Advanced Coordination Method for Overcurrent Protection Relays Using New Hybrid and Dynamic Tripping Characteristics for Microgrid

Abstract

Nowadays, the Overcurrent (OC) and Earth Fault (EF) relays coordination problem is one of the most complex and challenging concerns of power protection and network operators due to the high and volatile generation capacity of renewable energy sources in the grid. In this article, a new and dynamic optimal coordination scheme based on a novel hybrid tripping characteristic has been designed and developed for Over Current Relays (OCRs). Considering the impact of renewable energy sources such as the photovoltaic (PV) system on fault characteristic, this work presents and verifies a novel dynamic and hybrid tripping to achieve minimum tripping time and improve the OCR and EF relays coordination performance in terms of security, sensitivity, and selectivity. The proposed dynamic and hybrid scheme will help the OCRs to cover the EF events, and it has been tested under different fault scenarios compared to the literature. The IEEE-9 and IEEE-33 bus systems are implemented in the ETAP package to validate the effectiveness of the proposed hybrid characteristics against traditionally well-established IEC characteristics. Furthermore, the performance of the proposed advance and dynamic protection approach which doesn't require a communication infrastructure is investigated for a power network with PV plants under different grid operation modes and topology to provide more robustness protection system. The results, as presented using Industrial software (ETAP), showed that the novel dynamic and hybrid tripping scheme improved the speed of the total time tripping different fault scenarios and location by more than 50% and covers all EF events compared to traditional OCR schemes from the literature. The proposed novel dynamic approach has superior performance in detecting high-impedance faults and significantly reducing the tripping time on the IEEE 33 bus network by 47%.INDEX TERMS Over current relays, Earth fault relay, Dynamic coordination scheme, Renewable energy sources, PV.

Propagation Mechanism and Suppression Strategy of DC Faults in AC/DC Hybrid Microgrid

“…As the non-periodic components of the current decay, the three-phase current exhibits a sinusoidal symmetric waveform in a steady state. The calculated and simulated current amplitudes under steady-state conditions are 67.24 A and 65.5 A, respectively, with an error of 2.66%, which generally conforms to the current expression in Equation (25). The waveform of phase A fault current when a single-pole ground fault occurs in the DC sub-grid is shown in Figure 17.…”

“…Furthermore, researchers are investigating fault current mitigation strategies that involve the coordination of protective devices [25][26][27][28], such as circuit breakers and fault detection systems, to improve the speed and accuracy of fault detection and isolation in DC sub-grid systems. Through integrating intelligent protection schemes and communication technologies, researchers aim to enhance the reliability and safety of hybrid AC/DC microgrid systems by effectively suppressing fault currents and minimizing the impact of DC grounding faults.…”

Protection Coordination of Photovoltaic Power Plant in the Time Domain

“…Research on short-circuit current flows (maximum and minimum) through the contribution of the power plant and the grid is used to adjust overcurrent protections (I>, I>>) in any configuration, ensuring the achievement of basic requirements set for each short-circuit protection and efficient separation under inappropriate conditions of parallel operation of the grid and the power plant [16][17].…”

Setting and Coordination Strategy of Over Current Relays in Medium Voltage DNs with DG Integration

“…, denoted as the discrimination margin time (DMT) or for a breaker-breaker scenario, is the combined result of , °, and , measured in seconds. As per IEEE-242, this interval is commonly approximated in research to fall within the range of 0.2 to 0.5 seconds [26].…”