Protection system for DC-link circuit of back-to-back converter of PMSG （Permanent Magnet Synchronous Generator） based wind turbine is essential part for the system to ride through a network fault in grid system. Vo...Protection system for DC-link circuit of back-to-back converter of PMSG （Permanent Magnet Synchronous Generator） based wind turbine is essential part for the system to ride through a network fault in grid system. Voltage on the DC-link circuit can be increased significantly due to power unbalance between stator side converter and grid side converter. Increase of DC-link circuit voltage can lead to a damage of IGBT of the converter and control system failure. In this paper performance enhancement of DC-link protection of PMSG based Wind turbine by using new control system of buck converter is proposed. The buck converter is used to control supplied voltage of a breaking resistor to dissipate energy from the wind generator during network disturbance. In order to investigate effectiveness of the proposed DC-link protection system, fault analysis is performed in the simulation study by using PSCAD/EMTDC software program. In addition, comparative analysis between the proposed protection system and the conventional protection system using DC chopper is also performed.展开更多
In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kin...In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kinetic energy from the rotating masses during sudden load disturbances.An auxiliary storage controller is applied to achieve effec-tive frequency response.The coot optimization algorithm(COA)is applied to allocate the optimum parameters of the fractional-order proportional integral derivative(FOPID),droop and auxiliary storage controllers.The fitness function is represented by the summation of integral square deviations in tie line power,and Areas 1 and 2 frequency errors.The robustness of the COA is proven by comparing the results with benchmarked optimizers including:atomic orbital search,honey badger algorithm,water cycle algorithm and particle swarm optimization.Performance assessment is confirmed in the following four scenarios:(i)optimization while including PID controllers;(ii)optimization while including FOPID controllers;(iii)validation of COA results under various load disturbances;and(iv)validation of the proposed controllers under varying weather conditions.展开更多
This paper presents a nonlinear control approach to variable speed wind turbine(VSWT)with a wind speed estimator.The dynamics of the wind turbine(WT)is derived from single mass model.In this work,a modified Newton Rap...This paper presents a nonlinear control approach to variable speed wind turbine(VSWT)with a wind speed estimator.The dynamics of the wind turbine(WT)is derived from single mass model.In this work,a modified Newton Raphson estimator has been considered for exact estimation of effective wind speed.The main objective of this work is to extract maximum energy from the wind at below rated wind speed while reducing drive train oscillation.In order to achieve the above objectives,VSWT should operate close to the optimal power coefficient.The generator torque is considered as the control input to achieve maximum energy capture.From the literature,it is clear that existing linear and nonlinear control techniques suffer from poor tracking of WT dynamics,increased power loss and complex control law.In addition,they are not robust with respect to input disturbances.In order to overcome the above drawbacks,adaptive fuzzy integral sliding mode control(AFISMC)is proposed for VSWT control.The proposed controller is tested with different types of disturbances and compared with other nonlinear controllers such as sliding mode control and integral sliding mode control.The result shows the better performance of AFISMC and its robustness to input disturbances.In this paper,the discontinuity in integral sliding mode controller is smoothed by using hyperbolic tangent function,and the sliding gain is adapted using a fuzzy technique which makes the controller more robust.展开更多
This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and a full-scale power converter in a stand-alone system.An energy storage system(ESS)including battery and fuel ce...This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and a full-scale power converter in a stand-alone system.An energy storage system(ESS)including battery and fuel cell-electrolyzer combination is connected to the DC link of the full-scale power converter through the power electronics interface.Wind is the primary power source of the system,the battery and FC-electrolyzer combination is used as a backup and a long-term storage system to provide or absorb power in the stand-alone system,respectively.In this paper,a control strategy is proposed for the operation of this variable speed wind turbine in a stand-alone system,where the generator-side converter and the ESS operate together to meet the demand of the loads.This control strategy is competent for supporting the variation of the loads or wind speed and limiting the DC-link voltage of the full-scale power converter in a small range.A simulation model of a variable speed wind turbine in a stand-alone system is developed using the simulation tool of PSCAD/EMTDC.The dynamic performance of the stand-alone wind turbine system and the proposed control strategy is assessed and emphasized with the simulation results.展开更多
