Search Results for author: Florian Dörfler

Found 73 papers, 9 papers with code

The Continuous-Time Weighted-Median Opinion Dynamics

no code implementations25 Apr 2024 Yi Han, Ge Chen, Florian Dörfler, Wenjun Mei

It turns out that the proof methods for the original discrete-time asynchronous model are no longer applicable to the analysis of the continuous-time model.

Cross-Forming Control and Fault Current Limiting for Grid-Forming Inverters

no code implementations20 Apr 2024 Xiuqiang He, Maitraya Avadhut Desai, Linbin Huang, Florian Dörfler

We propose two feasible control strategies to realize the cross-forming concept, enabling inverters to fast-limit the fault current at a prescribed level while preserving voltage angle forming for grid-forming-type synchronization and dynamic ancillary services provision during fault ride-through.

Stability Certificates for Receding Horizon Games

no code implementations18 Apr 2024 Sophie Hall, Dominic Liao-McPherson, Giuseppe Belgioioso, Florian Dörfler

Game-theoretic MPC (or Receding Horizon Games) is an emerging control methodology for multi-agent systems that generates control actions by solving a dynamic game with coupling constraints in a receding-horizon fashion.

Autonomous Driving Decision Making +1

Dynamic Complex-Frequency Control of Grid-Forming Converters

no code implementations15 Apr 2024 Roger Domingo-Enrich, Xiuqiang He, Verena Häberle, Florian Dörfler

Complex droop control, alternatively known as dispatchable virtual oscillator control (dVOC), stands out for its unique capabilities in synchronization and voltage stabilization among existing control strategies for grid-forming converters.

Saturation-Informed Current-Limiting Control for Grid-Forming Converters

no code implementations11 Apr 2024 Maitraya Avadhut Desai, Xiuqiang He, Linbin Huang, Florian Dörfler

In this paper, we investigate the transient stability of a state-of-the-art grid-forming complex-droop control (i. e., dispatchable virtual oscillator control, dVOC) under current saturation.

Karma: An Experimental Study

no code implementations3 Apr 2024 Ezzat Elokda, Heinrich Nax, Saverio Bolognani, Florian Dörfler

A system of non-tradable credits that flow between individuals like karma, hence proposed under that name, is a mechanism for repeated resource allocation that comes with attractive efficiency and fairness properties, in theory.

Fairness

Decoupling parameter variation from noise: Biquadratic Lyapunov forms in data-driven LPV control

no code implementations25 Mar 2024 Chris Verhoek, Jaap Eising, Florian Dörfler, Roland Tóth

A promising step from linear towards nonlinear data-driven control is via the design of controllers for linear parameter-varying (LPV) systems, which are linear systems whose parameters are varying along a measurable scheduling signal.

LEMMA Scheduling

Control Strategies for Recommendation Systems in Social Networks

no code implementations10 Mar 2024 Ben Sprenger, Giulia De Pasquale, Raffaele Soloperto, John Lygeros, Florian Dörfler

A closed-loop control model to analyze the impact of recommendation systems on opinion dynamics within social networks is introduced.

Recommendation Systems

Tuning and Testing an Online Feedback Optimization Controller to Provide Curative Distribution Grid Flexibility

no code implementations4 Mar 2024 Lukas Ortmann, Fabian Böhm, Florian Klein-Helmkamp, Andreas Ulbig, Saverio Bolognani, Florian Dörfler

A flexibility request from the transmission grid to a distribution grid then needs to be split up onto the different flexibility providing units (FPU) in the distribution grid.

Optimal Dynamic Ancillary Services Provision Based on Local Power Grid Perception

no code implementations31 Jan 2024 Verena Häberle, Xiuqiang He, Linbin Huang, Eduardo Prieto-Araujo, Florian Dörfler

In this paper, we propose a systematic closed-loop approach to provide optimal dynamic ancillary services with converter-interfaced generation systems based on local power grid perception.

Towards a Systems Theory of Algorithms

no code implementations25 Jan 2024 Florian Dörfler, Zhiyu He, Giuseppe Belgioioso, Saverio Bolognani, John Lygeros, Michael Muehlebach

Traditionally, numerical algorithms are seen as isolated pieces of code confined to an {\em in silico} existence.

