Model Of Induction Generator Research Articles

Modelling and comparison analysis of grid‐connected DFIG‐based wind farm in weak grid

This study proposes a generic method for modelling and comparison analysis of grid-connected double-fed induction generator (DFIG)-based wind farms in a weak grid. A detailed model of DFIG in a weak grid is established and used as a benchmark. Specifically, the detailed model consists of the mechanical part, generator part, rotor side converter, and phase-locked loop (PLL). Two simplified models of grid-connected DFIG-based wind farms in a weak grid are compared with the detailed model to investigate the mechanism of sub-synchronous oscillation (SSO) as well as the influential factors through linear system analysis. The first simplified model ignores shafting dynamics, stator flux dynamics, and PLL dynamics. The same assumptions are used in the latter, except that PLL dynamics are considered. Time-domain simulation and eigenvalue analysis are used to verify the accuracy of the simplified models. The block diagrams of the linearised system are derived based on the proposed model, and the oscillation mechanism is explained by linear system analysis. Through eigenvalue analysis and the root locus method, the influences of the parameters of the DFIG and its controllers on the system stability are identified and analysed.

Modeling, simulation and control of a doubly-fed induction generator for wind energy conversion systems

In recent years, wind energy has become one of the most promising renewable energy sources. Various wind turbine concepts with different generator topologies have been developed to convert this abundant energy into electric power. The doubly-fed induction generator (DFIG) is currently the most common type of generator used in wind farms. Usually the DFIG generator is a wound rotor induction machine, where the stator circuit is directly connected to grid while the rotor’s winding is connected to the grid via a three-phase converter. This paper describes an approach for the independent control of the active and reactive powers of the variable-speed DFIG. The simulation model including a 1.5 MW-DFIG driven by a wind turbine, a PWM back-to-back inverter and the proposed control strategy are developed and implemented using MATLAB/Simulink/SimPowerSystems environment.

Modeling and Simulation of 1.1 kW Wind Energy Conversion System

Over the last thirty years, renewable energy sources have been attracting great attention due to the cost increase, limited reserves, and environmental impact of fossil fuels. In the main time, technological advancements, cost reduction, and governmental incentives have made some renewable energy sources more competitive in the market. Among them, wind energy is one of the fastest growing renewable energy sources. This work is applied to investigate whether WADI-SEIDNA region (North Khartoum, Sudan) is suitable to generate electrical power or not, according to a design and modeling of horizontal blade turbine. A detailed mathematical model of a squirrel-cage induction generator (SCIG) coupled to wind turbine system using vector control computing technique is also done. The performance of wind energy conversion system (WECS) is studied using simulation developed in MATLAB/SIMULINK.

Stator winding fault detection of induction generator based wind turbine using ANN

This paper presents a stator winding faults detection in induction generator based wind turbines by using artificial neural network (ANN). Stator winding faults of induction generators are the most common fault found in wind turbines. This fault may lead to wind turbine failure. Therefore, fault detection in induction generator based wind turbines is vital to increase the reliability of wind turbines. In this project, the mathematical model of induction generator based wind turbine was developed in MATLAB Simulink. The value of impedance in the induction generators was changed to simulate the inter-turn short circuit and open circuit faults. The simulated responses of the induction generators were used as inputs in the ANN model for fault detection procedures. A set of data was taken under different conditions, i.e. normal condition, inter-turn short circuit and open circuit faults as inputs for the ANN model. The target outputs of the ANN model were set as ‘0’ or ‘1’, based on the fault conditions. Results obtained showed that the ANN model can detect different types of faults based on the output values of the ANN model. In conclusion, the stator winding faults detection procedure for induction generator based wind turbines by using ANN was successfully developed.

Modeling, analysis, and control of wind-driven induction generators supplying DC loads under various operating conditions

A configuration of a self-excited induction generator supplying DC loads with constant voltage through a diode bridge rectifier and a buck-type DC–DC converter is proposed. The rectifier input current is made continuous, by connecting a suitably designed series filter inductor. The method of binary search algorithm is used to solve for the operating parameters of the generator. The performance of the entire unit is predetermined for the various patterns of speed and power operations. For the dynamic analysis of the induction machine, an abc-dq modeling has been employed and the simulation results on the unit are obtained under both steady state and transient state using MATLAB/Simulink toolbox. A prototype model of the unit has been built in the laboratory and the experimental results have been presented, thereby validating the performance and usefulness of the system.

