The setting values of thresholds for fault feature parameters are critical in all kinds of protection schemes.When the detected feature parameter value exceeds the setting value,the protection will trip.However,the se...The setting values of thresholds for fault feature parameters are critical in all kinds of protection schemes.When the detected feature parameter value exceeds the setting value,the protection will trip.However,the setting value based conventional protection schemes sometimes cannot satisfy the protection requirements of neutral ineffectively earthed power systems(NIEPS)due to wide variations in operating conditions and the complexities of fault cases.In this paper,a novel single phase grounding fault protection scheme without threshold setting is proposed.The fault detection is achieved based on operating states rather than setting values.A fuzzy c-means algorithm is used to divide the operating state of the protected feeder into non-fault states and fault states.The cluster center of each state is then obtained by classifying the historical feature samples of the protected feeder extracted under various operating conditions into their corresponding states in a constructed multi-dimensional fault feature space.The distances between the detected feature samples and the cluster centers of the non-fault and the fault states are calculated.If the distance to the fault state is shorter than that to the non-fault state,a fault is detected.Otherwise,the feeder is considered normal.A PSCAD/EMTDC simulator is used to simulate a 35 kV NIEPS under various operating conditions,non-linear loads,and complex fault cases.Results show that the proposed single phase grounding fault protection scheme without threshold setting can protect the system correctly under all kinds of faults.展开更多
研究3.0百万吨每年(Million Tonnes Per Annum,MTPA)浮式液化天然气生产储卸装置(Floating Liquefied Natural Gas Production,Storage and Unloading Device,FLNG)配电系统。根据3.0 MTPA FLNG的典型工况,分析其电力负荷和发电机组配置...研究3.0百万吨每年(Million Tonnes Per Annum,MTPA)浮式液化天然气生产储卸装置(Floating Liquefied Natural Gas Production,Storage and Unloading Device,FLNG)配电系统。根据3.0 MTPA FLNG的典型工况,分析其电力负荷和发电机组配置,并从经济性和可靠性等方面对比不同电压等级配电系统型式,包括馈线式配电网和环式配电网。对较大容量配电系统设计中的关键点进行研究,包括中压配电系统保护、单相接地故障电容电流、中性点接地方式选择和功率管理系统。展开更多
基金supported in part by National Natural Science Foundation of China under Grant 61233008 and Grant 51277014.
文摘The setting values of thresholds for fault feature parameters are critical in all kinds of protection schemes.When the detected feature parameter value exceeds the setting value,the protection will trip.However,the setting value based conventional protection schemes sometimes cannot satisfy the protection requirements of neutral ineffectively earthed power systems(NIEPS)due to wide variations in operating conditions and the complexities of fault cases.In this paper,a novel single phase grounding fault protection scheme without threshold setting is proposed.The fault detection is achieved based on operating states rather than setting values.A fuzzy c-means algorithm is used to divide the operating state of the protected feeder into non-fault states and fault states.The cluster center of each state is then obtained by classifying the historical feature samples of the protected feeder extracted under various operating conditions into their corresponding states in a constructed multi-dimensional fault feature space.The distances between the detected feature samples and the cluster centers of the non-fault and the fault states are calculated.If the distance to the fault state is shorter than that to the non-fault state,a fault is detected.Otherwise,the feeder is considered normal.A PSCAD/EMTDC simulator is used to simulate a 35 kV NIEPS under various operating conditions,non-linear loads,and complex fault cases.Results show that the proposed single phase grounding fault protection scheme without threshold setting can protect the system correctly under all kinds of faults.
文摘研究3.0百万吨每年(Million Tonnes Per Annum,MTPA)浮式液化天然气生产储卸装置(Floating Liquefied Natural Gas Production,Storage and Unloading Device,FLNG)配电系统。根据3.0 MTPA FLNG的典型工况,分析其电力负荷和发电机组配置,并从经济性和可靠性等方面对比不同电压等级配电系统型式,包括馈线式配电网和环式配电网。对较大容量配电系统设计中的关键点进行研究,包括中压配电系统保护、单相接地故障电容电流、中性点接地方式选择和功率管理系统。