Decision Making

Power Grid Parameter Estimation Without Phase Measurements: Theory and Empirical Validation

no code implementations18 Jan 2024 Jean-Sébastien Brouillon, Keith Moffat, Florian Dörfler, Giancarlo Ferrari-Trecate

The primary result of the paper is that, while the impedance of a line or a network can be estimated without synchronized phase angle measurements in a consistent way, the admittance cannot.

Advanced safety filter based on SOS Control Barrier and Lyapunov Functions

no code implementations12 Jan 2024 Michael Schneeberger, Silvia Mastellone, Florian Dörfler

The second part of this work details the implementation of the safety filter as a Quadratically Constrained Quadratic Program (QCQP), whose constraints encode the CBF and CLF conditions as well as the input constraints.

Urban traffic congestion control: a DeePC change

no code implementations16 Nov 2023 Alessio Rimoldi, Carlo Cenedese, Alberto Padoan, Florian Dörfler, John Lygeros

Urban traffic congestion remains a pressing challenge in our rapidly expanding cities, despite the abundance of available data and the efforts of policymakers.

Management

Quantitative Stability Conditions for Grid-Forming Converters With Complex Droop Control

no code implementations15 Oct 2023 Xiuqiang He, Linbin Huang, Irina Subotić, Verena Häberle, Florian Dörfler

In this paper, we study analytically the transient stability of grid-connected distributed generation systems with grid-forming (GFM) complex droop control, also known as dispatchable virtual oscillator control (dVOC).

Passivity and Decentralized Stability Conditions for Grid-Forming Converters

no code implementations15 Oct 2023 Xiuqiang He, Florian Dörfler

We prove that the popular grid-forming control, i. e., dispatchable virtual oscillator control (dVOC), also termed complex droop control, exhibits output-feedback passivity in its large-signal model, featuring an explicit and physically meaningful passivity index.

Dynamic Ancillary Services: From Grid Codes to Transfer Function-Based Converter Control

no code implementations2 Oct 2023 Verena Häberle, Linbin Huang, Xiuqiang He, Eduardo Prieto-Araujo, Florian Dörfler

Namely, we translate the piece-wise linear time-domain curves for active and reactive power provision in response to a frequency and voltage step change into a desired rational parametric transfer function in the frequency domain, which defines a dynamic response behavior to be realized by the converter.

Gain and Phase: Decentralized Stability Conditions for Power Electronics-Dominated Power Systems

no code implementations14 Sep 2023 Linbin Huang, Dan Wang, Xiongfei Wang, Huanhai Xin, Ping Ju, Karl H. Johansson, Florian Dörfler

This paper proposes decentralized stability conditions for multi-converter systems based on the combination of the small gain theorem and the small phase theorem.

Joint Oscillation Damping and Inertia Provision Service for Converter-Interfaced Generation

no code implementations4 Sep 2023 Cheng Feng, Linbin Huang, Xiuqiang He, Yi Wang, Florian Dörfler, Qixin Chen

To address this gap, this paper defines the joint oscillation damping and inertia provision services at the system level, seeking to encourage converter-interfaced generation to provide enhanced damping and fast frequency response capabilities.

Experimental Validation of a Dynamic Virtual Power Plant Concept Based on Multiple-Converter Power Hardware-In-the-Loop Test Bench

no code implementations2 Sep 2023 Moritz Andrejewski, Verena Häberle, Nico Goldschmidt, Florian Dörfler, Horst Schulte

Recently, the concept of dynamic virtual power plants (DVPP) has been proposed to collectively provide desired dynamic ancillary services such as fast frequency and voltage control by a heterogeneous ensemble of distributed energy resources (DER).

Providing Curative Distribution Grid Flexibility Using Online Feedback Optimization

no code implementations26 Jun 2023 Florian Klein-Helmkamp, Fabian Böhm, Lukas Ortmann, Alexander Winkens, Florian Schmidtke, Saverio Bolognani, Florian Dörfler, Andreas Ulbig

Distribution grid flexibility is discussed as a possible measure in curative system operation, yielding a need for an efficient and robust coordination mechanism for the joint flexibility provision by individual units to the transmission grid.

