Instituto Tecnológico de Morelia

About: Instituto Tecnológico de Morelia is a education organization based out in Morelia, Mexico. It is known for research contribution in the topics: Electric power system & AC power. The organization has 498 authors who have published 572 publications receiving 4600 citations.

A new harmonic power flow method based on the instantaneous power balance

Abstract: In this paper an instantaneous power flow (IPF) solution method for analysing the harmonic power flow problem is proposed. The IPF uses the instantaneous power balance to formulate the problem. The methodology uses the harmonic domain as a frame-of-reference and the Newton-Raphson method. This method is fully formulated in the frequency domain and applicable to systems which also contain nonlinear elements and FACTS devices. The method also offers a flexible and modular formulation which shows excellent convergence properties. The IPF is developed, implemented and proved with simple examples for linear and nonlinear concentrated loads and the thyristor controlled reactor (TCR) in the control of reactive power.

A New Approach for PV Nodes Using an Efficient Backward/Forward Sweep Power Flow Technique

Abstract: Most of the distribution networks may contain reactive power sources such as distributed generators with reactive support, static VARs compensators or even switching capacitors. In this sense, it is necessary to have an appropriate and convenient model for controlled-voltage (PV) nodes to be applied in power flow distribution networks. On the other hand, the conventional power flow analysis has been an important tool for all power systems engineers. The nonlinear methods based on the Newton- Raphson method and its decoupled forms and the Gauss-Seidel with Ybus factorized method have been popular to nowadays. However, these methods have presented some convergence problems when are applied to distribution networks analysis. The reasons are the inherent characteristics of distribution networks, such as high r/x ratios, very low branch impedances, radial feeder configurations, among others. In this sense, the techniques based on Backward/Forward Sweep (BFS) methods for power flows have been widely applied in distribution systems. However, as above mentioned for controlled-voltage (PV) nodes some challenges in BFS power flow algorithms are presented, some authors have proposed hybrid methods, iterative methods, sensitivities matrix- based methods, among others. Unfortunately, those methods usually require complex formulations and long execution times. In this paper a new approach and easily controlled-voltage (PV) formulation joint with a simple power flows methodology, called LRSV method, is presented. The results show that this no-complex methodology permits to obtain better execution times, responses in a better way for different load, generation and configurations and some tests cases to demonstrate the effectiveness of the proposed methodology.

Quasi-3-D Finite-Element Modeling of a Power Transformer

Abstract: A strong circuit-field coupling technique that can analyze multiple magnetic field systems (2-D Cartesian and axisymmetric) is adapted to study power transformers. The technique is based on finite-element (FE) and modified nodal analyses, leading to a multi-field system approach that can effectively take account of the 3-D magnetic field existing inside and outside the transformer core. Hence, cumbersome 3-D FE simulations are circumvented, overcoming high computational costs. A 2-D Cartesian FE model is set up to represent the cross section of the transformer core and its three-phase winding, whereas an axisymmetric representation is employed for the end sections of each set of windings (one per phase). All models and their associated circuit systems are simultaneously solved, providing a circuit-field method that is easy to implement at low computational cost, keeping the well-known advantages of 2-D FE modeling. Electrical currents and local values of magnetic flux density are calculated for two limiting conditions: rated load and short-circuit operation. Our approach shows a remarkably small difference (no higher than 1%) with a full 3-D FE model.

Effect of Heating Rate and Silicon Content on Kinetics of Austenite Formation during Continuous Heating

Abstract: The first step in a heat treating cycle is the austenitizing of the as-received material. Despite its importance, this step has received relatively little attention. In this work, the kinetics of austenite formation during continuous heating tests of steel samples with low and high silicon content was determined as a function of heating rate. The microstructural evolution was characterized through dilatometric analysis of cylindrical samples (7 mm × 20 mm), continuously heated in a protective atmosphere at constant heating rates ranging from 2 to 40 °C/min. The critical temperatures and the transformation kinetics were determined from the derivative of the relative length change as a function of temperature. As the heating rate increases the critical temperatures and the transformation temperature range increase; the addition of silicon produces a more marked effect. The transformation kinetics data were correlated using an Avrami-type equation. The kinetic parameter n is nearly independent of heating rate while the parameter k is a strong function of the heating rate; in both cases, slightly larger values were obtained for the high-silicon steel.