This study presents the preliminary results of a new methodology for detecting high‐impedance faults in distribution systems based on interharmonic signatures. The methodology involves incorporation of an interharmonic current analysis system into a conventional protection system, such as automatic reclosers and sectionalisers. To check the functionality of the proposed methodology, the authors carried out field tests on different types of soil, involving instantaneous current waveform measurements during the occurrence of faults. The results suggest that the methodology, based on interharmonic currents produced by variations in electric arc length during the occurrence of high‐impedance faults, shows great promise when it comes to detection of the disturbance.

This paper presents an analysis of the fault current contributions of small‐scale single‐phase photovoltaic inverters under grid‐connected operation and their potential impact on the protection of distribution systems. To conduct this analysis, an autotransformer‐based voltage dip generator is proposed as a means to test the photovoltaic inverters' contribution to short‐circuit currents. Laboratory tests are then performed to obtain the short‐circuit current contribution of eight single‐phase photovoltaic inverters. Using the short‐circuit current data obtained, a behaviour model is developed and simulated on Matlab‐Simulink. The model is then applied to a real distribution system and case studies are conducted to simulate the potential impacts on the protection system. Results indicate that while the massive penetration of small‐scale single‐phase photovoltaic inverters can alter the protection system's operating time, the impacts are not significant. Only in very specific scenarios, such as events related to high impedance faults, some impact can be observed. In these situations, the presence of photovoltaic inverters further complicates the already difficult task of identifying high impedance faults through conventional overcurrent protections. This study provides valuable insights into the integration of photovoltaic inverters into distribution systems, and can aid in the development of effective protection measures for future grid designs.

This research aims to quantify the skin effect and estimate expressions that well represent the phenomenon for harmonic power flow studies. The primary focus is to validate the behavior of the skin effect at harmonic frequencies ranging from 60 Hz to 960 Hz, while considering various amplitudes of electric current. The investigation not only examines the measurement of the skin effect, but also considers the temperature of the tested conductors, aiming to analyze the increase in resistance resulting from temperature rise and resistivity changes. The measurement outcomes demonstrate notable increments in electrical resistance, with resistivity increases of up to 1.9% observed throughout the measurement process. Finally, based on the results obtained through laboratory measurements, mathematical expressions were estimated as a function of frequency. In order to evaluate the simulation time reduction by the proposed expressions, OpenDSS (version: 9.4.1.2; Electric Power Research Institute, Knoxville, TN, USA) software was used, which aims at quantifying the impact of the skin effect on the technical losses. The results from these simulations demonstrate that the proposed expressions to account for the skin effect in conductors reduce the simulation time by around 17% for harmonic power flow.

Considering the guidelines contained in documents such as the IEEE Standard 519 and IEC 61000-3-6 that includes, among other indexes of power quality, the thematic of the harmonic distortion, the mentioned text refers to issues associated with definitions, measuring procedures, reference values, etc. Taking under consideration these determinations, and recognizing that the mitigating solutions for the adequacy of performance indexes involve significant financial costs, the proposition of finding ways to determine the responsibility for possible violations of pre-established limits for harmonic distortion arises. Among the proposals found to detect the contribution portions coming from the supplier and the customer, it is noteworthy that, in general, the methodologies based on principles use the frequency domain harmonized with the superposition of effects. Despite the simplicity of this procedure, it is emphasized that it relies on measuring information and on the previous knowledge of the equivalent harmonic impedances of the utility and customer, whose information are of difficult access. In this context, this paper is focused on a feasibility proposition to solve the above mentioned difficulties in obtaining the percentage of responsibility between the parties.