OPTIMAL POWER FLOW FOR LARGE SCALE AC-DC SYSTEM WITH CONTINGENCY ANALYSIS
Abstract
In the operation of power system, aside from minimizing operating cost, considerations have to be given to security and reliability of the system subjected to certain plausible contingencies. Ever since 1961, the optimal power flow formulation has been accepted as the approach to achieve these objectives, but it is not until recently that we have suitable algorithms to solve this problem for large scale system. This thesis presents a suitable mathematical formulation and solution procedure for the large scale AC-DC system optimal power flow problem. The solution procedure utilizes a sequence of linearly constrained quadratic subprograms to solve the nonlinear optimal power flow problem. Modified IEEE 30 and 118 bus systems were used to test the performance of the quadratic program based algorithm. These tests included an evaluation of three different methods used to establish initial estimates of the Lagrange multiplier. The results obtained showed that the proposed algorithm performed satisfactorily for these systems. These results also indicate that additional advantage could be obtained by coordinating the dispatch of dc power transfers with the conventional controllable sources. Also presented in this thesis is a comparative study of the performance of three different contingency selection methods. These are: the first iteration of fast decoupled load flow, the modified first iteration of fast decoupled load flow, and the concentric relaxation method. It is shown that one iteration of fast decoupled load flow can provide reliable results for contingency ranking, and the concentric relaxation technique is a good alternative.
Degree
Ph.D.
Subject Area
Electrical engineering
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