Design Of Power System Damping Controller Based On Wide-Area Measurement System

The inter-area low frequency oscillation is a dominating obstacle to limit the enhancement of transfer capability between different areas of interconnected power system. In this dissertation, three approaches to design power system damping controller based on the Phasor Measurement Unit and Wide-Area Measurement/ Monitoring System have been proposed, and remote signals'delay was considered. Those approaches provide some new views on improvement for the dynamic performance of interconnected power system.(1) A new approach to design the wide-area PSS, that is the PSS with remote input signals, based on the evolutionary strategy is proposed. Delay's impact on stability of power systems is analysed in details, and pade approximation is used to express the time delay. By this way, the close loop system turns into implicit about time delay. The locations of PSS and feedback signals are chosen according to residue matrix. Finally, evolutionary strategy is used to coordinate the PSS parameters. Those PSS can increase the maximum allowable time delay and the robustness on time delay is enhanced. This method can make the control system implicit on time delay, so the analysis and design theory unrelated to delay can be used.(2) A new method to design the wide-area H∞controller based on the H∞loop-shaping theory is proposed. In fact, diversified uncertainties exist widely in the power systems. How to improve the robustness of the controller has been a topic issue. The open-loop power systems model is built with consideration of the remote signal's time delay, which is replaced by Pade approximation. Then the model is shaped to give desired open-loop properties at interested frequencies and the shaped plant is robustly stabilized using the normalized coprime factor approach of H∞optimization. The realized controller is not only robust but also endurable for larger time delay.(3) A new type of state feedback controller, named wide-area state feedback controller, with consideration of remote signals'time delay, is designed based on the LMI theory. To take into consideration of the precision of time-delay system, it is useful to build the model with exact time delay. On the other hand, Choice of weight function is a difficult problem of H∞controller design. In this dissertation, the state feedback controller with partial delay states, which are far beyond the local states in distance, is constructed. A new delay-dependent stability condition is deduced with linear matrix inequalities (LMI) theory and the LMI toolbox of MATLAB can be used to optimize the solution. By this condition, a group of controllers can be achieved and the maximum allowable time delay can be calculated. By this approach, choice of weight function was avoided. In this sense, it is better than the method based on H∞theory.