Renewable energy production plays a major role in satisfying electricity demand.Wind power conversion is one of the most popular renewable energy sources compared to other sources.Wind energy conversion has two major ...Renewable energy production plays a major role in satisfying electricity demand.Wind power conversion is one of the most popular renewable energy sources compared to other sources.Wind energy conversion has two major types of generators such as the Permanent Magnet Synchronous Generator(PMSG)and the Doubly Fed Induction Generator(DFIG).The maximum power tracking algo-rithm is a crucial controller,a wind energy conversion system for generating maximum power in different wind speed conditions.In this article,the DFIG wind energy conversion system was developed in Matrix Laboratory(MATLAB)and designed a machine learning(ML)algorithm for the rotor and grid side converter.The ML algorithm has been developed and trained in a MATLAB environment.There are two types of learning algorithms such as supervised and unsupervised learning.In this research supervised learning is used to power the neural networks and analysis is made for various hidden layers and activation functions.Simulation results are assessed to demonstrate the efficiency of the proposed system.展开更多
This paper discusses the robust control of a grid-connected doubly-fed induction generator (DFIG) controlled by vector control using a nonlinear feedback linearization strategy in order to ameliorate the performance...This paper discusses the robust control of a grid-connected doubly-fed induction generator (DFIG) controlled by vector control using a nonlinear feedback linearization strategy in order to ameliorate the performances of the control and to govern the developed stator active and reactive power in a linear and decoupled manner, in which an optimal operation of the DFIG in subsynchronous operation is given, as well as the control stator power flow with the possibility of keeping stator power factor at a unity. The use of the state-all-flux induction machine model gives place to a simpler control model. So, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability and the robustness of the parametric variations.展开更多
Based on Hamiltonian energy theory, this paper proposes a robust nonlinear controller for the wind turbine with doubly fed induction generator (DFIG), such that the closed-loop system can achieve its stability. Furt...Based on Hamiltonian energy theory, this paper proposes a robust nonlinear controller for the wind turbine with doubly fed induction generator (DFIG), such that the closed-loop system can achieve its stability. Furthermore, in the presence of disturbances, the closed-loop system is finite-gain L2 stable by the Hamiltonian controller. The Hamiltonian energy approach provides us a physical insight and gives a new way to the controller design. The simulation results illustrate that the proposed method is effective and has its advantage.展开更多
This paper deals with robust direct power control of a grid-connected bmshless doubly-fed induction generator(BDFIG). Using a nonlinear feedback lineariza- tion strategy, an attempt is made to improve the desired pe...This paper deals with robust direct power control of a grid-connected bmshless doubly-fed induction generator(BDFIG). Using a nonlinear feedback lineariza- tion strategy, an attempt is made to improve the desired performances by controlling the generated stator active and reactive power in a linear and decoupled manner. There- fore, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability. Thus, an optimal operation of the BDFIG in sub-synchronous operation is obtained as well as the stator power flows with the possibility of keeping stator power factor at a unity. The proposed method is tested with the Matlab/Simulink software. Simulation results illustrate the performances and the feasibility of the designed control.展开更多
The amount of electrical energy produced by wind mills is constantly increasing.Nowadays detailed analyzes considering the impact of wind energy integration on the transmission system are required.The goal of this stu...The amount of electrical energy produced by wind mills is constantly increasing.Nowadays detailed analyzes considering the impact of wind energy integration on the transmission system are required.The goal of this study is to investigate the dynamic response of a wind turbine with doubly fed induction generator connected to the power system during grid disturbance.The current and future wind power situation is modeled as two cases and a transient fault is simulated.In order to analyze the impact of wind energy integration in electrical power grid,a power system model has been developed,integrated with wind turbine using doubly fed induction generator and transient analysis are performed.Here,an attempt has been made to compare the impact,in terms of voltages,currents,total harmonic distortion,etc.,of adding wind turbines into electrical power grid.展开更多
