Data supporting the improvement of forecasting and control of electricity consumption in hotels

Improving and managing the electricity efficiency in hotel facilities is essential to reduce the hotel operation costs and its environmental impacts. The data presented shows the evolution of the electricity consumption and management between 2013 and 2015 in two hotel facilities in Cuba (one beach hotel and one city hotel). The data additionally includes the daily measures used to develop control tools for an energy management system. The data presented in the article relates to the research study: Tools to improve forecasting and control of the electricity consumption in hotels Cabello et al., 2016, and it corresponds to the energy audits developed in one beach hotel (Hotel A) and one city hotel (Hotel B) in Cuba

Recent trends of the most used metaheuristic techniques for distribution network reconfiguration

Distribution network reconfiguration (DNR) continues to be a good option to reduce technical losses in a distribution power grid. However, this non-linear combinatorial problem is not easy to assess by exact methods when solving for large distribution networks, which requires large computational times. For solving this type of problem, some researchers prefer to use metaheuristic techniques due to convergence speed, near-optimal solutions, and simple programming. Some literature reviews specialize in topics concerning the optimization of power network reconfiguration and try to cover most techniques. Nevertheless, this does not allow detailing properly the use of each technique, which is important to identify the trend. The contributions of this paper are three-fold. First, it presents the objective functions and constraints used in DNR with the most used metaheuristics. Second, it reviews the most important techniques such as particle swarm optimization (PSO), genetic algorithm (GA), simulated annealing (SA), ant colony optimization (ACO), immune algorithms (IA), and tabu search (TS). Finally, this paper presents the trend of each technique from 2011 to 2016. This paper will be useful for researchers interested in knowing the advances of recent approaches in these metaheuristics applied to DNR in order to continue developing new best algorithms and improving solutions for the topi

Analysis of energy quality and charge status in a sectioning station and energy transformation

This work presents the application of a procedure for the analysis of energy quality, specific to voltage deviation and unbalance, in a sectioning and energy transformation (PT) station, as well as evaluating the state of charge of its main elements. In order to carry out the procedure, it is not necessary to carry out invasive or very expensive tests.The work describes the steps of the procedure and deals with the main theoretical aspects applied to stories such as power quality problems, with emphasis on voltage imbalance and deviation.The procedure is applied in the (PT) of the Torre do Tombo neighborhood, in the city of Namibe, belonging to the National Electricity Company (ENE) of the Republic of Angola. For each voltage and current reading, the parameters and curves that allowed evaluating the state of charge of the transformer, the circuit breakers and the conductors of each circuit of the (PT) were determined, as well as performing an analysis of the power quality of one of the circuits, detecting power quality problems and poor selection of circuit breakers.En este trabajo se presenta la aplicación de un procedimiento para el análisis de calidad de la energía, específicamente de desvío y desbalance de tensión, en un puesto de seccionamiento y transformación de energía (PT), así como se evalúa el estado de carga de sus principales elementos. Para la ejecución del procedimiento no es necesaria la realización de pruebas invasivas o muy costosas. En el trabajo se describen los pasos del procedimiento y se tratan los principales aspectos teóricos aplicados tales como los problemas de la calidad de energía, haciéndose énfasis en el desbalance y desvío de tensión. El procedimiento es aplicado en el (PT) del barrio Torre do Tombo, en la ciudad de Namibe, perteneciente a la Empresa Nacional de Electricidad (ENE) de la República de Angola. Se determinó para cada lectura de tensión y corriente, los parámetros y curvas que permitieron evaluar el estado de carga del transformador, de los disyuntores y de los conductores de cada circuito del (PT), así como realizar un análisis de la calidad de energía de uno de los circuitos, detectándose problemas de calidad de la energía y mala selección de disyuntores

Energy management of compressed air systems. Assessing the production and use of compressed air in industry

The use of compressed air in industry is an important and yet overlooked energy carrier. Although there are different energy-saving measures discussed in the specialized literature, there is little discussion on the energy performance of the production and use of compressed air. This study developed a new approach to assess the energy performance of compressed air systems based on a six-step local energy benchmarking methodology. The methodology includes an energy management procedure to monitor and control the electricity consumption and sustain the energy performance of compressed air systems in time. The procedure monitors the production and use of compressed at plant and at manufacturing section levels based on the real-time monitoring of relevant variables to calculate energy performance indicators, energy baselines, and CUSUM charts. Monitoring the consumption of compressed air at the section level in a case study reduced the demand between 11 and 47%. While electricity consumption to produce compressed air at the plant level reduced by an estimated 23%. This approach permits the rapid detection of inefficiencies in the production and demand sides of the compressed air system, highlighting inefficiencies that are frequently hidden in the total electricity consumption of manufacturing plant

