juan perez florez - Academia.edu (original) (raw)
Papers by juan perez florez
Ingeniería e Investigación
The setting up process for support vector machines (SVM) is discussed in this paper. Such setting... more The setting up process for support vector machines (SVM) is discussed in this paper. Such settings are normally obtained from exhaustive testing of SVM, settled on by using several configuration parameter values and evaluating performance by using techniques such as cross validation. The linear approach presented in this paper is based on redefining the classical SVM second-order objective function. Better setting parameters were obtained by using low computational cost methodology for resolving new linear optimisation. The proposed approach was applied to a typical classification problem regarding fault location in power distribution systems; the results so obtained were compared to those obtained using classical methodology. An 80% improvement was achieved in mean error when estimating fault location and 56% reduction in the computing time needed for obtaining the best results when using classical approaches.
Ingeniería e Investigación
Fault location in power distribution systems is very important because of power service continuit... more Fault location in power distribution systems is very important because of power service continuity requirements, mainly imposed by current electricity market quality standards. A fault location approach is adopted in this paper using current waveforms as measured at electricity substations, knowledge of protection-device settings and ANFIS networks. Good results were obtained from tests carried out in a prototype power distribution system to locate where faults were occurring. These results revealed variation in fault-locator precision due to using different current signal characteristics or descriptors. An error lower than 1% was obtained in the best case. Two more alternatives are also presented where errors were lower than 4%; such results validate the approach presented here.
Ingeniería e Investigación
This paper reports a strategy for identifying and locating faults in a power distribution system.... more This paper reports a strategy for identifying and locating faults in a power distribution system. The strategy was based on the K nearest neighbours technique. This technique simply helps to estimate a distance from the features used for describing a particular fault being classified to the faults presented during the training stage. If new data is presented to the proposed fault locator, it is classified according to the nearest example recovered. A characterisation of the voltage and current measurements obtained at one single line end is also presented in this document for assigning the area in the case of a fault in a power system. The proposed strategy was tested in a real power distribution system, average 93% confidence indexes being obtained which gives a good indicator of the proposal’s high performance. The results showed how a fault could be located by using features obtained from voltage and current, improving utility response and thereby improving system continuity inde...
Phenological studies of coneflower on aspen range in Northern Utah showed that resumption of grow... more Phenological studies of coneflower on aspen range in Northern Utah showed that resumption of growth of mature plants begins at the time of snow melt and the initial or rosette stage is completed between mid-May and mid- June. The rate of growth in this stage is controlled by temperature, being greater at higher mean temperatures. The bolting stage is completed about 1 week after the initiation of stem elongation and the process of capitulum development is begun. Flowering is initiated between late July and mid- August. Cross-pollination is necessary for seed set which is completed by the end of August. Seed dissemination is begun at that time and is completed by the middle of September. Altitude appeared to have an effect on the extent of seed filling, since collections from higher altitudes had lower percentages of filled seeds. Seedling mortality increases as the season advances and reaches a maximum at the end of June when the associated species begin rapid growth. During the fir...
Resumen es: La localizacion de fallas en sistemas de distribucion no es un problema de facil solu... more Resumen es: La localizacion de fallas en sistemas de distribucion no es un problema de facil solucion, debido a que estos incluyen cargas intermedias, ramales latera...
Tecnura, 2006
Entre los problemas que afectan la calidad de la energia electrica se encuentra la inestabilidad ... more Entre los problemas que afectan la calidad de la energia electrica se encuentra la inestabilidad oscilatoria de las maquinas sincronas. Para mantener la estabilidad se usan controles suplementarios de excitacion, entre ellos los Estabilizadores del Sistema de Potencia (PSS). Este articulo presenta la implementacion de un PSS mediante la utilizacion de una tecnica adaptiva, para superar algunos de los problemas de inestabilidad ante perturbaciones causadas por la variacion en la carga o en el voltaje de referencia. Como resultado, se describen las pruebas realizadas en un prototipo real que permiten observar el buen comportamiento del PSS. La aplicabilidad y eficiencia del metodo aqui propuesto se muestran mediante la validacion experimental de los postulados teoricos.
