Model Of Synchronous Generator Research Articles

Analysis of inertia, damping, and synchronization characteristics in grid-connected photovoltaic systems with fuzzy logic control

The integration of renewable energy sources (RES) into DC-distributed power systems (DC-DPSS) is gaining traction as a sustainable energy solution. However, the inherent variability of RES output can introduce instability into the grid, posing challenges for maintaining system reliability and stability. Fuzzy logic controllers (FLCs) have emerged as a promising approach to mitigate these instability issues, offering a robust and adaptable control strategy that can effectively handle the complexities of DC-DPSS. This paper examines the application of FLCs in DC-DPSS, exploring their effectiveness in addressing instability caused by RES fluctuations. FLCs are a control system that leverages fuzzy logic, a form of logic that utilizes linguistic variables to represent uncertainty, make decisions, and improve the stability of DC-distributed power systems. The research analyzes various system parameters, including inertia, damping, and synchronization characteristics, using a static synchronous generator (SSG) model. The study builds upon prior findings by adding a fuzzy logic controller to the existing system. The results showed better performance which resulted in improved inertia, damping, and synchronization characteristics. The efficiency of the proposed controller is demonstrated using MATLAB/Simulink.

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

Virtual-stator Loss Model for Synchronous Generators with Fractional-slot Winding

Virtual-stator Loss Model for Synchronous Generators with Fractional-slot Winding

A Study on Maximum Power Point Tracking for Wind Power Generations

This paper presents a study on maximum power point tracking for a wind turbine generation (WTG). The general structure of a WTG will be introduced, including mechanical and electrical conversion blocks, to make clear about the role of all units. Moreover, mathematical models of both turbine and generator type permanent magnet synchronous generator (PMSG) will be presented to simulate and evaluate the operation of WTG. Working regions of the wind turbine corresponding to different values of wind speed and contents of some techniques to determine maximum power point will be made detailed. Hill climb search (HCS) is chosen to simulate and analyzed deeply to evaluate the ability to apply to real applications. Simulation results are carried out by MATLAB/Simulink software. By using a variation scenario of wind speed, the role of power converter and HCS controller will be presented in some simulation results about power and current at output terminals of the generator to show the ability to track instantaneous maximum power point. Research results show the high effectiveness and availability of HCS technique in real wind power system. Keywords: Maximum power point, Maximum power point tracking, Wind turbine, Wind generator, Wind speed, PMSG.

Разработка метода идентификации синхронного сопротивления турбогенератора и критериев выбора состава данных синхронизированных векторных измерений

To enhance power system dependability and efficiency, it is of great importance to obtain correct parameters of the models of key power system components such as a synchronous generator (SG). Technology of synchronized phasor measurements allows us to estimate the SG model parameters through measurements in power system steady states and transients states, without switching the SG off and conducting complex testing procedures. The theory of electric circuits and electric machines, theory of optimization and statistics, and matrix algebra are applied in this study. The developed parameter estimation method has been implemented in the MATLAB software. The method has been verified through real-world measurements captured by a phasor measurement unit installed at a large power plant in the United Power System. This paper presents an algorithm of the turbogenerator synchronous reactance estimation via a set of synchrophasor data taken under steady-state conditions. Also, the paper considers the criteria for an appropriate data array ensuring successful parameter estimation. An algorithm has been developed and implemented in MATLAB software package. To improve the parameter estimation accuracy, an algorithm has been proposed to modify a nominal value for the SG no-load excitation current depending on the heating of the field winding. The algorithm has been successfully tested out based on a set of steady state synchrophasor data captured for one of the turbogenerators in the Russian United Power System. The authors have developed and analyzed quantitative criteria to determine a set of measured parameters of steady-state modes, providing the most accurate results of the turbogenerator synchronous reactance. The developed algorithm allows accurate update of the turbogenerator synchronous parameters through synchrophasor measurements recorded in a steady state modes of electric power systems. Using the criteria for selecting phasor data, it seems possible to automate the process of generating a data array of measurement of various steady-state modes necessary for identification. The proposed procedure that considers the field winding temperature can be employed in math models to estimate SG transient and subtransient parameters based on phasor measurements in transient modes of electric power systems.

