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The Distribution System of the Zona Especial de Desarrollo Mariel (ZDEM) is deficient today because it was designed for a much higher load level than the one it works with. The indices of electrical losses in this scheme exceeded the limits established by the Unión Eléctrica de Cuba (UNE). In order to reduce these losses, five proposals for the reconfiguration of the distribution circuits were analyzed (transformer connections with the system), which were aimed at reducing the number of transformers connected in the substations, which contributed considerably to the increase in electrical losses as they were very underloaded concerning their rated power. After completing the analysis of the proposals, the electrical scheme improved reliability, the installed capacity was reduced by half, and total losses decreased. [ABSTRACT FROM AUTHOR]

The proliferation of renewable energy sources and their impact on power systems makes it necessary to conduct studies to ensure the proper operation of the power system. This paper investigates recent research on the impact of renewable energy sources on voltage stability and new methods used to assess this stability. The effects of solar and wind power generation both individually and collectively are studied, along with other inverter models through which renewable energy sources are connected to transmission systems or distribution networks. In addition, the results are highlighted by categorizing them into a deterministic and probabilistic approach. [ABSTRACT FROM AUTHOR]

Optimal distribution networks reconfiguration is very important in reducing losses and operating costs and in improving networks security, stability and reliability indicators. The work objective is reprogramming an algorithm that improves results obtained previously. Paper presents non-dominated classification genetic algorithm II parts adaptation and reprogramming, with a new coding that, unlike previous authors, avoids modified genetic operators and take better advantage of algorithm's potentialities. In addition, graph theory is used to transform non-feasible individuals and avoid new generations of them, dispensing with annoying mesh checking and reducing the search space and computational burden. Proposal's effectiveness was tested with 33 and 70 bars test distribution systems, showing promising results and better than previous proposals. [ABSTRACT FROM AUTHOR]

The problem of the optimal location and sizing of photovoltaic (PV) sources in electrical distribution systems is addressed in this article through the application of the black widow optimization algorithm (BWOA). This problem is of mixed-integer nonlinear nature and is addressed by a master-slave type optimization strategy. In the master stage, the BWOA defines the location and size of the PV generators through discrete-continuous coding, and with this information, the slave stage (power flow for distribution) determines the electrical variables of the system, with which is evaluated the objective function and the constraints of the problem. As an objective function, the minimization of the annual costs of operation and maintenance of the system is considered, added to the total costs of purchasing energy in the electrical network for a planning period of 20 years. The numerical results in the IEEE 34- and IEEE 85-node systems show that with the proposed optimization methodology it is possible to reduce around 27% of the annual operating costs in both systems with the optimal location of three photovoltaic sources. Comparisons with metaheuristics and exact methodologies reported in the specialized literature confirm the efficiency and robustness of the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper presents the optimal location and sizing of distributed generators and capacitor banks in radial distribution networks to minimize the active and reactive power losses. A mixed-integer nonlinear mathematical model is proposed to formulate the problem. This mathematical model is solved through general algebraic modeling system (GAMS) and the CONOPT solver. GAMS implementation is presented with 10 nodes test system classical used in the specialized literature. As test system, the 33 nodes system is used under three simulation scenarios. The first simulating scenario consists only in the location of distributed generators, while the second scenario evaluates only the location of capacitor banks and the third scenario combines both elements. The simulation results obtained show that the integration of both elements improve significantly the operating features of the system by comparison with the first two scenarios analyzed. [ABSTRACT FROM AUTHOR]

An efficient methodology for the optimal selection of conductor in distribution systems through the implementation of the metaheuristic optimization technique called Tabu Search is presented in this paper. To represent the problem a mono-objective mathematical model of nonlinear mixed integer type is used. The minimization of investment costs of conductors and operating costs (power losses) for a study period of one year is considered as objective function. A single-phase equivalent system is used for the evaluation. The set of constraints relates to technical and operational characteristics of the system, which are assessed through a backward/forward sweep load flow. Initial configuration to tabu search algorithm is created by using a constructive heuristic that ensures feasibility of the initial solution; to generate the neighborhood strategies of tree searching and graph theory are used. In order to verify its applicability and efficiency, two test feeders of specialized literature are employed, obtaining better quality results than those reported in the literature. [ABSTRACT FROM AUTHOR]