Tecnura, 2007
Este articulo presenta una nueva alternativa para resolver el problema de localizacion de fallas ... more Este articulo presenta una nueva alternativa para resolver el problema de localizacion de fallas en sistemas de distribucion de energia electrica, a partir de la utilizacion de los algoritmos de aprendizaje representados por los clasificadores. Se analiza el desempeno de un localizador de fallas basado en una tecnica de clasificacion con vectores de soporte; el desempeno se prueba mediante la variacion de la exigencia del clasificador para reconocer cada vez una zona de falla mas pequena. Un ejemplo de aplicacion con el modelo de un sistema real muestra que el localizador propuesto es altamente efectivo para resolver el problema, por lo que se obtienen aciertos superiores al 97% en la localizacion del nodo en falla, en el caso mas exigente.
Power system protection using distance relays in one of the most common relaying practices. Consi... more Power system protection using distance relays in one of the most common relaying practices. Considering the previously mentioned fact, in this paper an alternative to improve the performance of the distance estimation on the conventional algorithms is discussed. This alternative considers the analysis of the fault and return path impedances. The proposed method is tested in a 500kV, 100 km length power line, where the errors are lower than 5% even in case of fault resistance of 20Ω and return path resistance of 0,2Ω/km.
Este articulo presenta un analisis sobre el uso y el abuso de las componentes simetricas para sol... more Este articulo presenta un analisis sobre el uso y el abuso de las componentes simetricas para solucionar el problema de la localizacion de fallas en sistemas de distribucion de energia electrica. Se observa como uno de los errores mas comunes es el utilizar aproximaciones propias de los sistemas de transmision, el no considerar las componentes mutuas que se obtienen en las matrices de impedancias en forma de componentes simetricas o el asumir que la impedancia de falla siempre es igual en todas las fases involucradas.
En este articulo se presenta un analisis de la implementacion de sistemas hibridos, para integrar... more En este articulo se presenta un analisis de la implementacion de sistemas hibridos, para integrar varios metodos que permitan una solucion al problema de localizacion de fallas. Como resultados se muestra una propuesta de arquitectura generica para abordar el problema de la localizacion de fallas en sistemas de distribucion de energia electrica, y tambien las pruebas de localizacion donde se obtiene precision muy alta, para un circuito tipico de distribucion. Esta es una alternativa util para el aprovechamiento integrado y efectivo de los metodos de analisis de circuitos y las tecnicas de clasificacion para resolver un problema del sector electrico.
Ingeniería, 2006
Permanent and transient power supply interruption affects power quality indexes related to contin... more Permanent and transient power supply interruption affects power quality indexes related to continuity and causes negative effects in industry, commercial and residential users.As alternative to solve this problem,transmission networks have efficient fault location and protection schemes. Distribution facilities are constrained by technical,economical and operative aspects to implement fault identification and location strategies. In this paper an alternative solution of the fault location problem in power distribution systems, having a minimum of investment from utilities and giving appropriate information which helps to prevent and attend faults. By means of voltage signal characterization measured at the distribution substation and using an optimization and learning technique known as Support Vector Machines (SVM), the most probable zone where the fault was happened is located. The obtained results help to reduce time to locate faults in power distribution systems having a relativ...
Artificial neural networks (ANN) offer an alternative to implementation of conventional controlle... more Artificial neural networks (ANN) offer an alternative to implementation of conventional controllers due the good performance to identify and control nonlinear systems at high computational speed. This technique was used in the supplementary controller implementation (power stabilizer) aimed to maintain an acceptable behavior of the terminal voltage in a synchronous machine, when it is under disturbance conditions. In this paper the obtained results of the proposed approach are presented. The advantages of the use of neural nets over the classical adaptive implementation of power stabilizers are shown.
This paper presents a theoretical analysis of a small power plant wich uses biogas as its primary... more This paper presents a theoretical analysis of a small power plant wich uses biogas as its primary fuel. This biogas is obtained from Urban Solid Wastes (USW) landfills and specifically from La Glorita landfill in Pereira. The thermal plant proposed in this paper is a generic combined cycle power plant. The study here presented is focused on the possibility of generate electricity using wastes that are currently one of the most serious problems on public health and environmental sanitation. This paper also presents a detailed theoretical analysis of the average composition for the biogas produced by a USW landfill in Pereira.
