Frequency droop control is widely used in permanent magnet synchronous generators(PMSGs)based wind turbines(WTs)for grid frequency support.However,under frequency deviations,significant DC-link voltage fluctuations ma...Frequency droop control is widely used in permanent magnet synchronous generators(PMSGs)based wind turbines(WTs)for grid frequency support.However,under frequency deviations,significant DC-link voltage fluctuations may occur during the transient process due to sudden changes in real power of such WTs.To address this issue,a current feedforward control strategy is proposed for PMSG-based WTs to reduce DC-link voltage fluctuations when the WTs are providing frequency support under grid frequency deviations.Meanwhile,the desired frequency support capability of the PMSG-based WTs can be ensured.Simulation results verify the rationality of the analysis and the effectiveness of the proposed control method.展开更多
In a grid-connected wind farm based on permanent magnet synchronous generators(PMSGs),the wind speed and the number of operating PMSGs are the two most important influencing factors along with the stochastic nature of...In a grid-connected wind farm based on permanent magnet synchronous generators(PMSGs),the wind speed and the number of operating PMSGs are the two most important influencing factors along with the stochastic nature of sub-synchronous oscillation(SSO)from the point view of the farm.This paper proposes a method of unstable SSO risk evaluation for grid-connected PMSG-based wind farms based on the sequential Monte Carlo simulation(SMCS).The determination of critical wind speed(CWS)of SSO and the sequential simulation strategy of wind speed states and PMSG states in a wind farm at the same wind speed(S-WF),as well as in a wind farm at different wind speeds(D-WF),are studied.Five indices evaluating the expectation,duration,frequency and energy loss of SsO risk are proposed.Moreover,a strategy to reduce SsO risk by adjusting the cut-in wind speed is discussed.The effectiveness of the discussed issues in this paper are proved by the case studies of a 750-PMSG wind farm based on the actual wind speed data collected.展开更多
This paper provides a systematic analysis of the large scale PMsG(permanent magnet synchronous generator)-based WECS(wind energy conversion system)torsional vibration problem under MPPT(maximum power point tracking)co...This paper provides a systematic analysis of the large scale PMsG(permanent magnet synchronous generator)-based WECS(wind energy conversion system)torsional vibration problem under MPPT(maximum power point tracking)control and constant power control.This is from the perspective of SSo(sub-synchronous oscillation),SSH(sub-syn-chronous harmonics)and forced torsional vibration.The cause of SsO is the negative total system damping,weak-ened by the constant power control.The system is susceptible to inducing SSH in the grid current and voltage in the under-damped condition.To effectively suppress the torsional vibration of PMSG-based WECS,a stiffness compensa-tion control strategy based on adaptive damping is proposed.The results show that SSo,SSH and the forced torsional vibration can be suppressed at the source using the proposed suppression strategy.展开更多
This study explores tower vibrations in large-scale permanent magnet synchronous generator(PMSG)-based wind energy conversion system(WECS).First,the aerodynamic characteristics of wind turbines,including wind shear(WS...This study explores tower vibrations in large-scale permanent magnet synchronous generator(PMSG)-based wind energy conversion system(WECS).First,the aerodynamic characteristics of wind turbines,including wind shear(WS),tower shadow effect(TSE),and blade airfoil structure,are examined.Then,a mech-anism model of tower vibration is established,and the impacts of WS and TSE on tower vibration are analyzed.Suppression schemes,including crossing resonance zone method and tower damping control,are evaluated,and a robust variable-pitch strategy based on sliding mode control is proposed to mitigate tower vibration.Compar-ative analysis suggests that the proposed strategy out-performs the crossing resonance zone method and the tower damping control in achieving more effective tower vibration suppression and reducing the influence of the 3p frequency component.The effectiveness of the model and algorithm is verified through simulation experiments.展开更多
The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques ha...The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques have been developed for executing GC requirements in the event of grid faults.Among the methods,an intriguing strategy is to enhance the performance of back-to-back(BTB)converter controllers.In this research,the PID-type terminal sliding mode control(PID-TSMC)scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter,to reinforce the nonlinear relationship among the state-variable and the control input.The application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external disturbances.The grid-side converter tracks the maximum power point,contributing to the rapid decrease of generator active power output during faults.This frees up converter capacity for injecting GC-compliant reactive current into the grid.Besides,the machine-side converter regulates DC-link voltage,in which its variations during external disturbances decrease substantially with the PID-TSMC.The discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.展开更多
基金This work is jointly supported by the National Key R&D Programme of China(No.2017YFB0902000)the National Natural Science Foundation of China(No.U1766206)the Science and Technology Programme of the State Grid Corporation(No.52110418000P).
