Modelling, simulation and control of a distribution gas network for renewable gas integration

In the context of the gas industry, this thesis aims to analyse its general context, from its structure and organisation to the observation of regulations and its evolution in the context of the modern era. Fundamental to the thesis work will also be analysing the history of gas and its properties in the first part of the paper, and then also focusing on the history of the company and its modus operandi. In particular, my 6-month experience in the corporate world of Italgas S.p.A allowed me to understand and see more closely how gas distribution is managed in Italy. In this context, in order to fully assimilate all that was presented and discussed, the first period spent within the team that dealt with the management of SCADA (company applications for the management and global vision of all plants in the territory) and Remote Terminal Units (RTU) was fundamental. These devices, mounted near the final reducers and on the reduction and metering substations (IPRM), allow staff to monitor their operation and the trend of the parameters collected directly from their PC in the office (via the SCADA presented above). Operators interfacing with the company's management systems receive alarm signals from these devices or even from any calls from customers experiencing anomalies, alerting them precisely and clearly as to what the problem is and where to go to solve it. From the point of view of a 'digitised network' (a concept that will be explored in more detail), it is essential that their operation is continuous and scanned consistently over a period of time to be considered; this was essential for the acquisition of the data that allowed us to obtain consumption and pressure trends (also of other variables such as temperature, but which are not important in this context). The extraction of the data through the company's application was necessary to obtain the fluid-dynamic balance of the network, since the mathematical model implemented only allows us to obtain a complete simulation by including consumption at the various significant points of the network as input. The case study that represents the central focus of the thesis was to take a real existing gas network (Pozzuolo Martesana) in which a component was inserted into the main filling station that is currently unexploited, but which could allow remote control of the valves for pressure variation. After an in-depth analysis of the actuator from a technical point of view, it will be used as a real object for the realisation of the network control using MATLAB/Simulink. The block diagram implemented in the software aims to vary pressures according to inputs (such as network consumption in a given period) and disturbances, by acting on the set-point which represents the initial pressure with which the main cabin (IPRM) feeds gas into the network. Going specifically into a period of reduced consumption (summer) and keeping the flow rate of the biomethane cabin constant, the objective is to try to vary the outlet pressure of the main cabin so that in the vicinity of the GRF (final reduction group) it never exceeds the limit imposed by the regulations for urban networks (5 Bar). As in any control loop, the main element on which the controller evaluates and performs actions is the 'plant', which in this case is represented by the gas network in its entirety, trying to model its fluid-dynamic behaviour.