Primary distribution systems contain asymmetries in the lateral circuits and in the loads that are the source of the phase current unbalance. This work defines the phase balancing problem as the minimization of: the maximum current unbalance at selected points in the circuit for all possible operating conditions; the losses in the conductors of the primary feeder; and the number of reconnections required to achieve the two previous objectives. To solve this problem we have developed a Matlab application based on the non-dominated sorting genetic algorithm. The optimization program is complemented with an application developed to estimate the loads of the circuit from the available measurements. The results obtained in five circuits of distribution of the city of Santa Clara are presented to show the advantages of the presented approach. [ABSTRACT FROM AUTHOR]

The unbalance of the phase currents in the primary distribution circuits produces two fundamental problems: the energy losses in the primary conductors are increased and the presence of a high neutral current on normal operation make it difficult the detection of earth faults by the neutral over current relays. The present work implements a Non-dominated Sorting Genetic Algorithm (NSGA-II) application for the phase balancing problem, which search for the minimal reconnection needed for the two-phase three-wire and the singlephase two-wire circuit laterals, as well as for the three-phase transformer banks and the single-phase distribution transformers, to minimize both: the energy losses and the maximum neutral current of the circuit. The successful performance of this application is achieved by the new definition of the set of independent variables, which permits the NSGA-II to optimize the selection of the elements to be reconnected. A test example is solved to shows the features of the presented approach. [ABSTRACT FROM AUTHOR]

The reconfiguration of distribution electric systems constitutes an optimization problem of the electric power systems operation. The genetic algorithms (GA) present numerous applications in the field of the optimization. The main advantage resides in its relative simplicity to formulate problems mathematically complex. It also has been thought that the methods based on GA are better than the traditional heuristic algorithms in the global optimum obtainment. However, when the GA is applied to the reconfiguration problem appears the necessity of carrying out radiality verifications that recharge their mathematical algorithm notably. The random nature of the variants generation process makes that many of them should be rejected by not fulfilling the connection premises imposed to the problem. In this work a formulation is presented based on certain principles of the graph theory that avoids the inconveniences of the realization of these checkups. [ABSTRACT FROM AUTHOR]

Copyright of Revista Técnica Energía is the property of Centro Nacional de Control de Energia CENACE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article presents a new methodology for the optimal placement of reclosers on electric power distribution systems. The methodology simultaneously considers the installation of reclosers normally closed and open, in order to fault isolation and service restoration, respectively. The problem is described by a multi- objective mathematical model, where the first objective function minimizes the unserved energy level of the system (NENS) and the second one minimizes the investment costs of the project. The set of constraints considers operational criteria of the system. As a solution strategy the concept of operational areas is introduced, which reduce computational effort considering that the NENS by area remains constant. In the problem solution, a Non-dominated Sorting Genetic Algorithm II (NSGA-II) is employed. The results show the validity of the proposed methodology and its applicability to real distribution systems. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for optimal location of capacitors in medium voltage distribution systems, considering uncertainty in demand. This uncertainty is simulated using a probabilistic load flow, which was implemented based on the chain's method, used to solve the operational problem in the Montecarlo simulation. As a method of optimizing a modified version of genetic algorithm, called Chu Beasley, is used. In order to enhance the optimization method, sensitivity factors that establish a relationship between reactive power and system losses are used. To verify the validity of the methodology, a test system from the literature is used, which concluded that the stochastic load flow determines a mean value of demand, with similar results to those obtained with versions that use deterministic power flow. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for optimal relocation of transformers in distribution systems. The problem is formulated as an optimization model of multiobjective non-linear integer type, which considers investment and operating costs, and the benefit of the concept of assets to be recognized by usage charges as stipulated in Resolution CREG 097 of 2008. The model is solved using the multiobjective optimization algorithm NSGA II. To check the validity of the methodology, a real distribution system belonging to an electric utility in Colombia is used, which takes into account both single and three phase distribution transformers. The results compared with respect to the case without considering the relocation of distribution transformers, reflect the importance of this methodology and its benefits to the distribution companies, and serves as a support tool for compliance with the standards set by regulatory bodies that define the appropriate chargeability of distribution transformers. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to solve the problem of service restoration in electric distribution systems, which is proposed as a model of mixed integer non-linear optimization where the objective function is to maximize the load that is outside of service, subject to a set of technical and operational constraints. The problem is solved using heuristic techniques, through sensitivity indicators that guide the restoration process. The methodology is validated in distribution systems, finding good-quality results. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to reduce energy losses in primary distribution networks, considering a combined algorithm which involves the optimal reconfiguration of the system and phase balance. The mathematical model is nonlinear mixed integer, which takes into account the investment and operating costs of the network, subject to a set of technical constraints imposed by the system. To solve the problem of reconfiguration and phase balance algorithms are used Simulated Annealing and Ant Colony, respectively. The algorithm is tested on IEEE 37 node feeder. [ABSTRACT FROM AUTHOR]