Optimal frequency fault‐tolerant control of virtual synchronous generator based on adaptive dynamic programming with fuzzy critic estimator

AbstractWith the popularity of renewable energy sources, fault‐tolerant frequency stability of distributed generation systems has become a major challenge. This paper proposes an optimal frequency fault‐tolerant control method in the distributed generation system, utilizing adaptive dynamic programming combined with fuzzy critic estimation. First, based on the operational state of the system, a non‐linear dynamic model for the virtual synchronous generator is established. Then, considering the occurrence of actuator faults, the fault‐tolerant control problem is formulated as an optimal control problem, where a fault observer is designed to estimate the fault signals. Furthermore, the proposed adaptive dynamic programming method based on fuzzy critic estimation is employed to effectively solve the highly coupled nonlinear Hamilton–Jacobi–Bellman equation and ensure the state convergence of the system with uniform ultimate boundedness. The optimal fault‐tolerant control law ensures a bounded frequency error for the virtual synchronous generator system in the event of faults. Finally, the effectiveness of the optimal control method is verified by two sets of simulations.

Simulation and calculation of maximum transmission power for offshore wind plants accounting for the Electro-Magnetic transient process

The offshore wind power industry is witnessing a shift towards larger scale and longer offshore distances, pushing the transmission capacity and transmission distance of submarine cables to their maximum limits. Consequently, it is essential to evaluate the maximum transmission limit of offshore wind power. At the same time, the larger scale of the wind farm will make the Electro-Magnetic transient (EMT) processes have a greater impact on the system stability. To address these issues, this paper firstly established a wind generator (WG) model through a permanent magnet synchronous generator (PMSG) model with averaging parameters, as well as a cross-linked polyethylene (XLPE) submarine cable model to construct an offshore wind power system via AC transmission. Subsequently, a continuous EMT simulation method is proposed to calculate the maximum transmission capacity and transmission distance limit. Real-time transient simulations were conducted to check the transient stability constraints during the calculation process. Finally, through several case studies on different types of cables, the simulation and calculation results are presented to provide useful references for engineering applications.

Robust dynamic and algebraic state estimation for microgrids: A generalized approach

AbstractNetwork control, optimization, and security analysis are facilitated by accurate microgrid state estimation. By utilizing phasor measurement units (PMUs), a combined robust centralized dynamic algebraic approach is proposed in this paper for estimating algebraic states (voltage phasors) as well as dynamic states (associated with synchronous generators and wind turbines). Assuming that a load is placed on each bus, an innovative PMU placement method is also presented to provide measurements for all dynamic and algebraic state variables. As a robust link between algebraic state estimation and dynamic state estimation, the output results of the least absolute value (LAV) estimator, which is robust against bad data, are fed to dynamic state estimators as pseudo measurements. Next, to address the nonlinearity of synchronous generator and wind turbine models, an unscented Kalman filter (UKF) is applied to estimate dynamic states precisely. The numerical tests on a microgrid test system show that the suggested approach is suitable for both algebraic and dynamic state estimation. Synchronous generators and wind turbines are modeled using nonlinear models of the 9th and third orders, respectively, and static loads are modeled as voltage‐frequency dependent ones.

