The paper provides a short history of the phasor measurement unit(PMU) concept. The origin of PMU is traced to the work on developing computer based distance relay using symmetrical component theory. PMUs evolved from...The paper provides a short history of the phasor measurement unit(PMU) concept. The origin of PMU is traced to the work on developing computer based distance relay using symmetrical component theory. PMUs evolved from a portion of this relay architecture. The need for synchronization using global positioning system(GPS) is discussed, and the wide area measurement system(WAMS) utilizing PMU signals is described. A number of applications of this technology are discussed, and an account of WAMS activities in many countries around the world are provided.展开更多
This paper represents a design and development of a mobile sensing unit as well as its prototype implementation for railway track monitoring. The unit consists of an ultra-small personal computer (PC), a global positi...This paper represents a design and development of a mobile sensing unit as well as its prototype implementation for railway track monitoring. The unit consists of an ultra-small personal computer (PC), a global positioning system (GPS) receiver, an accelerometer and an ADC (Analog/Digital Converter) so that the unit can trace the route while capturing an acceleration response of a passenger vehicle. The unit enables more frequent and qualitative data acquisition compared with traditional and the state of the practice railway track inspection equipments. Locating disorder is the key of our unit, which has a reasonable accuracy of positioning with GPS data, existing facilities landmarks, and car acceleration responses. The proposed unit is a promising device for efficient properties management of railway agencies. The prototype implementation shows a result that car acceleration responses are related with the track displacements in low frequencies. The results also imply that sensor settlement on a vehicle floor, not axes or bogies, is effective for capturing track vertical displacements.展开更多
文摘The paper provides a short history of the phasor measurement unit(PMU) concept. The origin of PMU is traced to the work on developing computer based distance relay using symmetrical component theory. PMUs evolved from a portion of this relay architecture. The need for synchronization using global positioning system(GPS) is discussed, and the wide area measurement system(WAMS) utilizing PMU signals is described. A number of applications of this technology are discussed, and an account of WAMS activities in many countries around the world are provided.
基金the joint research project between East Japan Railway Company and the University of Tokyo
文摘This paper represents a design and development of a mobile sensing unit as well as its prototype implementation for railway track monitoring. The unit consists of an ultra-small personal computer (PC), a global positioning system (GPS) receiver, an accelerometer and an ADC (Analog/Digital Converter) so that the unit can trace the route while capturing an acceleration response of a passenger vehicle. The unit enables more frequent and qualitative data acquisition compared with traditional and the state of the practice railway track inspection equipments. Locating disorder is the key of our unit, which has a reasonable accuracy of positioning with GPS data, existing facilities landmarks, and car acceleration responses. The proposed unit is a promising device for efficient properties management of railway agencies. The prototype implementation shows a result that car acceleration responses are related with the track displacements in low frequencies. The results also imply that sensor settlement on a vehicle floor, not axes or bogies, is effective for capturing track vertical displacements.
