A Research On The Decomposition And Coordination Transient Stability Simulation For Control Centers In Power Systems

With the enlargement of the power grids and the increase of the load level, the modern power systems rely more and more on the online and accurate Transient Stability Simulation (TSS). The power systems are a whole unified entity, while their management and dispatch are separate. Thus sharing their private data is too difficult to satisfy the online and accurate requirements of a local TSS. So A decomposition and coordination (D & C) TSS is needed and necessary.This dissertation unified various D & C calculation modes by a 3-dimensional figure. Based on the figure, the internal relations between these modes are discussed. The dissertation analyzes the basic formulations of D & C calculation, and draws the conclusion that the key problem of D & C calculation is the coordination variables transferred between the decomposition subsystems and the coordination subsystem.According to the development of the modern communication devices, the D & C TSS should be put to use step by step. The online external dynamic equivalent mode is the easiest one and can be turned into reality in no time. The distributed asynchronous mode is based on more reliable and faster communication devices. It is a prospect of the near future. However, the synchronous mode is the most critical one in communication. It is not a real considerable mode unless the communication devices can be developed highly.In order to increase the accuracy of the online TSS, a buffer subsystem is introduced into the external model, and the standards and formulas for the buffer subsystem selection are proposed. A new dynamic equivalent algorithm based on EPRIE' and asymmetrical admittance matrix, named A- EPRIE' algorithm, is proposed. To increase the accuracy of the external modal, the number of external equivalent generators should be increased.Time-window and shifting time-window strategies are introduced to the asynchronous D & C TSS modes, together with a proposed double shifting time-window strategy. These strategies can decrease communication frequencies, speed up the convergence and accurate of TSS. A simple but efficient coordination algorithm based on the Norton equivalent models of the subsystems is proposed. It meets the requirements of the convergence, simulation speed and data transferring. The mathematic proof shows the converged solution simulated by this algorithm, distributed in different subsystems, is the solution of the whole power systems.This dissertation has analyzed the similarities and differences between the asynchronous and synchronous D & C TSS modes. And it has analyzed the relations between the synchronous D & C computation and parallel computation. Several achievements in parallel computation is applied in the research of synchronous D & C TSS algorithm.