New grid synchronization and power control scheme of doubly-fed induction generator based wind turbine system using fuzzy logic control.

This paper deals with the analysis, modeling and control of a doubly-fed induction generator in variable speed wind turbine systems. The start-up procedure of the wind turbine including the grid synchronization has been established. New sensorless control schemes were developed, the first one is designed for standalone mode and grid synchronization named direct voltage control, the second one is designed for grid-connected mode named direct power control. To improve the robustness of the controlled system performance in case of machine parameters variations, a fuzzy logic controller was introduced. Various operation modes have been tested including accelerating and braking of the wind turbine, limited power and speed operation mode, power maximization mode, standalone operation mode with supplying a variable load. Simulation of the full start-up procedure was performed using Matlab/SimPowerSystems. The simulation results for several transient conditions demonstrated the effectiveness of the proposed control strategy.

Mathematical modelling of doubly-fed induction generator

Mathematical representation of any machine in state space form enables the user to design proper controller parameters for exercising efficient control. In this work, differential equations have been used to develop the mathematical model of a doubly-fed induction generator (DFIG) in MATLAB. The model so developed has been compared with the existing MATLAB model. Using Vector control, the machine torque and stator currents have been obtained from the DFIG model developed. The torque and currents have been compared against the existing standard Simulink model output. The two sets of results are totally in agreement with each other.

Mathematical Formulation of Feedback Linearizing Control of Doubly Fed Induction Generator Including Magnetic Saturation Effects

This paper proposes a control methodology based on feedback linearization for a doubly fed induction generator (DFIG) incorporating the magnetic saturation. The feedback linearization algebraically converts a nonlinear system model into a linear model, allowing the use of linear control techniques. Feedback linearization control depends on the model of the system and is therefore sensitive to parameter variations. The doubly fed induction generator (DFIG) operating under the magnetic saturation conditions results in the nonlinear variation of magnetizing inductance, which affects the performance of the control algorithm. From this stand point, on the basis of the dynamic model of the doubly fed induction generator considering magnetic saturation, the feedback linearizing control technique has been formulated. The mathematical model of the doubly fed induction generator, integrating the magnetic saturation has been formulated in the stator flux-oriented reference frame with rotor current and stator magnetizing current as state variables. Simulation studies demonstrate that the inclusion of magnetic saturation in the feedback linearization control of the doubly fed induction generator model increases its accuracy and results in a more efficient and reliable synthesis of the control algorithm.

Determination of Minimum Reactive Power Compensation for the Stable Operation of Type-1 WTG in Grid-Connected mode

The current energy demand scenario leads to tremendous increase in the renewable energy sector, but the integration of these renewable causes various stability issues of the system. Increasing share Wind energy has several shortages due to its energy harnessed from the wind. These shortages can be improved by compensating reactive power into the wind plant. The wind farm consist of fixed speed squirrel cage Induction generator absorbs reactive power from the grid for stable operation and it can be injected using reactive power compensator. In this context, the main aim of the research is to find the minimum reactive power compensation required for stable operation for different rating of Type-1 WTG in grid connected mode. In this paper, a detailed model of constant speed Squirrel Cage Induction Generator is carried out in MATLAB/SIMULINK-2017a to analyze the need of reactive power compensation to maintain voltage and frequency stability of the system during normal condition. The work also focuses on to investigate the impact of induction generator inertia level on compensation level. The modified IEEE 5-bus radial distribution system is used to conduct these investigations and the simulation results clearly show that: (1) The necessity and minimum additional reactive power support to the wind farm to improve and maintain stability of the system; (2) the inertia level of wind farm and reactive power compensator level both are independent each other.

Nine Switch Back To Back Converter- Design and Simulation for Wind Turbines Based on Doubly Fed Induction Generator

A conventional power system diverges from a Wind Energy Conversion System (WECS). The power output from a wind turbine system varies as the wind varies. Thus, management, design and analysis of WECS become difficult. Various approaches are available theoretically to cram the behavior of WECS. This paper, uses MATLAB simulink model of DFIG based WECS to study steady state characteristics. The analysis is performed to inspect the characteristics of wind and Doubly Fed Induction Generator model. For efficient generation of electricity, it is necessary to operate the wind turbine at variable speed. This is achieved by the Power Electronic Converters. Many designs of converters are available, depending on the aspects of economy, configuration and application. Now-a-days attention of the researchers is diverted towards the Doubly Fed Induction Generator (DFIG). The paper signifies the design, simulation and analysis of back-to-back converters for DFIG based Wind Energy Conversion System WECS. A 9- switch Back to Back converter is designed, simulated in the paper and the results are compared with traditional AC-DC-AC converter. The functioning of the converter is simulated by means of MATLAB/SIMULINK. Results of the simulation illustrate the improved DC link voltage, when compared to that of the conventional converter.

