A Realistic Particle Physics Dark Energy Model

We present a realistic dark energy model derived from particle physics. Our model has essentially no free parameters and has an equivalent fit to the observational data (CMB, SN1a and LSS) as LCDM and a better fit than the best effective $w(z)$ model. With the lack of a clear determination of the cosmological parameters theoretical considerations should be taken seriously to distinguish between dark energy models.Comment: 5 pages, RevTex, 6 figure

Shunt Hybrid Active Power Filter Based on Two Compensation Strategies with PI and Fuzzy Logic Controllers

Industrial designs have tremendously changed within the last decade, with its time and nonlinear variation loads in power frameworks spectrum expanding widely. This revolution has resulted in increased quality control problems such as current unbalance, current and voltage harmonics, flicker and poor power factor in control frameworks. The aim of this paper is to address this problem through the development of Synchronous Reference Frame and Reactive Power (SRF and P-Q) control methods. The DC voltage was regulated to its set reference for providing the current reference using proportional-Integral (PI) and fuzzy logic controllers. From the results, Fuzzy logic control was shown to achieve an adequate DC capacitor energy storage optimization, the sinusoidal type of the current and the change of the power factor. A low Total Harmonic Distortion (THD) that met the suggestions of IEEE- 519 standard on symphonious levels was achieved with the proposed method

Load characterization in medium voltage of an electric distribution utility related to active filters

The behavior of the actual load of an electric energy distribution utility by means of voltage and current measurements is analyzed in this paper. Steady and transient states are taken into account. The main attention is fixed in points where present shunt compensation is installed. Results of field measurements and the connection and disconnection of capacitor banks are shown. Studies for future compensation are detailed and the possible advantages of active filter incorporation are analyzed in order to replace or complement the existing compensation. The minimal requirements are established in order to consider the design of the active filters and their compatibility with the existing installations.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Hybrid power filter to enhance power quality in a medium-voltage distribution network

This paper deals with the problem of reactive power and harmonics in a standard medium-voltage (MV) distribution network. It proposes a simple and inexpensive solution to enhance power quality when a particular connection to the high-voltage transmission network is required. It presents the design of a hybrid active filter topology connected to the MV level of a power distribution system. Its main task is to regulate a 132-kV voltage level. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The topology of a shunt hybrid active filter is analyzed. It is built with the series connection of a passive filter and a low-rated active filter. The proposed filter is directly connected to a 13.8-kV level with no need of a step-down transformer. The possibility of different levels of reactive power compensation is implemented. The proposal shows very good performance for different load demands.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Hybrid active filter for reactive and harmonics compensation in a distribution network

The problem of reactive power and harmonics in the medium voltage level of a power distribution system is considered in this paper. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The alternative of a shunt hybrid active filter connected to the 13.8-kV level to enhance the power quality is analyzed in this paper. This proposal uses the existing capacitor bank to build a hybrid filter in which the complementary compensation is performed by the active filter. The performance of the hybrid filter is evaluated with extensive simulations considering reactive power, harmonics, and unbalance compensation. It shows very good behavior in steady-state and transient conditions.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Análisis de la ubicación y diseño conveniente de un filtro activo en una planta industrial ante diferentes escenarios de operación

En este trabajo se presenta el análisis de un Filtro Activo de Potencia para la compensación de reactivo y armónicas en una planta industrial. Esta propuesta utiliza bancos de capacitores existentes en la planta, los cuales son transformados en filtros pasivos que conjuntamente con una parte activa conforman un sistema adaptable y económico de compensación. Actualmente la planta posee banco de capacitores en el nivel de Media Tensión (MT) 33kV, fundamentalmente para lograr un adecuado factor de potencia en el punto de conexión al sistema (132kV). Las cargas son principalmente motores de inducción. Se logran identificar aquellos que poseen sistemas para la regulación de velocidad (ASD o Drivers) y por ende conocer la ubicación y potencia de las principales cargas no-lineales que generan armónicas. Se poseen registros de mediciones efectuadas en dicha planta, donde se pueden apreciar los niveles de distorsión armónica. Se analizan diferentes escenarios actuales de operación, definidos a partir de la posibilidad de cambiar el punto de alimentación de algunas cargas de la planta y reconfiguraciones posibles de la red. Además, se estudian escenarios futuros donde se debe aumentar la compensación de reactivo dada el aumento de la demanda la planta. El objetivo del trabajo es diseñar y ubicar convenientemente el sistema de compensación activo-pasivo, eligiendo la combinación más económica y que mejor se adapte a las necesidades de la red. Como parte del diseño del sistema de control se determina el lugar de medición de las variables de referencias que cubran todos los estados de operación.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Comparison of active filters topologies in medium voltage distribution power systems

This paper presents the design of different topologies of active power filters to compensate reactive power and harmonics in the medium voltage level of a distribution power system. One pure active filter and two hybrid topologies, are implemented. A pure active compensation is obtained with a Shunt Active Power Filter (SAPF). The shunt combination of SAPF and passive filter, form one of the hybrid topologies implemented, named Shunt Hybrid Active Power Filter (SHAPF). The other hybrid topology, called Hybrid Shunt Active Power Filter (HSAPF), connects the active filter in series with two shunt passive filters. Simulation for different load demands and distortions are performed. Finally a comparative evaluation of the different filters is carried out.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE