As the core component of energy conversion for large wind turbines,the output performance of doubly-fed induction generators (DFIGs) plays a decisive role in the power quality of wind turbines.To realize the fast and ...As the core component of energy conversion for large wind turbines,the output performance of doubly-fed induction generators (DFIGs) plays a decisive role in the power quality of wind turbines.To realize the fast and accurate design optimization of DFIGs,this paper proposes a novel hybriddriven surrogate-assisted optimization method.It firstly establishes an accurate subdomain model of DFIGs to analytically predict performance indexes.Furthermore,taking the inexpensive analytical dataset produced by the subdomain model as the source domain and the expensive finite element analysis dataset as the target domain,a high-precision surrogate model is trained in a transfer learning way and used for the subsequent multi-objective optimization process.Based on this model,taking the total harmonic distortion of electromotive force,cogging torque,and iron loss as objectives,and the slot and inner/outer diameters as parameters for optimizing the topology,achieve a rapid and accurate electromagnetic design for DFIGs.Finally,experiments are carried out on a 3MW DFIG to validate the effectiveness of the proposed method.展开更多
This article proposes a dual-negative-objective coordinated control strategy for brushless doubly fed induction generator(BDFIG)based wind power generation system under unbalanced grid voltage.To alleviate the mechani...This article proposes a dual-negative-objective coordinated control strategy for brushless doubly fed induction generator(BDFIG)based wind power generation system under unbalanced grid voltage.To alleviate the mechanical stress and impaction on rotating shaft,the negative control objective(NCO)of machine side converter(MSC)is set to suppress the ripple of electromagnetic torque.While the NCO of grid side converter(GSC)is selected to suppress the oscillation of total output active power or the unbalanced degree of total output current for BDFIG generation system.In comparison with traditional single converter control scheme of the MSC or GSC,dual NCOs can be satisfied at the same time due to the enlarged freedom degree in the proposed improved coordinated control system for back-toback converters.The effectiveness of proposed control strategy is validated by simulation and experimental results on a dual-cagerotor BDFIG(DCR-BDFIG)prototype.展开更多
Owing to their stability,doubly-fed induction generator(DFIG)integrated systems have gained considerable interest and are the most widely implemented type of wind turbines and due to the increasing escalation of the w...Owing to their stability,doubly-fed induction generator(DFIG)integrated systems have gained considerable interest and are the most widely implemented type of wind turbines and due to the increasing escalation of the wind generation penetration rate in power systems.In this study,we investigate a DFIG integrated system comprising four modules:(1)a wind turbine that considers the maximum power point tracking and pitch-angle control,(2)induction generator,(3)rotor/grid-side converter with the corresponding control strategy,and(4)AC power grid.The detailed small-signal modeling of the entire system is performed by linearizing the dynamic characteristic equation at the steady-state value.Furthermore,a dichotomy method is proposed based on the maximum eigenvalue real part function to obtain the critical value of the parameters.Root-locus analysis is employed to analyze the impact of changes in the phase-locked loop,short-circuit ratio,and blade inertia on the system stability.Lastly,the accuracy of the small-signal model and the real and imaginary parts of the calculated dominant poles in the theoretical analysis are verified using PSCAD/EMTDC.展开更多
To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load ...To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.展开更多
When studying the phenomenon of the induced electromotive force, which originates from Faraday’s unipolar inductor, the contrast between Faraday’s view of the magnetic field dynamic lines and the theory of relativit...When studying the phenomenon of the induced electromotive force, which originates from Faraday’s unipolar inductor, the contrast between Faraday’s view of the magnetic field dynamic lines and the theory of relativity is revealed. In order to remove this contradiction, this phenomenon was studied in depth, theoretically and experimentally, using an experimental setup similar to Faraday’s. Calculations of the induced electromotive force, based on relativity on the one hand and on Faraday’s view on the other were made with the help of measurements of the magnetic field components. Accurate magnetic field measurements are confirmed by analytical calculations. Precise-induced electromotive force measurements confirmed Faraday’s view and contradicted the theory of relativity.展开更多
In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for ...In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for wind farms, is excited on the rotor circuit by a slip-frequency current injected to the rotor, from an exciter mounted on the same shaft of the machine. The resulting rotating magnetic field rotates at synchronous speed;as such the generated power has a constant frequency independent of the shaft speed. Effects of the excitation voltage magnitude and phase angle on the active and reactive power are studied, when the machine runs at constant speed. It has been shown that by controlling the excitation voltage magnitude and phase angle would control the mode of operation of the machine;motor mode or generator mode. Furthermore, the effects of the shaft speed on the active and reactive power at constant excitation voltage magnitude and constant phase angle are also investigated.展开更多