In this paper a voice command recognizing methodology using Support Vector Machines (SVM) is prop... more In this paper a voice command recognizing methodology using Support Vector Machines (SVM) is proposed. This is an important task in autonomous and semi-autonomous systems, because it is a natural and useful interaction way, especially in situations where there are special limitations as low visibility, low or any possibility of physical contact, among others. As application example, voice registered signals are characterized by using spectral bands and next these are classified by using SVMs. The proposed methodology is tested in vowels identification, having obtained a 98% of average successful results
El problema del deslizamiento de frecuencia asociado a la estimacion digital de las magnitudes el... more El problema del deslizamiento de frecuencia asociado a la estimacion digital de las magnitudes electricas, cuando se utiliza como algoritmo de medida la Transformada de Fourier es analizado en este articulo. Se mencionan algunos otros factores que influyen en la precision de las medidas de tension, corriente, potencia y frecuencia, y se obtienen analiticamente los errores de las senales basicas de tension y de corriente, cuando la frecuencia del sistema tiene variaciones y se mantiene fija la frecuencia de muestreo del medidor. En la parte final, se presentan algunos resultados y las conclusiones obtenidas para la estimacion de magnitudes electricas, cuando se tiene como entrada senales con contaminacion armonica y con magnitudes diferentes a plena escala del medidor.
The fundamental problem of the voltage control is to maintain its value in the synchronous machin... more The fundamental problem of the voltage control is to maintain its value in the synchronous machine terminals between established limits, by using several regulation strategies. The proposed approach presented in this paper is aimed to apply an adaptive methodology to develop an Automatic Voltage Regulator (AVR) capable to work well under different perturbations of the sincronous machine. To validate the proposed methodology, a real test system composed mainly by a sincronous machine and a semicontroled bridge is used. The obtained results are compared with the ones obtained from a classic proportional integral AVR.
Fault location methods applied to power distribution systems estimate the fault distance based on... more Fault location methods applied to power distribution systems estimate the fault distance based on the fundamental component of single end voltages and currents. Most of these methods do not consider the non homogeneity of the distribution lines, load taps, laterals, presence of single phase and three phase loads and fault resistance. This paper presents a fault location method to determine the fault distance on radial distribution power systems using single end voltages and currents. The presented method considers non equilibrate loads, laterals, and different types of conductors on the distribution circuit.
Model Based Methods (MBM), used for fault location methods in power distribution systems estimate... more Model Based Methods (MBM), used for fault location methods in power distribution systems estimate the fault distance based on the fundamental component of single end voltages and currents. As general disadvantages there are two; first, these methods require of a good system model; and second, these methods do not avoid the multiple fault location estimation problem. In this paper, a theoretical discussion about the development of hybrid systems starting from both, different types of knowledge related to a real problem, and the combination of artificial intelligent techniques or Knowledge Based Methods (KBM) is presented. Starting from the theoretical basis, and performing the analysis of disadvantages and advantages of each analyzed technique, a proposal to consider the fault location problem in power distribution systems, as a useful hybrid alternative to take advantage of both, MBM and KBM is proposed.
Fault location is close related to power service continuity. This task is more difficult in power... more Fault location is close related to power service continuity. This task is more difficult in power distribution systems than in power transmission systems due the complexity of the first ones. Power distribution systems are composed by non homogeneous line sections, laterals, variable loads, unbalances on loads and system and so on. In addition in such systems only measurements are available at the power substation. This paper proposes a new fault location method based on the graphical analysis of the fault impedance. The capability of the proposed method is tested in a real power distribution system, having obtained errors in distance estimation lower than 2.5%.
This paper presents a comparison of two methods for locating faults, considering the influence of... more This paper presents a comparison of two methods for locating faults, considering the influence of the ground resistivity and the fault resistance. The methods are the proposed by a commercial software developer and one of the classic impedance based methods. Tests were performed using three different ground resistivity models, obtained from field measurements. According to the results in a 34kV power distribution system, the performance of the impedance based fault locator is better than the obtained using the commercial software. Additionally, the soil resistivity models which best represent the real systems are those which give better results in fault location.
