# Cybersecurity of Microgrid: State-of-the-Art Review and Possible Directions of Future Research
## 2 The Microgrid Architecture  
To understand the threats posed to and vulnerabilities of microgrid electrical systems, this section provides a quick overview of the elements and components of a microgrid. A considerable number of studies have affirmed that the operation and data processing, transmission, and storage of microgrids must be secure to achieve reliable control [10; 11]. The fundamental elements and components of a microgrid are discussed below. The reference architecture of microgrid used in this research is given in [12]. To discuss the cybersecurity aspects of microgrid, the components of microgrid are categorized into four enclaves based on their functions: (i) distributed generation (DG) sources, (ii) energy storage, (iii) the distribution system and (iv) control and communication modules., as depicted in Figure 1.  
The description of every enclave is given below:  
* Enclave 1: DG sources DG source refers to technologies that generate power such as:
* Generator One of the sources of energy to a microgrid is the synchronous generator. Most of them are powered by natural gas or a diesel engine designed for stand  
Figure 1: Microgrid architecture with enclaves. alone or backup applications. A generator has two control algorithms, namely, an (1) exciter, which handles the voltage of the generator, and the (2) reactive power generator that is commonly used to minimise power loss and improve the voltage profile of power systems. Natural gas turbine The natural gas turbine is categorised based on the drive type, into single shaft and two shaft. The single-shaft light is generally used in microgrid systems as a distributed resource. To enhance the response speed, the governor control system uses an electronic control system. The gain and time are constantly monitored to achieve a reasonable response. Renewable energy source Renewable energy plays an essential role in maintaining the sustainability and survival of the microgrid. The prevalent sources of renewable energy are wind and photovoltaic. They are connected to the microgrid system through current-mode inverters, and can be operated at the maximum power point. (B) Enclave 2: Energy storage The reliability of the operations, power generation, and load stabilisation of the microgrid is ensured through a sophisticated storage management system, an indispensable element of the microgrid. Disturbances in power supply may occur in the grid due to variations in the load in terms of a mismatch between load generation and load time. Mechanical wear and failure of the battery are some other causes of a terminal voltage fault. Energy storage in microgrid architecture refers to devices that perform the following functions [12]: (a) Balances the power in microgrid despite of load fluctuation and other transients. (b) Provides ride-through capability and allows DGs to operate as dispatchable units during dynamic variations in intermittent energy sources. (c) Provides the initial energy during the transition between grid connected or/from microgrid island. Maintaining the stability of the microgrid is a challenging task because the system has various types of distributed generation, and demands for reactive and active power based on the needs of customers. Thus, the energy storage management system of the microgrid plays a vital role in stabilising its frequency and voltage for both the short and the long term [13]. The energy storage is connected to the grid through a micro-source, and absorbs power via the electronic converter. Subsequently, the energy storage exports power to the network in the island mode, enhancing the system's quality and stability [14]. The energy storage can be distributed via two applications: utilisation-scale and small-scale applications. Other than maintaining the management and control function of the storage device, the distributed energy storage system can help maintain maximal system safety, efficiency, and life.