On the Guarantees of Minimizing Regret in Receding Horizon

no code implementations26 Jun 2023 Andrea Martin, Luca Furieri, Florian Dörfler, John Lygeros, Giancarlo Ferrari-Trecate

Towards bridging classical optimal control and online learning, regret minimization has recently been proposed as a control design criterion.

Power Distribution Grid Enhancement via Online Feedback Optimization

no code implementations8 May 2023 Jonas G. Matt, Lukas Ortmann, Saverio Bolognani, Florian Dörfler

In this paper, we use real consumption and generation data on a low-voltage CIGR\'E grid model and an experiment on a real distribution grid feeder to analyze how different Volt/VAr methods can enhance grid capacity, i. e., by how much they can improve the grid's capability to transmit active power without building new lines.

Distributed State Estimation for Linear Time-Varying Systems with Sensor Network Delays

no code implementations29 Apr 2023 Sanjay Chandrasekaran, Vishnu Varadan, Siva Vignesh Krishnan, Florian Dörfler, Mohammad H. Mamduhi

We provide comparisons between the estimation performance of our proposed algorithm and a greedy algorithm that exhaustively selects an optimal subset of nodes.

MIMO Grid Impedance Identification of Three-Phase Power Systems: Parametric vs. Nonparametric Approaches

no code implementations29 Apr 2023 Verena Häberle, Linbin Huang, Xiuqiang He, Eduardo Prieto-Araujo, Roy S. Smith, Florian Dörfler

A fast and accurate grid impedance measurement of three-phase power systems is crucial for online assessment of power system stability and adaptive control of grid-connected converters.

Regret Optimal Control for Uncertain Stochastic Systems

1 code implementation28 Apr 2023 Andrea Martin, Luca Furieri, Florian Dörfler, John Lygeros, Giancarlo Ferrari-Trecate

Specifically, we focus on the problem of designing a feedback controller that minimizes the loss relative to a clairvoyant optimal policy that has foreknowledge of both the system dynamics and the exogenous disturbances.

Regularization for distributionally robust state estimation and prediction

no code implementations19 Apr 2023 Jean-Sébastien Brouillon, Florian Dörfler, Giancarlo Ferrari-Trecate

We provide a direct method using samples of the noise to create a moving horizon observer for linear time-varying and nonlinear systems, which is optimal under the empirical noise distribution.

New Perspectives on Regularization and Computation in Optimal Transport-Based Distributionally Robust Optimization

1 code implementation7 Mar 2023 Soroosh Shafieezadeh-Abadeh, Liviu Aolaritei, Florian Dörfler, Daniel Kuhn

We study optimal transport-based distributionally robust optimization problems where a fictitious adversary, often envisioned as nature, can choose the distribution of the uncertain problem parameters by reshaping a prescribed reference distribution at a finite transportation cost.

Designing Fairness in Autonomous Peer-to-peer Energy Trading

no code implementations9 Feb 2023 Varsha Behrunani, Andrew Irvine, Giuseppe Belgioioso, Philipp Heer, John Lygeros, Florian Dörfler

Several autonomous energy management and peer-to-peer trading mechanisms for future energy markets have been recently proposed based on optimization and game theory.

energy trading Fairness +2

Stochastic Wasserstein Gradient Flows using Streaming Data with an Application in Predictive Maintenance

no code implementations29 Jan 2023 Nicolas Lanzetti, Efe C. Balta, Dominic Liao-McPherson, Florian Dörfler

Since estimation problems can be posed as optimization problems in the probability space, we devise a stochastic projected Wasserstein gradient flow that keeps track of the belief of the estimated quantity and can consume samples from online data.

Decision Making

Convergence, Consensus and Dissensus in the Weighted-Median Opinion Dynamics

no code implementations17 Dec 2022 Wenjun Mei, Julien M. Hendrickx, Ge Chen, Francesco Bullo, Florian Dörfler

Moreover, we prove a necessary and sufficient graph-theoretic condition for the almost-sure convergence to consensus, as well as a sufficient graph-theoretic condition for almost-sure persistent dissensus.

Real-time Curative Actions for Power Systems via Online Feedback Optimization

no code implementations15 Dec 2022 Lukas Ortmann, Gianni Hotz, Saverio Bolognani, Florian Dörfler

Instead of pre-planning, we propose to calculate these complex curative actions in real-time after the occurrence of a contingency.