Reliable load frequency control(LFC) is crucial to the operation and design of modern electric power systems. Considering the LFC problem of a four-area interconnected power system with wind turbines, this paper prese...Reliable load frequency control(LFC) is crucial to the operation and design of modern electric power systems. Considering the LFC problem of a four-area interconnected power system with wind turbines, this paper presents a distributed model predictive control(DMPC) based on coordination scheme.The proposed algorithm solves a series of local optimization problems to minimize a performance objective for each control area. The generation rate constraints(GRCs), load disturbance changes, and the wind speed constraints are considered. Furthermore, the DMPC algorithm may reduce the impact of the randomness and intermittence of wind turbine effectively. A performance comparison between the proposed controller with and without the participation of the wind turbines is carried out. Analysis and simulation results show possible improvements on closed–loop performance, and computational burden with the physical constraints.展开更多
This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators(DFIGs) and synchronous generators(SGs).The proposed coordination approach is based...This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators(DFIGs) and synchronous generators(SGs).The proposed coordination approach is based on the zero dynamics method aims at enhancing the transient stability of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to the IEEE39-bus power systems. Transient stability margin measured in terms of critical clearing time along with eigenvalue analysis and time domain simulations were considered in the performance assessment. The obtained results were also compared to those achieved using a conventional power system stabilizer/power oscillation(PSS/POD) technique and the interconnection and damping assignment passivity-based controller(IDA-PBC). The performance analysis confirmed the ability of the proposed approach to enhance damping and improve system’s transient stability margin under a wide range of operating conditions.展开更多
An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, an...An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. The controller gains were auto-tuned using a fuzzy logic approach.The effectiveness of the proposed design was assessed under deep voltage sag conditions and parameter variations. Its dynamic response was also compared to that of a standard SMC approach.The performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power,currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions. It was also shown to be robust to uncertainties and parameter variations, while effectively mitigating chattering in comparison with the standard SMC.展开更多
In this research paper,an improved strategy to enhance the performance of the DC-link voltage loop regulation in a Doubly Fed Induction Generator(DFIG)based wind energy system has been proposed.The proposed strategy u...In this research paper,an improved strategy to enhance the performance of the DC-link voltage loop regulation in a Doubly Fed Induction Generator(DFIG)based wind energy system has been proposed.The proposed strategy used the robust Fractional-Order(FO)Proportional-Integral(PI)control technique.The FOPI control contains a non-integer order which is preferred over the integer-order control owing to its benefits.It offers extra flexibility in design and demonstrates superior outcomes such as high robustness and effectiveness.The optimal gains of the FOPI controller have been determined using a recent Manta Ray Foraging Optimization(MRFO)algorithm.During the optimization process,the FOPI controller’s parameters are assigned to be the decision variables whereas the objective function is the error racking that to be minimized.To prove the superiority of the MRFO algorithm,an empirical comparison study with the homologous particle swarm optimization and genetic algorithm is achieved.The obtained results proved the superiority of the introduced strategy in tracking and control performances against various conditions such as voltage dips and wind speed variation.展开更多
In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of equipment.Particularly in situations of weak-grid faults,the dynamic coupling between equipment becomes more prono...In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of equipment.Particularly in situations of weak-grid faults,the dynamic coupling between equipment becomes more pronounced.This may cause the system to experience small-signal instability during the fault steady-state.In this paper,multi-paralleled doubly fed induction generator(DFIG)-based wind farms(WFs)are taken as an example to study the dynamic coupling within a multi-fed system during fault steady-state of symmetrical low voltage ride-through(LVRT)in a weak grid.The analysis reveals that the dynamic coupling between WFs will introduce a damping shift to each WF.This inevitably affects the system’s dynamic stability and brings the risk of small-signal instability during fault steady-state in LVRT scenarios.Increasing the distance to fault location and fault severity will exacerbate the dynamic coupling between WFs.Because of the dynamic coupling,adjusting the control state of one WF will affect the stability of the remaining WFs in the system.Hence,a cooperative control strategy for multi-paralleled DFIG WFs is proposed to improve dynamic stability during LVRT.The analysis and the effectiveness of the proposed control strategy are verified by modal analysis and simu-lation.展开更多
