Simulation of Protective Mechanisms in District Heating Systems

Abstract

This paper presents a hybrid automata-based framework for simulating protective mechanisms in district heating systems under emergency conditions. District heating networks exhibit complex dynamics combining continuous thermo-hydraulic processes with discrete control actions triggered by accidents such as pipeline ruptures, pump failures, or valve malfunctions. Traditional modeling approaches struggle to capture this hybrid behavior. To address this, we develop a formal model where the physical system is represented as a hybrid automaton with discrete operational modes (normal, accident, recovery) and continuous state variables (pressures, flows, temperatures). Protective devices—such as pressure relief valves, pump trip logic, and emergency shutdown systems—are encoded as control automata with thresholds, time delays, hysteresis, and logical dependencies. These controllers interact with the plant automaton in a closedloop configuration, enabling realistic simulation of accident evolution and protection responses. The framework is applied to representative failure scenarios, including pipe breaks and pump outages, demonstrating its ability to evaluate the correctness, robustness, and coordination of safety mechanisms. Results highlight the value of automata-based modeling for identifying design weaknesses, tuning protection parameters, and supporting safety verification in thermal energy infrastructure.