An Adaptive Inertia and Damping Control Strategy Based on Enhanced Virtual Synchronous Generator Model

In modern converter-dominated power systems, total inertia is very variable and depends on the share of power generated by renewable-based converter-interfaced generation (CIG) at each specific moment. As a result, the limits required by the grid codes on the rate of change of frequency and its nadir or zenith during disturbances become challenging to achieve with conventional control approaches. Therefore, the transition to a novel control strategy of CIG with a grid-forming power converter is relevant. For this purpose, a control algorithm based on a virtual synchronous generator (VSG) is used, which simulates the properties and capabilities of a conventional synchronous generation. However, due to continuously changing operating conditions in converter-dominated power systems, the virtual inertia formed by VSG must be adaptive. At the same time, the efficiency of adaptive algorithms strongly depends on the used VSG structure. In this connection, this paper proposes an enhanced VSG structure for which the transfer function of the active power control loop was formed. With the help of it, the advantages over the conventional VSG structure were proven, which are necessary for the effective adaptive control of the VSG parameters. Then, the analysis of the impact of the VSG parameters on the dynamic response using the transient characteristics in the time domain was performed. Based on the results obtained, adaptive algorithms for independent control of the virtual inertia and the parameters of the VSG damper winding were developed. The performed mathematical modeling confirmed the reliable and effective operation of the developed adaptive control algorithms and the enhanced VSG structure. The theoretical and experimental results obtained in this paper indicate the need for simultaneous development and improvement of both adaptive control algorithms and VSG structures used for this purpose.

Higher order model of synchronous generator

<span lang="EN-US">Synchronous generator conventional model accurately describes only the stator circuit. Concerning the transients for rotor quantities, for example rotor voltage, rotor current, and rotor magneto-motor force, conceivable predetermined with acceptable accuracy if calculations are created on equivalent model properly on consideration of field and damper together with stator circuits. Unfortunately, it was recognized that simulated responses using conventional model with calculated machine parameters often did not match well with actual measured responses, particularly in the quantity’s rotor winding. For this intention, the newly method to producing the rotor circuit is to model it as well as the lines that conventionally viewed as the partition of current paths from the physical construction. Besides the physical field and damper circuits, a third circuit for the eddy currents induced in the pole surface could also be added. The all conclusions prove the correctness of synchronous generator model.</span>

Integrated simulation and performance analysis of Confined Piston Linear Generator (CPLG)

In this study, an energy conversion device referred to Confined Piston Linear Generator (CPLG) is proposed. Moreover, a modeling approach which takes the time-varying and non-linear factors into account is presented to build a real-time integrated model of the CPLG system. The Internal Combustion Engine (ICE) and Permanent Magnet Synchronous Linear Generator (PMSLG) model were built by GT-Power and Maxwell respectively, as well as the date transformation between them was realized by Simulink. The results indicated that, the shutdown areas of the PMSLG are located in the region of low load, low speed or low external load resistance. As the rise of external load resistance, the shutdown area A exists in the conditions of low load, and gradually moves to the high-speed region and reduces or even disappears, while the shutdown area B appears in the low-speed region and expands to the high-speed region. Within the operating area of the PMSLG, the energy conversion efficiency of the CPLG system is improved by 2.32% compared with the prototype ICE. In respect of parameter analysis, the influence of intake pressure on output power is much greater than those of ignition timing, air-fuel ratio and compression ratio.

A systematic approach to modeling synchronous generator using Markov parameters and Takagi–Sugeno fuzzy systems

The problem of precise modeling of Synchronous Generator (SG) devices is demanding and crucial for monitoring, stability, and control of electric grids and microgrids. SGs are known to exhibit nonlinear behavior, and because they may work in a wide range of operating points due to different electric network phenomena like load changes, current intermittent renewable energy resources, temperature variations, topological changes, etc., the modeling task of SG can be a challenging problem. This paper proposes a new method to find a global model for a synchronous generator from the input and output measurement data using state-of-the-art methods in artificial intelligence (AI) like fuzzy clustering, subspace identification, and Takagi–Sugeno (T–S) fuzzy modeling. The fuzzy C-means method is utilized to cluster the measurement data, and then using a subspace identification method based on Markov parameters concepts, the dynamic model of SG for each cluster is obtained in the form of a state space model. A Takagi–Sugeno fuzzy model is applied to determine the corresponding outputs based on the measured inputs and the available state space models. The effectiveness of the proposed approach is illustrated by applying it to the data obtained from simulations on a known fourth-order SG nonlinear model and the data obtained from real-world experimental tests.