This paper presents a comprehensive study on the model predictive control(MPC)of doubly fed induction generators(DFIG)in wind energy conversion systems(WECS);in particular the MPC of the rotor side converter.The gener...This paper presents a comprehensive study on the model predictive control(MPC)of doubly fed induction generators(DFIG)in wind energy conversion systems(WECS);in particular the MPC of the rotor side converter.The general principle of prevalent MPC strategies is discussed to introduce the theoretical framework in the first place.Furthermore,mainstream and high-performance MPC methods of DFIGs have been identified as model predictive current control(MPCC),model predictive torque control(MPTC),and model predictive power control(MPPC).Starting from analyzing dynamic models,these MPC strategies are investigated in terms of operating principles and technical developments.The paper further investigates implementation of MPC strategies in unbalanced grids.Based on the quantitative and qualitative analysis of several case studies,performance of various MPC schemes is compared and their special features are identified.Guidelines for designing MPC strategies of DFIGs in WECS are provided.展开更多
With more and more wind power generation integrated into power grids to replace the conventional turbine-generator (T-G) units,how the subsynchronous resonance (SSR) of conventional T-G units is affected becomes an im...With more and more wind power generation integrated into power grids to replace the conventional turbine-generator (T-G) units,how the subsynchronous resonance (SSR) of conventional T-G units is affected becomes an important technical issue.In this paper,a group of T-G units are interconnected with a series compensated transmission line,and some units are substituted by a nearby DFIG-based wind farm (WF).Under such circumstances,the SSR of power systems would change accordingly.This paper establishes the mathematical model to analyze the torsional interaction (TI) and the induction generator effect of the T-G units.Both eigenvalue analysis and time domain simulations demonstrate the impact of DFIG-based WF on SSR of power systems and how the control parameters of wind farms can affect the SSR.展开更多
This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed...This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-(P1) controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.展开更多
Emerging sub-synchronous interactions(SSI)in wind-integrated power systems have added intense attention after numerous incidents in the US and China due to the involvement of series compensated transmission lines and ...Emerging sub-synchronous interactions(SSI)in wind-integrated power systems have added intense attention after numerous incidents in the US and China due to the involvement of series compensated transmission lines and power electronics devices.SSI phenomenon occurs when two power system elements exchange energy below the synchro-nous frequency.SSI phenomenon related to wind power plants is one of the most significant challenges to main-taining stability,while SSI phenomenon in practical wind farms,which has been observed recently,has not yet been described on the source of conventional SSI literature.This paper first explains the traditional development of SSI and its classification as given by the IEEE,and then it proposes a classification of SSI according to the current research status,reviews several mitigation techniques and challenges,and discusses analysis techniques for SSI.The paper also describes the effect of the active damping controllers,control scheme parameters,degree of series compensation,and various techniques used in wind power plants(WPPs).In particular,a supplementary damping controller with converter controllers in Doubly Fed Induction Generator based WPPs is briefly pronounced.This paper provides a real-istic viewpoint and a potential outlook for the readers to properly deal with SSI and its mitigation techniques,which can help power engineers for the planning,economical operation,and future expansion of sustainable development.展开更多
Among different sources of alternate energy,wind and solar are two prominent and promising alternatives to meet the future electricity needs for mankind.Generally,these sources are integrated at the distribution utili...Among different sources of alternate energy,wind and solar are two prominent and promising alternatives to meet the future electricity needs for mankind.Generally,these sources are integrated at the distribution utilities to supply the local distribution customers.If the power generated by these sources is bulk,then they are either integrated at the distribution/transmission level or may be operated in an island mode if feasible.The integration of these renewables in the power network will change the fault level and network topologies.These fault levels are intermittent in nature and existing protection schemes may fail to operate because of their pre-set condition.Therefore,the design and selection of a proper protection scheme is very much essential for reliable control and operation of renewable integrated power systems.Depending upon the level of infeed and location of the renewable integration,the protection requirements are different.For low renewable infeed at the distribution level,the existing relay settings are immune from any small change in the network fault current from new incoming renewables.However,bulk renewable infeed requires modification in the existing protection schemes to accommodate the fault current variation from the incoming renewables.For bulk penetration of the renewable,the requirement of modified/additional protection schemes is unavoidable.Adaptive relaying and non-adaptive relaying schemes are discussed in the literature for protection of power networks,which are experiencing dynamic fault currents and frequent changing network topologies.This article presents a detailed review of protection schemes for renewable integrated power networks which includes distribution,transmission and microgrid systems.The merits and demerits of these protection schemes are also identified in this article for the added interest of the readers.The visible scope of advance protection schemes which may be suitable for providing reliable protection for dynamic fault current networks is also explored.展开更多
