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

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

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

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

Empleo de telemedición para calcular pérdidas de transformación considerando problemas de calidad de la energía

El objetivo principal de este trabajo es calcular las pérdidas de transformación cuando hay afectaciones de calidad de la energía. El método propuesto toma en consideración la variabilidad y asimetría de la carga, así como la presencia de problemas de calidad de la energía (PQ) como el desbalance y las variaciones de tensión. La metodología, que aprovecha la disponibilidad de datos provenientes de los sistemas de medición instalados actualmente en las subestaciones, se basa en un enfoque probabilístico. Se aplicó a subestaciones de distribuciónprimaria del municipio de Cumanayagua. Se comparó con el método de cálculos rápidos empleado actualmente, demostrándose su superioridad. El método puede ser generalizado a transformadores trifásicos de fuerza instalados en la industria, donde se quiera conocer su comportamiento energético.

Flow regulation at constant head in feedwater pumps in a sugar industry

In this paper the feasibility of energy saving by implementing flow regulation at constant load in feedwater pumps in a sugar industry is studied. As regulation strategy, the use of a variable speed drive in the hydraulic system is proposed. For the project evaluation, the Net Present Value and Payback Period techniques are used. Among the variables considered are the price of energy, the equipment useful life, financial data and those related to environmental impact. As a result, it was found that if only a commercial approach is considered, the energy saving strategy is profitable but not attractive, because investment is recovered in a period close to the useful life of technology. However, if a government focus that encourages the implementation of these energies saving strategies is considered, the investment of the project recovers in a short time

Using remote metering for transformation loss calculation considering power quality problems

El objetivo principal de este trabajo es calcular las pérdidas de transformación cuando hay afectaciones de calidad de la energía. El método propuesto toma en consideración la variabilidad y asimetría de la carga, así como la presencia de problemas de calidad de la energía (PQ) como el desbalance y las variaciones de tensión. La metodología, que aprovecha la disponibilidad de datos provenientes de los sistemas de medición instalados actualmente en las subestaciones, se basa en un enfoque probabilístico. Se aplicó a subestaciones de distribuciónprimaria del municipio de Cumanayagua. Se comparó con el método de cálculos rápidos empleado actualmente, demostrándose su superioridad. El método puede ser generalizado a transformadores trifásicos de fuerza instalados en la industria, donde se quiera conocer su comportamiento energético.Transformation loss calculation is the main objective in this paper. A new method that considers load asymmetry and variability, as well as the presence of power quality (PQ) problems - like unbalance and voltage variations - is proposed. The method takes advantage of existing data from measurement systems installed in substations and it is based on probabilistic methods. It was applied to primary distribution transformers in the mu-nicipality of Cumanayagua. This method was com-pared with the so called ̈fast calculation method ̈ employed nowadays; its advantage is demonstrated. The method can be generalized for industrial three-phase power transformers to evaluate its energetic behavio

Synchronous reluctance motors controlled by variable frequency converters: an application to save energy

Se presenta un estudio sobre aplicaciones de los motores sincrónicos de reluctancia (MSR) controlados por accionamientos de frecuencia variable (AFV), que posibilitan el ahorro de energía. Se realizó una comparación entre las características constructivas de los MSR y los motores asincrónicos de jaula (MA), evaluando las ventajas y limitaciones que aquellos presentan. Una ventaja notable del MSR es que las pérdidas en el rotor se eliminan prácticamente. Una comparación experimental evidenció que para igual momento, el MSR presenta una mayor eficiencia; y que para igual incremento de temperatura, con las mismas dimensiones IEC, se logra más potencia. Por comparaciones entre datos de un fabricante, se demostró las ventajas de utilizar, con el mismo AFV y para cargas centrífugas, un MSR de mayor clase de eficiencia que la de un MA. Un análisis económico con técnicas de descuento, evidenció una atractiva recuperación de la inversión cuando se opera todo el añoA study on applications of synchronous reluctance motor (SynRM) controlled by variable frequency drives (VFD) for energy saving is presented. A comparison between the basic construction elements of the SynRM and the squirrel cage induction motor (IM) is carried out, evaluating advantages and disadvantages. A nearly complete elimination of rotor losses is a significant asset of the SynRM. An experimental comparison showed that at the same torque, the SynRM presents a higher efficiency than the IM; and that at the same temperature rise, more power is obtained with the same IEC frame for both motor types. Comparing data from a manufacturer, the advantages of using, with the same VFD and for centrifugal loads, a higher efficiency class SynRM than that of a lower efficiency IM was demonstrated. An economical study using discount techniques, made evident an attractive pay back when operating all year aroun