An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of D...An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.展开更多
During the isolated use of a wind system, the output voltage of the self-excited induction generator depends on the variation characteristic of its parameters: the excitation condensers, the drive speed and the load. ...During the isolated use of a wind system, the output voltage of the self-excited induction generator depends on the variation characteristic of its parameters: the excitation condensers, the drive speed and the load. Therefore, the regulation of the tension appears to be of great interest. We focused on the use of an analogical regulator of tension, with the aim of controlling the tension at the exit of the self-excited induction generator. So we modelled, implanted and simulated a wind system (Self-excited induction generator, converters (AC/DC, DC/DC) and load it) in the Orcad/Pspice environment. In the first time the behaviour of the asynchronous generator was analyzed when the load, the excitation capacitor and the drive speed vary in the absence of any form of regulation. This analysis was conducted with the aim of defining the limits of the machine exploitation. In the second time the functioning mode is controlled by an analogical control of tension. The results of simulation show the good performances of the system during the application of the proposed voltage regulator.展开更多
This paper deals a detailed performance investigation of asymmetrical six-phase grid connected induction generator(GCIG)in two proposed configurations in variable speed operation.During the system development,regulati...This paper deals a detailed performance investigation of asymmetrical six-phase grid connected induction generator(GCIG)in two proposed configurations in variable speed operation.During the system development,regulation of DC-link voltage has been proposed using particle swarm optimization(PSO)based PI controller,ensuring the power flow to utility grid through back to back converters.The closed loop operation of asymmetrical six-phase GCIG using indirect field oriented control in different configurations has been carried out in Matlab/Simulink environment.Analytical results have been verified using real time test results on virtual platform of Typhoon HIL supported with some experimental validation.展开更多
The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position obser...The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding(PW)in terms of magnitude and frequency,without any speed/position sensors.The proposed algorithm does not require any additional observers for obtaining the generator speed.The proposed technique can directly achieve the desired DVC based on the estimated rotor position,which may reduce the overall system cost.The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation.In addition,the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties.Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG,which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions.Furthermore,the analysis confirms the robustness of the proposed observer via the machine parameter changes.展开更多
To save on the island area's power supply cost and protect the clean environment, the Isolated MicroGrid is being duly considered. Consisting of the Wind Turbine Generator (WT), photovoltaic generator, battery sys...To save on the island area's power supply cost and protect the clean environment, the Isolated MicroGrid is being duly considered. Consisting of the Wind Turbine Generator (WT), photovoltaic generator, battery system, back-up diesel generator, etc., Isolated MicroGrid, which usually uses the inverter to maintain voltage and frequency of the system, is very weak in terms of voltage and frequency stability compared to the large-scale electrical power system. If wind turbine generator is applied to this weak power system, it could experience many problems in terms of maintaining its voltage and frequency. In this paper, the measurement result of voltage and frequency is presented for MicroGrid, which consists of the Wind Turbine Generator adopting the induction generator and the battery system. MicroGrid’s voltage waveform distortion and Wind Turbine Generator’s output oscillation problems are analyzed using PSCAD/EMTDC. Based on the analyzed result, the importance of type and capacity choice has been suggested in case the Wind Turbine Generator is applied to the Isolated MicroGrid.展开更多
Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipp...Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipped with doubly-fed induction generators differ fundamentally from synchronous generators.Therefore,more considerations are needed to analyze the performances of the distance protection relays.The protection of a wind farm with distance relay is inspected.By changing the conditions of the wind farm,the characteristics of the distance relay are studied.展开更多
