Dynamic Circuit Model Research Articles

Comprehensive Analysis on Rotor Vibration Characteristics Based on a Novel Dynamic Stator Interturn Short Circuit Model of Synchronous Generator

Comprehensive Analysis on Rotor Vibration Characteristics Based on a Novel Dynamic Stator Interturn Short Circuit Model of Synchronous Generator

Applicability of linear models in modeling dynamic behavior of alkaline water electrolyzer stack

Linear equivalent circuit models are commonly used to estimate the effect of current ripple on the performance of water electrolyzers, thus it is important that the validity of this approach is examined. The effect of the amplitude and frequency of the sinusoidal current ripple on the performance of the alkaline water electrolyzer stack is studied experimentally. The increased current ripple amplitude produces additional losses in the electrolyzer stack, while the effect of ripple frequency appears to be insignificant. Linear models based on an equivalent circuit and polarization curve tangent are compared with waveform measurements with differing ripple amplitudes and frequencies to study their dynamic modeling capabilities. Under dynamic operation the experimental results show that operating voltage differs considerably from the static polarization curve, especially at low operating currents, due to nonlinear behavior. It is also shown that the dynamic equivalent circuit model using only linear components is not enough to accurately model electrolyzer behavior under dynamic operation.

On the Impact of Some Fixed Point Theorems on Dynamic Programming and RLC Circuit Models in R-Modular b-Metric-like Spaces

In this study, we significantly extend the concept of modular metric-like spaces to introduce the notion of b-metric-like spaces. Furthermore, by incorporating a binary relation R, we develop the framework of R-modular b-metric-like spaces. We establish a groundbreaking fixed point theorem for certain extensions of Geraghty-type contraction mappings, incorporating both 𝒵 simulation function and E-type contraction within this innovative structure. Moreover, we present several novel outcomes that stem from our newly defined notations. Afterwards, we introduce an unprecedented concept, the graphical modular b-metric-like space, which is derived from the binary relation R. Finally, we examine the existence of solutions for a class of functional equations that are pivotal in dynamic programming and in solving initial value problems related to the electric current in an RLC parallel circuit.

Theoretical and experimental studies on the self‐healing properties of metallised capacitor films under multiple stresses

AbstractMetallised film capacitors, for the most important merits is the excellent self‐healing property, have significant electrical insulation advantage. The essential factors affecting the self‐healing properties of metallised polypropylene film capacitors (MPPFCs) are first analysed, and a self‐healing performance characterisation test platform for metallised polypropylene capacitor films was built. Both the voltage/current waveforms and discharge patterns of the self‐healing process under multiple stresses including temperature, voltage and inter‐layer pressure were recorded and discussed. The correlation between self‐healing performance characterisation and the carbon that appeared on the surface of the dielectric layer during the arc extinction time is clarified. Finally, by virtue of an equivalent dynamic circuit model, the influence of square resistance and the equivalent capacitance of the power grid on self‐healing has been theoretically studied.

Anti-Interference Control Method of Buck–Boost Converter Based on High-Order Nonlinear Disturbance Observer

A compound anti-interference control method based on a high-order nonlinear disturbance observer (HONDO) is proposed to address the impact of system disturbances on output voltage when applying the Buck–Boost converter in a microgrid to provide power to loads. Initially, the dynamic circuit model of the Buck–Boost converter is formulated, taking into account the system disturbance. Subsequently, HONDOs are designed to provide real-time estimates of uncertain factors in both the voltage loop and current loop of the circuit. These estimates are then utilized to design backstepping controllers aimed at effectively tracking the load output voltage set point. The simulation and experimental findings indicate that, when faced with load mutations, input voltage variations, and uncertainties in system parameters, the proposed compound anti-interference control method outperforms traditional control techniques by offering superior response speed, broader disturbance estimation capabilities, and enhanced dynamic performance of the Buck–Boost converter.

Modelling, analysis and validation of a dynamic dense medium separation circuit model for detecting medium losses

Dense medium separation circuits use a dense medium to separate low density waste material from high density valuable minerals. Since the dense medium is an expensive consumable, it is recovered after separation of the valuable minerals from waste. A dynamic nonlinear model of a dense medium separation circuit of an iron ore plant in South Africa is developed to track the flow of medium in the circuit. An extended Kalman filter is designed for estimating observable but unmeasured states. The model is validated using online plant data. This paper serves as a precursor for further work to detect and mitigate expensive medium losses in the circuit.

