Identification Based Dynamic Equivalents Of Power Systems Interconnected With Three Areas

Dynamic equivalent can reduce the computing effort and manifest the main characteristics. By reason of needing to know system structure and parameters of the equivalent system, coherency method and mode method are mainly used for off-line dynamic equivalent and not suitable for on-line dynamic equivalent. Just so, a method not needing system parameters is worth studying. Here identification method is used. The main work of this thesis is as following:1. The dynamic equivalent model of power systems interconnected with three areas is studied in this thesis. With the development of modern power systems, the connection among big power systems becomes more and more compact. When there are more than one external subsystems and multi-lines, the problem becomes very complex, and it needs more accurate models to replace the external system. In this thesis, the dynamic equivalent model of power systems interconnected with three areas is given and its identifiability is studied.2. The identification methods for dynamic equivalent are studied. In the case studies of a 36-bus system, an evolutionary strategy algorithm is used for the parameter estimation. Under different kinds of fault, the parameters and dynamic responses are compared to check up the validity of the model and the parameter estimation. And then, other characteristics of the system, such as the power limit and the power angle of a generator, are studied.3. The sensitivity of the parameters is studied. On the base of the study, several parameters which have slight influence on the system dynamic response are decided through coherency-based dynamic equivalent. The other parameters can be got by parameter estimation. As above, under different kinds of fault, the parameters and dynamic responsesare compared to check up the validity.