Transmission Characteristics Of Electronic Transformers And Its Impacts On PMU Measurements

The Phasor Measurement Unit(PMU) is a main information source of the real-time data platform in smart grid, which provides a new technical method for the realization of the dynamic process monitoring. At the present stage, researches about the impacts of the traditional power transformer, secondary internal device, phasor algorithm and environmental disturbance on PMU measurements have effectively improved the measurement accuracy of analog PMU. But in smart substation environment, electronic transformers are the key to accurately access to the primary system information in PMU. However, there are few research about the impact of electronic transformers on PMU measurements. Therefore, it is theoretically and practically valuable to study the transmission characteristics of electronic transformer and to analyze its impact on PMU.Firstly, in this thesis, Rogowski current transformer is studied. Using the Laplace transform and FFT analysis, a mathematical model of the transformer is built to analyze its static and dynamic transmission characteristics. The impacts of the current transformers on PMU measurements can be proved by simulation and experiments. Secondly, we study the voltage electronic transformers. Based on transmission theory, we analyze the reasons why voltage transformers produce measurement error and how they influence PMU. Besides, the simulation models are built to verify the impact on PMU measurements. At the same time, a digital PMU test system based on IEC61850-9-2 message is developed in this thesis to promote the application of digital PMU in smart substation, in which the GPS time synchronization signal and the message signal are tested to verify the high accuracy of test system.