As power systems experience increased wind penetration,an effective analysis and assessment of the influence of wind energy on power system transient stability is required.This paper presents a novel center of inertia...As power systems experience increased wind penetration,an effective analysis and assessment of the influence of wind energy on power system transient stability is required.This paper presents a novel center of inertia(COI)approach to understand how integrated doubly fed induction generators(DFIGs)affect the transient dynamics of a power system.Under the COI coordinate,the influence of integrated DFIGs is separated into the COI related and individual synchronous generator related parts.Key factors that affect the COI’s dynamic motion as well as the rotor dynamics of each individual synchronous generator with respect to the DFIG integration are investigated.To further validate the analysis,comparative simulations of three different scenarios with varying DFIG capacities,access locations,and the replacement of synchronous generators are conducted.The results show that the dynamics of the COI and the individual generators are affected by the integrated DFIGs via different mechanisms,and are sensitive to different variables in the DFIG’s integration condition.展开更多
With more and more big wind farms integrating to grid,the faults of doubly fed induction generators(DFIGs)grouping tripped off(GTO)have occurred and bring serious power impacts on the grid.Usually,it was considered th...With more and more big wind farms integrating to grid,the faults of doubly fed induction generators(DFIGs)grouping tripped off(GTO)have occurred and bring serious power impacts on the grid.Usually,it was considered that the fault of DFIGs GTO is only related to the low/high voltage disturbances in the grid and manipulated as an electromagnetic transients.But,we discover that the fault of DFIGs GTO are also related to operating condition of DFIGs and schemes of crowbar protection equipped with DFIGs,and it may be extended to an electromechanical transient in some situations.Based on the investigation of the factors related to DFIGs GTO,such as degree of voltage disturbances,operating conditions of DFIGs and schemes of crowbar protection,three types of DFIGs GTOs are classified and corresponding mechanisms are revealed.The calculation methods to confirm the mechanism are established.The effectiveness of the proposed methods are verified by simulating some cases of DFISs GTO.展开更多
Increased penetration of wind energy systems has serious concerns on power system stability. In spite of several advantages, doubly fed induction generator (DFIG) based wind energy systems are very sensitive to grid d...Increased penetration of wind energy systems has serious concerns on power system stability. In spite of several advantages, doubly fed induction generator (DFIG) based wind energy systems are very sensitive to grid disturbances. DFIG system with conventional vector control is not robust to disturbances as it is based on PI controllers. The objective of this paper is to design a new vector control that is robust to external disturbances. To achieve this, inner current loop of the conventional vector control is replaced with sliding mode control. In order to avoid chattering effect and achieve finite time convergence, the control gains are selected based on positive semi-definite barrier function. The proposed barrier function adaptive sliding mode (BFASMC) is evaluated by testing it on a benchmark multi-machine power system model under various operating conditions. The simulated results show that the proposed method is robust to various disturbances.展开更多
Due to several factors, wind energy becomes an essential type of electricity generation. The share of this type of energy in the network is becoming increasingly important. The objective of this work is to present the...Due to several factors, wind energy becomes an essential type of electricity generation. The share of this type of energy in the network is becoming increasingly important. The objective of this work is to present the modeling and control strategy of a grid connected wind power generation scheme using a doubly fed induction generator (DFIG) driven by the rotor. This paper is to present the complete modeling and simulation of a wind turbine driven DFIG in the second mode of operating (the wind turbine pitch control is deactivated). It will introduce the vector control, which makes it possible to control independently the active and reactive power exchanged between the stator of the generator and the grid, based on vector control concept (with stator flux or voltage orientation) with classical PI controllers. Various simula- tion tests are conducted to observe the system behavior and evaluate the performance of the control for some optimization criteria (energy efficiency and the robustness of the control). It is also interesting to play on the quality of electric power by controlling the reactive power exchanged with the grid, which will facilitate making a local correction of power factor.展开更多
