WAMS Based Power System Stabilizer (PSS) Research

With the development of interconnected power grids in China, the power systems are becoming larger and more complex. Therefore, the phenomenon of low-frequency oscillations are becoming more familiar, especially the inter-area mode oscillations. Conventional PSSs, the input signals of which come from local machine, can damp the local mode oscillations well, but not the inter-area mode oscillations.The development of Synchronized Phasor Measurements, computer networks technology and modern communication technology give birth to WAMS, which is a good platform to monitor the real time states of large power systems. The WAMS can provide different globe signals between different areas at the same time, and these signals(Δw ,Δδ) reflect the character of inter-area mode oscillation., which may be helpful to redesign PSS. Of course, the time delay of the globe signals must be taken into account in the WAMS environment.The classical theory of small signal stability analysis can help us to understand the problem of low-frequency oscillation. The WAMS can provide the general information of power system. Therefore, it is necessary and feasible to research PSS based on WAMS. This thesis redesigns a new PSS using the law of Residues and LMI. The new PSS adopts both local and globe signals and it can increase the ability of a testing power system. This thesis 1) introduces the concept and mechanism of low-frequency oscillation, and expounds the theory of small signal stability analysis, then linearizes the power system with multi-machine and gets its state space equation.2) introduces the composing and framework of WAMS, discusses the problem of wide-area control.3) analyzes the time delay in WAMS and compares 3 means to delay with the impact of time delay on control design in power systems.4) designs a PSS based on WAMS considering the time delay, finally validates the designing method by digital simulation in a typical power system.