Challenges, issues and opportunities for the development of smart grid

Received Jun 8, 2019 Revised Oct 11, 2019 Accepted Oct 10, 2019 The development smart grids have made the power systems planning and operation more efficient by the application of renewable energy resources, electric vehicles, two-way communication, self-healing, consumer engagement, distribution intelligence, etc. The objective of this paper is to present a detailed comprehensive review of challenges, issues and opportunities for the development of smart grid. Smart grids are transforming the traditional way of meeting the electricity demand and providing the way towards an environmentally friendly, reliable and resilient power grid. This paper presents various challenges of smart grid development including interoperability, network communications, demand response, energy storage and distribution grid management. This paper also reviews various issues associated with the development of smart grid. Local, regional, national and global opportunities for the development of smart grid are also reported in this paper.


INTRODUCTION
Smart grid (SG) technologies are vital to meet world's vast and growing electricity needs. Smart grids (SGs) are transforming the traditional way of meeting the electricity demand and providing the way towards an environmentally friendly, reliable and resilient power grid. Micro grids operate at the distribution level, and they are natural innovation zones for the Smart Grid (SG) because they have experimentation scalability and flexibility, and delivers power is a local area. SG contains protection against the cyber attacks, interoperability and designed for pricing in real-time [1]. Super grid is a high voltage DC transmission and capacity to minimize losses and enhance reliability. MGs operates as a standalone or as a grid-connected system. Microgrid (MG) technology is not equipped with automation and communication support. Further work is required to enhance self-healing, reconfigurable, adaptive and predictive capability. MG includes special purpose inverters enabling it to link to the legacy grid and contains special purpose filters build to overcome issues with harmonics, while improving power quality and efficiency [2]. Various characteristics of SG include optimizing the asset utilization and efficient operation is presented in [3]. Increased renewable power penetration, electricity markets participation throughout the world will realize new opportunities for the cost-effective smart grids controls and energy storage at all scales. These changes, coupled with increased consumer awareness and participation will lead to a new paradigm in energy system analysis that must also be accounted for energy security, stability and reliability. The SG will incorporates new networking technology, including controls and sensors, from this the electricity can be monitored in real time and can be made automatic changes which will reduce the energy waste [4].
The computational intelligence feature consists of advanced analytical tools that will optimize the bulk power network using heuristic, evolution programming, decision support tools and adaptive optimization approaches, are promising tools for the design and computation need of SG. Renewable energy development utilizes the variability and its usage is also technically and economically feasible to meet the shortage in demand uncertainty and also increase in reliability, reduce losses and reduce the impact of carbon foot print caused by the thermal and gas based energy sources. The development of automation, communication and standards are required to ensure fast decision making that promotes efficiency and responsible operation. These decisions are made by the utility and customers. The security and interoperability issues are also guaranteed by designing and enforcing the rules and procedures for managing, operating and marketing the SG networks [20].
Pathways for the sustainable development of SG are human development, home grown technology, role of government and scholars, interconnection challenges, technology challenges, technology in design, operation and maintenance of the plant, development of SG with distinguished architecture for supporting energy efficiency and demand supply management. In general, the main technical challenge in the power system operation in a deregulated/ competitive environment is to increase the power transfer capability of existing transmission systems to avoid congestion in the system [21]. There are several approaches have been proposed to handle this issue. Some of them include optimal power flow based generation scheduling, use of advanced technologies such as FACTS and distributed generations, and they can help to mitigate congestive network conditions on the constrained transmission path. Issues for consideration in computational challenges for the development of SG include the following factors [22]:  Penetration of renewable energy resources (RERs); bidding strategies of participants prevent companies from providing solutions with environmental goals.  High dependency of power system models on intelligent operation and control, power system planning and control prevent companies from providing solutions with technical goals.  Lack of extensive knowledge by engineers and/or operators of computational tools that are user friendly and readily interpretable.  Complexity in operation and control of power system due to the complexity in computational tools used for modeling and uncertainties.  Forecasting of load demand, price and ancillary services prevent the companies from providing solutions with economic goals.  Increased distributed generations (DGs) and demand response (DR) in electric market; and tuning of controller parameters in varying operating conditions prevent the electric utility companies from providing smart solutions with economic, environmental, and technical goals.  Risk minimization in electric power sector with investment in computational tools seeks to determine trade-off between maximizing the expected returns.
The main technical challenges of SG are interoperability, network communications, demand response, energy storage and distribution grid management. The brief analysis of these challenges has been presented next:

Interoperability
Interoperability describes open architecture of technologies and their software systems to allow their interaction with other systems and technologies. To realize the capabilities of SG technology deployments must connect large numbers of smart devices and systems involving software and hardware [23]. Interoperability is considered as one of highest priorities for the Internet of Things (IoT) systems and devices. It is important between smart objects and existing infrastructures and between smart objects from different manufacturers.
Plug in Hybrid Electric Vehicles (PHEV) is an essential part of future SG and their interoperability with SG should be checked in detail for optimization of the assets. The challenges include developing and researching smart energy management, power utilization and sharing of energy stored in batteries [3]. Advanced power electronics will be implemented at each stage of SG, and their interoperability in SG requires to be verified. Especially, disturbance and complexity they add into the system must be solved before their actual implementation [24].

