In electric power systems, it is very common to find problems of power quality. The flow of harmonics significantly affect the operation of three-phase induction motors, and its energy characterization becomes difficult. There are different methods in situ to estimate motor efficiency. However, it is necessary to deepen the in situ efficiency analysis under nonsinusoidal voltage conditions. In this paper, a procedure is presented based on the equivalent circuits with losses segregation and using a bacterial foraging algorithm (BFA). It allows induction motors' energy efficiency determination in field conditions with low invasiveness and working under harmonic distortion. The method was successfully tested on a 1.5 kW motor fed with significant levels of voltage harmonic.Index Terms-Bacterial foraging algorithm (BFA), harmonics, induction motor, in situ efficiency estimation.

Hotels are among the most energy intensive tourism facilities. To monitor and control the monthly and yearly energy consumption in hotels, different indicators have been proposed. These indicators, developed on yearly or annual basis, do not permit rapid detection and mitigation of malpractices and overconsumptions in hotel facilities. Moreover, these indicators do not consider the influence of physical parameters such as outdoor temperature, or, when they do, rather complex coefficients are used, precluding implementation in hotel facilities. This study discusses the use of Energy Performance Indicators to assess and control the electricity consumption in hotels. To this end a new indicator considering the outdoor temperature is introduced. Based on this indicator daily control graphs are developed, allowing a more rapid detection of overconsumptions and malpractices towards a higher electricity efficiency. One advantage of this approach is that no investments are required to implement it. The tools were implemented in two Cuban hotels of different characteristics, where reductions of the electricity consumption in 2014 compared to 2013 of 10 and 11%, were achieved.

For driving constant loads in industry, the use of direct-on-line-start permanent-magnet-assisted synchronous reluctance motors with ferrite magnets (DOL-Start-PMa-SynRM) is proposed. The bibliographic search demonstrated that this new motor has greater efficiency than one similar induction motor (IM). It was evidenced that the main element that is required for direct starting is to insert a squirrel cage into the rotor of a PMa-SynRM, which does not produce negative operational effects in a steady state. An economic evaluation was carried out in a sugar mill company, applying the differential net present value (NPV) method, and a sensitivity analysis, considering the four factors that present the most variation. It was demonstrated, by means of a Pareto diagram standardized for the NPV that the most significant factors are fuel factor, lifespan and the multiplication of both. With response surfaces that are obtained with a multilevel factorial experiment, it was determined that, by varying the factors in the ranges considered, the NPV always remains positive and higher than 2200 USD. This is mainly due to the notable difference between the efficiency of the DOL-Start-PMa-SynRM and that of the IM. Consequently, is proved that an investment in the DOL-Start-PMa-SynRM may be feasible.

Different methods have been developed to estimate the energy efficiency of induction motors. The accuracy of these methods vary with the load factor, the unbalanced voltage (UV) and harmonics. The feasibility of these methods for efficiency estimation in real-time were theoretically and experimentally assessed during the operation under different operational conditions (i.e. balanced sinusoidal voltage (BSV), harmonics, UV and harmonics with UV). Results show that for load factors over 80%, the air-gap method is applicable under any condition, while the slip method is only applicable under BSV or balanced harmonic voltage. Moreover, for load factors over 40%, the nameplate method is applicable under BSV. Other methods result in errors over 8% and optimization methods are not applicable for real-time monitoring. Electric systems generally operates with some degree of UV and harmonics, while induction motors mostly operate with load factors below 60%, limiting the use of these methods for real-time measurement.

Electricity stands as the main energy used for lead-acid battery (LAB) manufacturing. This study introduces an energy management methodology to address the electricity consumption in lead-acid battery plants, improving efficiency standards. The "equivalent battery production" is introduced to define the energy performance criteria to be met in the different production sections of the battery plant. The methodology combines the guidelines of the ISO 50001 standard with the energy management framework for manufacturing plants. The result is a structured approach for detecting inefficiencies and pinpointing their sources. The management methodology was implemented during 2016. In the formation area 222 MWh were saved during 2016. This saving accounts for 3.9% less electricity than forecasted by the energy baseline of the area. Additionally, the emission of some 40 tCO2.eq. associated with the generation of the electricity production were saved. Moreover, at plant level 424 MWh were saved, which account for 3.6% less electricity than forecasted by the energy baseline of the plant. In total, around 76 tCO2.eq. were saved as a result of the electricity savings in the plant.

Microgrids have been proposed as a solution to the growing deterioration of traditional electrical power systems and the energy transition towards renewable sources. One of the most important aspects of the efficient operation of a microgrid is its topology, that is, how the components are connected. Some papers have studied microgrid topologies; however, these studies do not perform an exhaustive analysis of the types of topologies, their applications, characteristics, or technical advantages and disadvantages. The contribution of this paper is the integration of the most important functional properties of microgrid topologies in terms of reliability, efficiency, structure, costs, and control methods. The study analyzes 21 topologies divided into six classifications with their respective sub-classifications. The analysis was based on the characteristics of the current (AC or DC), the control mechanisms, the transition between the operating modes, and the operating costs. As a result of the evaluation, it was evidenced that SST-based completely isolated coupled AC topologies, completely isolated two-stage AC decoupled, and multiple microgrids show the best performances. In contrast, the use of two-stage and three-stage partially isolated AC decoupled topologies is not recommended because of their high operating cost and low efficiency and reliability.

En el presente trabajo se diseña y aplica un procedimiento de planificación energética, compatible con la norma ISO 50001, a una lavandería industrial. Se analizan tres variables de entrada: nivel de producción, estado técnico del sistema y régimen de operación. Se examina el pasado, presente y futuro del consumo del fuel oíl en el sistema de generación y uso del vapor, estableciendo las causas del deterioro del indicador de consumo. A través de un estudio de carga y capacidad en el sistema se identificaron las potencialidades de ahorro mejorando el esquema de operación. Se propuso un nuevo esquema para la operación de las calderas el cual fue implementado lográndose un ahorro del 16% de combustible. Con los resultados de las mediciones se elabora la línea base y se establecen nuevas metas.Palabras clave: Ahorro de combustible, indicador de consumo, ISO 50001, planificación energética, calderas.

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