Analysis And Study Of The WAMS-based Real-time Damping Control Of Power System

With the interconnection of the power systems in China, the inter-area low-frequency oscillations have become one of the key factors affecting the stability of the interconnected power system, while the development and application of the GPS (Global Positioning System) - based WAMS (wide-area measurement system) have provided a new approach to the real-time control of the low-frequency oscillations. Based on practice of the South Power Network of China and that of Guizhou power systems, together with the researches on damping control made up to now, the main studies in this dissertation are as follows:1. This dissertation expatiates on the basic principles of low-frequency oscillations in order to present and analyze the existing methods of low-frequency oscillations study as well as their disadvantages respectively. With the establishment of the WAMS, it is possible to monitor the whole system at real time, which has provided a new approach to study the on-line low-frequency oscillations with Prony method. Hence the basic principles of Prony method and its characteristics are expatiated in this dissertation.2. Based on the stability analysis of small signals, this dissertation studies the damping features of power system, introduces the ways to classify and select the oscillation modes of multi-motor power system. It is widely accepted that the total damping of the system is the trace of matrix of the system state, or, the sum of all the latent roots of matrix of the system state. The conversation law of damping is derived and the damping distribution law of the low-frequency oscillations of the multi-motor system is discussed.3. The dissertation briefly introduces the GPS-based WAMS and puts forward the concept of stabilizers in the wide-area power system on the basis of WAMS and Prony method. The working principles of the stabilizers are studied. The algorithm of the factors involved in is also proposed under the on-line set of PSS. With the simulation and checking calculation with PSASP program, the real-time damping control is realized.4. A model of generator set-power terminal is constructed in the dissertation to solve the problem of the off-line real-time damping control of the varying running modes of the system. It is concluded that the oscillation modes of the generator set with corresponding power terminal is the inherent characteristics under certain running modes.5. In the dissertation, BPA simulation program and Prony method are employed to tell the oscillation modes of some generator sets of Guizhou power system. With careful comparison and analysis, the validity of the generator set-power terminal model is testified. The distribution rules of the oscillation modes of the generator sets are also achieved .Sampling from the generator sets, the reasonable set of the PSS parameters of the corresponding generating sets is obtained with the oscillation modes recognized and checked with BPA simulation.