@misc{HerrmannPlietzschRoseetal., author = {Herrmann, Ulrike and Plietzsch, Anton and Rose, Max and Gernandt, Hannes and Schiffer, Johannes}, title = {A predictive operation management scheme for hydrogen networks based on the method of characteristics}, series = {2024 European Control Conference (ECC)}, journal = {2024 European Control Conference (ECC)}, publisher = {IEEE}, doi = {10.23919/ECC64448.2024.10591107}, pages = {1084 -- 1089}, abstract = {As future hydrogen networks will be strongly linked to the electricity system via electrolysers and hydrogen power plants, challenges will arise for their operation. A suitable response to phenomena, such as rapidly changing boundary conditions and unbalanced supply and demand, requires the implementation of operational concepts based on transient pipe models. The transient pipe flow can be described by the isothermal Euler equations, which we discretize using an explicit Method Of Characteristics. Based on this, we develop a nonlinear space-time discretized network model that incorporates various other components, including hydrogen storage facilities, active elements such as valves and compressor stations, as well as electrolyzers and fuel cells. This network model serves as the foundation for the development of a tailored economic model predictive control algorithm designed for fast timescales. The algorithm enables controlled pressure changes within specified bounds in response to changes in supply and demand while simultaneously minimizing fast pressure fluctuations in the pipelines. Through a detailed case study, we demonstrate the algorithm's proficiency in addressing these transient operation challenges.}, language = {en} } @misc{TexisLoaizaZuritaBustamanteSchiffer, author = {Texis-Loaiza, Oscar and Zurita-Bustamante, Eric W. and Schiffer, Johannes}, title = {A BL-homogeneous observer for inter-turn short-circuit fault detection in PMSMs}, series = {2024 IEEE Conference on Control Technology and Applications (CCTA)}, journal = {2024 IEEE Conference on Control Technology and Applications (CCTA)}, publisher = {IEEE}, doi = {10.1109/CCTA60707.2024.10666505}, pages = {248 -- 253}, abstract = {Electric vehicle propulsion systems heavily depend on the reliable operation of permanent magnet synchronous motors (PMSMs). However, the susceptibility of PMSMs to electrical faults, particularly inter-turn short circuit (ITSC) faults, poses a significant threat to their overall reliability. With the purpose of enabling an immanent fault detection, we design a fault detection observer using the recently developed bi-limit-homogeneous sliding mode observer (BL-H SMO) technique. The BL-H SMO has the ability to offer zero error estimates within finite or fixed-time intervals even in the presence of unknown inputs, which is a distinctive advantage enhancing its efficacy in fault detection for PMSMs compared to standard Kalman filter schemes. These advantages are illustrated via a simulation study that validates and compares the proposed BL-H SMO's performance with that of a Kalman filter.}, language = {en} } @misc{LorenzMeyerSuchantkeSchiffer, author = {Lorenz-Meyer, Nicolai and Suchantke, Ren{\´e} and Schiffer, Johannes}, title = {Dynamic state and parameter estimation in multi-machine power systems—Experimental demonstration using real-world PMU-measurements}, series = {Control Engineering Practice}, volume = {135}, journal = {Control Engineering Practice}, issn = {0967-0661}, doi = {10.1016/j.conengprac.2023.105491}, abstract = {Dynamic state and parameter estimation (DSE) plays a key role for reliably monitoring and operating future, power-electronics-dominated power systems. While DSE is a very active research field, experimental applications of proposed algorithms to real-world systems remain scarce. This motivates the present paper, in which we demonstrate the effectiveness of a DSE algorithm previously presented by parts of the authors with real-world data collected by a Phasor Measurement Unit (PMU) at a substation close to a power plant within the extra-high voltage grid of Germany. To this end, at first we derive a suitable mapping of the real-world PMU-measurements recorded at a substation close to the power plant to the terminal bus of the power plants' synchronous generator. This mapping considers the high-voltage transmission line, the tap-changing transformer and the auxiliary system of the power plant. Next, we introduce several practically motivated extensions to the estimation algorithm, which significantly improve its practical performance with real-world measurements. Finally, we successfully validate the algorithm experimentally in an auto- as well as a cross-validation.