Ingeniería e Investigación
The setting up process for support vector machines (SVM) is discussed in this paper. Such setting... more The setting up process for support vector machines (SVM) is discussed in this paper. Such settings are normally obtained from exhaustive testing of SVM, settled on by using several configuration parameter values and evaluating performance by using techniques such as cross validation. The linear approach presented in this paper is based on redefining the classical SVM second-order objective function. Better setting parameters were obtained by using low computational cost methodology for resolving new linear optimisation. The proposed approach was applied to a typical classification problem regarding fault location in power distribution systems; the results so obtained were compared to those obtained using classical methodology. An 80% improvement was achieved in mean error when estimating fault location and 56% reduction in the computing time needed for obtaining the best results when using classical approaches.
Ingeniería e Investigación
Fault location in power distribution systems is very important because of power service continuit... more Fault location in power distribution systems is very important because of power service continuity requirements, mainly imposed by current electricity market quality standards. A fault location approach is adopted in this paper using current waveforms as measured at electricity substations, knowledge of protection-device settings and ANFIS networks. Good results were obtained from tests carried out in a prototype power distribution system to locate where faults were occurring. These results revealed variation in fault-locator precision due to using different current signal characteristics or descriptors. An error lower than 1% was obtained in the best case. Two more alternatives are also presented where errors were lower than 4%; such results validate the approach presented here.
Ingeniería e Investigación
This paper reports a strategy for identifying and locating faults in a power distribution system.... more This paper reports a strategy for identifying and locating faults in a power distribution system. The strategy was based on the K nearest neighbours technique. This technique simply helps to estimate a distance from the features used for describing a particular fault being classified to the faults presented during the training stage. If new data is presented to the proposed fault locator, it is classified according to the nearest example recovered. A characterisation of the voltage and current measurements obtained at one single line end is also presented in this document for assigning the area in the case of a fault in a power system. The proposed strategy was tested in a real power distribution system, average 93% confidence indexes being obtained which gives a good indicator of the proposal’s high performance. The results showed how a fault could be located by using features obtained from voltage and current, improving utility response and thereby improving system continuity inde...
Phenological studies of coneflower on aspen range in Northern Utah showed that resumption of grow... more Phenological studies of coneflower on aspen range in Northern Utah showed that resumption of growth of mature plants begins at the time of snow melt and the initial or rosette stage is completed between mid-May and mid- June. The rate of growth in this stage is controlled by temperature, being greater at higher mean temperatures. The bolting stage is completed about 1 week after the initiation of stem elongation and the process of capitulum development is begun. Flowering is initiated between late July and mid- August. Cross-pollination is necessary for seed set which is completed by the end of August. Seed dissemination is begun at that time and is completed by the middle of September. Altitude appeared to have an effect on the extent of seed filling, since collections from higher altitudes had lower percentages of filled seeds. Seedling mortality increases as the season advances and reaches a maximum at the end of June when the associated species begin rapid growth. During the fir...
Resumen es: La localizacion de fallas en sistemas de distribucion no es un problema de facil solu... more Resumen es: La localizacion de fallas en sistemas de distribucion no es un problema de facil solucion, debido a que estos incluyen cargas intermedias, ramales latera...
Tecnura, 2006
Entre los problemas que afectan la calidad de la energia electrica se encuentra la inestabilidad ... more Entre los problemas que afectan la calidad de la energia electrica se encuentra la inestabilidad oscilatoria de las maquinas sincronas. Para mantener la estabilidad se usan controles suplementarios de excitacion, entre ellos los Estabilizadores del Sistema de Potencia (PSS). Este articulo presenta la implementacion de un PSS mediante la utilizacion de una tecnica adaptiva, para superar algunos de los problemas de inestabilidad ante perturbaciones causadas por la variacion en la carga o en el voltaje de referencia. Como resultado, se describen las pruebas realizadas en un prototipo real que permiten observar el buen comportamiento del PSS. La aplicabilidad y eficiencia del metodo aqui propuesto se muestran mediante la validacion experimental de los postulados teoricos.
