation of decentralized robust controls is proposed and tested in a two-area 68 nodes system. View full abstract»

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