A new methodology for identifying and locating faults in distribution systems of electric power is proposed. The installation of electronic meters to record the electrical service continuity is proposed. These meters facilitated the detection of permanent faults or transient nonhomogeneous networks, providing information about weaknesses in power systems. This allows adopting corrective action with respect to the duration and frequency of interruptions in the circuits of local distribution systems. The proposal mitigates the discontinuity of the service and the significant costs for the electricity companies and especially for the users of electricity. [ABSTRACT FROM AUTHOR]

Copyright of Tecnura is the property of Tecnura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A discussion has taken place regarding the possibility of using international arbitration as a mechanism for overcoming the protection afforded to commercial agents under Colombian Law, once their contracts terminate. The parties to these contracts may agree to solve their disputes by international arbitration and under a foreign applicable law to the mentioned contracts. In this sense, a distinction should be drawn between the possibility of opting for international arbitration and the fact that arbitration tribunals should apply or not Colombian law to the merits of the case; local rules protecting commercial agents may not be characterized as "international public policy" rules or as "truly international public policy rules". The Colombian State, when entering into international instruments such as the FTA with the United States, might be confirming that the mentioned local rules do not amount to international public policy rules in Colombia, at least to date. It is not evident that European case law, protecting commercial agents, may be applicable to local legal reality. In Colombia, exequatur of foreign arbitration awards should not be a problem, regarding commercial agency cases. However, the debate is open. There are possible mechanisms and arguments protecting Colombian commercial agents, depending on the circumstances of the case. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia e Ingenieria Neogranadina is the property of Ciencia e Ingenieria Neogranadina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article is given the evaluation obtained of an industrial network with the presence of harmonic contamination, where the non lineal loads correspond fundamentally to rectifiers and variators of speed. Where the typical harmonic generated by these loads settled down and it allowed it to determine the levels of harmonic distortion of tension and current to analyze their influence in the selection of the bank of condensers during the compensation of the power it reactivates assisting to the behavior of the system before different load states. [ABSTRACT FROM AUTHOR]

Fault location in power distribution systems is an important aspect of power quality, in particular, in relation to power supply continuity. Currently, there are two clearly defined methods commonly used to locate faults, those which are based on the power system model and those which are based on knowledge. Fault location methods based on knowledge use information obtained from signals of voltage and current measured during fault situations, and normally require a considerable amount of fault registers to have a successful performance. This paper presents the modeling of a power distribution system and its protective relaying, settled in a fuse saving scheme. Using the described power system, it is possible to obtain a fault database by means of an event automatic generation using the Alternative Transient Program (ATP) and Matlab. The fault database can be used to perform different types of system analysis and in this specific case to solve the problem of fault location in power distribution systems using knowledge based methods. As a result, a data base which contains 930 different fault simulations on a 25 node test system was obtained. [ABSTRACT FROM AUTHOR]

Distribution systems operate in unbalanced form because of their configuration characteristics and nature of their loads. It is advisable to increase the balance level of the system because an operation in unbalanced conditions presents a greater level of losses. In this document, an ants colony methodology is presented and applied to a phase balance problem; likewise, the main characteristics of this methodology are shown by solving a test system. [ABSTRACT FROM AUTHOR]

Distribution systems can present a high harmonic level due to existence of non linear loads such as electronic equipment. The analysis of these systems is the objective of harmonic load flow. This document shows a new methodology of harmonic load flow which considers the distribution systems characteristics. Likewise it shows an object oriented software developed in Windows. IEEE test systems are presented. [ABSTRACT FROM AUTHOR]