Direct current (DC) microgrid control in the presence of electrical vehicle/photovoltaic (EV/PV) systems and hybrid energy storage systems: A Case study of grounding and protection issue

Abstract

In recent years, the interest in using DC microgrids has greatly increased due to their higher efficiency, less complexity, and greater transmission power compared to AC microgrids. To address challenges in DC microgrids in the presence of electrical vehicles (EVs) and the uncertainty of charging EVs, researchers have used PV/EV combination systems with energy storage systems (ESS). Controlling DC microgrids, including PV/EV/ESS, is crucial to cope with the existing challenges. On the other hand, the research on DC microgrids' protection systems is in the early stages, and there are still many challenges in this field. In addition, differences in control systems can pose different challenges for the protection system. The simulation results in this paper demonstrate that considering the best case (use of unipolar resistance grounding system) the DC bus voltage is improved by 22.3% (based on MAPE% data comparison). In the protection part, the empiricalmode decomposition (EMD) method and selecting a suitable intrinsic mode functions (IMF) have been used to protect the DC microgrid. The proposed protection method has been tested under pole-to-pole and pole-to-ground fault conditions. The results show that the proposed method is capable of detecting various fault types in the studied microgrid.

Enhanced Fault Detection and Localization Strategy for High-Speed Protection in Medium-Voltage DC Distribution Networks Using Extended Kalman Filtering Algorithm

“…Reference [13] introduced a fault detection method for DC microgrids with electric vehicles and energy storage, combining dynamic mode decomposition and instantaneous frequency calculation using voltage and current signals to minimize transient effects. Similarly, authors in [14] suggested a fault detection technique for DC microgrids, merging dynamic mode decomposition and instantaneous frequency calculation from voltage and current signals to reduce transient impacts. Reference [15] presented a fault detection technique based on Teager energy on DC current signal at line ends.…”

“…The equations are repeatedly applied at each time step to update the state estimate based on new measurements to generate CR. Secondly, another index named DCDF is computed using eq (14). It is just similar to conventional total harmonic distortion.…”

Minimizing Voltage Ripple of a DC Microgrid via a Particle-Swarm-Optimization-Based Fuzzy Controller

“…This training improves the performance of the traditional fuzzy controller by considering the goals defined in the objective function. Additionally, unlike other papers that used EV batteries as energy storage in DC microgrids [37], this study considers the battery charge and discharge to lower its wear and tear. This consideration plays a crucial role in increasing battery lifetime, addressing a limitation overlooked in prior research involving EV batteries.…”

Fault Detection in a Single-Bus DC Microgrid Connected to EV/PV Systems and Hybrid Energy Storage Using the DMD-IF Method

“…Most of the existing methods use the current signal for fault detection or, like differential methods, need to create high-speed communication links for fault detection [40]. The use of the current signal alone can reduce the accuracy of the protection systems or improper performance during the creation of various transients, especially the transients created by the control system [41]. Using methods with communication links or multiple IEDs to protect a DC microgrid, although solving this problem, will increase the operating cost of DC microgrids, which is one of the most important obstacles in the expansion of DC microgrids.…”