A New Loss of Field Detection Scheme for Synchronous Generators by Incorporating a Dynamic Equivalent Circuit Model

A New Loss of Field Detection Scheme for Synchronous Generators by Incorporating a Dynamic Equivalent Circuit Model

Calculation method of external fault short-circuit current for variable-speed pumped storage units based on time-domain dynamic circuit

The calculation method of the external fault short-circuit current of large units with clear mechanisms and practicality is of great value in engineering practice. Due to the special AC excitation structure and control mode, the external fault short-circuit characteristics of variable-speed pumped storage units (VSPSUs) are very different from those of conventional units. Therefore, this paper proposes a calculation method for external fault short-circuit current based on a time-domain dynamic circuit. According to the excitation and control characteristics of VSPSUs under external fault, the VSPSU under external fault is divided into two cases: continuous excitation and jumper action. Based on space vector analysis, the time-domain dynamic circuit models are established, respectively. On this basis, the analytical formula of the external fault short-circuit current of VSPSUs is derived by combining the transition boundary conditions of the two cases and the dynamic characteristics of the stator flux linkage. Finally, the comparison with PSCAD/EMTDC simulation results shows that the proposed VSPSUs’ external fault short-circuit current calculation method has high accuracy and practical value, which can meet the needs of primary equipment selection and relay protection of variable-speed pumped storage power plants.

An Active Power Dynamic Oscillation Damping Method for the Grid-Forming Virtual Synchronous Generator Based on Energy Reshaping Mechanism

The grid-forming virtual synchronous generator (GFVSG) with large virtual inertia can provide a friendly grid-connected operational mode for power electronic converters, but it may also introduce the active power dynamic oscillation problems similar to traditional synchronous generators. In view of this, the dynamic equivalent circuit model of the GFVSG grid-tied active power-angle is established firstly, and, then, the understanding of the GFVSG active power oscillations under variable disturbances is revealed from the perspective of circuit energy flow in this paper. On this basis, an active power dynamic oscillation damping method based on an energy reshaping mechanism for the GFVSG is proposed, and a parameter design method using the second-order equivalent reduced-order control model is given. The MATLAB 2016a simulation as well as experimental test platforms of a 100 kV·A GFVSG grid-connected system are established, then, both the feasibility and effectiveness of the proposed active power dynamic oscillation damping method are verified by using the simulation and experimental comparison results.

Dynamic Electrical Circuit Modeling of a Proton Exchange Membrane Electrolyzer for Frequency Stability, Resiliency, and Sensitivity Analysis in a Power Grid

Dynamic Electrical Circuit Modeling of a Proton Exchange Membrane Electrolyzer for Frequency Stability, Resiliency, and Sensitivity Analysis in a Power Grid

Design and analysis of a microminiature omnidirectional wave energy-harvesting device based on a spatial slider–crank mechanism

Energy-harvesting devices using wave energy and ocean current energy can provide higher endurance and operation capacity for small floating or mobile equipment in offshore operations. In this paper, a microminiature omnidirectional wave energy-harvesting device based on a spatial slider–crank mechanism was designed for equipment whose length is less than ordinary ocean wavelength. It can harvest the ocean wave energy from the omnidirectional swing of the buoy and convert the reciprocating swing motion of the buoy into the unidirectional rotation motion of the generator to improve the energy conversion efficiency. The dynamic model and equivalent circuit model of the energy-harvesting device were established by the Lagrangian method and circuit-based analysis method, respectively. The model was simulated, and the effects of parameters such as crank length, wave period, etc. were investigated. The results showed that the device has good energy-harvesting performances, especially in medium and low sea conditions. In addition, the performance of the device can be improved by adjusting the length of the crank and rod.

A Compact Bandwidth and Frequency-Range Reconfigurable CM Filter Using Varactor-Loaded Dual-Slot-Based Defected Ground Structure

A reconfigurable common-mode (CM) filter with a wide tunable bandwidth and frequency-range is proposed in this article. The filter adopts four compact dual-slot-based defected ground structure (DGS) cells to achieve a wide suppression of CM noise. To simplify the design, only one varactor and one dc-blocking capacitance are loaded on one DGS cell directly, which retains the original structure of the DGS cell. A wide continuously adjustable frequency range and bandwidth can be achieved when different voltages are applied to different varactors. A dynamic equivalent circuit model is built to explain the filter's working principle, which is helpful to obtain the filtering characteristics under different varactor parameters quickly and accurately. In order to verify the feasibility of the scheme, a DGS-based filter with an area of 19 mm × 9.2 mm is implemented under the microstrip line. The simulated results show the filter can achieve a continuously tunable CM suppression of frequency range from 1.9 to 7.3 GHz, and a tunable bandwidth using different voltage supplies. Good agreement between full-wave simulation and measured results is observed.