Online Feedback Optimization for Subtransmission Grid Control

1 code implementation15 Dec 2022 Lukas Ortmann, Jean Maeght, Patrick Panciatici, Florian Dörfler, Saverio Bolognani

The increasing electric power consumption and the shift towards renewable energy resources demand for new ways to operate transmission and subtransmission grids.

Minimal regret state estimation of time-varying systems

no code implementations25 Nov 2022 Jean-Sébastien Brouillon, Florian Dörfler, Giancarlo Ferrari-Trecate

Kalman and H-infinity filters, the most popular paradigms for linear state estimation, are designed for very specific specific noise and disturbance patterns, which may not appear in practice.

Stability and Robustness of Distributed Suboptimal Model Predictive Control

no code implementations14 Nov 2022 Giuseppe Belgioioso, Dominic Liao-McPherson, Mathias Hudoba de Badyn, Nicolas Pelzmann, John Lygeros, Florian Dörfler

In distributed model predictive control (MPC), the control input at each sampling time is computed by solving a large-scale optimal control problem (OCP) over a finite horizon using distributed algorithms.

Model Predictive Control

Real-time Projected Gradient-based Nonlinear Model Predictive Control with an Application to Anesthesia Control

no code implementations14 Nov 2022 Sophie Hall, Lukas Ortmann, Miguel Picallo, Florian Dörfler

Medical drug infusion problems pose a combination of challenges such as nonlinearities from physiological models, model uncertainty due to inter- and intra-patient variability, as well as strict safety specifications.

Model Predictive Control

Nonlinear Stability of Complex Droop Control in Converter-Based Power Systems

no code implementations28 Oct 2022 Xiuqiang He, Verena Häberle, Irina Subotić, Florian Dörfler

In previous work, the global stability of dVOC (i. e., complex droop control) has been proven by prespecifying a nominal synchronous steady state.

Trust Region Policy Optimization with Optimal Transport Discrepancies: Duality and Algorithm for Continuous Actions

no code implementations20 Oct 2022 Antonio Terpin, Nicolas Lanzetti, Batuhan Yardim, Florian Dörfler, Giorgia Ramponi

In this paper, we explore optimal transport discrepancies (which include the Wasserstein distance) to define trust regions, and we propose a novel algorithm - Optimal Transport Trust Region Policy Optimization (OT-TRPO) - for continuous state-action spaces.

Continuous Control

Modeling of Political Systems using Wasserstein Gradient Flows

no code implementations12 Sep 2022 Nicolas Lanzetti, Joudi Hajar, Florian Dörfler

The study of complex political phenomena such as parties' polarization calls for mathematical models of political systems.

Time Series Time Series Analysis

Complex-Frequency Synchronization of Converter-Based Power Systems

no code implementations29 Aug 2022 Xiuqiang He, Verena Häberle, Florian Dörfler

In this paper, we study phase-amplitude multivariable dynamics in converter-based power systems from a complex-frequency perspective.

CARMA: Fair and efficient bottleneck congestion management via non-tradable karma credits

no code implementations15 Aug 2022 Ezzat Elokda, Carlo Cenedese, Kenan Zhang, Andrea Censi, John Lygeros, Emilio Frazzoli, Florian Dörfler

In our CARMA scheme, the bottleneck is divided into a fast lane that is kept in free flow and a slow lane that is subject to congestion.

Fairness Management +1

Approximation by Simple Poles -- Part I: Density and Geometric Convergence Rate in Hardy Space

no code implementations8 Jul 2022 Michael W. Fisher, Gabriela Hug, Florian Dörfler

The goal of this two-part article is to introduce a new Galerkin-type method based on approximation by transfer functions with a selection of simple poles, and to apply this simple pole approximation for optimal control design.

A self-contained karma economy for the dynamic allocation of common resources

no code implementations1 Jul 2022 Ezzat Elokda, Saverio Bolognani, Andrea Censi, Florian Dörfler, Emilio Frazzoli

This paper presents karma mechanisms, a novel approach to the repeated allocation of a scarce resource among competing agents over an infinite time.

