The Method For Small Signal Stability Analysis And Control Of Power System

With the development of power system, the research standard on the small signal stability needs to improve. In this thesis, the researches about small signal stability reducing-order analysis and control method for multi-machine power system based on decoupling and reducing-order model are as follows. A decoupling and reducing-order method is brought forward to analyze the small signal stability of multi-machine power system. Then the reducing-order analysis based on the method in frequency domain is realized. Scheme of PSS of multi-machine power system is devised using the decoupling and reducing-order method and compared with the result of the traditional method. The small signal stability of a region power system is analyzed by the eigenvalue method and decoupling and reducing-order method. And the scheme of improving the stability is introduced. The program of small signal stability analysis of multi-machine power system and devising PSS based on the decoupling and reducing-order method is compiled using MATLAB.In this thesis, a decoupling and reducing-order method is brought forward to analyze the small signal stability of multi-machine power system. Based on the method, the reducing-order analysis in frequency domain is achieved from two ways. The closed-loop main poles of each single-machine are attained intuitively by the pole-zero cancellations. The absolute and relative stability of multi-machine is analyzed intuitivelly using the open-loop frequency characteristic charts and the performance index of open-loop frequency domain of each decoupling single-machine. The method could not only realize reducing-order of the linearization model of multi-machine power system, but also avoid losing the main poles of the system. At the same time, stability margins and damping coefficient of main poles of the decoupling machines could provide definite information for improvement of the system stability.In this thesis, the oscillation model method is improved, and a method of design of PSS of multi-machine power system is put forward based on the decoupling and reducing-order model. The improved oscillation model method is not at single-machine infinite-bus equivalence system, but diagonal elements of the linear coefficient matrix K1 ~ K6 of multi-machine system replace the linear coefficient matrix K1 ~ K6 of single-machine infinite-bus equivalence system. The method avoids the difficult ofsingle-machine infinite-bus system equivalence. The method of design of PSS of multi-machine power system based on the decoupling and reducing-order model takes the influence into account in full that the machines with PSS are subject to from others. The rationality of the improved oscillation model method is verified by the method.The small signal stability of a region power system with 62 machines and 428 buses is analyzed using the program "PSASP" of Electric Power Research Institute China and MATLAB program by myself under K1-K6 model and C1-C15 model. Then the scheme of PSS is brought forward according to the result of analysis. The result implies that the calculation result of the decoupling and reducing-order method is coincident with the result of the eigenvalue method, and the effect of the PSS is favorable.