## 2 Recent Trends in DC & Hybrid Microgrids
This issue is even more critical when the CPL is potentially fed only by the battery, causing the DC bus to float. A valuable method for studying the system stability of DC microgrids feeding CPLs is the Lyapunov theory, which demonstrates how the region of asymptotic stability (RAS) shrinks, as the state of charge of the battery diminishes and the bus voltage decreases. Once the accuracy of the RAS is validated by comparing it to the real basin of attraction (BA) and numerically derived using continuation methods, a smart power management of the CPL is proposed in the paper to preserve the system stability, even in presence of a low bus voltage. As discussed in the paper, a suitably designed criterion for limiting the load power can guarantee the invariance of RAS and BA for each equilibrium point. An electric vehicle was also used in the paper as particular DC microgrid component for evaluating the performance derating given by the power limitation. The seventh paper [7], entitled \"Multidimensional Optimal Droop Control for DC Microgrids in Military Applications\", is by [PERSON] at al. from the USA, from the Department of Electrical and Computer Engineering, Michigan Technological University in Houghton; the Rocky Mountain Institute, Boulder; and the Department of Mechanical Engineering and Engineering Mechanics, Michigan Technological University. The paper deals with reliability issues of microgrids when they are used for defense applications. Droop control provides a simple option without requiring communication between microgrid components, increasing the control system reliability. As discussed in the paper,traditional droop control does not allow the microgrid to utilize much of the power available from solar renewable sources, such as a photovoltaic resource. The paper shows the application of an optimal multidimensional droop control strategy for a solar resource connected in a microgrid at a military patrol base to solve this issue. The paper reports simulation and hardware-in-the-loop experiments of a proof-of-concept microgrid to show that much more power from the solar resource can be utilized, while maintaining the system's bus voltage around a nominal value, and still avoiding the need for communication between the various components. The last original research paper of the special issue [8], entitled \"Energy Management Strategy for Rural Communities' DC Micro Grid Power System Structure with Maximum Penetration of Renewable Energy Sources\", written by [PERSON] et al., it is a collaborative work by three research groups from the Department of Electrical and Electronics Engineering, SRM University, Chennai, India; the Faculty of Engineering, \(\O\)stfold University College, Norway; and the Department of Energy Technology, Aalborg University, Denmark. Regarding classic AC grid with power distribution to many DC loads, DC microgrids are suitable to provide high efficiency, consistency, reliability, and load sharing performance, particularly when interconnected to DC renewable and storage sources. The main control objective for any DC microgrid is providing proper load-power balancing based on the distributed generator sources. Due to the intermittent nature of renewable energy sources, batteries play an important role in load-power balancing in a DC microgrid. State-of-the-art energy management strategies may be able to meet the load demand, but often such techniques are not suitable for rural communities. To solve this issue, the paper proposes an energy management strategy (EMS) for a DC microgrid to supply power to rural communities with solar, wind, fuel cell, and batteries as input sources. The proposed EMS performs the load-power balancing between each source (renewable and storage) in a DC microgrid for dynamic load variations. The EMS proposed in the paper, which manages two battery sources, is capable of achieving load-power balancing using renewable energy sources with less consumption than non-conventional energy sources such as a diesel generator.