Fairness

Wasserstein Distributionally Robust Estimation in High Dimensions: Performance Analysis and Optimal Hyperparameter Tuning

no code implementations27 Jun 2022 Liviu Aolaritei, Soroosh Shafiee, Florian Dörfler

Wasserstein distributionally robust optimization has recently emerged as a powerful framework for robust estimation, enjoying good out-of-sample performance guarantees, well-understood regularization effects, and computationally tractable reformulations.

Vocal Bursts Intensity Prediction

Robust and Kernelized Data-Enabled Predictive Control for Nonlinear Systems

no code implementations4 Jun 2022 Linbin Huang, John Lygeros, Florian Dörfler

This paper presents a robust and kernelized data-enabled predictive control (RoKDeePC) algorithm to perform model-free optimal control for nonlinear systems using only input and output data.

Receding Horizon Games with Coupling Constraints for Demand-Side Management

no code implementations3 Jun 2022 Sophie Hall, Giuseppe Belgioioso, Dominic Liao-McPherson, Florian Dörfler

Distributed energy storage and flexible loads are essential tools for ensuring stable and robust operation of the power grid in spite of the challenges arising from the integration of volatile renewable energy generation and increasing peak loads due to widespread electrification.

Management Model Predictive Control

Robust online joint state/input/parameter estimation of linear systems

no code implementations12 Apr 2022 Jean-Sébastien Brouillon, Keith Moffat, Florian Dörfler, Giancarlo Ferrari-Trecate

This paper presents a method for jointly estimating the state, input, and parameters of linear systems in an online fashion.

regression

Approximation by Simple Poles -- Part II: System Level Synthesis Beyond Finite Impulse Response

no code implementations31 Mar 2022 Michael W. Fisher, Gabriela Hug, Florian Dörfler

In Part II, this approximation is applied to system level synthesis, a recent approach based on a clever reparameterization, to develop a new technique for optimal control design.

Safe Control with Minimal Regret

1 code implementation1 Mar 2022 Andrea Martin, Luca Furieri, Florian Dörfler, John Lygeros, Giancarlo Ferrari-Trecate

As we move towards safety-critical cyber-physical systems that operate in non-stationary and uncertain environments, it becomes crucial to close the gap between classical optimal control algorithms and adaptive learning-based methods.

Augmentation of Generalized Multivariable Grid-Forming Control for Power Converters with Cascaded Controllers

no code implementations17 Feb 2022 Meng Chen, Dao Zhou, Ali Tayyebi, Eduardo Prieto-Araujo, Florian Dörfler, Frede Blaabjerg

The classic design of grid-forming control strategies for power converters rely on the stringent assumption of the timescale separation between DC and AC states and their corresponding control loops, e. g., AC and DC loops, power and cascaded voltage and current loops, etc.

Learning Stable Deep Dynamics Models for Partially Observed or Delayed Dynamical Systems

1 code implementation NeurIPS 2021 Andreas Schlaginhaufen, Philippe Wenk, Andreas Krause, Florian Dörfler

To this end, neural ODEs regularized with neural Lyapunov functions are a promising approach when states are fully observed.

Adaptive Real-Time Grid Operation via Online Feedback Optimization with Sensitivity Estimation

no code implementations3 Oct 2021 Miguel Picallo, Lukas Ortmann, Saverio Bolognani, Florian Dörfler

In this paper we propose an approach based on an Online Feedback Optimization (OFO) controller with grid input-output sensitivity estimation for real-time grid operation, e. g., at subsecond time scales.

Cross-layer Design for Real-Time Grid Operation: Estimation, Optimization and Power Flow

no code implementations28 Sep 2021 Miguel Picallo, Dominic Liao-McPherson, Saverio Bolognani, Florian Dörfler

In this paper, we propose a combined Online Feedback Optimization (OFO) and dynamic estimation approach for a real-time power grid operation under time-varying conditions.

Generalized Multivariable Grid-Forming Control Design for Power Converters

no code implementations14 Sep 2021 Meng Chen, Dao Zhou, Ali Tayyebi, Eduardo Prieto-Araujo, Florian Dörfler, Frede Blaabjerg

The grid-forming converter is an important unit in the future power system with more inverter-interfaced generators.

