Electromagnetic Transients Research Articles

Parameter Identification of PMSG-Based Wind Turbine Based on Sensitivity Analysis and Improved Gray Wolf Optimization

With the large-scale integration of wind power, it is essential to establish an electromagnetic transient (EMT) model of a wind turbine system. Focusing on the problem of the difficulty in obtaining the parameters of the direct-driven permanent magnet synchronous generator (PMSG) model, this manuscript proposes a method based on trajectory sensitivity analysis and improved gray wolf optimization (IGWO) for identifying the parameters of the PMSG EMT model. First, a model of a PMSG wind turbine is established on an EMT simulation platform. Then, the key parameters of the model are determined based on the sensitivity analysis. Five control parameters are selected as the key parameters for their higher sensitivity indexes. Finally, the key parameters are accurately identified, using the proposed IGWO algorithm. The final case study demonstrates that the proposed IGWO algorithm has better optimization performance compared with the GWO algorithm and particle swarm optimization (PSO) algorithm. In addition, the simulation waveforms show that the identified parameters are accurate and applicable to other operating conditions.

МАТЕМАТИЧНА ТА КОМП’ЮТЕРНА МОДЕЛІ АСИНХРОННОГО ДВИГУНА З ФАЗНИМ РОТОРОМ У РЕЖИМІ ДИНАМІЧНОГО ГАЛЬМУВАННЯ З САМОЗБУДЖЕННЯМ

One of the important challenges of today is to ensure energy efficiency and improve the performance of the most common induction electric drives (IEDs) for production and lifting and handling machines. Increasing the overall control range and stable speed control in AEDs is often ensured by the use of pulse-key or phase-pulse control systems for the speed of rotation of the AD FR, in which the control is carried out in the rectified rotor current circuit. The presence in such schemes of a rotor winding voltage rectifier creates conditions for the use of the dynamic self-excitation braking (DSB) mode. The paper proposes a mathematical model of the AD FR in the DBS mode in the system of coordinate axes (d, q) fixed relative to the rotor, taking into account the saturation characteristics of the magnetic system of the machine. The model was tested by computer simulation using the capabilities of the Simulink Matlab package. The created model is of practical value; in the formation of energy-efficient braking modes of AEPs, it will allow analysing complex electromag-netic transients and reasonably choosing the structure and parameters of their electrical circuits. Ref. 4, fig. 6.

On the portability of EMT models in different power system simulation software tools

This paper presents the investigation carried out on the portability and compatibility of a model in different simulation software. The offer of simulation software for power system simulation is wide, with each program having its own modelling interface and its own methods of model development. The lack of a widespread standard for portability between applications implies that the same organisation needs to carry out studies on different applications, requiring the development of a model of the same element or system for each application. This study presents an example of the integration of an inverter model in DigSilent, PSCAD and Simulink by means of the Multilink tool. Throughout the article, the differences found when performing the integration and the same simulation scenario in these three simulation tools are listed. It concludes with a comparison of the results obtained from an electromagnetic transients (EMT) simulation in the three simulation software. The results show a greater similarity between PSCAD and Simulink, with respect to the results obtained in DigSilent.

Experimental Study of Electromagnetic Interference from Concentrated Discharge Channels within the Soil to Adjacent Directly Buried Cables during Lightning Current Inflow to the Ground

Independent lightning rods are often installed in substation grounding systems for lightning protection. The concentrated discharge channel formed when a lightning current flows to the ground through a grounding electrode will cause electromagnetic interference to the directly buried secondary cable. And the three-dimensional structure of the discharge channel will affect the transient electromagnetic field distribution, thereby affecting the electromagnetic transients on cable shields. In order to explore the influence of soil discharge phenomena on the electromagnetic interference of the directly buried secondary cable, in this paper, we carried out experiments on cables in two different grounding modes, single-ended and double-ended grounding, and captured image of soil discharge channels. The results show that the cable grounding mode will affect the coupling mode that causes the shielding layer current. The relative spatial position of the soil discharge channel and the cable has a significant impact on the magnitude of the shielding layer current under both grounding modes. The water content and salt content of the soil also have different degrees of influence on the coupling current of the shielding layer in different grounding modes.