Vector control of a Doubly Fed Induction Generator wind turbine

Nowadays, the most currently installed variable speed wind turbines based on Doubly Fed Induction Generator, due to main advantages such as high stability, improved power quality, high energy efficiency, controllability and mature control technology. In This paper, a modeling of Double-Fed Induction Generator (DFIG) and Direct Vector Oriented Field (DFOC) are presented, then the Proportional-Integral (PI).We developed the model for the simulation and the analysis of a double-fed induction generator to facilitate the electrical production control such as machine is considered. The results of simulations realized under the Matlab/Simulink software are analyzed and interpreted. The aim of this study is to apply the vector control independently of the active and reactive powers generated by the Doubly-Fed Induction Generator.

Dynamic Performance of a Stand-Alone Self-Excited Induction Generator for a Variable Speed Wind Turbine

Induction generators are more appropriate machines for wind energy conversion. Induction generators generally can be operated in two modes i.e. grid or self-excited mode. Among the two, later is of improving importance due to its capability of wind energy conversion (primary) into electrical energy (secondary) for wide range of variations in the operating speed. Poor voltage regulation is observed in machine analysis. Steady-state and transient analysis of self-excited induction generator surveys that such generators are not efficient enough to maintain the frequency and terminal voltage in the absence of conventional controllers but are only used for stator and rotor currents variations. In this paper modeling of self-excited induction generator for wind energy conversion systems is designed and simulated in MATLAB environment. The system is studied for dynamic period simulation during the starting period, and load variation.

Comparative analysis of single-phase self-excited induction generators of various rotor cages

The paper deals with a simulation study of influence of conductive material of the rotor squirrel cage on output characteristics of single-phase self-excited induction generators. For calculation of performance characteristics, two-dimensional field-circuit model of the single-phase induction generator was applied. A comparison of self-excitation waveforms of terminal voltage and load characteristics of the generators for rotor bars of the same shape, made of aluminium and copper, was presented. The obtained simulation results by the field-circuit model and analysis may be utilized for designing new constructions of single-phase self-excited induction generators as well for modifying construction of the generators designing on the base of general-purpose single-phase induction motors.

Coordinated Secondary Frequency Regulation Strategy of Doubly-Fed Induction Generator and Electric Vehicle

Wind turbines can participate in frequency regulation by controlling active power output, but the indeterminacy and volatility of wind power result in low reliability of frequency support. Therefore, as a kind of energy storage system, an electric vehicle is adopted to coordinate with wind turbines to regulate system frequency considering its large-scale development. First, based on the reasonable division of wind speed regions and operation point selection of pitch angle, the de-loading strategy of doubly-fed induction generator for reserve capacity under continuously varying wind speed is proposed. Then, through the combination of rotor speed and pitch angle control, frequency regulation model of a doubly-fed induction generator in whole wind speed range is established. Finally, taking into account the driving demand of electric vehicle owners, through the real-time allocation of system frequency regulation task based on frequency regulation capacity, the coordinated control strategy of doubly-fed induction generator and electric vehicle cluster for secondary frequency regulation is put forward. The simulation results show that the coordinated frequency regulation strategy based on real-time allocation can suppress frequency deviation effectively, and the regulation effect is better than the situations of wind turbine coordinating with the conventional unit or coordinating with electric vehicle cluster based on fixed allocation ratio.

Modeling and dynamic response of double-feed induction generator and back-to-back converters in unbalanced grid voltage conditions

Double-feed induction generators are one of the most commonly used generators in wind power plants. Therefore, studying this type of generators in different grid conditions such as unbalanced grid voltage is of great importance. In this article, double-feed induction generators, in synchronous reference frame, and back-to-back converters are reviewed and modeled. The advantage of this model, compared with previous ones, is that it can be used in unbalanced grid voltage conditions. Hence, different parts of the generator in synchronous positive reference frame are studied and governing equations in such conditions are analyzed. Stator output power, rotor side converters, grid side converters, and electromagnetic torque, mentioned in the model, are analyzed, as well. The model is also applied in balanced conditions. Therefore, the model proposed in this article is perfect for analyzing wind turbine-based power plants with double-feed induction generators. The accuracy of the suggested function was confirmed through simulation.