Control Design of Dynamic Virtual Power Plants: An Adaptive Divide-and-Conquer Approach

1 code implementation2 Aug 2021 Verena Häberle, Michael W. Fisher, Eduardo Prieto-Araujo, Florian Dörfler

Our control approach relies on an adaptive divide-and-conquer strategy: first, we disaggregate the desired frequency and voltage control specifications of the aggregate DVPP via adaptive dynamic participation matrices (ADPMs) to obtain the desired local behavior for each device.

Bayesian Error-in-Variables Models for the Identification of Power Networks

no code implementations9 Jul 2021 Jean-Sébastien Brouillon, Emanuele Fabbiani, Pulkit Nahata, Keith Moffat, Florian Dörfler, Giancarlo Ferrari-Trecate

The increasing integration of intermittent renewable generation, especially at the distribution level, necessitates advanced planning and optimisation methodologies contingent on the knowledge of thegrid, specifically the admittance matrix capturing the topology and line parameters of an electricnetwork.

Dynamic Virtual Power Plant Design for Fast Frequency Reserves: Coordinating Hydro and Wind

1 code implementation7 Jul 2021 Joakim Björk, Karl Henrik Johansson, Florian Dörfler

To ensure frequency stability in future low-inertia power grids, fast ancillary services such as fast frequency reserves (FFR) have been proposed.

Robust Data-Enabled Predictive Control: Tractable Formulations and Performance Guarantees

no code implementations15 May 2021 Linbin Huang, Jianzhe Zhen, John Lygeros, Florian Dörfler

The proposed framework enables us to obtain model-free optimal control for LTI systems based on noisy input/output data.

Structural Balance and Interpersonal Appraisals Dynamics: Beyond All-to-All and Two-Faction Networks

no code implementations18 Dec 2020 Wenjun Mei, Ge Chen, Noah E. Friedkin, Florian Dörfler

structural balance configurations of the appraisal networks.

Social and Information Networks Discrete Mathematics Systems and Control Systems and Control 93-10, 91D30, 68R10

Quadratic Regularization of Data-Enabled Predictive Control: Theory and Application to Power Converter Experiments

no code implementations8 Dec 2020 Linbin Huang, Jianzhe Zhen, John Lygeros, Florian Dörfler

Moreover, when the input/output constraints are inactive, the quadratic regularization leads to a closed-form solution of the DeePC algorithm and thus enables fast calculations.

Decentralized Data-Enabled Predictive Control for Power System Oscillation Damping

no code implementations27 Nov 2019 Linbin Huang, Jeremy Coulson, John Lygeros, Florian Dörfler

Further, we discuss how to relieve the computational burden of the Min-Max DeePC by reducing the dimension of prediction uncertainty and how to leverage disturbance feedback to reduce the conservativeness of robustification.

Experimental Validation of Feedback Optimization in Power Distribution Grids

no code implementations8 Oct 2019 Lukas Ortmann, Adrian Hauswirth, Ivo Caduff, Florian Dörfler, Saverio Bolognani

On a real distribution grid, we compare the local Volt/VAr droop control recommended in recent grid codes, a centralized dispatch based on optimal power flow (OPF) programming, and a feedback optimization (FO) controller that we propose.

Closing the Loop: Dynamic State Estimation and Feedback Optimization of Power Grids

no code implementations6 Sep 2019 Miguel Picallo, Saverio Bolognani, Florian Dörfler

This consists in continuously driving the controllable power injections and loads towards the optimal set-points in time-varying conditions based on real-time measurements performed on the grid.

Interactions of Grid-Forming Power Converters and Synchronous Machines -- A Comparative Study

no code implementations27 Feb 2019 Ali Tayyebi, Dominic Groß, Adolfo Anta, Friederich Kupzog, Florian Dörfler

An inevitable consequence of the global power system transition towards nearly 100% renewable-based generation is the loss of conventional bulk generation by synchronous machines, their inertia, and accompanying frequency and voltage control mechanisms.

Optimization and Control

Generic Existence of Unique Lagrange Multipliers in AC Optimal Power Flow

no code implementations18 Jun 2018 Adrian Hauswirth, Saverio Bolognani, Gabriela Hug, Florian Dörfler

Even if the KKT conditions are applicable, the multipliers may not be unique.

Optimization and Control

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