Small-Signal Stability Modeling, Sensitivity Analysis, and Parameter Optimization of Improved Virtual Synchronous Machine Based Standalone Inverter

The virtual synchronous machine (VSM) concept is emerging as a flexible approach for controlling power electronic converters in grid-connected and standalone applications. In this study, we have used the mathematical model of a Virtual machine with a virtual exciter and governor for the standalone inverter to optimize the parameter for small-signal stability. Firstly, the small-signal models of virtual synchronous generator with load have developed, and subsequently, the system eigenvalues were obtained by solving the state Jacobian matrix. Next, the sensitivity of the eigenvalue location on controller parameters has been studied. The parameters are optimized on the basis of the location of dominant eigenvalues using a genetic algorithm. Finally, the optimal controller parameters are used to test the system’s dynamics by solving the model equations with Ordinary Differential Equation (ODE) solver. Moreover, our conclusions were also tested using the actual switching devices on Matlab/Simulink. The results indicate that the frequency stability can be enhanced drastically by optimizing a wide range of VSM parameters. The frequency stability sensitivity with respect to load variation has been improved. The transient settling time of system response for optimized values is 0.25 sec which is only 5% of that for general values. The results of this work are relevant for the VSM-based microgrid small-signal stability analysis.

Analytical Design Methodology for Wind Power Permanent Magnet Synchronous Generators

In this paper a novel analytical design methodology for wind power permanent magnet synchronous generators is presented. This kind of electric generator plays a major role in small-scale wind energy conversion systems up to 10 kW. The proposed diameter-cubed sizing equation is based both on the generator requirements, imposed by the application, and the design parameters that rely on the designer criteria. The magnetic field waveforms of both the permanent magnets field and the armature field are considered from the first moment through the winding factors, as well as the slots effects given by the Carter factor. The analytical model of the permanent magnet synchronous generator is validated with the finite element method, showing good agreement, both with no load and under load. As the generator is unsaturated, the main source of divergence between the analytical and the finite element model are the iron losses, due to the nonuniform magnetic field distribution.

Thermal Analysis for Improving the Design of Radial Flux Permanent Magnet Synchronous Generators

In this paper, the analytical thermal model of a radial flux permanent magnet synchronous generator (RF-PMSG) is developed for applications in variable speed direct-drive low-power wind turbines. The thermal model takes the form of a lumped parameter thermal network to estimate temperatures and heat fluxes for a wide operating range of the RF-PMSG. The proposed thermal model is fully coupled with the electromagnetic solution of a flexible analytical design methodology of RF-PMSGs and its algorithmic solution is coded in Matlab. The thermal analysis is an essential requirement for enhancing the design performance of radial flux permanent magnet synchronous generators. Finally, the performance of a 10 kW RF-PMSG is analyzed using the thermal model, for a wide steady-state operation range.

Effect of Unbalanced and Non-Linear Loads on Operation of the Turbogenerator of a Distributed Generation Unit

The article presents a description of models and results of research on separate and joint effects of unbalanced and non-linear loads on the operation of a lower-power synchronous generator. The modeling of the generator included automatic regulators of excitation and rotor speed. For our studies, we used computer models built in the MATLAB environment and the Fazonord package, as well as a physical model of a low-power synchronous generator. The simulation results attested to the occurrence of the following negative effects: there was a noticeable negative sequence current, the generator began to emit higher harmonics into the network, and the amplitude of forced oscillations of the excitation current increased. The presence of these effects can lead to additional mechanical vibrations of the rotor, accelerated wear of the equipment, and loss of stability. To ensure that low-power generators can operate in the presence of unbalance and harmonic distortion, it is necessary to limit their load. The maximum phase current difference, which must not exceed 12% of the nominal current, can be used as a criterion. Furthermore, when distributed generation units serve non-linear and unbalanced loads, it is necessary to implement special measures to protect the generating equipment: the use of direct current links, the use of harmonic filters, the installation of generator protections limiting negative sequence current, the use of automatic excitation current limitation, etc.

