The contact between an energized conductor and a low-conductivity surface can originate High Impedance Faults (HIFs). Current signals measured during HIFs have low amplitude, hindering their detection by traditional protection methods, and are usually nonlinear. Therefore, many HIF Detection Methods (HIFDMs) are based on the signals' harmonics, which have peculiar characteristics during HIFs. However, most existing HIFDMs do not consider the influence of current transformers (CTs) at the interface between the power grid and the relay during the testing stages. In this context, this paper analyzes CT's influence on the amplitude and angle of harmonics extracted from current signals measured during HIFs and on existing HIFDMs. The results demonstrate the influence of CT transformation ratio, overload factor, ratio error, and HIF incidence bus on the analyzed parameters. Thus, this paper has the goal to assist researchers in developing methodologies tested in increasingly realistic situations.
Condition monitoring (CM) and predictive maintenance (PM) techniques can provide a system to achieve a high quality of service with minimal maintenance costs. Using CM -based data, repairing assets is possible based on predictions of the occurrence of faults in assets. Underground medium voltage (MV) cables are vulnerable to deterioration due to stress factors and degradation of the insulating material that lead to cable failure. The gradual deterioration produces incipient faults that lead to MV cable breakdown if not diagnosed at early stages. Efficient diagnosis avoids unscheduled outages and partial discharge (PD) analysis is the most effective method for CM and diagnostics of MV cables. The health of the MV cable can be monitored by collecting and processing a huge amount of data. A use case is developed that shows how data is transferred using emerging technologies to the supervisory control and data acquisition (SCADA) system for diagnostic purposes.
In the world, the energy transition requires the participation of multiple disciplines and technologies. The technologies that allow the development of projects with solutions employing alternative and renewable energy sources, such as Typhoon HIL and Opal-RT, are very expensive. In countries with emerging economies, these technologies are only affordable in large universities and technological research centers, exclusively enabling them to actively participate in these transformations. Small companies do not have the economic resources to acquire these technologies, which hinders their participation. This article describes the implementation of a low-cost HIL-RT platform for testing and development in the control of small electrical microgrids located in remote regions. The platform consists of a Raspberry Compute 4 that supports the GNU Open Modelica simulator on Linux and interacts in RT with power converters that form a single-phase AC microgrid, typical of small users with domestic and agricultural loads in Non-Interconnected Zones (NIZ).
Nonlinear devices and the high penetration of inverter-based distributed generations have contributed to increase harmonic distortions in distribution systems, affecting the quality of power delivered to consumers. In this sense, determining the responsibility sharing of harmonic distortions allows the application of effective mitigating actions. Thus, the present paper aims to determine the harmonic contributions at points of common coupling (PCC). From voltages and currents measured at the PCC, a feature extraction stage was employed, where root mean square, crest factor, form factor and total harmonic distortion were calculated. These features were used as inputs to decision trees responsible to identify the contribution side (none, utility-side, consumer-side or both sides). Next, adaptive neural-fuzzy inference systems were used to estimate the harmonic contribution, if necessary, for each side. The decision trees were able to reach more than 99% of accuracy, while the neural-fuzzy systems obtained mean square errors between 1.1e-2 and 3.0e-9.
This paper proposes a framework to evaluate the resilience and vulnerability of Puerto Rico's power distribution system in the face of wind challenges. The study comprises three key components essential for achieving this objective: firstly, the paper undertakes the simulation and analysis of extreme wind events induced by hurricanes. Secondly, it puts forth parametrical fragility functions specifically tailored for utility poles, taking into account the stresses imposed by wind loads. Finally, the research endeavors to comprehensively assess the fragility and overall resilience of the power distribution network. By undertaking this multifaceted analysis, the paper seeks to provide valuable insights into enhancing the robustness of Puerto Rico's power distribution systems in the face of adverse climatic conditions.
