The objective of this Doctorate Thesis is to provide a framework for developing and testing modular, fast-acting, coordinated, real-time, power control methodology which can be extended to myriad of Hybrid Power System (HPS) applications. End goal of such hybridization is to offer grid stability, resiliency, higher efficiency and smaller carbon footprint. As the variable energy sources become predominant in the energy mix, power system stability and resiliency have become the topics of prime research. Grid connected or island systems face similar challenges for multiple applications like frequency control, economic dispatch, peak shaving, black start or spinning reserve. Grid stability is interlinked with grid inertia and the reaction time of an electrical power network. We have studied an island microgrid application consisting of a BESS (Battery Energy Storage System) and Gas Turbine Generator (GTG) system used for spinning reserve application. In this research we present the integrated architecture of Hybrid Power System and determine the control algorithm for such operation. We ascertain the response time for the power system, ensuring there is enough spinning reserve available on the grid for smooth operation of the plant. Later these results are verified through the theoretical framework of Rate of Change of Frequency (RoCoF) and physical testing through Hardware in-the-Loop simulation (HIL). The modular design of the control algorithms should allow a variety of new and existing Distributed Energy Resources (DERs) in the 1‐20 MWe size range to adopt the technology. To accomplish this objective, a Hybrid Power System is modeled and simulated on Controller Hardware in Loop (CHIL) simulator and various operating scenarios and plant disturbance conditions are tested to validate the design. A market assessment of the proposed hybrid power system is also reviewed highlighting the technical challenges, policy issues, economic and market benefits to global plant operators and the larger electric grid. Scope: In this dissertation, a Hybrid Power System (HPS) consists of Gas Turbine Generator (GTG) and a Battery Energy Storage System (BESS). It is assumed that Battery Storage could be charged through GTG or if the site had a provision, it could be charged through feature specific, renewable energy resources like PV or Wind. Test Bed: This dissertation was completed through the implementation of control algorithms developed using Rockwell® Programmable Logic Controller (PLC) and validation of the various operation modes of the Microgrid were performed on Typhoon® Hardware In Loop (HIL) simulator. As a final step the simulated test results were also validated on actual test facility consisting of GTG and BESS. The proposed hybrid power system technology and control methods will provide an effective solution for islanded microgrids and grid operators looking to strengthen grid stability with lowest emissions. Chapter 1 provides the introduction of Hybrid Power System (HPS), this is further expounded in Chapter 2 highlighting the proposed system description, followed by its architecture and applications. Chapter 3 builds upon the spinning reserve application and concepts of grid inertia. We later discuss the control algorithms used to optimize the operation and provide a theoretical framework for calculating system reaction time. In Chapter 4 we layout the building blocks of modelling. In Chapter 5 theoretical calculations of reaction and response time are validated by Hardware In-the-Loop-Simulation(HIL) and loop back dynamical simulation assuring reliable operation of the proposed hybrid power system. The results of these simulation runs are discussed in Chapter 6. Policy potential for this technology adoption is addressed in Chapter 7. Finally, the data from HPS model is validated through field testing and conclusion is provided in in Chapter 8 of this dissertation.