Study of a Numerical Integral Interpolation Method for Electromagnetic Transient Simulations

In the fixed time-step electromagnetic transient (EMT)-type program, an interpolation process is applied to deal with switching events. The interpolation method frequently reduces the algorithm’s accuracy when dealing with power electronics. In this study, we use the Butcher tableau to analyze the defects of linear interpolation. Then, based on the theories of Runge–Kutta integration, we propose two three-stage diagonally implicit Runge–Kutta (3S-DIRK) algorithms combined with the trapezoidal rule (TR) and backward Euler (BE), respectively, with TR-3S-DIRK and BE2-3S-DIRK for the interpolation and synchronization processes. The proposed numerical integral interpolation scheme has second-order accuracy and does not produce spurious oscillations due to the size change in the time step. The proposed method is compared with the critical damping adjustment method (CDA) and the trapezoidal method, showing that it does not produce spurious numerical oscillations or first-order errors.

Monitoring of space radiation and electromagnetic transients by Moscow State University nano-satellites

Nano-satellites of cubesat format can be used effectively to study different aspects of space weather phenomena, such as high energy charge particle flux variations at near-Earth space as well as for monitoring cosmic gamma-ray bursts (GRBs) and hard X-ray and gamma-ray emission of solar flares. Using a constellation of CubeSats enables cost-effective synchronous measurements of radiation fluxes at different points in space, effectively separating the spatial and temporal effects of observed flux variations.Since July 5, 2019, M. V. Lomonosov Moscow State University (MSU) has realized its own program of cubesat employment. To the present date, 18 satellites in 1.5U, 3U, and 6U formats with the instruments developed at MSU have been launched, and 11 of them continue to operate on the solar-synchronous low-altitude orbits (400–600 km). The number of instruments elaborated especially for cubesats includes the universal Detector of Cosmic Radiation (DeCoR-1, DeCoR-2, and DeCoR-3 modifications), the Advanced Ultraviolet Radiometer (AURA, AURA-2) and the Complex Radiation Detector (CoRaD, i.e., KODIZ in Russian acronym). The DeCoR-1, DeCoR-2 and DeCoR-3 instruments allow for the detection of gamma-quanta and electrons in the energy ranges of 0.02–2.0 MeV and 0.3–10.0 MeV, respectively. The KODIZ instrument is intended especially to detect protons with energies higher than 300 MeV and electrons with energies higher than several MeV. The AURA and AURA-2 instruments are used to monitor atmospheric UV glow in ∼200–400 nm bands. Up until now, the good experience has been accumulated by using these instruments to measure different space weather effects, such as polar cups filling with solar cosmic rays, the dynamics of outer belt boundaries during geomagnetic storms, and electron precipitation in different areas of near-Earth space, including low-latitude regions. As a by-product, a number of GRB candidates were detected. The possibility of further development of multi-satellite group and perspectives to study the mentioned phenomena will be discussed in this paper.

Black-Box Modelling of Active Distribution Network Devices Based on Neural ODEs

Abstract The morphological structure and dynamic characteristics of power distribution systems are rapidly evolving due to the widespread application of distributed renewable energy and the rapid advancement of power electronics technology. The stability analysis of these complex new distribution systems depends on electromagnetic transient (EMT) simulation. However, the intellectual property rights protection by manufacturers leads to many distribution network devices that can only use black-box models with missing parameters, which challenges the simulation. This reduces the accuracy of the dynamic analysis of these new distribution systems. To address this problem, this paper proposes a black-box modelling method based on neural Ordinary Differential Equation (ODE) for active distribution equipment. The method uses port measurement data to construct a data-driven model that accurately captures the black-box device characteristics, transforming the uncertainties in the user-side black-box devices into observable, controllable, and analysable models. The paper also builds an IEEE-33 node system that includes the energy storage black-box model for validation, and the results confirm the accuracy of the model.

