In the early 1990s, there was a simple GPS-based positive-sequence voltage phase angle measuring device. In the late 1990s, PMU monitoring systems were already in operation in the field. For example, the American Electric Power Research Institute installed a number of PMUs across the United States. There are two, more than a dozen, to study the dynamic behavior of the power system under various fault conditions, and to study the real-time transmission and processing of phase angle data. In the mid-1990s, some universities and research institutes began to study phase angle measuring devices (mostly positive phase angles, uploaded once per second), and some were put into trial operation. In February 2003, the National Electric Power Dispatch and Communication Center met in Beijing and formulated the main technical specifications for the real-time dynamic monitoring system project of the power system. For the first time, Spain used PMU information for state estimation. Some grids introduce measurement results into state estimates, improving state estimation accuracy. For example, SDE Power Company of Spain cooperated with SEPSC of the United States to add phase angle measurement to the SCADA system to correct the state estimation. The experimental study was carried out under the conditions of adding 23 phase angle measurements on 100 bus bars. The results show that the estimation accuracy can be improved when the phase angle measurement error is less than 0.12 degrees, and it is not harmful when the phase angle measurement error is large.

Yu Changyong, Xu Weimao, Zhang Mingli, Li Fang, Lu Tianqi. Research on Integrated Optimization of Distributed Distribution Network. Academic Journal of Engineering and Technology Science (2020) Vol. 3 Issue 4: 1-11. https://doi.org/10.25236/AJETS.2020.030401.

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