This paper proposes a design and implementation of the bi-directional DC-DC converter for Wind Energy Conversion System. The proposed project consists of boost DC/DC converter, bi-directional DC/DC converter (BDC), pe...This paper proposes a design and implementation of the bi-directional DC-DC converter for Wind Energy Conversion System. The proposed project consists of boost DC/DC converter, bi-directional DC/DC converter (BDC), permanent magnet DC generator and batteries. A DC-DC boost converter is interface with proposed wind system to step up the initial generator voltage and maintain constant output voltage. The fluctuation nature of wind makes them unsuitable for standalone operation. To overcome the drawbacks an energy storage device is used in the proposed system to compensate the fluctuations and to maintain a smooth and continuous power flow in all operating modes to load. Bi-directional DC-DC converter (BDC) is capable of transforming energy between two DC buses. It can operate as a boost converter which supplies energy to the load when the wind generator output power is greater than the required load power. It also operates in buck mode which charges from DC bus when output power is less than the required load power. The proposed converter reduces the component losses and increases the performance of the overall system. The complete system is implemented in MATLAB/SIMULINK and verified with hardware.展开更多
The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive co...The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive control(MPC)for the renewable energy power plants of wind and solar power connected to a weak sending-end power grid(WSPG).Wind turbine generators(WTGs),photovoltaic arrays(PVAs),and a static synchronous compensator are coordinated to maintain voltage within a feasible range during operation.This results in the full use of the reactive power capability of WTGs and PVAs.In addition,the impact of the active power outputs of WTGs and PVAs on voltage control are considered because of the high R/X ratio of a collector system.An analytical method is used for calculating sensitivity coefficients to improve computation efficiency.A renewable energy power plant with 80 WTGs and 20 PVAs connected to a WSPG is used to verify the proposed voltage control strategy.Case studies show that the coordinated voltage control strategy can achieve good voltage control performance,which improves the voltage quality of the entire power plant.展开更多
This paper presents a real approach for thermal unit commitment(UC)problem solution in Niamey(Niger).The proposed methodology consists of four conventional thermal generating units and imported power(IMP)from a neighb...This paper presents a real approach for thermal unit commitment(UC)problem solution in Niamey(Niger).The proposed methodology consists of four conventional thermal generating units and imported power(IMP)from a neighboring country as the existing grid in addition to the inclusion of Photovoltaic(PV)power,Wind Turbine Generators(WTGs),and Battery Energy Storage System(BESS).Minimization of the total daily operating cost is considered as the objective function in two cases.In the first case,UC with thermal units considering the IMP,PV and BESS is described.In the second case,WTGs are introduced beside high penetration of PV and BESS and the IMP is removed in order to get rid of its economical and mostly political problems.MILP(Mixed-Integer Linear Programming)is used here as the optimization technique to obtain an optimal unit commitment problem solution with consideration of PV,WTGs and BESS.The effectiveness and robustness of the proposed scheme is verified by numerical simulations using MATLAB environment.展开更多
Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method ...Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method and classical probability estimation method were introduced to estimate the value interval of shape parameter considering the engineering practice. Secondly,taking this value interval into the optimal confidence limit method,the reliability and reliability lifetime of WTG could be obtained under different confidence levels. Finally,the results of optimal confidence limit method and Bayesian method were compared. And the comparison results show that the rationality of this estimated range.Meantime, the rule of confidence level selection in the optimal confidence limit method is provided, and the reliability and reliability lifetime prediction of WTG can be acquired.展开更多
Shape optimization of turbine blade to maximize the output power usually changes the power factor due to compensate Repower in a wind turbine. This article presents a multidisciplinary optimization technique to maximi...Shape optimization of turbine blade to maximize the output power usually changes the power factor due to compensate Repower in a wind turbine. This article presents a multidisciplinary optimization technique to maximize the output power in Doubly Fed Induction Generator (DFIG) wind turbine. The most common parameters when operating the turbine, namely, active power, reactive power and power factor, are considered as the problem constraints and the pitch angle grid side variable frequency converter of the turbine blades are optimized to maximize the output power. Numerical simulation has been illustrated to present the performance of the proposed design approach.展开更多
微软在企业版上提供的Windows To Go(简称WTG)是一项非常神奇实用的功能,能把Windows系统完整安装到U盘或移动硬盘上,并且能随处在不同的电脑硬件上直接运行,让系统可以真正随身携带。而且,WTG既不是WinPE,也不是精简版,而是完整的Wind...微软在企业版上提供的Windows To Go(简称WTG)是一项非常神奇实用的功能,能把Windows系统完整安装到U盘或移动硬盘上,并且能随处在不同的电脑硬件上直接运行,让系统可以真正随身携带。而且,WTG既不是WinPE,也不是精简版,而是完整的Windows操作系统,与正常安装在硬盘上几乎没有什么区别。有了Windows To Go,用户可以在任何地方任何计算机上有效启用工作桌面。因此,员工可以轻松实现在家、办公室以及外地任何一台电脑上办公。展开更多
