EFFECT OF RISK-SENSITIVE STOCHASTIC OPTIMAL CONTROL WITH TRACKING IN AN EVAPORATOR

This work presents an application of the Risk-Sensitive (R-S) control with tracking applied to a stochastic nonlinear system which models the operation of an electronic expansion valve (EEV) in a conventional evaporator. A novel dynamical stochastic equation represents the mathematical model of the evaporator system. The R-S stochastic optimal problem consists of the design of an optimal control u(t) such that the state reaches setpoint values (SP) and minimizes the exponential quadratic cost function. The presence of disturbances and errors in the sensor measurements is represented by Gauss white noise in the state equation, with the coefficient v(e/(2?^2 )) . One novel characteristic in this proposal is that the coefficient of the control into the state equation contains the state term. The error and exponential quadratic cost function show that the R-S control has a better performance versus the classical PID (Proportional, Integral Derivative) control. Key Words: Optimal Risk-Sensitive control with tracking, modelling of the evaporator.

ADAPTIVE COORDINATION OF DISTANCE PROTECTION ON SUBTRANSMISSION LINES CONSIDERING THE INFEED EFFECT

ABSTRACT: This article describes an algorithm for an adaptive distance protection in a sub-transmission system considering operating conditions with changes in the topology due to an abnormal condition, electrical failure or a natural disaster, includes the effect of adjacent generation in the distance relay protection zones, with the incorporation of renewable energies in mixed participation. Two scenarios are proposed, in the first case occurred a contingency, and the transmission systems changes the initial topology. Protections are automatically reparametrized. The second case includes the income of renewable energy generation in a specific point of power electrical Systems. Protections are automatically recalculated. The objective of an automatic coordination permit to operator to restore the sensitivity, selectivity and reliability the electrical protection system in the lowest time. Keywords: Adaptive distance relay, renewable energy, distance protection, infeed effect..)

EXPERIMENTAL COMPARATIVE STUDY BETWEEN MPPT, HYBRID P&O AND FUZZY CONTROL FOR A SMALL WIND TURBINE APPLICATION

ABSTRACT This study focuses on a comparison between different maximum power extraction controls for a small wind turbine application. In this case, a vertical axis wind turbine (VAWT) coupled to a permanent magnet synchronous generator (PMSG) is used. The analysis is performed for variable winds, so that a real small wind turbine application is simulated. An experimental platform and a wind tunnel are used to recreate the different wind profiles. Diverse controls are compared, a "classical" MPPT, a hybrid Perturb & Observe control and a fuzzy control. Artificial intelligence allows the creation of control algorithms that are not bound by the mechanical parameters of the wind turbine, thus avoiding the need to characterize the wind turbine and define the maximum power curve. It is determined that, for almost constant wind profiles, the hybrid Perturb & Observe extracts more energy. However, for the same profile with greater variability, the fuzzy controller extracts more energy.

STUDY OF DIRECT CURRENT POWER TOPOLOGIES AND TECHNOLOGY APPLIED ON HIGH VOLTAGE CHARGING SYSTEMS

ABSTRACT This article describes the actual state of art of the current battery charging systems, with a special focused on its technical, technological features and its operation modes. The most important factors considered for this functional and theoretical study are from the following points of view: State of the art: This article reviews the technological division between lithium batteries and the most suitable power topology for each one. Technological factor: The article reviews the technological state from the point of view of the power components as: MOSFET transistors, diodes, with special focused in the power ranges, technological limits and costs. Theoretical factor: This factor is focused in the description of the power topologies and its preferred selection depending on the voltage and the current range of its potential application. This chapter also shows the basic theoretical approach and the key differences between uni-directional and bi-directional power architectures. Control Theory: The current control systems have a lot of similarities between each other, either in alternating current or direct current. However The operation of battery charging systems has common and functional drifts in its behaviours with standard direct current converters. This article describes and analyses their similarities and their differences.

CHANGES IN THE COMMUNITY HEATING SHARE. INFLUENCE OF COEFFICIENTS ON THE NEW QUOTES

ABSTRACT In the next months the heating and D.H.W cost sharing criteria must be modified in many pre-existing buildings. A special case is the buildings with vertical pipelines, for these buildings the recognized form of the rule for the cost sharing is to install “allocators” or “calorimeters" in each heater. In this article a review of the percentages and coefficients adopted in other countries of the union is made and their influence is analyzed. Variants are proposed to calculate and apply the correction factors.A simple procedure is proposed to estimate consumption and new quotes, using a spreadsheet. The main conclusion is that only after a detailed study can a solution be reached that can be assumed by the majority of the community members. Keywords: Efficient buildings, Community heating. Cost Sharind, Estimates fees.

SHORT-TERM EFFECTS OF THE CLOSURE OF COAL-FIRED POWER PLANTS ON THE SPANISH ELECTRICITY MARKET

ABSTRACT: This article analyses the effect of the closure of the Spanish coal-fired power stations on the price and quantity of energy sold in the daily electricity market. The comparative statics analysis is based on the hourly data of energy offer and demand bids published by the OMIE (Operator of the Iberian Energy Market) and made by the participants in the daily electricity market during the year 2018. Our analysis does not require any simulation of the market supply and demand curves, since they are obtained by aggregation using real data from the wholesale market. The main conclusion of our analysis is that, after the closure of the coal-fired stations, the hourly price of energy would increase 12,06% on average while the average amount of energy would decrease 2,57%. Keywords: Price of electricity; coal plants; ecological transition; supply and demand surpluses; renewable energy.