文摘Frequency droop control is widely used in permanent magnet synchronous generators(PMSGs)based wind turbines(WTs)for grid frequency support.However,under frequency deviations,significant DC-link voltage fluctuations may occur during the transient process due to sudden changes in real power of such WTs.To address this issue,a current feedforward control strategy is proposed for PMSG-based WTs to reduce DC-link voltage fluctuations when the WTs are providing frequency support under grid frequency deviations.Meanwhile,the desired frequency support capability of the PMSG-based WTs can be ensured.Simulation results verify the rationality of the analysis and the effectiveness of the proposed control method.
基金supported by the National Natural Science Foundation of China under Grant(51777066).
文摘In a grid-connected wind farm based on permanent magnet synchronous generators(PMSGs),the wind speed and the number of operating PMSGs are the two most important influencing factors along with the stochastic nature of sub-synchronous oscillation(SSO)from the point view of the farm.This paper proposes a method of unstable SSO risk evaluation for grid-connected PMSG-based wind farms based on the sequential Monte Carlo simulation(SMCS).The determination of critical wind speed(CWS)of SSO and the sequential simulation strategy of wind speed states and PMSG states in a wind farm at the same wind speed(S-WF),as well as in a wind farm at different wind speeds(D-WF),are studied.Five indices evaluating the expectation,duration,frequency and energy loss of SsO risk are proposed.Moreover,a strategy to reduce SsO risk by adjusting the cut-in wind speed is discussed.The effectiveness of the discussed issues in this paper are proved by the case studies of a 750-PMSG wind farm based on the actual wind speed data collected.
基金supported by Shaanxi Provincial Department of Education Project(17JK0691)。
文摘This paper provides a systematic analysis of the large scale PMsG(permanent magnet synchronous generator)-based WECS(wind energy conversion system)torsional vibration problem under MPPT(maximum power point tracking)control and constant power control.This is from the perspective of SSo(sub-synchronous oscillation),SSH(sub-syn-chronous harmonics)and forced torsional vibration.The cause of SsO is the negative total system damping,weak-ened by the constant power control.The system is susceptible to inducing SSH in the grid current and voltage in the under-damped condition.To effectively suppress the torsional vibration of PMSG-based WECS,a stiffness compensa-tion control strategy based on adaptive damping is proposed.The results show that SSo,SSH and the forced torsional vibration can be suppressed at the source using the proposed suppression strategy.
基金supported by the Natural Science Foundation of Shaanxi Province(No.2023-JC-QN-0515 and No.2023-JC-QN-0534)Guangdong Basic and Applied Basic Research Foun-dation(No.2024A1515011580)+1 种基金partially sup-ported by Shaanxi Provincial Department of Education Project(No.23JK0660)the Xi’an Municipal Bu-reau of Science and Technology(No.24GXF0085).
文摘This study explores tower vibrations in large-scale permanent magnet synchronous generator(PMSG)-based wind energy conversion system(WECS).First,the aerodynamic characteristics of wind turbines,including wind shear(WS),tower shadow effect(TSE),and blade airfoil structure,are examined.Then,a mech-anism model of tower vibration is established,and the impacts of WS and TSE on tower vibration are analyzed.Suppression schemes,including crossing resonance zone method and tower damping control,are evaluated,and a robust variable-pitch strategy based on sliding mode control is proposed to mitigate tower vibration.Compar-ative analysis suggests that the proposed strategy out-performs the crossing resonance zone method and the tower damping control in achieving more effective tower vibration suppression and reducing the influence of the 3p frequency component.The effectiveness of the model and algorithm is verified through simulation experiments.
文摘The provision of wind farm(WF)grid codes(GCs)has become imperative for sustained grid operations,especially for WFs with permanent-magnet synchronous generator(PMSG)wind energy conversion system.Numerous techniques have been developed for executing GC requirements in the event of grid faults.Among the methods,an intriguing strategy is to enhance the performance of back-to-back(BTB)converter controllers.In this research,the PID-type terminal sliding mode control(PID-TSMC)scheme is implemented for both machine-side and grid-side converter-modified controllers of BTB-converter,to reinforce the nonlinear relationship among the state-variable and the control input.The application of this control scheme decreases the response time and improves the robustness of the BTB-converter controllers regarding uncertainty of parameters and external disturbances.The grid-side converter tracks the maximum power point,contributing to the rapid decrease of generator active power output during faults.This frees up converter capacity for injecting GC-compliant reactive current into the grid.Besides,the machine-side converter regulates DC-link voltage,in which its variations during external disturbances decrease substantially with the PID-TSMC.The discussions on the simulations contemplate on the robustness and efficiency of the implemented PID-TSMC strategy in comparison to other BTB-converter control strategies.