Oscillation accidents emerge in power systems inte grated with increasing penetration of renewable energy sources.The impedance of electromagnetic dynamics is investigated in recent years,where the mechanical dynamics...Oscillation accidents emerge in power systems inte grated with increasing penetration of renewable energy sources.The impedance of electromagnetic dynamics is investigated in recent years,where the mechanical dynamics are neglected.So far,the low-frequency oscillations are not well addressed with the impedance analysis method.A novel analytical impedance is formulated and implemented for wind energy conversion sys tem consisting of wind turbine generators(WTGs)and wind farm,which fills the gap in the mechanical dynamics of the im pedance.Instead of assuming constant values,the electrome chanical dynamics of the rotor speed and the pitch angle are in volved in the WTG impedance.Besides,the impedance frame work is generally and modularly designed and is adaptive to different operating regions.With the developed analytical im pedance,the stability assessment can cover the low-frequency oscillations,providing an in-depth insight into the mechanical parameters influencing the small-signal stability performance.As an application,the impedance characteristic and stability performance of systems with active power reserve for grid sup porting are analyzed and optimized.Furthermore,the shafting torsional vibrations of WTGs in wind farms are analyzed with modal decomposition and the low-frequency impedance model.The improved accuracy of the developed analytical impedance is illustrated by comparison with commonly used impedance,which ignores the coupling between the electrical and mechani cal dynamics.It is proven that the mechanical dynamics have a significant influence on the impedance,particularly in the lowfrequency range.Experimental validation is carried out to vali date the low-frequency impedance model and the stability per formance.展开更多
The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT me...The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT method,the decreased torque gain(DTG)method is developed to improve turbine acceleration through a reduction of the torque gain coefficient.However,the DTG method does not fully align with the acceleration performance required by wind turbines,which subsequently limits improvements in wind energy capture efficiency.To address these concerns,a novel MPPT control strategy is proposed,which introduces redefined torque curve and torque command conceptualized based on a higher-order function relative to rotor speed.Additionally,an adaptive algorithm for the periodic update of the torque command is suggested to better accommodate the variability of turbulent wind speeds,thus aiming to improve the wind energy capture efficiency.The effectiveness of the proposed MPPT control strategy is substantiated through the wind turbine simulator(WTS)-based experiments.展开更多
The current paper talks about the variable speed wind turbine generation system （WTGS）. So, the WTGS is equipped with a doubly-fed induction generator （DFIG） and two bidirectional converters in the rotor open circ...The current paper talks about the variable speed wind turbine generation system （WTGS）. So, the WTGS is equipped with a doubly-fed induction generator （DFIG） and two bidirectional converters in the rotor open circuit. A vector control （VC） of the rotor side converter （RSC） offers independent regulation of the stator active and reactive power and the optimal rotational speed tracking in the power maximization operating mode. A VC scheme for the grid-side converter （GSC） allows an independent regulation of the active and reactive power to exchange with the grid and sinusoidal supply currents and keeps the DC-link voltage constant. A fuzzy inference system （FIS） is adopted as an alternative of the conven- tional proportional and integral （PI） controller to reject some uncertainties or disturbance. The performances have been verified using the Matlab/Simulink soft-ware.展开更多
Increased penetration of wind energy in the electric grid has necessitated studying the impact of wind integration on the transient stability of the power system,with urgency to develop appropriate electromechanical m...Increased penetration of wind energy in the electric grid has necessitated studying the impact of wind integration on the transient stability of the power system,with urgency to develop appropriate electromechanical models of the wind turbine generator(WTG).The representation and control of the WTG’s electric signals are typically in a rotational dq coordinate system whose reference angle is provided by a phase-lockedloop(PLL).The PLL is commonly considered as a measurement device and is often absent in existing WTG electromechanical models.This paper studies the impact of PLL on the DFIG-based WTG electromechanical response by theoretical and simulation analyses.The dynamics of the PLL are found to greatly influence the WTG electromechanical response,suggesting that PLL should be regarded as an indispensable control loop rather than a measurement device,and its impact should be modeled when establishing the WTG electromechanical model.展开更多
文摘This paper proposes a design and implementation of the bi-directional DC-DC converter for Wind Energy Conversion System. The proposed project consists of boost DC/DC converter, bi-directional DC/DC converter (BDC), permanent magnet DC generator and batteries. A DC-DC boost converter is interface with proposed wind system to step up the initial generator voltage and maintain constant output voltage. The fluctuation nature of wind makes them unsuitable for standalone operation. To overcome the drawbacks an energy storage device is used in the proposed system to compensate the fluctuations and to maintain a smooth and continuous power flow in all operating modes to load. Bi-directional DC-DC converter (BDC) is capable of transforming energy between two DC buses. It can operate as a boost converter which supplies energy to the load when the wind generator output power is greater than the required load power. It also operates in buck mode which charges from DC bus when output power is less than the required load power. The proposed converter reduces the component losses and increases the performance of the overall system. The complete system is implemented in MATLAB/SIMULINK and verified with hardware.
