A Fundamental Research for Dynamic Security Assessment and Knowledge Based Preventive Strategy of Power Systems by Global Monitoring of Electric Power Fluctuations

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The most important objective of operation and control in large-scale power systems is to avoid the blackout in wide area of the systems. In order to achieve this objective, our research project has studied the advanced techniques of dynamic security assessment and preventive control strategy of power systems. Our approach is based on the monitoring of small fluctuations observed on the active power flow of tie-line or the rotor speeds of generators because those fluctuations include the electromechanical modes which are the useful informations for evaluating the system stability. The main results obtained through the project are as follows :1. A combined technique of FFT processing and principle component analysis is developed for systematically extracting the features of electromechanical modes from line flow fluctuations. The application of the developed technique to the field data shows that the technique is effective for detecting the change in the characteristics of modes from the … More small fluctuations.2. A new approach for evaluating the damping effect of power system on the modes is developed. The approach is based on the interesting characteristics that the energy of modes changes with the increase or decrease of total generating power of the system.3. A new type of filter for extracting dominant modes of power systems is devised. This filter can be obtained by using the inherent characteristics of power system network and the covariance matrix of rotor speed fluctuations of generators. There are many applications of the filter to the power system problems such as on-line stability monitoring, fault identification and creation of control signals for power system stabilizer.4. A preventive control strategy for enhancing the stabilizing capability of power systems is proposed which is based on artificial neural network and monitoring of line flow fluctuations. In addition, the scheduling technique of economic load dispatch coordinating. the system economy and stability is developed using the neural network and the fluctuations. Less