International Conference on Renewable Energies and Power Quality (ICREPQ’13) Bilbao (Spain), 20 th to 22 th March, 2013       (RE&PQJ) ISSN 2172-038 X, No.11, March 2013 A Compression Method for Power Quality Data R. E. Dapper 3 , C. D. P. Crovato 2 , A. A. Susin 3 , S. Bampi 1 1 Informatics Institute – Microelectronics Program (PGMicro) Federal University of Rio Grande do Sul (UFRGS) Campus do Vale – Av. Bento Gonçalves, 9500, Porto Alegre (Brazil) Phone/Fax number:+55 (51) 3308-6156 / +55 (51) 3308-7308, e-mail: {lbsoares, bampi}@inf.ufrgs.br, 2 Feevale University ERS239, 2755, Novo Hamburgo – CEP: 93352-000 (Brazil) Phone number:+55 (51) 3358-4016, e-mail: cesarc@feevale.br 3 Electrical Engineering department Federal University of Rio Grande do Sul (UFRGS) Av. Osvaldo Aranha, 103, Porto Alegre (Brazil) Phone number:+55 (51) 3308-3515, e-mail: {roque.dapper, altamiro}@ufrgs.br Abstract. This paper presents a compression method for power quality (PQ) signals. This method consists of polynomial approximation algorithm and a lossless compression algorithm The proposed method uses the Deflate algorithm as lossless compression algorithm. The polynomial approximation is intended to decrease the entropy of the signal, thus increasing the compression ratio of the Deflate algorithm. The proposed method is characterized by high compression ratio and low computational cost, making feasible its implementation in embedded systems. Key words Power Quality, Power Systems, Deflate, LZ77, Huffman Coding, Signal Compression. 1. Introduction Due to evolution of the electronic technology, electronic devices with switching power supplies, rectifiers and inverters, and non-linear loads are becoming more present in industries and residences [1]. These devices have contributed to the increase of power quality disturbances, for example, increase of harmonic distortion present in the power network[1]. Beside affecting the PQ parameters these electronic loads are very sensitive to disturbances in the power network [2, 3]. Power quality problems can cause malfunctions in sensitive equipments, production stoppages or poor operation of protection systems [1]. In order to monitor these disturbances more and more power quality analyzers are being distributed in different points of the power network to monitor and analyze the parameters of power quality [1,4]. The power quality parameters are defined by international standards, such as IEC 61000-4-30. However regional standards are also edited to complement and add new parameters and characteristics necessary for certain region [4]. The IEC 61000-4-30 standard defines a list of power quality parameters to be evaluated, as well as their methods of calculation. These parameters are mostly evaluated every period of approximately 200mS. However other aggregation times are defined, for example, 3 seconds and 10 minutes [5]. The measurement campaigns can last a few hours in small industries up to weeks or months in large distribution or transmission systems. Many power quality analyzers do not have processing capacity to analyze and store all power quality parameters at the same time. However, with the increasing processing capacity, more and more devices have the ability to simultaneously process and store all power quality parameters required by the standards. However, to achieve long periods of measuring, even with the increasing size of memory available, it is necessary to compress the information saved in memory. Currently, most researches and papers are focused on the compression of short sampling periods of high frequency transient signals or even in the compression of the power network oscillography. In the research weren't found any academic reference about the compression of power quality parameters, only some incomplete methods and/or patent protected methods implemented in totally different hardware targets, sampling rates, resolutions, etc, making any comparison extremely hard or in some cases no sense. https://doi.org/10.24084/repqj11.374 579 RE&PQJ, Vol.1, No.11, March 2013