Assessment of the energy efficiency estimation methods on induction motors considering real-time monitoring

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

Analysis of harmonic distortion generated by PWM motor drives

This paper evaluates the harmonic distortion generated by PWM motor drives in an electrical industrial system of a wheat flour mill company. For this, a comparative study between two industrial circuits connected at the same point of common coupling with similar characteristics of load and transformers is presented. The difference is that one circuit has PWM motor drives and the other does not have them. In the study, a practical method based on the statistical characterization of the total harmonic distortion of voltage (THDV) and current (THDI), individual voltage distortion (IVD), individual current distortion (ICD) and K-Factor is applied. As result, it was observed that PWM motor drives generated harmonics voltage mainly of fifth and seventh order with values that exceed limits established by standards in both circuits. In the work is also demonstrated that in the analysis of harmonics is necessary to consider various parameters and not only one

Solar radiation prediction for dimensioning photovoltaic systems using artificial neural networks

This paper presents a prediction model of solar radiation for dimensioning photovoltaic generation systems in the Atlantic Coast of Colombia, using artificial neural networks. As a case of study is presented the municipality "El Carmen de Bolivar" located in this region. To obtain the model, the average data of daily temperature, relative humidity and solar radiation from the last ten years, reported by weather stations in this city were used. Six neural networks were designed with six variants of input variables (temperature, humidity and month) and the output variable (solar radiation). The best result was obtained using all input variables. In the training process, the correlation index (R) between solar radiation estimated by the model and the recorded data was 0.8. In validating the correlation index was 0.77

Theoretical analysis of the voltage unbalance factor to characterize unbalance problems in induction motors

Voltage Unbalance (VU) is one of the most common power quality problems in industrial electrical systems and it is a subject of systematic study. This problem affects the operation and the efficiency of Induction Motors (ims), which are the loads that demand more energy in the industrial sector with around 68%. The Voltage Unbalance Factor (VUF), defined by the international IEC standard, is the main factor used to characterize this problem. This article aims to present a theoretical analysis of VUF focused on its limitations for characterizing the effects of VU on ims. As a result of the analysis, it is shown that the use of the VUF indicator only is insufficient since it does not consider other aspects that affect the operation of the ims such as voltage variation. As an alternative, the use of the Complex Voltage Unbalance Factor and the Equivalent Voltage Magnitude Factor are suggested as parameters that, together with the VUF, allow deepening the characterization of the effects of the UV on the ims

Reducing torque pulsations in PMa-SynRM: A way for improving motor performance

This paper aims to evaluate the performance of synchronous reluctance motors assisted by a permanent magnet (PMa-SynRM) focused on efficiency and torque pulsations. PMa-SynRM shows high efficiency and power factor, compared to induction motors (IM), although they have a greater cost. These machines develop relatively high torque ripple, cogging torque, and torque imbalances. Consequently, the electromagnetic torque is reduced, the motor temperature is increased, and mechanical vibrations are induced. The optimal design of the machine structures such as flow barriers, permanent magnets, and stator slots, among others, allow reducing torque pulsations. A comparison is made between different designs of the PMa-SynRM reported in the scientific literature, and the effects on efficiency, torque pulsation, and operating costs are evaluated. A case study on the motor driving the air conditioner blower in a hotel room was made, to determine the best economic variant between IM or PMa-SynRM. A sensitive analysis was made to evaluate several uncertainties. The advantages of using one of the PMa-SynRM analyzed were demonstrated. Also, it was proved that the investment is feasible economically, although NPV and payback are not the best, due to low load factor in inverter-controlled motors in air conditioners

Estimating induction motor efficiency under no-controlled conditions in the presences of unbalanced and harmonics voltages

This paper presents the application of a method to determine the output power, losses, and efficiency of induction motors, working in no-controlled conditions, in the presences of unbalanced and harmonics voltages. The method uses the steady state equivalent circuits, with some considerations for the analysis of motor performance, fed with unbalanced and harmonic voltages. The parameters of circuits are determined with low invasiveness, by applying a Bacterial Foraging Algorithm as technique of evolutionary search. With this, the efficiency and other operational parameters can be estimated at any operating point. The method was tested in a 12.6 kW motor working in an industrial network, with harmonics and voltage unbalanced