Frequency regulation in a generation mix having large wind power penetration is a critical issue, as wind units isolate from the grid during disturbances with advanced power electronics controllers and reduce equivale...Frequency regulation in a generation mix having large wind power penetration is a critical issue, as wind units isolate from the grid during disturbances with advanced power electronics controllers and reduce equivalent system inertia. Thus, it is important that wind turbines also contribute to system frequency control. This paper examines the dynamic contribution of doubly fed induction generator (DFIG)-based wind turbine in system frequency regulation. The modified inertial support scheme is proposed which helps the DFIG to provide the short term transient active power support to the grid during transients and arrests the fall in frequency. The frequency deviation is considered by the controller to provide the inertial control. An additional reference power output is used which helps the DFIG to release kinetic energy stored in rotating masses of the turbine. The optimal speed control parameters have been used for the DFIG to increases its participation in frequency control. The simulations carried out in a two-area interconnected power system demonstrate the contribution of the DFIG in load frequency control.展开更多
文摘Renewable energy production plays a major role in satisfying electricity demand.Wind power conversion is one of the most popular renewable energy sources compared to other sources.Wind energy conversion has two major types of generators such as the Permanent Magnet Synchronous Generator(PMSG)and the Doubly Fed Induction Generator(DFIG).The maximum power tracking algo-rithm is a crucial controller,a wind energy conversion system for generating maximum power in different wind speed conditions.In this article,the DFIG wind energy conversion system was developed in Matrix Laboratory(MATLAB)and designed a machine learning(ML)algorithm for the rotor and grid side converter.The ML algorithm has been developed and trained in a MATLAB environment.There are two types of learning algorithms such as supervised and unsupervised learning.In this research supervised learning is used to power the neural networks and analysis is made for various hidden layers and activation functions.Simulation results are assessed to demonstrate the efficiency of the proposed system.
文摘This paper discusses the robust control of a grid-connected doubly-fed induction generator (DFIG) controlled by vector control using a nonlinear feedback linearization strategy in order to ameliorate the performances of the control and to govern the developed stator active and reactive power in a linear and decoupled manner, in which an optimal operation of the DFIG in subsynchronous operation is given, as well as the control stator power flow with the possibility of keeping stator power factor at a unity. The use of the state-all-flux induction machine model gives place to a simpler control model. So, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability and the robustness of the parametric variations.
基金supported by the National Natural Science Foundation of China(No.51007019)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Coastal Development Conservancy)
文摘Based on Hamiltonian energy theory, this paper proposes a robust nonlinear controller for the wind turbine with doubly fed induction generator (DFIG), such that the closed-loop system can achieve its stability. Furthermore, in the presence of disturbances, the closed-loop system is finite-gain L2 stable by the Hamiltonian controller. The Hamiltonian energy approach provides us a physical insight and gives a new way to the controller design. The simulation results illustrate that the proposed method is effective and has its advantage.
文摘This paper deals with robust direct power control of a grid-connected bmshless doubly-fed induction generator(BDFIG). Using a nonlinear feedback lineariza- tion strategy, an attempt is made to improve the desired performances by controlling the generated stator active and reactive power in a linear and decoupled manner. There- fore, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability. Thus, an optimal operation of the BDFIG in sub-synchronous operation is obtained as well as the stator power flows with the possibility of keeping stator power factor at a unity. The proposed method is tested with the Matlab/Simulink software. Simulation results illustrate the performances and the feasibility of the designed control.
文摘The amount of electrical energy produced by wind mills is constantly increasing.Nowadays detailed analyzes considering the impact of wind energy integration on the transmission system are required.The goal of this study is to investigate the dynamic response of a wind turbine with doubly fed induction generator connected to the power system during grid disturbance.The current and future wind power situation is modeled as two cases and a transient fault is simulated.In order to analyze the impact of wind energy integration in electrical power grid,a power system model has been developed,integrated with wind turbine using doubly fed induction generator and transient analysis are performed.Here,an attempt has been made to compare the impact,in terms of voltages,currents,total harmonic distortion,etc.,of adding wind turbines into electrical power grid.
