Non-Intrusive Electrical Load Monitoring System Applying Neural Networks with Combined Steady-State Electrical Variables

This paper presents a full electrical load identification model that considers steady-state parameters obtained easily from low-cost residential smart meters. The model was developed using neural networks including combinations of real power, current, impedance and admittance variables to identify the best input parameters. The monitoring model was improved by training one neural network to identify changing events and another neural network to identify the load state. The proposed model was tested using two different groups of residential loads: residential appliances measured in the laboratory and a public database of electrical measurements. The results show that the impedance model and a feedforward neural network achieved the best performance to characterise the load. In addition, when combining the different input parameters, those that consider impedance as an input parameter produced better results. The output provides simultaneous information about the operation state of all the loads before and after an event occurs

Numerical and experimental validation with bifurcation diagrams for a controlled DC–DC converter with quasi-sliding control

Este artículo presenta un análisis de estabilidad del convertidor buck usando la técnica de control de promediado cero (ZAD) y el control por inducción de punto fijo (FPIC), cuando se cambian el parámetro de control , el voltaje de referencia υref, y el valor de la tensión de la fuente de alimentación E. El estudio se basó en un análisis previo en el cual se ajustó el parámetro de control en =1 y el parámetro fue cambiado durante la simulación, encontrando la zona de estabilidad y regiones con comportamiento caótico. Así, este nuevo estudio determina los comportamientos transitorios y de estado estacionario y la robustez del convertidor buck cuando el parámetro de control varía, comparando los resultados de la simulación y pruebas experimentales. Los resultados muestran que el sistema regula la tensión de salida con un error bajo cuando se cambia la tensión en la fuente E. Además, el sobre impulso del voltaje aumenta y el tiempo de estabilización disminuye cuando el parámetro de control N es aumentado y el parámetro de control es constante. También, el convertidor buck controlado por las técnicas ZAD y FPIC es eficaz en la regulación de voltaje de salida del circuito, incluso cuando hay dos períodos de atraso.This paper presents a stability analysis of a buck converter using a Zero Average Dynamics (ZAD) controller and Fixed-Point Induction Control (FPIC) when the control parameter , the reference voltage υref, and the source voltage are changed. The study was based on a previous analysis in which the control parameter was adjusted to =1 and the parameter was changed during the simulation, finding the stability zone and regions with chaotic behavior. Thus, this new study presents the transient and steady-state behaviors and robustness of the buck converter when the control parameter changes. Moreover, numerical simulation results are compared with experimental observations. The results show that the system regulates the output voltage with low error when the voltage is changed in the source E. Besides, the voltage overshoot increases, and the settling time decreases when the control parameter is augmented and the control parameter is constant. Furthermore, the buck converter controlled by ZAD and FPIC techniques is effective in regulating the output voltage of the circuit even when there are two delay periods and voltage input disturbances

Automatización de cultivos aeropónicos de cilantro libres de pesticidas

Introduction−Aeroponics allows the possibility to grow plants in places where conventional open-field agriculture is difficult. The use of technology improves the efficiency of the process although some energy control and irrigation system solutions must be improved.Objective−Implement an autonomous power supply and an irrigation control system for pesticide-free food pro-duction.Methodology−The autonomous system was designed using MATLAB-Simulink-MPLAB tool to perform the control model and to be applied to the crop. A dsPIC was programmed for the irrigation cycle control algorithms using MATLAB-Simulink blocks.Results−The results show that the irrigation cycle and power supply of the aeroponic system help maintain uni-formity of plant growth during the tests period, which allows a better development of the aeroponic crop.Conclusions−Cultivation by aeroponics reduces the use of pesticides, growing space, water consumption, and nu-trients consumption. Automation in irrigation and power supply systems allows good growth in coriander, which can be evidenced by increases in the weight and volume of the test plants.Introducción−La aeroponía permite la posibilidad de cultivar plantas, en lugares donde la agricultura conven-cional de campo abierto es difícil. El uso de la tecnología permite mejorar la eficiencia de los procesos, aunque se requiere incorporar algunas mejoras y soluciones en los sistemas de suministro energético y control del riego.Objetivo−Implementar una fuente autónoma de sumin-istro energético y un sistema de control del riego para la producción de alimentos libres de pesticidas.Metodología−El sistema autónomo se diseñó utilizando la herramienta Matlab-Simulink-MPLAB, para desarr-ollar el modelo de control y aplicarlo al cultivo. Además, se programó un dsPIC para los algoritmos de control del ciclo de riego utilizando bloques Matlab-Simulink. Resultados−Los resultados muestran que el ciclo de riego y el suministro de energía, ayudan a mantener plantas uniformes en el cultivo durante el periodo de las pruebas, lo que permite a su vez incorporar mejoras en el desarrollo de los cultivos aeropónicos.Conclusiones−Cultivar de manera aeropónica reduce el uso de pesticidas, espacio, agua y nutrientes. La automa-tización en los sistemas de irrigación y de suministro de potencia, permite lograr un buen crecimiento en el cilan-tro, lo cual se puede evidenciar mediante el incremento en los niveles de peso y volumen, registrados en las medi-ciones de las plantas de prueba