}, language = {en} } @misc{RoseHansSchiffer, author = {Rose, Max and Hans, Christian A. and Schiffer, Johannes}, title = {A Predictive Operation Controller for an Electro-Thermal Microgrid Utilizing Variable Flow Temperatures}, series = {IFAC-PapersOnLine}, volume = {56}, journal = {IFAC-PapersOnLine}, number = {2}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2023.10.195}, pages = {5444 -- 5450}, abstract = {We propose an optimal operation controller for an electro-thermal microgrid. Compared to existing work, our approach increases flexibility by operating the thermal network with variable flow temperatures and in that way explicitly exploits its inherent storage capacities. To this end, the microgrid is represented by a multi-layer network composed of an electrical and a thermal layer. We show that the system behavior can be represented by a discrete-time state model derived from DC power flow approximations and 1d Euler equations. Both layers are interconnected via heat pumps. By combining this model with desired operating objectives and constraints, we obtain a constrained convex optimization problem. This is used to derive a model predictive control scheme for the optimal operation of electro-thermal microgrids. The performance of the proposed operation control algorithm is demonstrated in a case study.}, language = {en} } @misc{Mendoza‐AvilaEfimovAngelMercado‐Uribeetal., author = {Mendoza-Avila, Jesus and Efimov, Denis and Angel Mercado-Uribe, Jose and Schiffer, Johannes}, title = {Design of control laws for robust global stabilization of multistable state periodic systems}, series = {International journal of robust and nonlinear control}, journal = {International journal of robust and nonlinear control}, publisher = {Wiley}, address = {New York, NY}, issn = {1049-8923}, doi = {10.1002/rnc.70206}, pages = {1 -- 20}, abstract = {This paper continues with the development of the input-to-state stability (ISS)-control Leonov function (CLeF) approach. The definitions of practical ISS and integral ISS (iISS)-CLeFs are refined, and the proposed methodology for control synthesis is improved to simplify the final control law. Then, it is shown that the existence of practical ISS- and iISS-CLeFs is a sufficient condition to guarantee the existence of a controller that endows multistable state periodic systems with the ISS and iISS properties, respectively. Furthermore, a methodology for the design of such a controller is provided via the well-known Sontag's universal formula. Besides, an extension of the main result is presented to connect the ISS-CLeF approach with the standard Leonov function method such that the maximal invariant set of the closed-loop system is compact on a manifold. Finally, the proposed approach is applied to the design of an excitation controller for a synchronous generator, which guarantees global ISS properties for the closed-loop system, unlike the usual local results reported in the literature. The obtained control is also independent of the load angle. The effectiveness of the designed controller is demonstrated in simulations.}, language = {en} } @misc{ŞenMachadoSchiffer, author = {Şen, G{\"o}k{\c{c}}en Devlet and Machado, Juan E. and Schiffer, Johannes}, title = {A cost-optimal predictive operation scheme for sector-coupled energy plants with start-up delays and start-up costs}, series = {IFAC-PapersOnLine}, volume = {59}, journal = {IFAC-PapersOnLine}, number = {9}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2025.08.143}, pages = {241 -- 246}, abstract = {In this work we present a cost-optimal energy management scheme for sector-coupled energy plants, focusing on systems that enable gas-to-electricity, gas-to-heat, and power-to-heat conversions. To capture realistic operational challenges, the considered system model incorporates dynamic constraints, including start-up delays and off-time-dependent start-up costs. By accounting for the impact of these factors, we demonstrate on a case study that they can significantly reduce overall operational costs. The energy management problem is cast as a mixed-integer nonlinear programming (MINLP) problem, which is then solved within a model predictive control (MPC) framework. The proposed approach provides a structured methodology for real-time energy management, enhancing energy efficiency while minimizing costs.