DYNAMIC MODELLING OF THREE-PHASE MICROGRIDS INCLUDING DQ0 CURRENT CONTROLLED PHOTOVOLTAIC GENERATION UNDER TRANSIENT CONDITIONS

ABSTRACT: The photovoltaic generation can be interconnected to power systems or to insulated grids to satisfy the growing electrical demand as an alternative renewable energy source. The photovoltaic generator dynamics affects the control, protection, stability, and power quality of the electrical grid, this network dynamics requires to be examined and conveniently regulated and adjusted. The dynamic averaged model for the dq0 current controlled DC/AC inverter is applied to obtain the time-domain response to electromagnetic transients under special conditions such as electrical load fluctuations, unbalanced faults, voltage and current transients to verify e.g., the ride through capability or to adjust the protection and control devices, these transients can be present during the operation of electrical microgrids and power systems interconnected with photovoltaic generation. The system modelling includes the photovoltaic plant interconnected with the microgrid using the dq0 current controlled DC/AC inverter. The case studies are applied to analyse three-phase electrical microgrids, their time-domain response, and the obtained voltage and current waveforms can be used to verify the dynamic behaviour and stability of the electrical system interconnected with photovoltaic generation and similarly to verify the operation of the dq0 current controller for the inverter. The results can be used to control the microgrid dynamic behaviour. Keywords: current control, dq0 transform, inverter, microgrids, photovoltaic generation, power quality, protection, time-domain, transients, unbalanced faults, unbalanced voltage sags, voltage source converter

Kilonova light-curve interpolation with neural networks

Kilonovae are the electromagnetic transients created by the radioactive decay of freshly synthesized elements in the environment surrounding a neutron star merger. To study the fundamental physics in these complex environments, kilonova modeling requires, in part, the use of radiative transfer simulations. The microphysics involved in these simulations results in high computational cost, prompting the use of emulators for parameter inference applications. Utilizing a training set of 22 248 high-fidelity simulations (composed of 412 unique ejecta parameter combinations evaluated at 54 viewing angles), we use a neural network to efficiently train on existing radiative transfer simulations and predict light curves for new parameters in a fast and computationally efficient manner. Our neural network can generate millions of new light curves in under a minute. We discuss our emulator's degree of off-sample reliability and parameter inference of the AT2017gfo observational data. Finally, we discuss tension introduced by multiband inference in the parameter inference results, particularly with regard to the neural network's recovery of viewing angle. Published by the American Physical Society 2024

An open-source parallel EMT simulation framework

As the integration level of inverter-based resources (IBRs) increases, ensuring the reliable operation of the bulk power systems requires the use of electromagnetic transient (EMT) simulation tools to identify and mitigate system-wide stability risks. Conducting EMT studies for large-scale, IBR-rich grids, however, is challenging due to the inherent computational bottleneck caused by the underlying high-fidelity models and required small time steps. This paper introduces ParaEMT: an open-source, generic EMT simulation framework designed to accelerate simulations by leveraging advanced parallel computational technologies, such as high-performance computers. This paper presents a comprehensive exposition of ParaEMT, covering its modeling library, simulation strategy, framework structure, operational procedures, and auxiliary features, alongside its extensible parallel computational architecture. Notably, ParaEMT is a publicly accessible and modularized framework written in Python, thereby facilitating future development and the integration of new models and algorithms. The accuracy and efficiency of ParaEMT are demonstrated by rigorous validations via multiple case studies.

An Impulse Equivalent VSC Model for Large Power Grids Containing Multiple Converters

Abstract This paper explores the impulse equivalent method for constructing voltage source converter (VSC) model in large power grids containing multiple converters. It addresses the challenge of simulation cycle mismatch with device switching moments and proposes a cross-cycle correction method. The method enhances the VSC electromagnetic transient (EMT) simulation model, making it suitable for large-scale power grid simulations. The approach is validated through case studies, confirming its accuracy and computational efficiency for complex power electronic networks.

Novel estimation framework for short-circuit current contribution of type IV wind turbines at transient and steady-state of the faults

Given the increasing penetration of converter-interfaced resources in power systems, properly estimating the short-circuit current (SCC) contribution in large networks has become a growing challenge and necessity to ensure the security and stability of the systems and assets. This paper presents two novel methods to estimate the SCC contribution of type IV wind turbines at both the transient and steady-state stages of unbalanced and balanced faults: (1) a machine learning-based method trained with electromagnetic transient (EMT) simulations and capable of estimating some of the initial peak and transient current magnitudes; (2) an analytical approach to estimate the steady-state SCC based on the voltage and grid code dependency of the converter during the fault. The methods are coupled into a single framework and compared to field-validated EMT models of a real turbine. The results show that the majority of the estimated currents in the transient stages present errors below 5%. In steady-state, the errors are not greater than 1.21%. Given the complexity of the problem, these margins may be deemed acceptable for short-circuit studies.