基金supported by National Natural Science Foundation Joint Key Project of China(2016YFB0900900).
文摘The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive control(MPC)for the renewable energy power plants of wind and solar power connected to a weak sending-end power grid(WSPG).Wind turbine generators(WTGs),photovoltaic arrays(PVAs),and a static synchronous compensator are coordinated to maintain voltage within a feasible range during operation.This results in the full use of the reactive power capability of WTGs and PVAs.In addition,the impact of the active power outputs of WTGs and PVAs on voltage control are considered because of the high R/X ratio of a collector system.An analytical method is used for calculating sensitivity coefficients to improve computation efficiency.A renewable energy power plant with 80 WTGs and 20 PVAs connected to a WSPG is used to verify the proposed voltage control strategy.Case studies show that the coordinated voltage control strategy can achieve good voltage control performance,which improves the voltage quality of the entire power plant.
文摘This paper presents a real approach for thermal unit commitment(UC)problem solution in Niamey(Niger).The proposed methodology consists of four conventional thermal generating units and imported power(IMP)from a neighboring country as the existing grid in addition to the inclusion of Photovoltaic(PV)power,Wind Turbine Generators(WTGs),and Battery Energy Storage System(BESS).Minimization of the total daily operating cost is considered as the objective function in two cases.In the first case,UC with thermal units considering the IMP,PV and BESS is described.In the second case,WTGs are introduced beside high penetration of PV and BESS and the IMP is removed in order to get rid of its economical and mostly political problems.MILP(Mixed-Integer Linear Programming)is used here as the optimization technique to obtain an optimal unit commitment problem solution with consideration of PV,WTGs and BESS.The effectiveness and robustness of the proposed scheme is verified by numerical simulations using MATLAB environment.
基金National Natural Science Foundation of China(No.51265025)
文摘Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes( WTGs),the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method and classical probability estimation method were introduced to estimate the value interval of shape parameter considering the engineering practice. Secondly,taking this value interval into the optimal confidence limit method,the reliability and reliability lifetime of WTG could be obtained under different confidence levels. Finally,the results of optimal confidence limit method and Bayesian method were compared. And the comparison results show that the rationality of this estimated range.Meantime, the rule of confidence level selection in the optimal confidence limit method is provided, and the reliability and reliability lifetime prediction of WTG can be acquired.
文摘Shape optimization of turbine blade to maximize the output power usually changes the power factor due to compensate Repower in a wind turbine. This article presents a multidisciplinary optimization technique to maximize the output power in Doubly Fed Induction Generator (DFIG) wind turbine. The most common parameters when operating the turbine, namely, active power, reactive power and power factor, are considered as the problem constraints and the pitch angle grid side variable frequency converter of the turbine blades are optimized to maximize the output power. Numerical simulation has been illustrated to present the performance of the proposed design approach.