基金supported by National Natural Science Foundation of China(61533013,61273144)Scientific Technology Research and Development Plan Project of Tangshan(13130298B)Scientific Technology Research and Development Plan Project of Hebei(z2014070)
文摘Reliable load frequency control(LFC) is crucial to the operation and design of modern electric power systems. Considering the LFC problem of a four-area interconnected power system with wind turbines, this paper presents a distributed model predictive control(DMPC) based on coordination scheme.The proposed algorithm solves a series of local optimization problems to minimize a performance objective for each control area. The generation rate constraints(GRCs), load disturbance changes, and the wind speed constraints are considered. Furthermore, the DMPC algorithm may reduce the impact of the randomness and intermittence of wind turbine effectively. A performance comparison between the proposed controller with and without the participation of the wind turbines is carried out. Analysis and simulation results show possible improvements on closed–loop performance, and computational burden with the physical constraints.
文摘This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators(DFIGs) and synchronous generators(SGs).The proposed coordination approach is based on the zero dynamics method aims at enhancing the transient stability of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to the IEEE39-bus power systems. Transient stability margin measured in terms of critical clearing time along with eigenvalue analysis and time domain simulations were considered in the performance assessment. The obtained results were also compared to those achieved using a conventional power system stabilizer/power oscillation(PSS/POD) technique and the interconnection and damping assignment passivity-based controller(IDA-PBC). The performance analysis confirmed the ability of the proposed approach to enhance damping and improve system’s transient stability margin under a wide range of operating conditions.
文摘An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. The controller gains were auto-tuned using a fuzzy logic approach.The effectiveness of the proposed design was assessed under deep voltage sag conditions and parameter variations. Its dynamic response was also compared to that of a standard SMC approach.The performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power,currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions. It was also shown to be robust to uncertainties and parameter variations, while effectively mitigating chattering in comparison with the standard SMC.
文摘In this research paper,an improved strategy to enhance the performance of the DC-link voltage loop regulation in a Doubly Fed Induction Generator(DFIG)based wind energy system has been proposed.The proposed strategy used the robust Fractional-Order(FO)Proportional-Integral(PI)control technique.The FOPI control contains a non-integer order which is preferred over the integer-order control owing to its benefits.It offers extra flexibility in design and demonstrates superior outcomes such as high robustness and effectiveness.The optimal gains of the FOPI controller have been determined using a recent Manta Ray Foraging Optimization(MRFO)algorithm.During the optimization process,the FOPI controller’s parameters are assigned to be the decision variables whereas the objective function is the error racking that to be minimized.To prove the superiority of the MRFO algorithm,an empirical comparison study with the homologous particle swarm optimization and genetic algorithm is achieved.The obtained results proved the superiority of the introduced strategy in tracking and control performances against various conditions such as voltage dips and wind speed variation.
基金the National Natural Science Foundation of China(NSFC)(No.51977019)in part by the Joint Research Fund in Smart Grid under Cooperative Agreement between the National Natural Science Foundation of China(NSFC)(No.U1966208)State Grid Corporation of China(SGCC).
文摘In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of equipment.Particularly in situations of weak-grid faults,the dynamic coupling between equipment becomes more pronounced.This may cause the system to experience small-signal instability during the fault steady-state.In this paper,multi-paralleled doubly fed induction generator(DFIG)-based wind farms(WFs)are taken as an example to study the dynamic coupling within a multi-fed system during fault steady-state of symmetrical low voltage ride-through(LVRT)in a weak grid.The analysis reveals that the dynamic coupling between WFs will introduce a damping shift to each WF.This inevitably affects the system’s dynamic stability and brings the risk of small-signal instability during fault steady-state in LVRT scenarios.Increasing the distance to fault location and fault severity will exacerbate the dynamic coupling between WFs.Because of the dynamic coupling,adjusting the control state of one WF will affect the stability of the remaining WFs in the system.Hence,a cooperative control strategy for multi-paralleled DFIG WFs is proposed to improve dynamic stability during LVRT.The analysis and the effectiveness of the proposed control strategy are verified by modal analysis and simu-lation.
基金supported in part by RMIT Startup fund under CC 101219in part by the National Natural Science Foundation of China under Grant 62101473in part by the Guangdong Natural Science Foundation under Grant 2023A1515010653.
