Análise de desempenho dinâmico de sistemas de controle de carga-frequência em plantas térmicas com turbina a gás aplicando controle fracionário

Abstract

With the growing energy demand, added to the difficulty of acquiring resources and taking advantage of the hydroelectric matrix, energy alternatives such as wind, solar, and gas-fired thermal have been sought, which have received incentives in hydrogen consumption to increase efficiency and reduce carbon emissions. In line with the energy transition, the use of hydrogen associated with gaseous fuel, such as natural gas, and the ease of installing gas-fired thermoelectric units close to consumer units has been an incentive factor for the increasingly frequent installation of these generating units. Under this scenario, gas-fired generating units are increasingly inserted in the electrical power system, which has brought several studies regarding the dynamic behavior and possible technical problems in the face of disturbances such as loss of generating units in parallel or with loss of load, which demands a quick action of the load-frequency control system. Another predominant factor is the unavailability of gas turbines, especially due to emergency or scheduled maintenance. How the turbine is operated, the control system employed, and its tunings can result in unnecessary thermal stress and fuel consumption. The search for a system that can adapt the dynamic response to minimize these inconveniences directly results in the expansion of downtime events for maintenance, reduction of component changes, and fuel economy. In this work, a new fractional order control technique is analyzed to the detriment of the classical control that aims to improve the performance of the control of speed, load, and frequency of an industrial gas turbine (heavy-duty) to make the response of the turbine more efficient in the face of variations in load and generation, as well as to analyze performance regarding its fuel consumption. Initially, a brief theory of the types of gas turbines and their configurations is presented, as well as a description of the mechanical operation of components. Then, the modeling of the gas turbine and its control loops, described in MATLAB and Simulink computational environment, is performed. The data and parameters were acquired using operational data and entered into the transfer functions of the system. The classical lead-lag compensators are tuned through the Oustaloup methodology, and the pole placement of fractional poles with the Charef approximation is made an approximation of a fractional order function to one of an integer order. It sought to compare the controllers' performance regarding reaction speed and stabilization time and how the control can influence fuel consumption and increase thermal stress related to the system's dynamic stabilization time.