A Study on the Feasibility and Effectiveness of Digital Filters Approach for Power Quality Monitoring in Compliance with IEC 61000-4-7

Large scale monitoring of power quality in electrical apparatuses is nowadays a pressing need due to the liberalization of electrical market and the deeper interconnections of electrical networks. Many instruments are today available on the market. Even if they grant good accuracy and measurement capability, they are generally developed for single point measurements. Their use in large scale monitoring leads to high costs. These costs are also due to the accurate processing tasks they shall realize. In this framework research activity, the authors aim at the realization of a measurement instrument for power quality monitoring in compliance with IEC 61000-4-30 and 61000-4-7 standards capable of granting good accuracy, satisfying repeatability, and cost effectiveness since the use in large scale monitoring is allowed. In this paper the attention is paid to the measurement algorithm to be adopted. The use of alternative measurement approach respect to the FFT one is proposed. Digital filters tuned on the single spectral line, and digital filters shaped on the harmonic group are optimized thoroughly for grouping measurements required by IEC EN 61000-4-7 standard. The obtained results allowing promising development in the use of this approach.