Artificial Neural Network-Based Nonlinear Black-Box Modeling of Synchronous Generators

This article deals with the black-box modeling of synchronous generators based on artificial neural networks (ANN). The ANN is applied to define the relationship between the excitation and terminal generator voltage values, and the Levenberg–Marquardt algorithm is used for determining the ANN weight coefficients. The relation is made based on generator response on reference voltage step changes. The proposed approach is checked using the experimental results obtained from the measurements on a real 120 MVA generator from a hydroelectric power plant Piva in Montenegro. Furthermore, a fair comparison of the nonlinear autoregression model with the exogenous input (NARX) and Hammerstein–Wiener model is made. For the validation, different experiments were conducted—different values of step disturbances, other controller parameters, and different rotating speeds. Based on the presented results, it can be noted that the proposed ANN model is very accurate and provides a very high degree of matching with the experimental results and outperforms the other considered nonlinear models. Furthermore, the proposed test procedure and model are easy to implement and do not require disconnection of the generator from the grid or additional equipment for experimental realization. Such obtained models can be used for different testing types related to the excitation system.

Admittance-Based Stability Analysis of Current-Controlled VSG Considering the Frequency Coupling Characteristics

Due to the dynamic interaction between the inverter and the grid, the inverter may have power oscillation problems under a weak grid. In this article, considering frequency coupling, the more precise broadband sequence admittance model of the current-controlled virtual synchronous generator (CVSG) is established, and the admittance characteristics of CVSG and traditional grid-connected inverter (TGCI) are compared and analyzed. The amplitude of the sequence admittance of CVSG is generally larger than that of TGCI in the low-frequency region, and in the entire frequency sweep range, the coupling admittance amplitude of CVSG is larger than that of TGCI. In the low-frequency region, the coupling admittance has a great impact on the stability of CVSG and TGCI, so the coupling admittance cannot be neglected when analyzing the stability of the system. The generalized Nyquist stability criterion is used to compare and analyze the influence of power grid strength, phase-locked loop (PLL) bandwidth, and output power on the stability of CVSG and TGCI according to the established admittance model. It can be seen from the stability analysis results that, compared with TGCI, when the PLL bandwidth is relatively large, CVSG has stronger adaptability to the weak grid and power changes. Finally, experiments verify the correctness of the theoretical analysis.

The strategy of VSG rotational inertia adaptive inverter dual-output seamless shore power connection

This paper introduces the seamless power supply of the inverter dual output virtual synchronous generator(VSG) model based on the characteristics of ship generator grid connection and transfer load. By establishing VSG mathematical model, it introduces the advantages and deficiencies of VSG adaptive control of inertia (ACI), and the improved adaptive control of inertia(IACI) is proposed. Then, the setting method of VSG frequency tracking coefficient, rotational inertia and other parameters is given. Finally, we provide experimental proof for the ACI and IACI control effects.

Dynamic Modeling and Analysis of a Virtual Synchronous Generator with Supercapacitor

With the continuous integration of new energy sources, the power system gradually begins to present the characteristics of a weak power grid. The system’s inertia decreases, leading to problems in the stability of the power grid. In this paper, a virtual synchronous generator model with a supercapacitor is analyzed. The supercapacitor provides additional virtual inertia to the system and suppresses system frequency disturbances more quickly. Bifurcation theory is used to analyze the nonlinear dynamics of the model. The bifurcation diagram of input active power is given in this paper, and the phase portraits and sequence diagrams of the frequency and power angle are presented to verify that, if the initial value of the system falls inside the stability region, the system can remain stable. If the initial value of the system falls outside the stability region, conversely, the system will lose stability. Finally, the simulation verifies the influence of the supercapacitor on the system inertia. The results show that the recovery speed of a small capacitance system is faster than that of a large capacitance system when disturbance occurs. It is concluded that, the smaller the supercapacitor is, the greater the virtual inertia it can provide.