文摘微软在企业版上提供的Windows To Go(简称WTG)是一项非常神奇实用的功能,能把Windows系统完整安装到U盘或移动硬盘上,并且能随处在不同的电脑硬件上直接运行,让系统可以真正随身携带。而且,WTG既不是WinPE,也不是精简版,而是完整的Windows操作系统,与正常安装在硬盘上几乎没有什么区别。有了Windows To Go,用户可以在任何地方任何计算机上有效启用工作桌面。因此,员工可以轻松实现在家、办公室以及外地任何一台电脑上办公。
基金supported by State Grid Corporation of China Science and Technology Project Funding(No.5100-202399360A-2-2-ZB)。
文摘Oscillation accidents emerge in power systems inte grated with increasing penetration of renewable energy sources.The impedance of electromagnetic dynamics is investigated in recent years,where the mechanical dynamics are neglected.So far,the low-frequency oscillations are not well addressed with the impedance analysis method.A novel analytical impedance is formulated and implemented for wind energy conversion sys tem consisting of wind turbine generators(WTGs)and wind farm,which fills the gap in the mechanical dynamics of the im pedance.Instead of assuming constant values,the electrome chanical dynamics of the rotor speed and the pitch angle are in volved in the WTG impedance.Besides,the impedance frame work is generally and modularly designed and is adaptive to different operating regions.With the developed analytical im pedance,the stability assessment can cover the low-frequency oscillations,providing an in-depth insight into the mechanical parameters influencing the small-signal stability performance.As an application,the impedance characteristic and stability performance of systems with active power reserve for grid sup porting are analyzed and optimized.Furthermore,the shafting torsional vibrations of WTGs in wind farms are analyzed with modal decomposition and the low-frequency impedance model.The improved accuracy of the developed analytical impedance is illustrated by comparison with commonly used impedance,which ignores the coupling between the electrical and mechani cal dynamics.It is proven that the mechanical dynamics have a significant influence on the impedance,particularly in the lowfrequency range.Experimental validation is carried out to vali date the low-frequency impedance model and the stability per formance.
基金supported in part by the National Key R&D Program of China(No.2021YFB1506904)the National Natural Science Foundation of China(No.51977111).
文摘The optimal torque(OT)method,which is preferred for its simplicity,is widely employed in maximum power point tracking(MPPT)control strategies for wind energy capture in wind turbine generators(WTGs).Based on the OT method,the decreased torque gain(DTG)method is developed to improve turbine acceleration through a reduction of the torque gain coefficient.However,the DTG method does not fully align with the acceleration performance required by wind turbines,which subsequently limits improvements in wind energy capture efficiency.To address these concerns,a novel MPPT control strategy is proposed,which introduces redefined torque curve and torque command conceptualized based on a higher-order function relative to rotor speed.Additionally,an adaptive algorithm for the periodic update of the torque command is suggested to better accommodate the variability of turbulent wind speeds,thus aiming to improve the wind energy capture efficiency.The effectiveness of the proposed MPPT control strategy is substantiated through the wind turbine simulator(WTS)-based experiments.
文摘The current paper talks about the variable speed wind turbine generation system （WTGS）. So, the WTGS is equipped with a doubly-fed induction generator （DFIG） and two bidirectional converters in the rotor open circuit. A vector control （VC） of the rotor side converter （RSC） offers independent regulation of the stator active and reactive power and the optimal rotational speed tracking in the power maximization operating mode. A VC scheme for the grid-side converter （GSC） allows an independent regulation of the active and reactive power to exchange with the grid and sinusoidal supply currents and keeps the DC-link voltage constant. A fuzzy inference system （FIS） is adopted as an alternative of the conven- tional proportional and integral （PI） controller to reject some uncertainties or disturbance. The performances have been verified using the Matlab/Simulink soft-ware.
基金supported by Science and Technology Program of State Grid Corporation of China under Grant XT71-14-051.
文摘Increased penetration of wind energy in the electric grid has necessitated studying the impact of wind integration on the transient stability of the power system,with urgency to develop appropriate electromechanical models of the wind turbine generator(WTG).The representation and control of the WTG’s electric signals are typically in a rotational dq coordinate system whose reference angle is provided by a phase-lockedloop(PLL).The PLL is commonly considered as a measurement device and is often absent in existing WTG electromechanical models.This paper studies the impact of PLL on the DFIG-based WTG electromechanical response by theoretical and simulation analyses.The dynamics of the PLL are found to greatly influence the WTG electromechanical response,suggesting that PLL should be regarded as an indispensable control loop rather than a measurement device,and its impact should be modeled when establishing the WTG electromechanical model.