文摘This paper presents a comprehensive study on the model predictive control(MPC)of doubly fed induction generators(DFIG)in wind energy conversion systems(WECS);in particular the MPC of the rotor side converter.The general principle of prevalent MPC strategies is discussed to introduce the theoretical framework in the first place.Furthermore,mainstream and high-performance MPC methods of DFIGs have been identified as model predictive current control(MPCC),model predictive torque control(MPTC),and model predictive power control(MPPC).Starting from analyzing dynamic models,these MPC strategies are investigated in terms of operating principles and technical developments.The paper further investigates implementation of MPC strategies in unbalanced grids.Based on the quantitative and qualitative analysis of several case studies,performance of various MPC schemes is compared and their special features are identified.Guidelines for designing MPC strategies of DFIGs in WECS are provided.
文摘With more and more wind power generation integrated into power grids to replace the conventional turbine-generator (T-G) units,how the subsynchronous resonance (SSR) of conventional T-G units is affected becomes an important technical issue.In this paper,a group of T-G units are interconnected with a series compensated transmission line,and some units are substituted by a nearby DFIG-based wind farm (WF).Under such circumstances,the SSR of power systems would change accordingly.This paper establishes the mathematical model to analyze the torsional interaction (TI) and the induction generator effect of the T-G units.Both eigenvalue analysis and time domain simulations demonstrate the impact of DFIG-based WF on SSR of power systems and how the control parameters of wind farms can affect the SSR.
文摘This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-(P1) controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.
基金supported financially by the Ministerio de Ciencia e Innovación(Spain)and the European Regional Development Fund,under Research Grant WindSound project(Ref.:PID2021-125278OB-I00).
文摘Emerging sub-synchronous interactions(SSI)in wind-integrated power systems have added intense attention after numerous incidents in the US and China due to the involvement of series compensated transmission lines and power electronics devices.SSI phenomenon occurs when two power system elements exchange energy below the synchro-nous frequency.SSI phenomenon related to wind power plants is one of the most significant challenges to main-taining stability,while SSI phenomenon in practical wind farms,which has been observed recently,has not yet been described on the source of conventional SSI literature.This paper first explains the traditional development of SSI and its classification as given by the IEEE,and then it proposes a classification of SSI according to the current research status,reviews several mitigation techniques and challenges,and discusses analysis techniques for SSI.The paper also describes the effect of the active damping controllers,control scheme parameters,degree of series compensation,and various techniques used in wind power plants(WPPs).In particular,a supplementary damping controller with converter controllers in Doubly Fed Induction Generator based WPPs is briefly pronounced.This paper provides a real-istic viewpoint and a potential outlook for the readers to properly deal with SSI and its mitigation techniques,which can help power engineers for the planning,economical operation,and future expansion of sustainable development.
文摘Among different sources of alternate energy,wind and solar are two prominent and promising alternatives to meet the future electricity needs for mankind.Generally,these sources are integrated at the distribution utilities to supply the local distribution customers.If the power generated by these sources is bulk,then they are either integrated at the distribution/transmission level or may be operated in an island mode if feasible.The integration of these renewables in the power network will change the fault level and network topologies.These fault levels are intermittent in nature and existing protection schemes may fail to operate because of their pre-set condition.Therefore,the design and selection of a proper protection scheme is very much essential for reliable control and operation of renewable integrated power systems.Depending upon the level of infeed and location of the renewable integration,the protection requirements are different.For low renewable infeed at the distribution level,the existing relay settings are immune from any small change in the network fault current from new incoming renewables.However,bulk renewable infeed requires modification in the existing protection schemes to accommodate the fault current variation from the incoming renewables.For bulk penetration of the renewable,the requirement of modified/additional protection schemes is unavoidable.Adaptive relaying and non-adaptive relaying schemes are discussed in the literature for protection of power networks,which are experiencing dynamic fault currents and frequent changing network topologies.This article presents a detailed review of protection schemes for renewable integrated power networks which includes distribution,transmission and microgrid systems.The merits and demerits of these protection schemes are also identified in this article for the added interest of the readers.The visible scope of advance protection schemes which may be suitable for providing reliable protection for dynamic fault current networks is also explored.
