Modeling and state estimation for gas transmission networks

• Development of a robust general simulation framework for gas transmission networks.
• Simulation framework is capable of handling flow reversal and valve status changes.
• Proposing a set of heuristic rules for sensor placement in gas transmission networks.
• Proposed Heuristic rules are intended for efficient state estimation in gas networks.
• Performing recursive observability analysis to make it scalable for large networks.

In this paper, a non-isothermal model of natural gas in pipelines including mass, momentum and energy balance equations are used as model equations for modeling and state estimation in gas pipeline systems. It is shown that differential equations describing the dynamic behavior of a high-pressure and long-distance gas transmission network (GTN) can be solved efficiently using the orthogonal collocation method. The issues corresponding to the presence of discontinuities in the dynamic model is substantially discussed and studied. The non-isothermal model of a GTN can experience discontinuities during transient operations, which causes challenges in simulation and state estimation in this system. An algorithm is proposed to handle the discontinuities that appear in the dynamic model of a GTN. The states of GTN are estimated using the continuous/discrete form of the extended Kalman filter for two benchmarks and some heuristic rules for sensor placement in a GTN are concluded. To avoid the singularity in the observability analysis of GTNs, a recursive method for the observability analysis of these networks is used.