## 7 Conclusions  
The paper presents a brief overview of different aspects of a hybrid microgrid, i.e., its optimization and control topologies and challenges encountered in this regard. The hybrid microgrid is the next step in the realization of a decentralized power system and smart grid paradigm. It possesses many advantages over traditional power networks due to its improved reliability, removal of multiple conversions, and ancillary service.  
In this paper, different challenges faced regarding the integration of hybrid microgrids such as operational, coordination control, regulation, lack of standards, and market awareness are discussed, and possible solutions are presented. The non-linear control of interlinking converter is of utmost significance and holds the major attention of researchers regarding the integration of microgrids. The protection of hybrid microgrids presents a major research gap, and novel techniques compromising the power quality need to be further explored in this area.  
In optimization techniques, the power flow mechanism has been the beacon of research. In power flow optimization, updated models employing improved heuristic techniques have been used to ensure optimum power flow and reduce operational costs. The uncertainties regarding the DC generators were handled using stochastic, fuzzy logic, and robust techniques. The robust techniques have been found to be comparatively more cost-effective and efficient in this field. The planning and design of the hybrid AC/DC are of utmost significance and represent the first step towards the operational optimization of the hybrid grid. Over the past few years, the research pace regarding the design and topology of the hybrid microgrid has been slow and steady, and this area highlights a great need for further research. The development of new equipment, modeling of existing equipment, and application of improved heuristic techniques for optimal planning of storage and generators are important aspects of this area. It is further required to keep in view the high integration of DC generates, non-linear loads, and plugin hybrid vehicles in the hybrid grid system to optimize the system for future needs. The droop control methods have been widely explored regarding the control strategies in power generation and sharing in hybrid microgrids. Recently the trend is also shifting towards improved droop control strategies and non-linear control strategies involving model predictive control.  
The power management schemes and the control strategies are immensely important in hybrid microgrid operation, demanding a comprehensive review of different microgrids operating under variable scenarios. It also presents recommendations about future specified directions of research in this field.  
Conceptualization, O.A. and G.A.; Data curation, M.A.; Formal analysis, G.A. and M.R.H.; Funding acquisition, M.A. and A.A.; Investigation, G.A. and M.U.; Methodology, O.A. and A.A.; Project administration, G.A.; Resources, M.R.H.; Software, A.Q. and A.A.; Validation, G.A., M.R.H. and A.Q.; Visualization, M.A. and G.A.; Writing--original draft, O.A. and G.A.; Writing--review & editing, A.Q. and M.U. All authors have read and agreed to the published version of the manuscript.  
This research is financially supported by the Deanship of Scientific Research at King Khalid University under research grant number (R.G.P.1/188/41).  
Not applicable.  
The authors acknowledge the financial support by the Deanship of Scientific Research at King Khalid University under research grant number (R.G.P.1/188/41). The authors are also thankful to the Department of Electrical Engineering, The University of Lahore, Pakistan, for providing facilities to conduct this research.  
The authors declare no conflict of interest.