Enhanced multi-state estimation methods for lithium-ion batteries considering temperature uncertainties

Due to their high energy density and minimal emissions, lithium-ion batteries are frequently employed in electric vehicles (EVs). Accurate estimation of the micro-parameters, state of charge (SOC), and state of health (SOH) are a few primary monitoring functions of the battery management system (BMS) to increase the battery's efficiency and safety under various operating conditions. This paper proposes a SOC and SOH co-estimation method by adopting an ensemble empirical mode decomposition method with adaptive noise and an autoencoder (EEMDA) to extract, decompose, and reconstruct the full-scale charging voltage and current data for a dual extended Kalman filter (DEKF) with multi-parameter and time-scale updates for accurate estimation based on a variable forgetting factor limited memory recursive least squares (VFF-LMRLS) method. The VFF-LMRLS method is used to solve the data saturation phenomenon and identify the battery's characteristic micro-parameters based on a proposed dynamic migration second-order resistor-capacitor equivalent circuit model under different operating states. Battery tests are conducted at temperatures ranging from −10 to 50 °C under complex working conditions. Using the VFF-LMRLS method, the effects of different temperatures on the micro-parameters are discussed. The SOC and SOH results of the proposed EEMDA-DEKF method based on the dynamic migration battery model show that the mean absolute error and root mean square error metrics have the least values of 0.0233% and 0.0252%, which signify an optimal performance improvement of 93.26% and 93.66%, respectively, compared to the conventional DEKF method. Based on the experimental results and analyses, the proposed method has a high degree of accuracy and robustness, which makes it feasible for battery monitoring and prognostic BMS applications.

Study on Beat Vibration of a High Temperature Superconducting EDS Maglev Vehicle at Low Speed

Vertical displacement acceleration and the pitch angle record produce the phenomenon of beat vibration when testing a 200 m electro-dynamic suspension (EDS) magnetic levitation (maglev) test vehicle with high-temperature superconducting (HTS) at the CRRC Changchun Railway Vehicles Co., Ltd., where the vehicle is clamped and in planar motion. First, to examine this phenomenon, this paper establishes dynamic equations of the vehicle with three degrees of freedom (DOF), and the levitation force on each superconducting magnet (SCM) is calculated by dynamic circuit theory. Second, the theory vertical equilibrium point is obtained from the average of the levitation force for a different velocity and the magneto-motive force (MMF) of the SCM. Third, this paper decouples SCM levitation forces from each other using MATLAB/SIMULINK, and a multi-body dynamic model with six DOF is developed in SIMPACK. All vertical displacements and acceleration responses, as well as the pitch angle and acceleration response from the simulation, appear to show the phenomenon of beat vibration since there are two closing natural frequencies of approximately 2 Hz and 2.4 Hz. Finally, based on the traversing method considering the influence of the velocity, initial vertical displacement, and the MMF of the SCM, the multi-body dynamic model is frequently utilized to study the response of the mean and amplitude of vertical displacement and that of the pitch angle. The results show that increasing the MMF or velocity could decrease the vertical displacement and pitch angle; the mean vertical displacement is a little larger than the theory equilibrium point; and the amplitude of vertical displacement is small when the initial vertical displacement is near the theory equilibrium point. Both the numerical and experimental results verify the validity of the dynamic circuit model and mechanical model in this paper.

Computation of Effective Length of Enhancement for Vertical Electrode Under Lightning Transients

The performance of the grounding system is improved by adding enhancement conductors to the primary electrode as they result in low impulse impedance. This article proposes an optimized impulse impedance reduction approach to estimate the effective length of the enhancements of the primary electrode. The impedance of the enhanced primary electrode is computed by performing simulation experiments in a comprehensive dynamic circuit model. The enhancement's effective length is estimated from the correlation of the impedance with the enhancement length. From the relationship of the effective enhancement length with soil resistivity, impulse rise time, and current, an empirical expression to estimate the effective length of enhancement (ELEH) is obtained using numerical analysis. The obtained expression for ELEH is validated by field experiments.

