arXiv subjects

Mahdi Pourakbari-Kasmaei

Publications and source records attributed to Mahdi Pourakbari-Kasmaei.

4 recordsLinked to original sources

arXiv2026

Coordinated Dynamic Operation of Integrated Electrolyzer-Compressor Systems

The increasing interaction between power and hydrogen sectors highlights the importance of coordinated operation of electrolyzers and electric-driven compressor stations (EDCSs). This becomes particularly of higher importance under transient disturbances. However, coordinated dynamic interactions of these coupled subsystems remain largely unexplored. This article addresses such gap by developing a dynamic model for an integrated electrolyzer-EDCS system and designing appropriate PID control schemes to address the potential disturbances affecting either component. To this end, linearized models of the electrolyzer and EDCS are first derived to enable systematic controller design. Then, two PID controllers, representing conservative and fast-tracking designs, are developed to coordinate the system response. The developed coordinated model is examined and verified under four different cases. The results demonstrate the effectiveness of the proposed model under disturbances from the compressor driver or the electrolyzer. Controlling the electrolyzer flow in response to EDCS disturbances coordinates system dynamics and mitigates undesirable transient fluctuations. Conversely, under electrolyzer disturbances, regulating the EDCS torque eliminates inconsistent responses in pressure, flow, and rotational speed, while preventing hazardous transient undershoots and overshoots. Overall, the proposed framework guarantees transient stability and operational reliability of the integrated electrolyzer-EDCS system.

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arXiv2026

Comparative Analysis of Linepack Impact in Hydrogen and Natural Gas Networks under Dynamic Operating Conditions

Linepack is a critical buffer in gas networks, providing short-term storage and operational flexibility. This paper presents a comparative dynamic analysis of the linepack impact in hydrogen (H2) and natural gas (CH4) networks under compressor contingency conditions. A three-day dynamic simulation is conducted for a CH4 network and a H2 network integrated with a power system. Two cases are investigated: Case 1 with identical and Case 2 with different pipe inner diameters in CH4 and H2 networks. The results in both cases show that H2 exhibits faster transient recovery after the compressor contingency, although its linepack is less than that of CH4. On the other hand, depending on the selected pipe diameter, pressure losses in the two networks can differ significantly. With identical pipe diameters, H2 exhibits lower pressure drop than CH4, and its demand therefore experiences less curtailment. However, when the H2 pipe diameter is reduced, the pressure drop across the H2 pipes increases and the curtailed load becomes higher than in the CH4 network. These results can be used by gas TSOs in designing and operating their grid more efficiently.

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arXiv2018

Development of a Convex Programming Model for Optimal Power Flow Problems

The optimal power flow (OPF) is an optimization model dedicated to the development of computational tools used for the planning and operation of electric power systems (EPS). In this work, based on the polar formulation, an extended convex model is presented. To do so, the sinusoidal and cosinusoidal terms are the toughest part of the convexification process, since such types of functions oscillate between concave and convex. These functions are not initially convex, but there is a possibility of finding a convex underestimator (CU) for them. To obtain this CU, the Taylor series presents a good, however nonconvex, approximation for such trigonometric functions. Although the model remains nonconvex, these terms can be recast to the corresponding equivalent convex terms. The obtained convex model of the OPF is tested and analyzed using the IEEE 14-, 30-, 54-, and 118-bus test systems.

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arXiv2018

A Logic-Based Mixed-Integer Nonlinear Programming Model to Solve Non-Convex and Non-Smooth Economic Dispatch Problems: An Accuracy Analysis

This paper presents a solver-friendly logic-based mixed-integer nonlinear programming model (LB-MINLP) to solve economic dispatch (ED) problems considering disjoint operating zones and valve-point effects. A simultaneous consideration of transmission losses and logical constraints in ED problems causes difficulties either in the linearization procedure, or in handling via heuristic-based approaches, and this may result in outcome violation. The non-smooth terms can make the situation even worse. On the other hand, non-convex nonlinear models with logical constraints are not solvable using the existing nonlinear commercial solvers. In order to explain and remedy these shortcomings, we proposed a novel recasting strategy to overcome the hurdle of solving such complicated problems with the aid of the existing nonlinear solvers. The proposed model can facilitate the pre-solving and probing techniques of the commercial solvers by recasting the logical constraints into the mixed-integer terms of the objective function. It consequently results in a higher accuracy of the model and better computational efficiency. The acquired results demonstrated that the LB-MINLP model, compared to the existing (heuristic-based and solver-based) models in the literature, can easily handle the non-smooth and nonlinear terms and achieve an optimal solution much faster and without any outcome violation.

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