Estimação da impedância de transferência baseada em ICA para redes com múltiplas fontes harmônicas

Abstract

Currently, the increasing use of nonlinear loads and power electronics-based equipment has significantly contributed to the rise of harmonic distortions in electrical signals. This continuous growth in harmonic distortion levels in distribution electrical networks has raised serious concerns for both utilities and system customers, as the presence of these harmonic sources can compromise the efficiency of energy generation, transmission, and utilization. Traditionally, the analysis of harmonic distortion contributions at a specific point in the electrical system is conducted by considering only the contributions from the load side and the main source side. However, for a more accurate and reliable evaluation, it is essential to quantify the individual contributions of different harmonic sources. In this context, this paper presents an innovative methodology to estimate harmonic transfer impedances in power systems with multiple harmonic sources. The objective is to determine the responsibility of each harmonic source for the total harmonic distortion at a specific bus within the system, addressing a critical issue in the field of power quality. To achieve this objective, it is necessary to estimate not only the individual harmonic sources but also the transfer impedances between each source and the bus under analysis. Most methods to solve this problem rely on proper network modeling or restrict harmonic source variations to a single source at a time. The proposed methodology overcomes this limitation. For this purpose, synchronized current and voltage phasors are measured at the bus under analysis. After collecting the measurements, the Independent Component Analysis (ICA) method is applied to estimate the Norton equivalent. The harmonic transfer impedance is then determined using the information provided by ICA. To enhance the accuracy of harmonic transfer impedance estimation, three procedures are employed to analyze the data of the parameters provided by ICA over time, generating a well-conditioned system. Once the harmonic transfer impedance is satisfactorily determined, the individual harmonic contributions, i.e., harmonic responsibilities, can be accurately estimated. The effectiveness and performance of the method are demonstrated through computational simulations applied to distribution and transmission systems. Furthermore, the methodology is validated using real data collected from a Brazilian transmission system monitored by synchronized power quality measurement units. The simulated results show that the Total Vector Error (TVE) is less than 0.4%, and for the real data test, the TVE is less than 2%.