Damping Control Of Low Frequency Oscillation In Power Systems Based On WAMS

The Wide Area Measurement System is based on Synchronized Phasor Measurement. WAMS can provide synchronous signals of many nodes in a power system. These wide area signals are measured in real time with high precision. But design of inter-area low frequency oscillation damping control is affected by time delay of wide-area output feedback signals. Therefore, exploring the new theory, technology and method to research on delayed output feedback robust damping control to inhibit inter-area low frequency oscillations in large power systems, have enormous theoretic sense. The dissertation consists of three main parts as follows:First, by adopting real-time wide-area measurements from WAMS, one Prony algorithm for transfer function identification is brought forward, in order to obtain the reduced model of power systems with no need to model and remodel every device in power system in detail. This algorithm permits the appearance of non-zero initial states and any type of pumping signals in the system to be identified. Simulation and analysis results show that this algorithm identifies initial states and transfer function accurately. The general Prony identification algorithm is promising for online applications;Second, for the obvious delay of WAMS data, it conducts detailed analysis on delay characteristics of wide area measurement system from the system structure, and then to establish delay evaluation model according to WAMS Delays. On this basis, it describes the coordination control solutions for time delay of wide-area power system. The resulting time delay compensation method is proposed;Third, for preventing inter-area low-frequency oscillation in power systems, one novel strategy for robust damping controller design is proposed. That is applicable to single-input single-output control. Time delay model of power system is established by employing general Prony identification of transfer function and Pade approximation of dead time delay. The damping controller is designed based on the mixed-sensitivity Hoo control theory and pole placement approach. Time-domain simulations demonstrate this controller can inhibit inter-area low frequency oscillations evidently, meanwhile it is insensitive to time delay and robust to operating conditions.