A Comparison of Power Quality Controllers

This paper focuses on certain types of FACTS (Flexibile AC Transmission System) controllers, which can be used for improving the power quality at the point of connection with the power network. It focuses on types of controllers that are suitable for use in large buildings, rather than in transmission networks. The goal is to compare the features of the controllers in specific tasks, and to clarify which solution is best for a specific purpose. It is in some cases better and cheaper to use a combination of controllers than a single controller. The paper also presents the features of a shunt active harmonic compensator, which is a very modern power quality controller that can be used in many cases, or in combination with other controllers. The comparison was made using a matrix diagram that, resulted from mind mapsand other analysis tools. The paper should help engineers to choose the best solution for improving the power quality in a specific power network at distribution level

A Comparison of Power Quality Controllers

This paper focuses on certain types of FACTS (Flexibile AC Transmission System) controllers, which can be used for improving the power quality at the point of connection with the power network. It focuses on types of controllers that are suitable for use in large buildings, rather than in transmission networks. The goal is to compare the features of the controllers in specific tasks, and to clarify which solution is best for a specific purpose. It is in some cases better and cheaper to use a combination of controllers than a single controller. The paper also presents the features of a shunt active harmonic compensator, which is a very modern power quality controller that can be used in many cases, or in combination with other controllers. The comparison was made using a matrix diagram that, resulted from mind mapsand other analysis tools. The paper should help engineers to choose the best solution for improving the power quality in a specific power network at distribution level

Dynamic Model of Medium Voltage Vacuum Circuit Breaker and Induction Motor for Switching Transients Simulation using Clarke Transformation

Derivation of the dynamic model of medium voltage vacuum circuit breaker and induction motor in space vectors in coordinates 0 allow us to model switching transients in various dynamic states of the motor. In the case of the Clarke transformation, the corresponding numerical integration technique can be selected including variable time-step integration techniques to avoid numerical instabilities due to the stiffness of the system. Assymetrical operations such as switching cause that power system becomes unbalanced and the transformed equations , and 0 are not uncoupled. Therefore it is necessary to derive a coupling matrix between circuit breaker voltages and currents in the coordinate system 0. The behavior of the dynamic model was experimentally verified on a laboratory model during the transition between balanced and unbalanced states of the system. The subject of our interest are switching overvoltages that arise when turning off small inductive currents by a vacuum circuit breaker. When deriving the model of a vacuum circuit breaker, all its properties encountered during this action were taken into account, i.e. current chop, virtual current chop, dielectric barrier in the circuit breaker and its recovery rate and the ability of the vacuum circuit breaker to extinguish high frequency currents. Dynamic model is further extended by overvoltage protections and frequency-dependent line model. Simulation results are compared with the measured results on a medium voltage motor and as well as with the simulation results of the mathematical model of the test circuit according to IEC 62271-110 resolved using nodal method (EMTP algorithm). Models are implemented in the MATLAB/Simulink programming environment

Valley Fill Power Factor Correction Analysis

katedra elektrotechnologi

Weather Derivatives

The article deal with the problems of weather derivatives which take the value in sequence nowadays. The aim of this work is the definition of weather derivatives and the way how to price them. We show as well that linear and nonlinear models of time series of temperatures measured in Prague and in Brno have not good results in the estimation of parameters μ I and σ I of the probability distribution function P(I) of the weather index which is essential in their pricing.weather derivatives, pricing weather derivatives, time series

Dynamic Model of Medium Voltage Vacuum Circuit Breaker and Induction Motor for Switching Transients Simulation Using Clark Transformation

A derivation of the dynamic model of a medium voltage vacuum circuit breaker and induction motor in space vectors in coordinates αβ0 allow us to model switching transients in various dynamic states of the motor. In the case of the Clark transformation, the corresponding numerical integration technique can be selected including variable time-step integration techniques to avoid numerical instabilities due to the stiffness of the system. Assymetrical operations such as switching cause the power system to become unbalanced and the transformed equations α, β, and 0 are not uncoupled. Therefore, it is necessary to derive a coupling matrix between circuit breaker voltages and currents in the coordinate system αβ0. The subject of our interest is switching overvoltages that arise when turning off small inductive currents by a vacuum circuit breaker. When deriving the model of a vacuum circuit breaker, all its properties encountered during this action are taken into account, i.e., current chop, virtual current chop, dielectric barrier in the circuit breaker and its recovery rate, and the ability of the vacuum circuit breaker to extinguish high frequency currents. Simulation results are compared with the measured results on a medium voltage motor as well as with the simulation results of the mathematical model of the test circuit according to IEC 62271-110 resolved using the nodal method (EMTP algorithm). Models are implemented in the MATLAB/Simulink programming environment

A Comparison of Power Quality Controllers

This paper focuses on certain types of FACTS (Flexibile AC Transmission System) controllers, which can be used for improving the power quality at the point of connection with the power network. It focuses on types of controllers that are suitable for use in large buildings, rather than in transmission networks. The goal is to compare the features of the controllers in specific tasks, and to clarify which solution is best for a specific purpose. It is in some cases better and cheaper to use a combination of controllers than a single controller. The paper also presents the features of a shunt active harmonic compensator, which is a very modern power quality controller that can be used in many cases, or in combination with other controllers. The comparison was made using a matrix diagram that, resulted from mind mapsand other analysis tools. The paper should help engineers to choose the best solution for improving the power quality in a specific power network at distribution level