Frequency domain dynamic analysis method for steam network and leakage diagnosis

Steam network is an alternative resource to provide flexibility of integrated energy systems (IES), while accurate and efficient analysis is the key. However, it is prevented by the complicated thermohydraulic constraints and potential condensation during steam flow processes. Herein, we propose a Fourier transform-based frequency domain model for steam networks that takes compressibility and condensation into account. The frequency domain governing equations are split into linear and nonlinear parts, which are solved analytically and numerically, respectively, for high-efficiency computation. Compared with experiment data, the relative errors of mass flow rate and pressure of steam obtained from our method are within 5%, and the absolute temperature error is within 10 K. Compared with one-dimensional finite volume method, our method is 1-2 order of magnitude faster with the same accuracy. Then, a bilayer optimization algorithm is further proposed for the leakage diagnosis of steam networks. Case studies including single leakage and multiple leakages in single pipelines and in networks are conducted. Results show that the relative errors of the leakage location in all cases are within 0.7%, demonstrating the high accuracy and robustness of the diagnosis method. In conclusion, our method achieves both high accuracy and efficiency, offering an effective approach for steam network analysis and has significant potential in IES operation.