Sensitivity analysis of commutation failure in multi-infeed HVDC systems: Exploring the impact of ac system representations and fault types

This paper investigates commutation failure (CF) in line commutated HVdc converters within multi-infeed HVDC systems and thereby provides valuable insights for the operation and design of HVdc systems. CF susceptibility across various operational scenarios, fault types, and ac system representations at different frequencies is explored. An Electromagnetic Transients (EMT) model is constructed and parameter changes are applied using Monte-Carlo Simulation. The process is fully automated with the use of a controlling program written in Python, which varies parameter values and facilitates result retrieval and post-simulation analysis. A typical analysis results in several hundred thousands of simulation runs, requiring the procedure to be implemented on a parallel computing platform. The results show that two-phase faults are the most critical CF triggers, an aspect often overlooked in previous literature focused on three-phase or single-phase-to-ground faults. Furthermore, the frequency dependent characteristics of the ac network can result in very different CF susceptibilities.

Optimizing the performance of a new current source type grid-forming modular multilevel converter using genetic algorithms

Modular Multilevel Converters (MMC) have found extensive application in connecting Renewable Energy Sources to the power grid. Recently, MMCs operated in the Grid Forming (GFM) mode have garnered significant interest due to their superior performance in weak AC networks. The Virtual Synchronous Generator (VSG) is a GFM technology designed to emulate the behavior of a real synchronous generator (SG). There is flexibility in selecting the VSG’s parameters as they are not constrained by the physical attributes of an actual SG. This paper proposes employing the Genetic Algorithm (GA) to select these parameters, underscoring its simplicity and effectiveness in meeting diverse constraints and objectives. Small Signal (SS) models are constructed at potential operational points, with GA leveraging the SS model’s eigenvalues to select parameter values that enhance dynamic performance, ensuring resilience across a wide range of operating conditions. The effectiveness of these designed parameters is validated through Electromagnetic Transients (EMT) simulations.

Dynamic phasor model of HVDC links for linear analysis of dynamic performance

This paper presents a linearized HVDC link model, which was implemented in PacDyn software and is applicable to dynamic performance studies of power electronic equipment considering electrical network electromagnetic transients, differently from electromechanical studies where the network dynamics is usually neglected. The proposed HVDC model was developed employing equivalent switching functions concepts and dynamic phasors. Simulations and results for small and large-scale test systems are presented. Model validation is performed through comparisons between results obtained by PacDyn and PSCAD. In sequence, there are practical examples of controller tunning considering adverse dynamic interaction mitigation between HVDC Link and electrical grid. The final results on a large-scale model of the Brazilian power system demonstrate that the proposed HVDC model can be used in actual engineering studies.

Assessment of the accuracy of the modal-domain line models with real and frequency-independent transformation matrix for electromagnetic transient simulation in lines with underbuilt cables

This paper investigates the potential inaccuracies associated with using a modal-domain model featuring a real and frequency-independent transformation matrix in simulating electromagnetic transients on power overhead lines equipped with underbuilt wires. Three transmission line configurations are examined: one without underbuilt wires, one with a single underbuilt wire, and another with two underbuilt wires. Comparisons between the simulated voltages computed using the modal-domain approach and a more accurate phase-domain model as a reference reveal that the modal-domain approach leads to inaccuracies in the simulated voltages. These inaccuracies intensify with an increase in the number of underbuilt wires and the soil resistivity. Differences of up to approximately 24 % in the peak values of the simulated voltages were observed, considering the transmission line geometry analyzed in this study. Based on these findings, it is recommended that for simulating transients in overhead lines with installed underbuilt wires, phase-domain models, such as the Universal Line Model, should be employed.