A squirrel cage induction generator （SCIG） offers many advantages for wind energy conversion systems but suffers from poor voltage regulation under varying operating conditions. The value of excitation capacitance ...A squirrel cage induction generator （SCIG） offers many advantages for wind energy conversion systems but suffers from poor voltage regulation under varying operating conditions. The value of excitation capacitance （C exct ） is very crucial for the selfexcitation and voltage build-up as well as voltage regulation in SCIG. Precise calculation of the value of C exct is, therefore, of considerable practical importance. Most of the existing calculation methods make use of the steady-state model of the SCIG in conjunction with some numerical iterative method to determine the minimum value of C exct . But this results in over estimation, leading to poor transient dynamics. This paper presents a novel method, which can precisely calculate the value of C exct by taking into account the behavior of the magnetizing inductance during saturation. Interval analysis has been used to solve the equations. In the proposed method, a range of magnetizing inductance values in the saturation region are included in the calculation of C exct , required for the self-excitation of a 3-φ induction generator. Mathematical analysis to derive the basic equation and application of interval method is presented. The method also yields the magnetizing inductance value in the saturation region which corresponds to an optimum C exct（min） value. The proposed method is experimentally tested for a 1.1 kW induction generator and has shown improved results.展开更多
A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator（DFIG）equipped with a superconducting magnetic energy storage（SMES） device to enhance its transient volt...A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator（DFIG）equipped with a superconducting magnetic energy storage（SMES） device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter（GSC） is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter（RSC） has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive（priority） and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method.展开更多
A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) to est...A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) to estimate the rotational speed. In order to tune the MRAS observer and compensate for the parameter variation and uncertainties, a separate estimation of the speed is obtained from the rotor slot harmonics using an algorithm for spectral analysis. This algorithm can track fast dynamic changes in the rotational speed, with high accuracy. Two back to back pulse width modulated (PWM) inverters are used to interface the induction generator with the grid. The front-end converter is also vector controlled. The dc link voltage is regulated using a PI fuzzy controller. The proposed sensorless control strategy has been experimentally verified on a 2.5-kW experimentally set up with an induction generator driven by a wind turbine emulator. The emulation of the wind turbine is performed using a novel strategy that allows the emulation of high-order wind turbine models, preserving all of the dynamic characteristics. The experimental results show the high level of performance obtained with the proposed sensorless vector-control method.展开更多
High efficiency Double-Fed Induction Generator applies new power electronic technology, and utilizes vector control to fix the magnetic direction of the stator to the vertical axis. Adjusting the input current of roto...High efficiency Double-Fed Induction Generator applies new power electronic technology, and utilizes vector control to fix the magnetic direction of the stator to the vertical axis. Adjusting the input current of rotor via an inverter can separately control the cross axis and vertical axis current of real power and reactive power of a generator. Traditionally, rotating speed affects frequency and the output is unstable. This study concentrates on high efficiency Double-Fed Induction Generators and Traditional Generators from mathematic model to derive and control the characteristics simulation and comparison than get an output of high efficiency Double-Fed Industrial Generators. This study utilizes the simulation software MATLAB/Simulink to simulate the response characteristics of vector control of a Double-Fed Industrial Generator. The operating and control functions are better than those of a traditional generator.展开更多
The accuracy prediction for the performance of an induction generator depends much on the parameters of the equivalent circuit. This paper presented a new way for calculating these parameters of induction generator wi...The accuracy prediction for the performance of an induction generator depends much on the parameters of the equivalent circuit. This paper presented a new way for calculating these parameters of induction generator with double windings. The method is based on 2D time-dependent magnetic field coupled with electric circuit. An application example of a 12-phase self-excited induction generator (SEIG) was provided to demonstrate the effectiveness of the presented approach. Some of the calculated results show good coincidence with the experiment values.展开更多
This paper investigates the effects of various parameters on the terminal voltage and frequency of self excited induction generator using genetic algorithm. The parameters considered are speed, capacitance, leakage re...This paper investigates the effects of various parameters on the terminal voltage and frequency of self excited induction generator using genetic algorithm. The parameters considered are speed, capacitance, leakage reactance, stator and rotor resistances. Simulated results obtained using genetic algorithm facilitates in exploring the performance of self-excited induction generator. The paper henceforth establishes the application of user friendly genetic algorithm for studying the behaviour of self-excited induction.展开更多
