Power
P. Naderi; B. Ehsan Maleki; H. Beiranvand
Abstract
Background and Objectives: In this paper, a novel objective function is proposed for designing the power system stabilizers (PSSs). Although the object of the previous designs was to enhance the critical modes' stability, the derived stability indices were, to some extent, low and in some cases not acceptable ...
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Background and Objectives: In this paper, a novel objective function is proposed for designing the power system stabilizers (PSSs). Although the object of the previous designs was to enhance the critical modes' stability, the derived stability indices were, to some extent, low and in some cases not acceptable at all. The prospect of attaining higher stability motivated authors to design a new objective function in this study. In all the previous objective functions, the same priority is accorded to all modes, and an objective function is generally defined. A novel function is presented, called Variable Slope Damping Scale (VSDS), based on the assumed variable slope for the straight line in the fan-shaped region, which is an area in the complex plane for determining the eigenvalue placement range, with a reference tip at the negative point. This can be an efficient solution to the low value of critical modes' stability. In general, more damping for critical modes and lower priority for searching non-critical modes are taken as key points. The result of applying VSDS leads to a high value of damping scales for critical modes. The nonlinear simulation results and eigenvalues analysis has demonstrated that the proposed approach in this study is highly effective in damping the most critical modes.Methods: The proposed method assumes a variable slope for the straight line of the convergence region (specified area for placement of poles) in a fan-shaped type. Indeed, the increase in critical mode's damping scale is taken into account as a key point to introduce a powerful objective function.Results: The value of the damping scale and also the overall dynamic stability of the test system has increased by using the proposed objective function.Conclusion: Also, it has been shown that a variable slope convergence region is better than that of a constant slope one to the optimal tuning of WAPSS. In other words, the value of the damping scale with the proposed method over the existing techniques clearly shows that the proposed objective function is more effective than the other ones.
Power
B. Ehsan maleki; H. Beiranvand
Abstract
Background and Objectives: In this paper, a non-typical design method of flexible AC transmission systems power oscillation damping (FACTS-POD) controller is proposed to increase the efficiency of these devices. In all of the introduced FACTS-POD devices (taking IPFC-POD as an example), the supplementary ...
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Background and Objectives: In this paper, a non-typical design method of flexible AC transmission systems power oscillation damping (FACTS-POD) controller is proposed to increase the efficiency of these devices. In all of the introduced FACTS-POD devices (taking IPFC-POD as an example), the supplementary controller is designed based upon a conventional approach (i.e., based on optimization algorithms) and using a different method can be useful. Methods: In this paper, the graduated modal decomposition control (GMDC) is utilized as a specific strategy for POD controller design. Moreover, the dynamic model of the multi-machine power system with the presence of IPFC devices has been developed. Results: The obtained model is nonlinear; however, it is linearized around the operating point to design the controllers. The overall paper's structure is based upon the two scenarios, in the first of which conventional method for IPFC-POD design has been analyzed there upon the result compared with the introduced method in the second scenario. Finally, to ascertain responsive of the designed controller to load changes and stability of the system, the probabilistic sensitivity indices (PSIs) are investigated over a large set of operating conditions. As a verification, the time-domain simulations on a 10-machine power system emphasize the analysis of dynamic results and their information under the considered conditions. Conclusion: In general, the specific purpose of this paper is to enhance of the dynamic stability of concerned inter-area modes. The proposed method, especially using GRSA, offers better stability characteristics than the results of previous methods. ======================================================================================================Copyrights©2018 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.======================================================================================================
