The trend towards the implementation of Smart Grids results in a higher complexity of power signals and their voltage quality implication. Thus the need for more advanced signal processing techniques is required. A number of techniques have been recently developed and proposed in order to analyze the new environment and phenomena. Among these techniques this paper discusses different time-frequency methods used in power systems disturbance analysis. Filter Banks, Sliding-Window Recursive-DFT (SWR-DFT) and Wavelet Packet Transform (WPT) are compared. The methods are discussed based on their advantages and disadvantages. Signals with harmonic and inter-harmonics distortion are used in order to compare performance of the methods related to fundamental frequency variations, fast magnitude oscillations and interharmonics. The results presented in this work should assist quality expert to select the appropriate method according to application.
The trend towards the implementation of Smart Grids results in a higher complexity of power signals and their voltage quality implication. As a consequence, for this kind of environment, the traditional harmonic distortion analysis that assumes a balanced and steady-state condition is no longer sufficient to provide accurate information on the state of the system. For this reason, more advanced signal processing techniques are of vital importance. These should be able to track time-varying harmonics both in time and frequency domain. This paper uses Filter Banks and Sliding-Window Recursive-DFT (SWR-DFT) to track time-varying harmonics when a converter is connected to the grid. The experiment shows methods to extract time-varying harmonics, and lead to a better understanding of its time-varying nature.
This paper presents laboratory results on the behavior of time-varying harmonics caused by an electronic converter under a voltage sag and load variations in order to demonstrate the validity of digital time-frequency decomposition methods. A filter centered on the 7 th harmonic is used to capture the analog signal and its output is compared with the corresponding harmonic derived by digital signal processing techniques for physical and analog verification purposes. This approach allows engineers to look into the transient phenomena through the observation of the behavior of time-varying harmonics for a better understanding of associated causes of the signal characteristics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.