Several large-scale wind turbine tripping accidents occurred in Jiuquan wind power base in 2011.According to the on-site survey and analysis of these accidents related to relay protection,causes were found to be the c...Several large-scale wind turbine tripping accidents occurred in Jiuquan wind power base in 2011.According to the on-site survey and analysis of these accidents related to relay protection,causes were found to be the collection system defects and low correct operation rate of small current grounded line selectors of the unearthed neutral point collection system.By referring to both the characteristics of Jiuquan wind power base and arrangement of relay protection,the short-circuit features of wind power and its impacts on relay protection are analyzed.The collection system and the retrofit of the small current grounded line selector are improved by specific countermeasures.Finally,further research subjects are put forward.展开更多
A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),w...A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),which is built by real-time digital simulator (RTDS).Using the hardware communication interface of RTDS,a closed-loop testing experiment is accomplished to study the impacts of large-scale wind farms on the existing relay protection devices for wind farm outgoing transmission line.This paper points out problems existing in current relay protection devices as follows:fault phase selector can select unwanted phase due to the changes of fault features caused by special network connection of wind farms;blocking condition for distance protections needs to be re-examined due to the weak power-feed characteristics of wind farms;and power frequency parameter based relay protection devices cannot accurately operate due to the special transient voltage and current characteristics of wind farms during fault period.Results lay the foundation for improving the performances of the existing relay protection device and developing new principle relay protection.展开更多
With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to ...With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.展开更多
There were many accidents of large-scale wind turbines disconnecting from power grid in 2011.As singlephase-to-ground fault cannot be correctly detected,single-phase-to-ground fault evolved to phase-to-phase fault.Pha...There were many accidents of large-scale wind turbines disconnecting from power grid in 2011.As singlephase-to-ground fault cannot be correctly detected,single-phase-to-ground fault evolved to phase-to-phase fault.Phase-to-phase fault was isolated slowly,thus leading to low voltage.And wind turbines without enough low voltage ride-through capacity had to be disconnected from the grid.After some wind turbines being disconnected from the grid,overvoltage caused by reactive power surplus made more wind turbines disconnect from the grid.Based on the accident analysis,this paper presents solutions to above problems,including travelling waves based single-phase-to-ground protection,adaptive low voltage protection,integrated protection and control,and high impedance fault detection.The solutions lay foundations in theory and technology to prevent large-scale wind turbines disconnecting from the operating power grid.展开更多
处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检...处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。展开更多
基金supported by National High Technology Research and Development Program of China(863Program)(No.2011AA05A104)
文摘Several large-scale wind turbine tripping accidents occurred in Jiuquan wind power base in 2011.According to the on-site survey and analysis of these accidents related to relay protection,causes were found to be the collection system defects and low correct operation rate of small current grounded line selectors of the unearthed neutral point collection system.By referring to both the characteristics of Jiuquan wind power base and arrangement of relay protection,the short-circuit features of wind power and its impacts on relay protection are analyzed.The collection system and the retrofit of the small current grounded line selector are improved by specific countermeasures.Finally,further research subjects are put forward.
基金supported by the Special Fund of the National Basic Research Program of China (973 Program) (No.2009CB219704)
文摘A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),which is built by real-time digital simulator (RTDS).Using the hardware communication interface of RTDS,a closed-loop testing experiment is accomplished to study the impacts of large-scale wind farms on the existing relay protection devices for wind farm outgoing transmission line.This paper points out problems existing in current relay protection devices as follows:fault phase selector can select unwanted phase due to the changes of fault features caused by special network connection of wind farms;blocking condition for distance protections needs to be re-examined due to the weak power-feed characteristics of wind farms;and power frequency parameter based relay protection devices cannot accurately operate due to the special transient voltage and current characteristics of wind farms during fault period.Results lay the foundation for improving the performances of the existing relay protection device and developing new principle relay protection.
文摘With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.
基金supported by Major International Collaborative Project of National Natural Science Foundation of China(No.51120175001)Key Project of National Natural Science Foundation of China(No.50937003)
文摘There were many accidents of large-scale wind turbines disconnecting from power grid in 2011.As singlephase-to-ground fault cannot be correctly detected,single-phase-to-ground fault evolved to phase-to-phase fault.Phase-to-phase fault was isolated slowly,thus leading to low voltage.And wind turbines without enough low voltage ride-through capacity had to be disconnected from the grid.After some wind turbines being disconnected from the grid,overvoltage caused by reactive power surplus made more wind turbines disconnect from the grid.Based on the accident analysis,this paper presents solutions to above problems,including travelling waves based single-phase-to-ground protection,adaptive low voltage protection,integrated protection and control,and high impedance fault detection.The solutions lay foundations in theory and technology to prevent large-scale wind turbines disconnecting from the operating power grid.
文摘处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。