Inertia Provision and Small Signal Stability Analysis of a Wind-Power Generation System Using Phase-Locked Synchronized Equation

The inertia and damping of the modern power system are consistently decreased when wind energy has a high penetration level into the grid. This paper proposes a novel solution through transforming the wind turbine generator into an equivalent motion equation mimicking the basic characteristics of the synchronous generator (SG). This synchronized equation builds upon the phase-locked loop (PLL) model of the doubly-fed induction generator (DFIG), which characterizes the inertia constant, damping coefficient, and synchronizing torque. Thanks to this work, the dynamic performance of the inverter-based asynchronous generator could be analyzed from the perspective of the classical rotor motion equation. It further enables us to employ the analogy method to provide the DFIG with automated frequency response ability and to estimate the inertia constant quantitatively. Results also manifest that based on the synchronized equation, the PLL forms a power system stabilizer to enhance the power system oscillation. Hence, parameters tuning in PLL for coordinating inertia provision and damping enhancement are introduced. The contribution of this study lies in that the equivalent synchronized equation is established to optimize the system operation without alterations in the existing control structure of the DFIG. The theoretical analysis and the strategy are verified through the power system simulator.

Wind Energy Dynamics of the Separately Excited Induction Generator

This paper covers the analysis, dynamic modelling and control of an isolated self-excited induction generator (SEIG) driven by a wind turbine. The proposed dynamic model consists of induction generator, self-excitation capacitance and load model which are expressed in stationary d-q reference frame. The dynamic performance of SEIG is investigated under no load and on load. To predict the performance of the system, a MATLAB based simulation study using matlab embedded function block was carried out. Simulations from the variations of the speed and load display the dynamic behavior of the generator. A constant capacitor value of 100 micro-farads was used in this work. The simulation results obtained illustrate the changes in the voltage, currents, torque and magnetizing inductance of the generator. The wind velocity increase led to the increase in mechanical input from the wind turbine. This results in the increased rotor speed leading also to increased stator phase voltage. The obtained simulations also show that the output voltage of the induction generator depends greatly on its shaft speed and load; this poses a potential threat as it is capable of causing a significant variation in the power consumption in the load of the machine.

Modelling of DFIG‐based wind turbine for low‐frequency oscillation analysis of power system with high penetration of distributed energy

This study investigates modelling of doubly-fed induction generator (DFIG)-based wind turbines for low-frequency oscillation analysis of power systems with high penetration of distributed energy. A reduced order model of wind turbine with DFIG is proposed for small signal stability analysis in electromechanical time scale for low-frequency oscillation analysis. Furthermore, a Thevenin equivalent model of DFIG with internal voltage is also presented. Base on the derived model, the effect of phase-locked loop is emphasised, and explained by using the internal voltage derived. The model proposed is well verified by modal analysis and time-domain simulations.

A new model of self-excited induction generator to feed a single phase load with an application in lighting animal farm

This paper presents a new model of self-excited single-phase induction generator, used by a three-phase machine for lighting animal farm through biogas energy. The designs and applications of the previous generator models have been found to be very complex, for this reason simple and effective model of SEIG is proposed. The transient equations of the proposed model were represented by SIMULINK blocks, while the steady state equations by electrical equivalent circuit. The model is derived from Steinmetz connection circuit, stationary reference frame qd-axes theory and symmetrical component theorem. Experimental and simulation using MATLAB are the two methods used to prove the validity of the present model. Results obtained from the two methods were closed to each other. Also, the perfect balance point was achieved at unity power factor. This application proved that the output voltage and current have sinusoidal waves which implying that the generator was operating efficiently.

A New Model of Self-Excited Induction Generator (SEIG) to Feed a Single Phase Load with an Application in Lighting Animal Farm

This paper presents a new model of self-excited single-phase induction generator, used by a three-phase machine for lighting animal farm through biogas energy. The designs and applications of the previous generator models have been found to be very complex, for this reason simple and effective model of SEIG is proposed. The transient equations of the proposed model were represented by SIMULINK blocks, while the steady state equations by electrical equivalent circuit. The model is derived from Steinmetz connection circuit, stationary reference frame qd-axes theory and symmetrical component theorem. Experimental and simulation using MATLAB are the two methods used to prove the validity of the present model. Results obtained from the two methods were closed to each other. Also, the perfect balance point was achieved at unity power factor. This application proved that the output voltage and current have sinusoidal waves which implying that the generator was operating efficiently.