}, language = {en} } @misc{RoseGernandtFaulwasseretal., author = {Rose, Max and Gernandt, Hannes and Faulwasser, Timm and Schiffer, Johannes}, title = {Exact time-varying turnpikes for dynamic operation of district heating networks}, series = {IEEE control systems letters}, volume = {9}, journal = {IEEE control systems letters}, publisher = {IEEE}, address = {New York, NY}, issn = {2475-1456}, doi = {10.1109/LCSYS.2025.3582614}, pages = {1706 -- 1711}, abstract = {District heating networks (DHNs) are crucial for decarbonizing the heating sector. Yet, their efficient and reliable operation requires the coordination of multiple heat producers and the consideration of future demands. Predictive and optimization-based control is commonly used to address this task, but existing results for DHNs do not account for time-varying problem aspects. Since the turnpike phenomenon can serve as a basis for model predictive control design and analysis, this letter examines its role in DHN optimization by analyzing the underlying optimal control problem with time-varying prices and demands. That is, we derive conditions for the existence of a unique time-varying singular arc, which constitutes the time varying turnpike, and we provide its closed-form expression. Additionally, we present converse turnpike results showing a exact time-varying case implies strict dissipativity of the optimal control problem. A numerical example illustrates our findings.}, language = {en} } @misc{BuettnerWuerfelLiemannetal., author = {B{\"u}ttner, Anna and W{\"u}rfel, Hans and Liemann, Sebastian and Schiffer, Johannes and Hellman, Frank}, title = {Complex-phase, data-driven identification of grid-forming inverter dynamics}, series = {IEEE transactions on smart grid}, volume = {9}, journal = {IEEE transactions on smart grid}, number = {6}, publisher = {IEEE}, address = {New York, NY}, issn = {1949-3053}, doi = {10.1109/TSG.2025.3591891}, pages = {4854 -- 4864}, abstract = {The increasing integration of renewable energy sources (RESs) into power systems requires the deployment of grid-forming inverters to ensure a stable operation. Accurate modeling of these devices is necessary. In this paper, a system identification approach to obtain low-dimensional models of gridforming inverters is presented. The proposed approach is based on a Hammerstein-Wiener parametrization of the normal-form model. The normal-form is a gray-box model that utilizes complex frequency and phase to capture non-linear inverter dynamics. The model is validated on two well-known control strategies: droop-control and dispatchable virtual oscillators. Simulations and hardware-in-the-loop experiments demonstrate that the normalform accurately models inverter dynamics across various operating conditions. The approach shows great potential for enhancing the modeling of RES-dominated power systems, especially when component models are unavailable or computationally expensive.}, language = {en} } @misc{LorenzMeyerRuedaEscobedoMorenoetal., author = {Lorenz-Meyer, Nicolai and Rueda-Escobedo, Juan G. and Moreno, Jaime A. and Schiffer, Johannes}, title = {A robust consensus + innovations-based distributed parameter estimator}, series = {IEEE transactions on automatic control}, journal = {IEEE transactions on automatic control}, publisher = {IEEE}, address = {New York, NY}, issn = {0018-9286}, doi = {10.1109/TAC.2025.3597563}, pages = {1 -- 15}, abstract = {While distributed parameter estimation has been extensively studied in the literature, little has been achieved in terms of robust analysis and tuning methods in the presence of disturbances. However, disturbances such as measurement noise and model mismatches occur in any real-world setting. Therefore, providing tuning methods with specific robustness guarantees would greatly benefit the practical application. To address these issues, we recast the error dynamics of a continuous-time version of the widely used consensus + innovations-based distributed parameter estimator to reflect the error dynamics induced by the classical gradient descent algorithm. This paves the way for the construction of a strong Lyapunov function. Based on this result, we derive linear matrix inequality-based tools for tuning the algorithm gains such that a guaranteed upper bound on the L2-gain with respect to parameter variations, measurement noise, and disturbances in the communication channels is achieved. An application example illustrates the efficiency of the method.}, language = {en} } @misc{EstradaRuedaEscobedoMorenoetal., author = {Estrada, Manuel A. and Rueda-Escobedo, Juan G. and Moreno, Jaime A. and Schiffer, Johannes}, title = {Systematic and robust tuning of proportional-resonant controllers for current and voltage tracking}, series = {2025 IEEE Conference on Control Technology and Applications (CCTA), August 25-27, 2025, San Diego, CA, USA}, journal = {2025 IEEE Conference on Control Technology and Applications (CCTA), August 25-27, 2025, San Diego, CA, USA}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {979-8-3315-3908-5}, issn = {0018-9286}, doi = {10.1109/CCTA53793.2025.11151423}, pages = {768 -- 773}, abstract = {In the control and operation of power inverters, proportional-resonant (PR) controllers are used to track references and reject disturbances that can be described by a sum of sinusoidal signals of known frequency. The relevance of these controllers is increasing due to the