Tecnura, 2007
Este articulo presenta una nueva alternativa para resolver el problema de localizacion de fallas ... more Este articulo presenta una nueva alternativa para resolver el problema de localizacion de fallas en sistemas de distribucion de energia electrica, a partir de la utilizacion de los algoritmos de aprendizaje representados por los clasificadores. Se analiza el desempeno de un localizador de fallas basado en una tecnica de clasificacion con vectores de soporte; el desempeno se prueba mediante la variacion de la exigencia del clasificador para reconocer cada vez una zona de falla mas pequena. Un ejemplo de aplicacion con el modelo de un sistema real muestra que el localizador propuesto es altamente efectivo para resolver el problema, por lo que se obtienen aciertos superiores al 97% en la localizacion del nodo en falla, en el caso mas exigente.
Power system protection using distance relays in one of the most common relaying practices. Consi... more Power system protection using distance relays in one of the most common relaying practices. Considering the previously mentioned fact, in this paper an alternative to improve the performance of the distance estimation on the conventional algorithms is discussed. This alternative considers the analysis of the fault and return path impedances. The proposed method is tested in a 500kV, 100 km length power line, where the errors are lower than 5% even in case of fault resistance of 20Ω and return path resistance of 0,2Ω/km.
Este articulo presenta un analisis sobre el uso y el abuso de las componentes simetricas para sol... more Este articulo presenta un analisis sobre el uso y el abuso de las componentes simetricas para solucionar el problema de la localizacion de fallas en sistemas de distribucion de energia electrica. Se observa como uno de los errores mas comunes es el utilizar aproximaciones propias de los sistemas de transmision, el no considerar las componentes mutuas que se obtienen en las matrices de impedancias en forma de componentes simetricas o el asumir que la impedancia de falla siempre es igual en todas las fases involucradas.
En este articulo se presenta un analisis de la implementacion de sistemas hibridos, para integrar... more En este articulo se presenta un analisis de la implementacion de sistemas hibridos, para integrar varios metodos que permitan una solucion al problema de localizacion de fallas. Como resultados se muestra una propuesta de arquitectura generica para abordar el problema de la localizacion de fallas en sistemas de distribucion de energia electrica, y tambien las pruebas de localizacion donde se obtiene precision muy alta, para un circuito tipico de distribucion. Esta es una alternativa util para el aprovechamiento integrado y efectivo de los metodos de analisis de circuitos y las tecnicas de clasificacion para resolver un problema del sector electrico.
Ingeniería, 2006
Permanent and transient power supply interruption affects power quality indexes related to contin... more Permanent and transient power supply interruption affects power quality indexes related to continuity and causes negative effects in industry, commercial and residential users.As alternative to solve this problem,transmission networks have efficient fault location and protection schemes. Distribution facilities are constrained by technical,economical and operative aspects to implement fault identification and location strategies. In this paper an alternative solution of the fault location problem in power distribution systems, having a minimum of investment from utilities and giving appropriate information which helps to prevent and attend faults. By means of voltage signal characterization measured at the distribution substation and using an optimization and learning technique known as Support Vector Machines (SVM), the most probable zone where the fault was happened is located. The obtained results help to reduce time to locate faults in power distribution systems having a relativ...
Artificial neural networks (ANN) offer an alternative to implementation of conventional controlle... more Artificial neural networks (ANN) offer an alternative to implementation of conventional controllers due the good performance to identify and control nonlinear systems at high computational speed. This technique was used in the supplementary controller implementation (power stabilizer) aimed to maintain an acceptable behavior of the terminal voltage in a synchronous machine, when it is under disturbance conditions. In this paper the obtained results of the proposed approach are presented. The advantages of the use of neural nets over the classical adaptive implementation of power stabilizers are shown.
This paper presents a theoretical analysis of a small power plant wich uses biogas as its primary... more This paper presents a theoretical analysis of a small power plant wich uses biogas as its primary fuel. This biogas is obtained from Urban Solid Wastes (USW) landfills and specifically from La Glorita landfill in Pereira. The thermal plant proposed in this paper is a generic combined cycle power plant. The study here presented is focused on the possibility of generate electricity using wastes that are currently one of the most serious problems on public health and environmental sanitation. This paper also presents a detailed theoretical analysis of the average composition for the biogas produced by a USW landfill in Pereira.