For fixed speed wind turbines, the connection of its squirrel cage induction generator (SCIG) to the grid leads to inrush current which can reach an average of 2 p.u. up to 2.5 p.u. in higher wind speed even by using ...For fixed speed wind turbines, the connection of its squirrel cage induction generator (SCIG) to the grid leads to inrush current which can reach an average of 2 p.u. up to 2.5 p.u. in higher wind speed even by using a soft starter. We propose in this paper a new soft starting of squirrel cage induction generator based wind turbine connected to the grid. Our strategy overcomes such transient instability problems and pinpoints rapidly synchronous speed regardless the wind speed acting on pitch angle. The proposed strategy ensures at least 50% reduction of inrush current and 18% gain of WTG starting time. A state model of the system is given including the wind turbine model and the SCIG model in the synchronous reference frame. Simulation results are analysed and compared to the classic coupling procedure.展开更多
文摘As the core component of energy conversion for large wind turbines,the output performance of doubly-fed induction generators (DFIGs) plays a decisive role in the power quality of wind turbines.To realize the fast and accurate design optimization of DFIGs,this paper proposes a novel hybriddriven surrogate-assisted optimization method.It firstly establishes an accurate subdomain model of DFIGs to analytically predict performance indexes.Furthermore,taking the inexpensive analytical dataset produced by the subdomain model as the source domain and the expensive finite element analysis dataset as the target domain,a high-precision surrogate model is trained in a transfer learning way and used for the subsequent multi-objective optimization process.Based on this model,taking the total harmonic distortion of electromotive force,cogging torque,and iron loss as objectives,and the slot and inner/outer diameters as parameters for optimizing the topology,achieve a rapid and accurate electromagnetic design for DFIGs.Finally,experiments are carried out on a 3MW DFIG to validate the effectiveness of the proposed method.
基金supported in part by National Natural Science Foundation of China under Grant 61973073supported by Jiangsu Province Higher Education Basic Science (Natural Science) Research Project under Grant 23KJB470022
文摘This article proposes a dual-negative-objective coordinated control strategy for brushless doubly fed induction generator(BDFIG)based wind power generation system under unbalanced grid voltage.To alleviate the mechanical stress and impaction on rotating shaft,the negative control objective(NCO)of machine side converter(MSC)is set to suppress the ripple of electromagnetic torque.While the NCO of grid side converter(GSC)is selected to suppress the oscillation of total output active power or the unbalanced degree of total output current for BDFIG generation system.In comparison with traditional single converter control scheme of the MSC or GSC,dual NCOs can be satisfied at the same time due to the enlarged freedom degree in the proposed improved coordinated control system for back-toback converters.The effectiveness of proposed control strategy is validated by simulation and experimental results on a dual-cagerotor BDFIG(DCR-BDFIG)prototype.
基金supported by the Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology,Ministry of Education(Northeast Electric Power University),Jilin 132012,China(MPSS2023-06).
文摘Owing to their stability,doubly-fed induction generator(DFIG)integrated systems have gained considerable interest and are the most widely implemented type of wind turbines and due to the increasing escalation of the wind generation penetration rate in power systems.In this study,we investigate a DFIG integrated system comprising four modules:(1)a wind turbine that considers the maximum power point tracking and pitch-angle control,(2)induction generator,(3)rotor/grid-side converter with the corresponding control strategy,and(4)AC power grid.The detailed small-signal modeling of the entire system is performed by linearizing the dynamic characteristic equation at the steady-state value.Furthermore,a dichotomy method is proposed based on the maximum eigenvalue real part function to obtain the critical value of the parameters.Root-locus analysis is employed to analyze the impact of changes in the phase-locked loop,short-circuit ratio,and blade inertia on the system stability.Lastly,the accuracy of the small-signal model and the real and imaginary parts of the calculated dominant poles in the theoretical analysis are verified using PSCAD/EMTDC.
文摘To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.
文摘When studying the phenomenon of the induced electromotive force, which originates from Faraday’s unipolar inductor, the contrast between Faraday’s view of the magnetic field dynamic lines and the theory of relativity is revealed. In order to remove this contradiction, this phenomenon was studied in depth, theoretically and experimentally, using an experimental setup similar to Faraday’s. Calculations of the induced electromotive force, based on relativity on the one hand and on Faraday’s view on the other were made with the help of measurements of the magnetic field components. Accurate magnetic field measurements are confirmed by analytical calculations. Precise-induced electromotive force measurements confirmed Faraday’s view and contradicted the theory of relativity.