This paper studies on the change mechanisms of the voltage stability caused by the grid connection of front-end speed-controlled wind turbines(FSCWT)integrating into power system.First of all,the differential algebrai...This paper studies on the change mechanisms of the voltage stability caused by the grid connection of front-end speed-controlled wind turbines(FSCWT)integrating into power system.First of all,the differential algebraic equations describing the dynamic characteristics of wind turbines are illustrated.Then,under the guidance of IEEE3 node system model,the influence of the angular velocity of wind turbines,the reactive power and the active power at load bus on the voltage stability of grid-connection has been analyzed by using bifurcation theory.Finally,the method of linear-state feedback control has been applied to the original system in accordance with the bifurcation phenomenon of grid-connected voltage caused by the increase in the active power at load bus.Research shows that voltage at the grid-connected point would be changed with the fluctuation of turbines angular velocity.And increasing its reactive power can enhance voltage at the grid-connected point;problem of bifurcation at the grid-connected point can be delayed when increasing the gain k s of feedback controller within a certain range.展开更多
In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguis...In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguishing features are revealed.Firstly,the inertial response characteristics of VSG controlled WFs(VSG-WFs)are impaired by the dynamic coupling.Secondly,when the influence of WTRSR is dominant,the inertial response characteristics of VSG-WFs are even worse than the condition under which WFs do not participate in the response of grid frequency.Thirdly,this phenomenon cannot be eliminated by only enlarging the inertia parameter of VSG-WFs,because the influence of WTRSR would also increase with the enhancement of inertial response.A decoupling scheme to eliminate the negative influence is then proposed in this paper.By starting the WTRSR process after inertial response period,the dynamic coupling is eliminated and the inertial response characteristics of WFs are improved.Finally,the effectiveness of the analysis and the proposed scheme are verified by simulation results.展开更多
文摘Protection system for DC-link circuit of back-to-back converter of PMSG （Permanent Magnet Synchronous Generator） based wind turbine is essential part for the system to ride through a network fault in grid system. Voltage on the DC-link circuit can be increased significantly due to power unbalance between stator side converter and grid side converter. Increase of DC-link circuit voltage can lead to a damage of IGBT of the converter and control system failure. In this paper performance enhancement of DC-link protection of PMSG based Wind turbine by using new control system of buck converter is proposed. The buck converter is used to control supplied voltage of a breaking resistor to dissipate energy from the wind generator during network disturbance. In order to investigate effectiveness of the proposed DC-link protection system, fault analysis is performed in the simulation study by using PSCAD/EMTDC software program. In addition, comparative analysis between the proposed protection system and the conventional protection system using DC chopper is also performed.
文摘In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kinetic energy from the rotating masses during sudden load disturbances.An auxiliary storage controller is applied to achieve effec-tive frequency response.The coot optimization algorithm(COA)is applied to allocate the optimum parameters of the fractional-order proportional integral derivative(FOPID),droop and auxiliary storage controllers.The fitness function is represented by the summation of integral square deviations in tie line power,and Areas 1 and 2 frequency errors.The robustness of the COA is proven by comparing the results with benchmarked optimizers including:atomic orbital search,honey badger algorithm,water cycle algorithm and particle swarm optimization.Performance assessment is confirmed in the following four scenarios:(i)optimization while including PID controllers;(ii)optimization while including FOPID controllers;(iii)validation of COA results under various load disturbances;and(iv)validation of the proposed controllers under varying weather conditions.
