A Method Based on Fast Fourier Transform for Online Supervising of Power System and Control Structure Design

In recent years, with the increasing of renewable energy resources and electronic systems, the scales and complexity of power system in all sections including the generative systems and distribution are being developed. Today's power networks are comprised of non-linear systems at great dimensions affected by low frequency oscillations. Such frequencies lead to the divergence of the system from balanced stability, and the limitation of the power system performance. To increase the level of damping, the stabilizers of power systems are applied. With the enlargement of power networks and the addition of wind and solar power plants, the change of dynamic behavior of the system has become possible. A system, which previously had a desirable performance by using a stabilizer, may lose its desirable function due to the new power plants. In this article, a four machine power system equipped with a stabilizer has been used and its performance was processed online. When the dynamic behavior change is created and its range of oscillation goes beyond a specific threshold, another stabilizer can be used to achieve a better performance by using existing online data. Moreover, in this article, non-local signals have also been used to exert stabilizers because over time, the number of connections in the power system increases, and local signals might not enough to achieve damping of oscillations of future power networks. The results of simulations show the increase of system damping and its higher resistance when the new stabilizer is used. Therefore, by using the results of this study, the oscillations of low frequencies can be examined in a large power network, and it can be modified if it is necessary.