On the Formulation of Steady-State Initialization Problems in Object-Oriented Models of Closed Thermo-Hydraulic Systems

The object-oriented formulation of steady-state initialization for models of closed thermo-hydraulic systems yields singular problems; due to system-wide structural issues. The paper proposes how to solve this problem in an object-oriented fashion; by means of an additional component that helps to uniquely determine the initial conditions of the system. A method based on the analysis of the null space of the Jacobian of the initialization problem and on suitable annotations is also proposed to provide the end user with meaningful; high-level; context-relevant diagnostic messages; in case the singular problem arises. This diagnostic method can also be applied to other cases; such as closed systems with constant density fluid and electrical circuits lacking a ground connection.