Decomposition and aggregation of multimachine power system models

With the continual growth in power systems and interconnections there has been a corresponding demand for larger and larger generating units. This increasing interconnection has led to a complex power system and a change in the nature of the power system stability problem. A typical example of a large-scale power system is the North-American interconnected system. The total number of generating stations in this system is roughly 2000. The simulation of this single interconnected system in planning and operation studies would involve a prohibitively large number of differential-algebraic equations describing the interaction of generating plants and their controls through the transmission network. Such a simulation is impractical and would require large CPU time and memory.; The motivation for this research comes partly from the need to find a technique for reducing the large size of the system model without losing much accuracy in system stability analysis. Another related topic is the development and incorporation of controller and regulator models and the study of their dynamic effects in steady-state and transient stability studies. In relation to the reduction of higher-order power system models, the focus in this research is in part to develop an aggregation technique for synchronous generators with different structures and excitation types and to identify the parameters of the dynamic equivalents.; In the last decade, load modeling has been the focus of many studies. This focus arises from the distinct characteristics of different load types and their dynamic effects in simulations. One main load component is the induction machine. This is due to the large number of induction machines being used in industry and the continual growth in asynchronous machine application in the power system industry. In this research the dynamic interaction of induction machines with synchronous machines is addressed. Studies conducted in this research raise the possibility of developing a unified model for representing both synchronous and induction machines. The interaction between the synchronous and induction machines in a power system requires further investigation and it is dealt with in this research in order to investigate and understand this phenomenon. The possibility of including a unified model for both synchronous and induction machines in transient stability programs and its application in large power systems is also investigated. An aggregation theory used in earlier chapter of this thesis is extended to the aggregation of induction motors. This is done due to the large portion of induction machines used currently in industry and the difficulty to represent each motor with a detailed order model. An industrial system comprised of a mixture of large and low slip induction motors is selected to perform such aggregation. The equivalent machine parameters are also determined. Results obtained show the excellent accuracy of the aggregation method used in this research.