Searcharxiv⌕ Search

arXiv subjects

George S. Misyris

Publications and source records attributed to George S. Misyris.

4 recordsLinked to original sources

Neural Networks for Encoding Dynamic Security-Constrained Optimal Power Flow

This paper introduces a framework to capture previously intractable optimization constraints and transform them to a mixed-integer linear program, through the use of neural networks. We encode the feasible space of optimization problems characterized by both tractable and intractable constraints, e.g. differential equations, to a neural network. Leveraging an exact mixed-integer reformulation of neural networks, we solve mixed-integer linear programs that accurately approximate solutions to the originally intractable non-linear optimization problem. We apply our methods to the AC optimal power flow problem (AC-OPF), where directly including dynamic security constraints renders the AC-OPF intractable. Our proposed approach has the potential to be significantly more scalable than traditional approaches. We demonstrate our approach for power system operation considering N-1 security and small-signal stability, showing how it can efficiently obtain cost-optimal solutions which at the same time satisfy both static and dynamic security constraints.

eess.SY↗

Physics-Informed Neural Networks for Non-linear System Identification for Power System Dynamics

Varying power-infeed from converter-based generation units introduces great uncertainty on system parameters such as inertia and damping. As a consequence, system operators face increasing challenges in performing dynamic security assessment and taking real-time control actions. Exploiting the widespread deployment of phasor measurement units (PMUs) and aiming at developing a fast dynamic state and parameter estimation tool, this paper investigates the performance of Physics-Informed Neural Networks (PINN) for discovering the frequency dynamics of future power systems. PINNs have the potential to address challenges such as the stronger non-linearities of low-inertia systems, increased measurement noise, and limited availability of data. The estimator is demonstrated in several test cases using a 4-bus system, and compared with state of the art algorithms, such as the Unscented Kalman Filter (UKF), to assess its performance.

eess.SY↗

Multi-Terminal DC Fault Identification for MMC-HVDC Systems based on Modal Analysis -- A Localized Protection Scheme

We propose a localized protection scheme based on modal analysis in multi-terminal modular multilevel converter (MMC) based high voltage DC (HVDC) systems. The paper addresses the issues of localized protection scheme based DC fault identification, such as differentiating between external and internal faults, classification of type of fault contingency i.e., pole to pole (\textit{PTP}) or pole to ground (\textit{PTG}) for high impedance faults (HIFs) in the system. The scheme works on equivalent network of multi-terminal MMC-HVDC system for a DC fault, using phase-modal transformation to analyse line-mode and zero-mode voltage across the current limiting reactor (CLR) for different possible contingencies in the presence of fault resistance. The protection scheme is validated to be reliable for HIFs and in the presence of White Gaussian Noise (WGN) in measurement. The scheme operation is validated to be intact for varying fault location, fault resistances and system transients.

eess.SY↗

Physics-Informed Neural Networks for Power Systems

This paper introduces for the first time, to our knowledge, a framework for physics-informed neural networks in power system applications. Exploiting the underlying physical laws governing power systems, and inspired by recent developments in the field of machine learning, this paper proposes a neural network training procedure that can make use of the wide range of mathematical models describing power system behavior, both in steady-state and in dynamics. Physics-informed neural networks require substantially less training data and can result in simpler neural network structures, while achieving high accuracy. This work unlocks a range of opportunities in power systems, being able to determine dynamic states, such as rotor angles and frequency, and uncertain parameters such as inertia and damping at a fraction of the computational time required by conventional methods. This paper focuses on introducing the framework and showcases its potential using a single-machine infinite bus system as a guiding example. Physics-informed neural networks are shown to accurately determine rotor angle and frequency up to 87 times faster than conventional methods.

eess.SY↗