基金supported in part by the Major Program of the National Natural Science Foundation of China under Grant 51190103the National High Technology Research and Development Program of China under Grant 2012AA050208.
文摘As power systems experience increased wind penetration,an effective analysis and assessment of the influence of wind energy on power system transient stability is required.This paper presents a novel center of inertia(COI)approach to understand how integrated doubly fed induction generators(DFIGs)affect the transient dynamics of a power system.Under the COI coordinate,the influence of integrated DFIGs is separated into the COI related and individual synchronous generator related parts.Key factors that affect the COI’s dynamic motion as well as the rotor dynamics of each individual synchronous generator with respect to the DFIG integration are investigated.To further validate the analysis,comparative simulations of three different scenarios with varying DFIG capacities,access locations,and the replacement of synchronous generators are conducted.The results show that the dynamics of the COI and the individual generators are affected by the integrated DFIGs via different mechanisms,and are sensitive to different variables in the DFIG’s integration condition.
基金supported in part by the National Basic Research Program of China(2013CB228201)。
文摘With more and more big wind farms integrating to grid,the faults of doubly fed induction generators(DFIGs)grouping tripped off(GTO)have occurred and bring serious power impacts on the grid.Usually,it was considered that the fault of DFIGs GTO is only related to the low/high voltage disturbances in the grid and manipulated as an electromagnetic transients.But,we discover that the fault of DFIGs GTO are also related to operating condition of DFIGs and schemes of crowbar protection equipped with DFIGs,and it may be extended to an electromechanical transient in some situations.Based on the investigation of the factors related to DFIGs GTO,such as degree of voltage disturbances,operating conditions of DFIGs and schemes of crowbar protection,three types of DFIGs GTOs are classified and corresponding mechanisms are revealed.The calculation methods to confirm the mechanism are established.The effectiveness of the proposed methods are verified by simulating some cases of DFISs GTO.
文摘Increased penetration of wind energy systems has serious concerns on power system stability. In spite of several advantages, doubly fed induction generator (DFIG) based wind energy systems are very sensitive to grid disturbances. DFIG system with conventional vector control is not robust to disturbances as it is based on PI controllers. The objective of this paper is to design a new vector control that is robust to external disturbances. To achieve this, inner current loop of the conventional vector control is replaced with sliding mode control. In order to avoid chattering effect and achieve finite time convergence, the control gains are selected based on positive semi-definite barrier function. The proposed barrier function adaptive sliding mode (BFASMC) is evaluated by testing it on a benchmark multi-machine power system model under various operating conditions. The simulated results show that the proposed method is robust to various disturbances.
文摘Due to several factors, wind energy becomes an essential type of electricity generation. The share of this type of energy in the network is becoming increasingly important. The objective of this work is to present the modeling and control strategy of a grid connected wind power generation scheme using a doubly fed induction generator (DFIG) driven by the rotor. This paper is to present the complete modeling and simulation of a wind turbine driven DFIG in the second mode of operating (the wind turbine pitch control is deactivated). It will introduce the vector control, which makes it possible to control independently the active and reactive power exchanged between the stator of the generator and the grid, based on vector control concept (with stator flux or voltage orientation) with classical PI controllers. Various simula- tion tests are conducted to observe the system behavior and evaluate the performance of the control for some optimization criteria (energy efficiency and the robustness of the control). It is also interesting to play on the quality of electric power by controlling the reactive power exchanged with the grid, which will facilitate making a local correction of power factor.
文摘Frequency regulation in a generation mix having large wind power penetration is a critical issue, as wind units isolate from the grid during disturbances with advanced power electronics controllers and reduce equivalent system inertia. Thus, it is important that wind turbines also contribute to system frequency control. This paper examines the dynamic contribution of doubly fed induction generator (DFIG)-based wind turbine in system frequency regulation. The modified inertial support scheme is proposed which helps the DFIG to provide the short term transient active power support to the grid during transients and arrests the fall in frequency. The frequency deviation is considered by the controller to provide the inertial control. An additional reference power output is used which helps the DFIG to release kinetic energy stored in rotating masses of the turbine. The optimal speed control parameters have been used for the DFIG to increases its participation in frequency control. The simulations carried out in a two-area interconnected power system demonstrate the contribution of the DFIG in load frequency control.