increase in distortion and volatility of three-phase signals in the grid. However, as reported in the literature, the tuning of PR controllers is far from trivial due to their large number of parameters and the presence of pure imaginary poles in the associated transfer function. To address these issues, a time-domain framework based on linear matrix inequalities (LMIs) is presented for the tuning of PR controllers with applications to voltage and current tracking. The advantage of this approach is the straightforward combination with other techniques such as H∞ control. The effectiveness of the approach is illustrated through numerical simulations, where the injection of a constant active power is achieved in the presence of distorted voltages.}, language = {en} } @misc{OrtegaBobtsovFangetal., author = {Ortega, Romeo and Bobtsov, Alexey and Fang, Leyan and Texis-Loaiza, Oscar and Schiffer, Johannes}, title = {Interturn fault detection in PMSMs : two adaptive observer-based noise insensitive solutions}, series = {IEEE transactions on control systems technology}, journal = {IEEE transactions on control systems technology}, publisher = {IEEE}, address = {New York, NY}, issn = {1063-6536}, doi = {10.1109/TCST.2025.3612450}, pages = {1 -- 12}, abstract = {In this article, we address the problem of online detection of interturn short-circuit faults (ITSCFs) that occur in interior- and surface-mounted permanent magnet synchronous motors (PMSMs). We propose two solutions to this problem: 1)a very simple linear observer and 2) a generalized parameter estimation-based observer, that incorporates a high performance estimator—with both observers detecting the short-circuit current and the fault intensity. Although the first solution guarantees the detection of the fault exponentially fast, the rate of convergence is fully determined by the motor parameters that, in some cases, may be too slow. The second observer, on the other hand, ensures finite convergence time (FCT) under the weakest assumption of interval excitation (IE). To make the observers adaptive, we develop a parameter estimator that, in the case of surface-mounted motors, estimates online (exponentially fast) the resistance and inductance of the motor. It should be underscored that, in contrast with existing observers (including the widely popular Kalman filter) that provide indirect information of the fault current, our observers provide an explicit one—namely the amplitude of the fault current. An additional advantage of the observers is that they do not require the knowledge of the motor currents, making them insensitive to current measurement noise. The performance of both observers, in their linear and generalized parameter estimation-based versions, is illustrated with realistic simulation studies.}, language = {en} } @misc{HagemannWeichmannGernandtetal., author = {Hagemann, Willem and Weichmann, Jaßper and Gernandt, Hannes and Krenzlin, Franziska and Schiffer, Johannes}, title = {Modeling and optimization of borehole thermal energy storage systems using physics-based neural networks}, series = {Renewable energy : an international journal}, volume = {256, Part A}, journal = {Renewable energy : an international journal}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0960-1481}, doi = {10.1016/j.renene.2025.123753}, pages = {1 -- 14}, abstract = {Borehole thermal energy storage (BTES) systems are critical components in the decarbonization of district heating networks as they enhance operational flexibility by seasonally storing thermal energy. While various modeling approaches for BTES exist, they are typically unsuitable for optimization problems and model-based control design. In this work, we propose a novel modeling approach that leads to a physics-based neural network surrogate model of the BTES temperature dynamics, capturing the fundamental dynamics with sufficient accuracy, while maintaining a relatively low complexity that makes it suitable for deployment in operational optimization or control algorithms. Specifically, we examine a standard BTES system that combines multiple heat sources, heat pumps, and storage buffers, detailing the associated mass flows and temperatures. We utilize a Python-based operational optimization process for the theoretical system setup using Pyomo and demonstrate that our modeling approach enables accurate optimizations over planning horizons of up to one year with a sample time of one hour. The new modeling approach significantly improves prediction accuracy across the relevant system states, with mean absolute errors reduced by approximately one-third compared to a single-capacitance model identified with the sparse identification framework SINDy.