Development of PID based control strategy in maximum exergy efficiency of a geothermal power plant

• Published in: Renewable & sustainable energy reviews 2021-03, Vol.137, p.110623, Article 110623
• Main Authors: Çetin, Gürcan, Özkaraca, Osman, Keçebaş, Ali
• Format: Article
• Language: English
• Subjects: Exergy efficiency; Geothermal power plant; PID controller; Thermal modelling
• ISSN: 1364-0321; 1879-0690
• DOI: 10.1016/j.rser.2020.110623

The control strategy insures the efficiency, increased production and safety in new and complicated energy conversion systems. To this end, a thermodynamic model that simulates a real geothermal power plant is developed, and a new and optimal control strategy to increase exergy efficiency is presented on this model. In this study, real average daily data obtained during 2016 are used to verify the thermodynamic model of Sinem geothermal power plant in Turkey (S-GPP) and its control strategy. Thus, exergy efficiency of the system is maximized even under different and changed conditions by controlling flow rate, pressure and NCG percent content parameters in certain locations of S-GPP. Consequently, a new control strategy based on PID is developed. At the same time, different working conditions are provided by assigning disruptive values to these parameters. The thermodynamic model of S-GPP is used as a test system to demonstrate the efficiency of the proposed control strategy under various operating conditions. The results of the study prove that the model has a good statistical performance in terms of maximum exergy efficiency values. In addition, the proposed PID controller has a better performance compared to manual control, even in the presence of S-GPP. The effectiveness of the proposed control strategy is demonstrated by this case study, in which exergy efficiency of the system increased by 25% and power generation by 23%. Therefore, the proposed control strategy has the potential to create more reliable and controlled systems for geothermal and other power plants. •A thermodynamic model has been developed that can simulate an existing operating GPP in real time.•An exergy-based PID control strategy is used for the first time in the GPP under various operating conditions.•Maximum exergy efficiency of the GPP is ensured with control of flow rate, pressure and percent content.•The strategy has better control performance compared to the uncontrolled one in the GPP.•With the proposed strategy, its exergy efficiency and power rate can be increased by 25% and 23%, respectively.