文摘This paper presents a nonlinear control approach to variable speed wind turbine(VSWT)with a wind speed estimator.The dynamics of the wind turbine(WT)is derived from single mass model.In this work,a modified Newton Raphson estimator has been considered for exact estimation of effective wind speed.The main objective of this work is to extract maximum energy from the wind at below rated wind speed while reducing drive train oscillation.In order to achieve the above objectives,VSWT should operate close to the optimal power coefficient.The generator torque is considered as the control input to achieve maximum energy capture.From the literature,it is clear that existing linear and nonlinear control techniques suffer from poor tracking of WT dynamics,increased power loss and complex control law.In addition,they are not robust with respect to input disturbances.In order to overcome the above drawbacks,adaptive fuzzy integral sliding mode control(AFISMC)is proposed for VSWT control.The proposed controller is tested with different types of disturbances and compared with other nonlinear controllers such as sliding mode control and integral sliding mode control.The result shows the better performance of AFISMC and its robustness to input disturbances.In this paper,the discontinuity in integral sliding mode controller is smoothed by using hyperbolic tangent function,and the sliding gain is adapted using a fuzzy technique which makes the controller more robust.
文摘This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and a full-scale power converter in a stand-alone system.An energy storage system(ESS)including battery and fuel cell-electrolyzer combination is connected to the DC link of the full-scale power converter through the power electronics interface.Wind is the primary power source of the system,the battery and FC-electrolyzer combination is used as a backup and a long-term storage system to provide or absorb power in the stand-alone system,respectively.In this paper,a control strategy is proposed for the operation of this variable speed wind turbine in a stand-alone system,where the generator-side converter and the ESS operate together to meet the demand of the loads.This control strategy is competent for supporting the variation of the loads or wind speed and limiting the DC-link voltage of the full-scale power converter in a small range.A simulation model of a variable speed wind turbine in a stand-alone system is developed using the simulation tool of PSCAD/EMTDC.The dynamic performance of the stand-alone wind turbine system and the proposed control strategy is assessed and emphasized with the simulation results.
基金National Natural Science Foundation of China(No.61663019)
文摘This paper studies on the change mechanisms of the voltage stability caused by the grid connection of front-end speed-controlled wind turbines(FSCWT)integrating into power system.First of all,the differential algebraic equations describing the dynamic characteristics of wind turbines are illustrated.Then,under the guidance of IEEE3 node system model,the influence of the angular velocity of wind turbines,the reactive power and the active power at load bus on the voltage stability of grid-connection has been analyzed by using bifurcation theory.Finally,the method of linear-state feedback control has been applied to the original system in accordance with the bifurcation phenomenon of grid-connected voltage caused by the increase in the active power at load bus.Research shows that voltage at the grid-connected point would be changed with the fluctuation of turbines angular velocity.And increasing its reactive power can enhance voltage at the grid-connected point;problem of bifurcation at the grid-connected point can be delayed when increasing the gain k s of feedback controller within a certain range.
基金supported by Science and Technology Project of State Grid Corporation of China(No.5102-201956300A-0-0-00)。
文摘In this paper,the dynamic coupling between the wind turbine rotor speed recovery(WTRSR)and inertial response of the conventional virtual synchronous generator(VSG)controlled wind farms(WFs)is analyzed.Three distinguishing features are revealed.Firstly,the inertial response characteristics of VSG controlled WFs(VSG-WFs)are impaired by the dynamic coupling.Secondly,when the influence of WTRSR is dominant,the inertial response characteristics of VSG-WFs are even worse than the condition under which WFs do not participate in the response of grid frequency.Thirdly,this phenomenon cannot be eliminated by only enlarging the inertia parameter of VSG-WFs,because the influence of WTRSR would also increase with the enhancement of inertial response.A decoupling scheme to eliminate the negative influence is then proposed in this paper.By starting the WTRSR process after inertial response period,the dynamic coupling is eliminated and the inertial response characteristics of WFs are improved.Finally,the effectiveness of the analysis and the proposed scheme are verified by simulation results.