}, language = {en} } @misc{ArchilaWouwerSchiffer, author = {Archila, Oscar F. and Wouwer, Alain Vande and Schiffer, Johannes}, title = {A multiple artificial potential functions approach for collision avoidance in UAV systems}, series = {IEEE transactions on intelligent transportation systems}, volume = {26}, journal = {IEEE transactions on intelligent transportation systems}, number = {10}, publisher = {IEEE}, address = {New York, NY}, issn = {1524-9050}, doi = {10.1109/TITS.2025.3579157}, pages = {16688 -- 16699}, abstract = {Collision avoidance is a problem largely studied in robotics, particularly in uncrewed aerial vehicle (UAV) applications. The main challenges in this area are hardware limitations, the need for rapid response, and the uncertainty associated with obstacle detection. Artificial potential functions (APOFs) are a prominent method to address these challenges. However, existing solutions lack assurances regarding closed-loop stability and may result in chattering effects. Hence, we propose a high-level control method for static obstacle avoidance based on multiple artificial potential functions (MAPOFs), with a set of switching rules with conditions on the parameter tuning ensuring the stability of the final position. The stability proof is established by analyzing the closed-loop system using tools from hybrid systems theory. Furthermore, we validate the performance of the MAPOF control through simulations and real-life experiments, showcasing its effectiveness in avoiding static obstacles.}, language = {en} } @misc{TexisLoaizaMercadoUribeMorenoetal., author = {Texis-Loaiza, Oscar and Mercado-Uribe, Angel and Moreno, Jaime A. and Schiffer, Johannes}, title = {A finite-time convergent primal-dual gradient dynamics based on the multivariable super-twisting algorithm}, series = {2025 European Control Conference (ECC)}, journal = {2025 European Control Conference (ECC)}, publisher = {IEEE}, address = {New York, NY}, isbn = {978-3-907144-12-1}, doi = {10.23919/ECC65951.2025.11186834}, pages = {1892 -- 1898}, abstract = {We propose a novel primal-dual gradient dynamics (PDGD) algorithm to dynamically solve an optimization problem with linear equality constraints in finite time. To ensure finite-time convergence, we endow the PDGD with suitable homogeneity properties. More precisely, departing from the standard PDGD and based on the associated Lagrangian of the optimization problem, the algorithm is derived by suitably combining a change of coordinates of the standard PDGD with the multivariable super-twisting algorithm. In our new coordinates, the proposed PDGD's global convergence to the optimal solution of the optimization problem is then proven via a smooth, strong Lyapunov function. Additionally, we provide a numerical example to compare the performance of our algorithm with existing approaches from the literature.}, language = {en} } @misc{TexisLoaizaMorenoMercadoUribeetal., author = {Texis-Loaiza, Oscar and Moreno, Jaime A. and Mercado-Uribe, Angel and Schiffer, Johannes}, title = {A third-order bl-homogeneous sliding mode observer for uncertain triangular nonlinear systems}, series = {2025 European Control Conference (ECC)}, journal = {2025 European Control Conference (ECC)}, publisher = {IEEE}, address = {New York, NY}, isbn = {978-3-907144-12-1}, doi = {10.23919/ECC65951.2025.11186860}, pages = {1955 -- 1960}, abstract = {In this paper, we propose a global third-order homogeneous in the bi-limit sliding mode observer (BL-H SMO) that can estimate the states of an uncertain nonlinear system with unknown inputs in finite time. The system must be strongly observable w.r.t. unknown inputs (UIs) and uniformly observable w.r.t. known inputs. To handle the UIs and non-Lipschitz nonlinearities, the proposed observer combines sliding-mode and high-gain observers, extending the generalized super-twisting observer. The convergence of the BL-H SMO to the system states is proven through a Lyapunov function. Finally, to showcase the effectiveness of the proposed method, the paper includes an academic example and a practical example, namely a three-phase converter with LCL-filter.}, language = {en} } @misc{CortesMartinezSuryawanshiRuffertetal., author = {Cort{\´e}s Mart{\´i}nez, Rolando and Suryawanshi, Abhijeet Sanjay and Ruffert, Christine and Herglotz, Christian and Schiffer, Johannes}, title = {Towards a modular 5G motion capture testbed for indoor UAVs}, series = {MikroSystemTechnik Kongress 2025 : Mikroelektronik, Mikrosystemtechnik und ihre Anwendungen - Nachhaltigkeit und Technologiesouver{\"a}nit{\"a}t : proceedings : 27.-29. Oktober 2025, Duisburg}, journal = {MikroSystemTechnik Kongress 2025 : Mikroelektronik, Mikrosystemtechnik und ihre Anwendungen - Nachhaltigkeit und Technologiesouver{\"a}nit{\"a}t : proceedings : 27.-29. Oktober 2025, Duisburg}, publisher = {VDE VERLAG GmbH}, address = {Berlin}, isbn = {978-3-8007-6614-7}, pages = {373ff.}, language = {en} }