Novel dynamic equivalent circuit model of integrated energy systems

With the transformation from individual energy systems to integrated energy systems (IES), equivalent circuit IES modeling is developed to represent the heat and electricity consistently for coordinated analysis, control and optimization. However, physical properties of equivalent parameters are a mismatch, and the key operation characteristics, including dynamics and coupling, have not yet been fully described, remaining obstacles for optimal electricity-heat coordination. In this study, a novel IES equivalent circuit modeling methodology is proposed. From the perspective of physical characteristics, the similarity of heat transfer and micro conductivity processes is determined. A novel thermoelectric equivalent rule with matched energy units is proposed, showing the corresponding relations of the basic state, power, and energy quantities between electricity and heat. Then, the equivalent rule is applied in IES equivalent circuit modeling, where the equivalent heat element models are established to characterize the electrothermal coupling and dynamics of heat subsystems. Finally, following the IES system structure, the IES equivalent circuit model is completed. A numerical comparison is performed to verify the effectiveness of the model. The simulation results demonstrate that the proposed model can fully capture the dynamic and coupling characteristics of IES.

Validation of a dynamic non-linear grinding circuit model for process control

A step-wise algebraic routine is used to fit a dynamic non-linear model, specifically developed for process control, to steady-state process data of an industrial single-stage grinding mill circuit. Step-test data from the industrial plant is used to validate the response of the non-linear model. The results indicate that the model provides a qualitatively accurate response of the main process variables. Because the non-linear model parameters can be calculated from steady-state data, it provides an advantage over classical system identification methods as it does not require an expensive and disruptive step-test campaign to develop linear transfer function models. The model is ideal for model-based predictive process control.

Multiobjective optimization of 3-DOF magnetic bearing considering eddy current effects and saturation

The multiobjective optimization method of three-degrees-of-freedom hybrid magnetic bearings (3-DOF HMBs) is crucial compared to time-consuming finite element calculation due to their three dimensional magnetic field. Solid rotors are the first choice for high-speed applications because the yield strength of laminated rotors is lower. However, solid materials may induce eddy current effects and saturation problems. In addition, a 3-DOF HMB has solid and laminated materials and permanent magnet materials, and the material price presents a risk for the structure. In view of the above mentioned problems, a dynamic magnetic circuit model of the 3-DOF HMB with eddy current and saturation effects is initial given. Subsequently, a multiobjective optimization design method for maximum axial and radial bearing capacity and the lowest cost is proposed. Finally, the optimized parameters are given, and a prototype is manufactured. The range of all optimal solutions considering saturation is less than that without saturation, and the maximum reduction is 99%. The experimental results demonstrate the effectiveness of the optimized design results.

Comparison study between hybrid Nelder-Mead particle swarm optimization and open circuit voltage—Recursive least square for the battery parameters estimation

Recently, the whole world has turned to the rechargeable battery as the primary source of electric vehicles (EVs). Meanwhile, the majority of the automobile manufacturers quantify lithium as a key material for the development of battery chemistry. Currently, Lithium-ion (Li-ion) batteries are the dominant technology for battery electric vehicles (BEVs). The real value of Lithium is that they deliver high and fast energy densities in a small volume or configuration. Thus, the description, identification and modeling of the battery, during its operation, are essential actors for the success of EVs development. However, modeling Li-ion-based energy storage devices has not yet been easy enough due to the complexity of chemical reactions in real time. In this work, the modeling of Li-ion cells is performed with dynamic equivalent electrical circuit model (ECM). This study aims to exploit the advantages of two hybrid estimation methods for the identification of Li-ion battery model parameters. The first method is hybrid optimization algorithm PSO-NM which is composed of a particle swarm optimization algorithm (PSO) and a Nelder–Mead algorithm (NM). On the other hand, the second hybrid model, namely the OCV-RLS algorithm, benefits from the advantages of direct measurement of open circuit voltage (OCV) and of a Least Square Recursive (RLS) to obtain an optimum overall performance estimate. The validation results support the reliability of these proposed hybrid methods to identify the Li-ion battery model. In addition, they constitute a reference for the comparison of the two algorithms PSO-NM and OCV-RLS to solve the problem of Li-ion battery SOC estimating.

Transmission Line Dynamic Circuit Model for Effective Length of Ground Electrode Under Lightning Transients

The effective length of the ground electrode is one of the primary research interests of lightning grounding system design. In this article, using a practical numerical analysis, a new expression for estimating the effective length of the simple ground electrode is proposed. A new dynamic circuit model based on the transmission line is developed to derive the expression. The model considers the soil ionization, frequency-dependent soil parameters, mutual reactance, and skin effect. Several rigorous impulse test simulations are performed on different electrode lengths, soil properties, and lightning currents to estimate the effective length of ground electrode numerically. A new expression is arrived at using the curve-fitting and optimization technique from the relationships of the effective length with soil resistivity, impulse rise time, and current. The proposed dynamic model and the expression to obtain the effective length are validated by published results.