Research On The Dynamic Equivalence Of Power Systems Interconnected With Two Tie-Lines

The dynamic equivalence of large-scale power system is an important issue for on-line dynamic security analysis. The main work of this thesis is as following:1. The dynamic equivalent model of power systems interconnected with two tie-lines is developed in this thesis. With the development of the modern power system, the connection among of big power systems becomes more and more compact. When there are more than one external systems or multi-lines, the problem becomes very complex, and it needs very accurate models to replace the external systems.2. The theoretical method for dynamic equivalence of power systems interconnected with two tie-lines is studied. Coherent equivalent algorithm is a classical method applied in the large-scale power system off-line transient stability analysis. It is typically done in three steps: firstly, identification of the groups of coherent generators, secondly, reduction of the generator buses and the network, finally, aggregation of the generator models and their associated control devices. Coherent machines are identified using linear simulations, the coherent generator buses are reduced by constant MVA technology and the reduction of the network is done by current sink reduction (CSR) algorithm. At last, Powell frequency-domain algorithms are used to compute the parameters of the aggregate generator. The above methods are classical and effective.3. The identification based method for dynamic equivalence of power systems interconnected with two tie-lines is studied, which is an effective method to the on-line dynamic security analysis. The focus points of this method are confirming the frame of the dynamic equivalent model, making the equations of the model andestimating the parameter of the model through giving correlative disturbance.4. In this thesis, the coherent equivalent algorithm and the identification equivalent algorithm are integrated to study the dynamic equivalent model of power systems interconnected with two tie-lines and the equations of the model. How to identify the parameters of the model is discussed. Simulation results indicate that the models are effective to the power systems interconnected with two tie-lines.