In this paper a voice command recognizing methodology using Support Vector Machines (SVM) is prop... more In this paper a voice command recognizing methodology using Support Vector Machines (SVM) is proposed. This is an important task in autonomous and semi-autonomous systems, because it is a natural and useful interaction way, especially in situations where there are special limitations as low visibility, low or any possibility of physical contact, among others. As application example, voice registered signals are characterized by using spectral bands and next these are classified by using SVMs. The proposed methodology is tested in vowels identification, having obtained a 98% of average successful results
El problema del deslizamiento de frecuencia asociado a la estimacion digital de las magnitudes el... more El problema del deslizamiento de frecuencia asociado a la estimacion digital de las magnitudes electricas, cuando se utiliza como algoritmo de medida la Transformada de Fourier es analizado en este articulo. Se mencionan algunos otros factores que influyen en la precision de las medidas de tension, corriente, potencia y frecuencia, y se obtienen analiticamente los errores de las senales basicas de tension y de corriente, cuando la frecuencia del sistema tiene variaciones y se mantiene fija la frecuencia de muestreo del medidor. En la parte final, se presentan algunos resultados y las conclusiones obtenidas para la estimacion de magnitudes electricas, cuando se tiene como entrada senales con contaminacion armonica y con magnitudes diferentes a plena escala del medidor.
The fundamental problem of the voltage control is to maintain its value in the synchronous machin... more The fundamental problem of the voltage control is to maintain its value in the synchronous machine terminals between established limits, by using several regulation strategies. The proposed approach presented in this paper is aimed to apply an adaptive methodology to develop an Automatic Voltage Regulator (AVR) capable to work well under different perturbations of the sincronous machine. To validate the proposed methodology, a real test system composed mainly by a sincronous machine and a semicontroled bridge is used. The obtained results are compared with the ones obtained from a classic proportional integral AVR.
Fault location methods applied to power distribution systems estimate the fault distance based on... more Fault location methods applied to power distribution systems estimate the fault distance based on the fundamental component of single end voltages and currents. Most of these methods do not consider the non homogeneity of the distribution lines, load taps, laterals, presence of single phase and three phase loads and fault resistance. This paper presents a fault location method to determine the fault distance on radial distribution power systems using single end voltages and currents. The presented method considers non equilibrate loads, laterals, and different types of conductors on the distribution circuit.
Model Based Methods (MBM), used for fault location methods in power distribution systems estimate... more Model Based Methods (MBM), used for fault location methods in power distribution systems estimate the fault distance based on the fundamental component of single end voltages and currents. As general disadvantages there are two; first, these methods require of a good system model; and second, these methods do not avoid the multiple fault location estimation problem. In this paper, a theoretical discussion about the development of hybrid systems starting from both, different types of knowledge related to a real problem, and the combination of artificial intelligent techniques or Knowledge Based Methods (KBM) is presented. Starting from the theoretical basis, and performing the analysis of disadvantages and advantages of each analyzed technique, a proposal to consider the fault location problem in power distribution systems, as a useful hybrid alternative to take advantage of both, MBM and KBM is proposed.
Fault location is close related to power service continuity. This task is more difficult in power... more Fault location is close related to power service continuity. This task is more difficult in power distribution systems than in power transmission systems due the complexity of the first ones. Power distribution systems are composed by non homogeneous line sections, laterals, variable loads, unbalances on loads and system and so on. In addition in such systems only measurements are available at the power substation. This paper proposes a new fault location method based on the graphical analysis of the fault impedance. The capability of the proposed method is tested in a real power distribution system, having obtained errors in distance estimation lower than 2.5%.
This paper presents a comparison of two methods for locating faults, considering the influence of... more This paper presents a comparison of two methods for locating faults, considering the influence of the ground resistivity and the fault resistance. The methods are the proposed by a commercial software developer and one of the classic impedance based methods. Tests were performed using three different ground resistivity models, obtained from field measurements. According to the results in a 34kV power distribution system, the performance of the impedance based fault locator is better than the obtained using the commercial software. Additionally, the soil resistivity models which best represent the real systems are those which give better results in fault location.