An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of D...An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.展开更多
Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipp...Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipped with doubly-fed induction generators differ fundamentally from synchronous generators.Therefore,more considerations are needed to analyze the performances of the distance protection relays.The protection of a wind farm with distance relay is inspected.By changing the conditions of the wind farm,the characteristics of the distance relay are studied.展开更多
With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are ...With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are very sensitive to grid disturbances.The voltage swell can be caused by switching on capacitor banks or switching off large loads,which may result in the reversal of the power flow in the grid convertor;the current may flow from the grid into the DC link,which may step up DC voltage,and result in large faults of rotor currents and instantaneous power oscillation.The grid reactive compensation devices can not have the automatic swithing function after the low voltage fault,which will result in local reactive power surplus,so some wind power generators will retreat from the grid under high voltage protection.展开更多
Large-scale doubly-fed induction generator(DFIG)wind turbines are connected to the grid and required to remain grid-connection during faults,the short-circuit current contributed by the generation has become a signifi...Large-scale doubly-fed induction generator(DFIG)wind turbines are connected to the grid and required to remain grid-connection during faults,the short-circuit current contributed by the generation has become a significant issue.However,the traditional calculation methods aiming at synchronous generators cannot be directly applied to the DFIG wind turbines.A new method is needed to calculate the short-circuit current required by the planning,protection and control of the power grid.The short-circuit transition of DFIG under symmetrical and asymmetric short-circuit conditions are mathematically deduced,and the short-circuit characteristics of DFIG are analyzed.A new method is proposed to calculate the steady-state short-circuit current of DFIG based on the derived expressions.The time-domain simulations are conducted to verify the accuracy of the proposed method.展开更多
随着风电渗透率不断升高,世界各国的并网导则要求双馈风电机组具备高电压穿越(high voltage ride-through,HVRT)能力。采用传统HVRT控制策略,HVRT期间双馈风电机组可能发生超速脱网。针对该问题,根据我国国标要求,首先,基于双馈异步发电...随着风电渗透率不断升高,世界各国的并网导则要求双馈风电机组具备高电压穿越(high voltage ride-through,HVRT)能力。采用传统HVRT控制策略,HVRT期间双馈风电机组可能发生超速脱网。针对该问题,根据我国国标要求,首先,基于双馈异步发电机(doubly-fed induction generator,DFIG)的转子运动方程,推导了不发生超速脱网的DFIG定子有功功率参考值最小值的近似计算公式。其次,根据DFIG功率约束条件,阐明了HVRT期间传统控制策略下机组发生超速脱网的机理,导出了传统控制策略下机组发生超速脱网的机端电压骤升区间。在此基础上,以兼顾抑制超速脱网和无功支撑为目标,提出了有功优先结合网侧变流器(grid-side converter,GSC)的HVRT控制策略。基于PSCAD/EMTDC仿真软件,分别搭建了单台双馈风电机组和双馈风电场的HVRT仿真模型,对所提控制策略和传统控制策略进行了仿真对比分析,仿真结果验证了所提控制策略的有效性。展开更多
为解决双馈风力发电机(doubly-fed induction generator,DFIG)采用综合惯量控制时固有调速器的抑制作用,及转速恢复时系统频率二次跌落(secondary frequency dip,SFD)的问题,提出了基于模糊推算和动态控制的风储联合调频控制策略。首先...为解决双馈风力发电机(doubly-fed induction generator,DFIG)采用综合惯量控制时固有调速器的抑制作用,及转速恢复时系统频率二次跌落(secondary frequency dip,SFD)的问题,提出了基于模糊推算和动态控制的风储联合调频控制策略。首先分析了电力系统频率响应特性,揭示了输出功率抑制量(output power suppression amount,OPSA)与SFD的产生机理。其次在DFIG频率支撑阶段,基于系统频率指标对综合惯量控制系数进行模糊逻辑设计,减小OPSA影响并提升DFIG调频能力。然后在转速恢复阶段,根据DFIG转速变化动态计算储能有功功率参考值,调整储能输出以减小SFD,并设计变系数比例-积分(proportional-integral,PI)控制以平滑恢复储能荷电状态(state of charge,SOC)。最后,在MATLAB/Simulink中搭建风-储-火四机两区域电力系统仿真模型,验证了所提策略的有效性,保证了高风电渗透率电力系统的频率稳定性。展开更多
基金Project(2011DFA62240) supported by the International Scientific and Technological Cooperation Projects,ChinaProject(019945-SES6) supported by the European Union(EU)6th Framework Program UP-WIND Project,Denmark
文摘An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.
文摘Nowadays wind energy is the fastest growing renewable energy resource in the world.The problems of integrating wind farms are caused by changes of wind speed during a day.Moreover,the behaviors of wind turbines equipped with doubly-fed induction generators differ fundamentally from synchronous generators.Therefore,more considerations are needed to analyze the performances of the distance protection relays.The protection of a wind farm with distance relay is inspected.By changing the conditions of the wind farm,the characteristics of the distance relay are studied.
文摘With the rapid increase of wind farms,the grid code needs to be improved to meet the requirement of wind farms and enhance grid stability.Doubly-fed induction generators are largely used in wind turbines,but they are very sensitive to grid disturbances.The voltage swell can be caused by switching on capacitor banks or switching off large loads,which may result in the reversal of the power flow in the grid convertor;the current may flow from the grid into the DC link,which may step up DC voltage,and result in large faults of rotor currents and instantaneous power oscillation.The grid reactive compensation devices can not have the automatic swithing function after the low voltage fault,which will result in local reactive power surplus,so some wind power generators will retreat from the grid under high voltage protection.
基金supported by State Key Laboratory of Power Transmission Equipment and System Security(No.2007DA10512711102,No.2007DA10512709202)Program of Introducing Talents of Discipline to Universities("111"Program)(No.B08036)the Fundamental Research Funds for the Central Universities(No.CDJXS11150026)
文摘Large-scale doubly-fed induction generator(DFIG)wind turbines are connected to the grid and required to remain grid-connection during faults,the short-circuit current contributed by the generation has become a significant issue.However,the traditional calculation methods aiming at synchronous generators cannot be directly applied to the DFIG wind turbines.A new method is needed to calculate the short-circuit current required by the planning,protection and control of the power grid.The short-circuit transition of DFIG under symmetrical and asymmetric short-circuit conditions are mathematically deduced,and the short-circuit characteristics of DFIG are analyzed.A new method is proposed to calculate the steady-state short-circuit current of DFIG based on the derived expressions.The time-domain simulations are conducted to verify the accuracy of the proposed method.
文摘为解决双馈风力发电机(doubly-fed induction generator,DFIG)采用综合惯量控制时固有调速器的抑制作用,及转速恢复时系统频率二次跌落(secondary frequency dip,SFD)的问题,提出了基于模糊推算和动态控制的风储联合调频控制策略。首先分析了电力系统频率响应特性,揭示了输出功率抑制量(output power suppression amount,OPSA)与SFD的产生机理。其次在DFIG频率支撑阶段,基于系统频率指标对综合惯量控制系数进行模糊逻辑设计,减小OPSA影响并提升DFIG调频能力。然后在转速恢复阶段,根据DFIG转速变化动态计算储能有功功率参考值,调整储能输出以减小SFD,并设计变系数比例-积分(proportional-integral,PI)控制以平滑恢复储能荷电状态(state of charge,SOC)。最后,在MATLAB/Simulink中搭建风-储-火四机两区域电力系统仿真模型,验证了所提策略的有效性,保证了高风电渗透率电力系统的频率稳定性。