Detecting short-term gravitational waves from post-merger hyper-massive neutron stars with a kilohertz detector

Abstract Gravitational waves emanating from binary neutron star inspirals, alongside electromagnetic transients resulting from the aftermath of the GW170817 merger, have been successfully detected. However, the intricate post-merger dynamics that bridge these two sets of observables remain enigmatic. This includes if, and when, the post-merger remnant star collapses to a black hole, and what are the necessary conditions to power a short gamma-ray burst, and other observed electromagnetic counterparts. Our focus is on the detection of gravitational wave (GW) emissions from hyper-massive neutron stars (NSs) formed through binary neutron star (BNS) mergers. Utilizing several kilohertz GW detectors, we simulate BNS mergers within the detection limits of LIGO-Virgo-KARGA O4. Our objective is to ascertain the fraction of simulated sources that may emit detectable post-merger GW signals. For kilohertz detectors equipped with a new cavity design, we estimate that approximately 1.1%–32% of sources would emit a detectable post-merger GW signal. This fraction is contingent on the mass converted into gravitational wave energy, ranging from 0.01M sun to 0.1M sun. Furthermore, by evaluating other well-regarded proposed kilohertz GW detectors, we anticipate that the fraction can increase to as much as 2.1%–61% under optimal performance conditions.

Analysis of Power System Electromagnetic Transients Using the Finite Element Technique

In this paper, a numerical model for the analysis of electromagnetic transients in a power system, based on the finite element technique, was developed. The simplicity of the finite element technique is manifested in the fact that the problem of solving any mathematically described phenomena in an area is reduced to solving those same phenomena in a small part of that area, i.e., finite elements. Based on appropriate mathematical models, numerical models of the synchronous generator and other parts of the power system have been developed. System of differential equations of each power system element have been included in the numerical model in such a way that we employ numerical integration of the differential equations using the generalized trapezoidal rule (ϑ-method) and reduce it to a system of algebraic equations in each time step. In a practical sense, this method enables a very simple solution to the problem of a real power system, i.e., a system with many generators, transformers, transmission lines and other elements. The accuracy of the developed numerical model for the analysis of electromagnetic transients in a power system has been confirmed by comparing the calculated results with the results obtained using the EMTP software (version 3.3) package.

Coordinated reactive power control for hybrid cascaded high‐voltage direct‐current links in weak AC grids

AbstractThe hybrid cascaded high‐voltage direct‐current (HC‐HVDC) links are recently introduced for ultra‐high voltage bulky power transmissions. However, as wind power becomes more prevalent, the grid is gradually weakened and will face voltage stability issues. This paper proposes a coordinated reactive power control strategy for HC‐HVDC links to enhance the voltage stability of AC bus. Firstly, the impact of HC‐HVDC on the static voltage stability of the AC bus is studied by the voltage sensitivity coefficient. Then, the limitation of reactive power capability of modular multilevel converter in the HC structure is identified. Based on the analysis results, a coordinated reactive power control strategy based on adaptive voltage droop is proposed. In the strategy, the DC voltage ratio is regulated according to the fluctuation degree of the AC bus voltage to adjust the reactive power of HC‐HVDC, which realized the dynamic voltage support for the AC bus. Finally, electromagnetic simulations in power systems computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) are performed, and the results validate the theoretical findings and the effectiveness of the control strategy.

Redback: a Bayesian inference software package for electromagnetic transients

ABSTRACT Fulfilling the rich promise of rapid advances in time-domain astronomy is only possible through confronting our observations with physical models and extracting the parameters that best describe what we see. Here, we introduce redback; a Bayesian inference software package for electromagnetic transients. redback provides an object-orientated python interface to over 12 different samplers and over 100 different models for kilonovae, supernovae, gamma-ray burst afterglows, tidal disruption events, engine-driven transients among other explosive transients. The models range in complexity from simple analytical and semi-analytical models to surrogates built upon numerical simulations accelerated via machine learning. redback also provides a simple interface for downloading and processing data from various catalogues such as Swift and FINK. The software can also serve as an engine to simulate transients for telescopes such as the Zwicky Transient Facility and Vera Rubin with realistic cadences, limiting magnitudes, and sky coverage or a hypothetical user-constructed survey or a generic transient for target-of-opportunity observations with different telescopes. As a demonstration of its capabilities, we show how redback can be used to jointly fit the spectrum and photometry of a kilonova, enabling a more powerful, holistic probe into the properties of a transient. We also showcase general examples of how redback can be used as a tool to simulate transients for realistic surveys, fit models to real, simulated, or private data, multimessenger inference with gravitational waves, and serve as an end-to-end software toolkit for parameter estimation and interpreting the nature of electromagnetic transients.