A modified backward/forward sweep-based method for reconfiguration of unbalanced distribution networks

A three-phase unbalanced power flow method can provide a more realistic scenario of how distribution networks operate. The backward/forward sweep-based power flow method (BF-PF) has been used for many years as an important computational tool to solve the power flow for unbalanced and radial power systems. However, some of the few available research tools produce many errors when they are used for network reconfiguration because the topology changesafter multiple switch actions and the nodes are disorganized continually. This paper presents a modifiedBF-PF for three-phase unbalanced radial distribution networks that is capable of arranging the system topology when reconfiguration changes the branch connections. A binary search is used to determine the connections between nodes, allowing the algorithm to avoid those problems when reconfiguration is carried out, regardless of node numbers. Tests are made to verify the usefulness of the proposed algorithm in both the IEEE 13-node test feeder and the 123-node test feeder, converging in every run where constraints are accomplished. This approach can be used easily for a large-scale feeder network reconfiguration. The full version of this modified backward/forward sweep algorithm is available for research at MathWorks

Comparación de algoritmos multiobjetivo inspirados en búsqueda armónica, búsqueda cuco y murciélagos para la ubicación de generación distribuida renovable

Electric power losses have a significant impact on the total costs of distribution networks. The use of renewable energy sources is a major alternative to improve power losses and costs, although other important issues are also enhanced such as voltage magnitudes and network congestion. However, determining the best location and size of renewable energy generators can be sometimes a challenging task due to a large number of possible combinations in the search space. Furthermore, the multiobjective functions increase the complexity of the problem and metaheuristics are preferred to find solutions in a relatively short time. This paper evaluates the performance of the cuckoo search (CS), harmony search (HS), and bat-inspired (BA) algorithms for the location and size of renewable distributed generation (RDG) in radial distribution networks using a multiobjective function defined as minimizing the energy losses and the RDG costs. The metaheuristic algorithms were programmed in Matlab and tested using the 33-node radial distribution network. The three algorithms obtained similar results for the two objectives evaluated, finding points close to the best solutions in the Pareto front. Comparisons showed that the CS obtained the minimum results for most points evaluated, but the BA and the HS were close to the best solution.Las pérdidas eléctricas tienen un impacto significativo en los costos totales de las redes de distribución. El uso de las energías renovables es una gran alternativa para mejorar las pérdidas y los costos, aunque también otros problemas en las magnitudes de las tensiones y la congestión de la red pueden ser mejorados. Sin embargo, determinar la mejor localización y dimensionamiento de generadores eléctricos renovables puede ser a veces una tarea difícil debido al gran número de combinaciones posibles existentes en el espacio de búsqueda. Además, el uso de funciones multiobjetivo incrementa la complejidad del problema y se prefiere usar las metaheurísticas para encontrar soluciones en un tiempo relativamente corto. En este trabajo se evalúa el desempeño de los algoritmos inspirados en búsqueda cuco, búsqueda armónica y murciélagos para la localización y dimensionamiento de la generación distribuida renovable en redes de distribución radiales, usando funciones como la minimización de las pérdidas de energía y los costos de la generación distribuida renovable. Las metaheurísticas fueron programadas en Matlab y evaluadas usando la instancia denominada red de distribución radial de 33 nodos. Los tres algoritmos evaluados obtuvieron resultados similares para los dos objetivos evaluados, encontrando Frentes de Pareto cercanos a las mejores soluciones. La comparación realizada mostró que la búsqueda cuco obtiene los mejores resultados, pero los algoritmos inspirados en murciélagos y búsqueda armónica obtuvieron resultados cercanos a la mejor solución

Buck converter controlled with ZAD and FPIC for DC-DC signal regulation

This paper presents the performance of a fixed-point induction control (FPIC) technique working in conjunction with the non-linear control technique called zero average dynamics (ZAD) to control chaos in a buck converter. The control technique consists of a sliding surface in which the error tends to zero at each sampling period. A switch is controlled by using centered pulse width modulation (CPWM) control signal. The converter controlled with ZAD-FPIC has been simulated in Matlab and implemented using rapid control prototyping (RCP) in a DSP to make comparisons between simulation and experimental tests. To perform this comparison, some variations in the control parameter and the voltage reference are made in order to evaluate the performance of the system. Results are obtained with errors lower than 1 % which demonstrates the good performance of the control techniques

Fractal representation of the power demand based on topological properties of julia sets

In a power system, the load demand considers two components such as the real power (P) because of resistive elements, and the reactive power (Q) because inductive or capacitive elements. This paper presents a graphical representation of the electric power demand based on the topological properties of the Julia Sets, with the purpose of observing the different graphic patterns and relationship with the hourly load consumptions. An algorithm that iterates complex numbers related to power is used to represent each fractal diagram of the load demand. The results show some representative patterns related to each value of the power consumption and similar behaviour in the fractal diagrams, which allows to understand consumption behaviours from the different hours of the day. This study allows to make a relation among the different consumptions of the day to create relationships that lead to the prediction of different behaviour patterns of the curves