文摘In this paper, we present the steady state analysis of a double-fed induction generator (DFIG) adopted for wind power generation. The three-phase induction machine connected to the network, to work as a generator for wind farms, is excited on the rotor circuit by a slip-frequency current injected to the rotor, from an exciter mounted on the same shaft of the machine. The resulting rotating magnetic field rotates at synchronous speed;as such the generated power has a constant frequency independent of the shaft speed. Effects of the excitation voltage magnitude and phase angle on the active and reactive power are studied, when the machine runs at constant speed. It has been shown that by controlling the excitation voltage magnitude and phase angle would control the mode of operation of the machine;motor mode or generator mode. Furthermore, the effects of the shaft speed on the active and reactive power at constant excitation voltage magnitude and constant phase angle are also investigated.
基金Project(2011DFA62240) supported by the International Scientific and Technological Cooperation Projects,ChinaProject(019945-SES6) supported by the European Union(EU)6th Framework Program UP-WIND Project,Denmark
文摘An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.
文摘During the isolated use of a wind system, the output voltage of the self-excited induction generator depends on the variation characteristic of its parameters: the excitation condensers, the drive speed and the load. Therefore, the regulation of the tension appears to be of great interest. We focused on the use of an analogical regulator of tension, with the aim of controlling the tension at the exit of the self-excited induction generator. So we modelled, implanted and simulated a wind system (Self-excited induction generator, converters (AC/DC, DC/DC) and load it) in the Orcad/Pspice environment. In the first time the behaviour of the asynchronous generator was analyzed when the load, the excitation capacitor and the drive speed vary in the absence of any form of regulation. This analysis was conducted with the aim of defining the limits of the machine exploitation. In the second time the functioning mode is controlled by an analogical control of tension. The results of simulation show the good performances of the system during the application of the proposed voltage regulator.
文摘This paper deals a detailed performance investigation of asymmetrical six-phase grid connected induction generator(GCIG)in two proposed configurations in variable speed operation.During the system development,regulation of DC-link voltage has been proposed using particle swarm optimization(PSO)based PI controller,ensuring the power flow to utility grid through back to back converters.The closed loop operation of asymmetrical six-phase GCIG using indirect field oriented control in different configurations has been carried out in Matlab/Simulink environment.Analytical results have been verified using real time test results on virtual platform of Typhoon HIL supported with some experimental validation.
基金This work was supported in part by the National Natural Science Foundation of China(NSFC)under Grants 51707079 and 51877093in part by the National Key Research and Development Program of China(Project ID:YS2018YFGH000200)in part by the Fundamental Research Funds for the Central Universities(Project ID:2019kfyXMBZ031).
文摘The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding(PW)in terms of magnitude and frequency,without any speed/position sensors.The proposed algorithm does not require any additional observers for obtaining the generator speed.The proposed technique can directly achieve the desired DVC based on the estimated rotor position,which may reduce the overall system cost.The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation.In addition,the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties.Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG,which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions.Furthermore,the analysis confirms the robustness of the proposed observer via the machine parameter changes.
文摘To save on the island area's power supply cost and protect the clean environment, the Isolated MicroGrid is being duly considered. Consisting of the Wind Turbine Generator (WT), photovoltaic generator, battery system, back-up diesel generator, etc., Isolated MicroGrid, which usually uses the inverter to maintain voltage and frequency of the system, is very weak in terms of voltage and frequency stability compared to the large-scale electrical power system. If wind turbine generator is applied to this weak power system, it could experience many problems in terms of maintaining its voltage and frequency. In this paper, the measurement result of voltage and frequency is presented for MicroGrid, which consists of the Wind Turbine Generator adopting the induction generator and the battery system. MicroGrid’s voltage waveform distortion and Wind Turbine Generator’s output oscillation problems are analyzed using PSCAD/EMTDC. Based on the analyzed result, the importance of type and capacity choice has been suggested in case the Wind Turbine Generator is applied to the Isolated MicroGrid.
文摘Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipped with doubly-fed induction generators differ fundamentally from synchronous generators.Therefore,more considerations are needed to analyze the performances of the distance protection relays.The protection of a wind farm with distance relay is inspected.By changing the conditions of the wind farm,the characteristics of the distance relay are studied.
