| Modern power systems are becoming larger and more complex with large generation units installed, extra-high voltage transmission network with AC/DC mixed and other new technologies adopted and power markets. All these bring a new challenge on the security of the power networks. Therefore, the power system stability control becomes more and more important. The voltage phasor real-time measurement is the key for power system stability control because it can offer effective basis for stability control. In this thesis the significance and progress of synchronized phasor measurement based on GPS are introduced at first, and its application in the power system is presented at the same time. Then the zero-crossing detection method and the DFT algorithm adopted in the phasor measurement are discussed in detail. To minimize the errors, some novel methods are included in the zero-crossing detection. To improve measurement accuracy, also a double-rate sampling method is proposed. One recursive DFT algorithm requiring less computational work is investigated, and a new frequency measurement method based on this algorithm is given. In order to improve the accuracy of the frequency measurement, the measurement errors, which are caused by decaying the DC component, the frequency variation and etc, are discussed in detail. Furthermore, the effects of the power system transient on synchronized phasor measurement are investigated in the thesis. The variations of the bus voltage during the course of fault (including three-phase fault, two-phase fault and single-phase ground fault) are simulated and analyzed, and the results show that phase step changes would be appear. Then an effective method is proposed to detect the phasor during the step changes. In this thesis, a practical scheme of high performance PMU is designed, in which ARM technology is used to realize the Ethernet communications among control center, substations and plants. The hardware and the software of PMU are explained as well.
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