A Study And Application Of Real-Time Power Angle Measuring Method Based On GPS In Power System

With the development of power industry and system capacity, the stability of power system becomes more and more important. It is an important topic of the secure and economical operation in power system, and it is one of the kernel in large power system.The stability of power system is associated with many facts. According to experience, the secure operation of power system is closely related with the state of operation. Generator, the important equipment in the power system, its stable operation becomes the most important thing. The power angle of generator is not only an important parameter that reflects energy changed within the generator, but also one of the most important variables to represent the working condition of synchronous generators and the stability of power system. Through monitoring the changes of power angle, we can provide very important reference basis for the analyses of generator being at unusual, fault and lose of step situations. The connotation of generator's power angle in operation and control is reported in the paper, followed by measuring methods.The paper lists existed measuring methods of generator's power angle, and also analyzing these methods, pointing out their shortcoming and proposing improving method, designing a new measuring device of power angle of a synchronous generator, which is used in the study of power system stability, explaning its theory and the components of hardware and software in detail.In order to realize direct measuring of generator's power angle, the paper adopts improving real-time power angle measuring system, and verifies the inspection by the indirect measuring method at the time of the steady state.The measuring system adopts up and down CPU structure, in which industrial mainboard is based on AT96 bus and A/D data sample and disposal is based on DSP. We can gear and set up channels to complete the sample of AC electrical signal through software. Adopt outside interrupt method to import the photo-electricity pulse signals into the measuring system, which is signify generator rotor mechanical positions.In order to separate the base-frequency component from the disturbed electrical signal, the theory of improving Fourier Transformer is explained. The obtained power angles by measuring are then predicted real-timely using theLeast Square Method, which is applied in generator's local control.Power angle applies to stability control of mul-generators and large system, synchronized time is necessary. This paper introduces Gloabal Position System (GPS), which has the highest precision, and applies it to real-time power angle measuring system.A dynamic simulation after RTDS's calibration is conducted to validate the proposed method. Results demonstrate that the developed approach can achieve very satisfied accuracy both in steady state and transient period of power system.At last, the paper analyses the future of measuring power angle in power system, and points out that transient stability control theory based on synchronized phasor is still required further research and development.