Research And Development Of The Distributed Synchronous Measuring System Based On GPS Synchronous Clock-carrier Power Source

The demand on real-time investigation of global synchronized monitoring system in power systems becomes more critical, with the scale of inter-connected power systems becoming larger and the load increasing rapidly. At present, supervisory control and data acquisition (SCADA) system and wide area measurement system (WAMS) are the main monitoring systems of the power systems. In the SCADA systems, the sampling data from RTUs on different installation sites is short of high precision clock signal and synchronous time-tag. The SCADA systems can only provide steady and asynchronous data of time cross-section. It is not used for the analysis of the dynamic characteristic of the whole system. The measurement data from PMUs based on GPS clock synchronization technology carries high precision global synchronous time-tag. It provides an important method to observe dynamic behavior of the power systems intuitively, making up the disadvantages of the SCADA systems effectively. But the PMUs can't be installed comprehensively due to the immature technology and the high cost.By adding the global uniform time-tag and high-speed sampling to the traditional RTU, a novel synchronized RTU (SMU) is formed and the traditional SCADA systems can be extended to distributed synchronous measuring system (DSMS), which can solve the conflict above effectively. The developing state of the power system dispatching automation systems is described and the purpose of the project of DSMS is introduced in the first part of this paper. Then the influences to the state estimation accuracy of the power systems are analyzed because of the asynchronous measurement data error of the SCADA systems. And the concept of the SMU is proposed in the second part. Next the characteristics of the SMU are introduced in the third part and the design of the hardware structure of SMU is studied. The distributed synchronous measuring system (DSMS) is built based on the SMU unit by the GPS synchronous clock-carrier power source in the fourth part of this paper. Deep research to the relevant technology, including the frequency measurement, phase calculation, selection of the synchronous time-tag and the checking of the synchronous clock is carried on in the fifth part. Finally the total work of this paper is summarized and the future work is presented.