文摘A squirrel cage induction generator （SCIG） offers many advantages for wind energy conversion systems but suffers from poor voltage regulation under varying operating conditions. The value of excitation capacitance （C exct ） is very crucial for the selfexcitation and voltage build-up as well as voltage regulation in SCIG. Precise calculation of the value of C exct is, therefore, of considerable practical importance. Most of the existing calculation methods make use of the steady-state model of the SCIG in conjunction with some numerical iterative method to determine the minimum value of C exct . But this results in over estimation, leading to poor transient dynamics. This paper presents a novel method, which can precisely calculate the value of C exct by taking into account the behavior of the magnetizing inductance during saturation. Interval analysis has been used to solve the equations. In the proposed method, a range of magnetizing inductance values in the saturation region are included in the calculation of C exct , required for the self-excitation of a 3-φ induction generator. Mathematical analysis to derive the basic equation and application of interval method is presented. The method also yields the magnetizing inductance value in the saturation region which corresponds to an optimum C exct（min） value. The proposed method is experimentally tested for a 1.1 kW induction generator and has shown improved results.
基金supported by the National Natural Science Foundation of China(Grant No.51307124)the Major Program of the National Natural Science Foundation of China(Grant No.51190105)
文摘A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator（DFIG）equipped with a superconducting magnetic energy storage（SMES） device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter（GSC） is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter（RSC） has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive（priority） and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method.
文摘A sensorless vector-control strategy for an induction generator in a grid-connected wind energy conversion system is presented. The sensorless control system is based on a model reference adaptive system (MRAS) to estimate the rotational speed. In order to tune the MRAS observer and compensate for the parameter variation and uncertainties, a separate estimation of the speed is obtained from the rotor slot harmonics using an algorithm for spectral analysis. This algorithm can track fast dynamic changes in the rotational speed, with high accuracy. Two back to back pulse width modulated (PWM) inverters are used to interface the induction generator with the grid. The front-end converter is also vector controlled. The dc link voltage is regulated using a PI fuzzy controller. The proposed sensorless control strategy has been experimentally verified on a 2.5-kW experimentally set up with an induction generator driven by a wind turbine emulator. The emulation of the wind turbine is performed using a novel strategy that allows the emulation of high-order wind turbine models, preserving all of the dynamic characteristics. The experimental results show the high level of performance obtained with the proposed sensorless vector-control method.
文摘High efficiency Double-Fed Induction Generator applies new power electronic technology, and utilizes vector control to fix the magnetic direction of the stator to the vertical axis. Adjusting the input current of rotor via an inverter can separately control the cross axis and vertical axis current of real power and reactive power of a generator. Traditionally, rotating speed affects frequency and the output is unstable. This study concentrates on high efficiency Double-Fed Induction Generators and Traditional Generators from mathematic model to derive and control the characteristics simulation and comparison than get an output of high efficiency Double-Fed Industrial Generators. This study utilizes the simulation software MATLAB/Simulink to simulate the response characteristics of vector control of a Double-Fed Industrial Generator. The operating and control functions are better than those of a traditional generator.
文摘The accuracy prediction for the performance of an induction generator depends much on the parameters of the equivalent circuit. This paper presented a new way for calculating these parameters of induction generator with double windings. The method is based on 2D time-dependent magnetic field coupled with electric circuit. An application example of a 12-phase self-excited induction generator (SEIG) was provided to demonstrate the effectiveness of the presented approach. Some of the calculated results show good coincidence with the experiment values.
文摘This paper investigates the effects of various parameters on the terminal voltage and frequency of self excited induction generator using genetic algorithm. The parameters considered are speed, capacitance, leakage reactance, stator and rotor resistances. Simulated results obtained using genetic algorithm facilitates in exploring the performance of self-excited induction generator. The paper henceforth establishes the application of user friendly genetic algorithm for studying the behaviour of self-excited induction.
文摘For fixed speed wind turbines, the connection of its squirrel cage induction generator (SCIG) to the grid leads to inrush current which can reach an average of 2 p.u. up to 2.5 p.u. in higher wind speed even by using a soft starter. We propose in this paper a new soft starting of squirrel cage induction generator based wind turbine connected to the grid. Our strategy overcomes such transient instability problems and pinpoints rapidly synchronous speed regardless the wind speed acting on pitch angle. The proposed strategy ensures at least 50% reduction of inrush current and 18% gain of WTG starting time. A state model of the system is given including the wind turbine model and the SCIG model in the synchronous reference frame. Simulation results are analysed and compared to the classic coupling procedure.