Network communications
Before the SG, there was a one-way power flow and it allows a simple interactions. Whereas, after the SG, it is a two-way power flow and it allows multi-stakeholder interactions. Presently, the SG faces challenges in terms of security and reliability in both wireless and wired communication environments. Effective communications strategies are critical to successful smart grid deployments, and the substation is the heart of any power utility communications strategy. The SG domains and sub-domains will use a variety  [2]. This variety of networking environments is critical to identify performance metrics, maintain appropriate security and access controls, and validate core operational requirements of various applications, users, and domains. Synchrophasors have very wide area of applications and some of the possible benefits are not evaluated yet [3]. Especially, their benefits in protection are not discussed in detail and not tested in practical systems. So, these areas should be given emphasize for study.

Demand response
Demand response (DR) is used to reduce peak load demand and improve the system reliability in which the end users modify their electricity consumption patterns in response to price variations. DR has been used in industrial and commercial sectors for some time to increase the stability and health of electrical grid. However, with an emerging SG, the DR is now has potential to expand into residential electricity markets on a large scale. The SG adds bidirectional and intelligence communication capabilities, which enables the utilities to provide real-time pricing information to their consumers [25]. Demand response (DR) mechanisms and incentives characterize basic Smart Grid (SG) objectives for utilities, industrial, business, and residential customers to optimize the balance of power supply and load demand regardless of system size [2].
DR promotes the responsiveness and interaction of customers, and may offer a broad range of potential benefits on system expansion and operation, and on the efficiency of market. When consumers participate in DR, there are 3 possible ways in which they can change their use of electricity [26]. The demand response programs (DRPs) can be roughly classified into 3 groups according to the party that initiates the demand reduction action, incentive or event-based DR programs, rate-based or price DR programs, and demand reduction bids. The benefits are bills savings for participants and other customers, reliability benefits, improved choice, market performance, and system security.

Energy storage
SG requires a means of storing energy, directly or indirectly. The biggest challenge today for any electrical power system is an economical storage technology. Even though many good storage technologies are available but either they are not economical or they are not efficient. Additionally, penetration of this technologies and its optimal power flow has attracted many researchers. Research studies have analyzed the application of energy storage with respect to voltage support, peak shaving, frequency stability, renewable firming, transmission upgrade deferral, and a host of other uses. Among the all possible generation facility only hydro and thermal can accommodate sudden higher production up to certain extent. Nuclear power plant generates constant power and renewable energy resources are dependent on the climate conditions for the output. Therefore, an efficient storage technology is very important part for reliability of electric power system. There are different storage options available, i.e., Hydrogen storage, batteries, superconducting magnet energy storage (SMES), flywheel, compressed air, pumped hydro etc. They have their own advantages and disadvantages. So, storage technology to be used for particular application chosen accordingly [27]. Many researchers are also proposing hybrid approach of using one or more technology altogether. Batteries and other energy storage technologies are required for the successful incorporation of increased levels of RERs into electrical grid. Storing electrical energy was significantly inefficient and costly, but in contrast, it has high market demand. With the recent developments in converter technologies and different chemical and nano-technologies, energy storage systems have developed into economically viable and relatively efficient than earlier.
Usually battery energy storage systems (BESSs) are result of electrochemical processes, DC-DC converters and DC-AC converters. Electrochemical process require electrolyte, anode and cathode, where anions and cations interact. It also consists of power conditioning system with converters, power absorption/ injection of BESS. A variety of technologies of battery cell, include lead-acid, lithium-ion, zinc air, nickelcadmium, etc. Lead acid batteries have been using from last few decades and they are well suited for various on-grid applications. They are robust and less sensitive to application conditions, and they have low cost per kWh [28]. Lithium-ion battery is one of the most widely applied battery technologies for ESSs, but their cost is approximately $ 1/Wh, makes them to the slot of most expensive of battery technologies.
Mechanical energy storage includes a dynamo and flywheel. The principle of pumped hydroelectric storage technology is use up level water reservoir to store energy. The main advantage of it is has a very large energy storage and long lifetime. They can be readily used the energy management, frequency control and reserve provision. ESS selection is based on the certain parameters.  Fly-wheel Based ESS: In this ESS, the energy is stored in the form of kinetic energy. Life cycle of 10,000 cycles, it has relatively low energy density of approximately 20Wh/I, used for stationary applications.
Here, the permanent magnet electric machine or induction machine is used. It has fast dynamic response, high self discharge rate, long life span, high power, energy density, high cycling rate, and has high energy conversion efficiency. The efficiency of flywheel technology is about 99%, and it is one of the large scale ESS. It is ideal for primary regulation purposes [29].  Hydrogen Based ESS: In this ESS, the electricity is generated through reverse electro-chemical reaction within fuel cell. It has the life cycle of 20,000 cycles, Hydrogen can be stored for long period, it has low efficiency of around 50%, it has adequate dynamic response, and has no emissions as only water is the by-product.  Thermal ESS: This storage system stores the thermal energy converted from electric energy during the off-peak hours. This system consists of heating/cooling setup, storage heat exchanger, air handling unit. This charging can be done locally or centrally, and the load shifting is also available in this storage system [30]. The advantages of this ESS is the large storage capacity, rapid response rate and frequency regulation. Also, the efficiency close to 100%. Therefore, depending on the different criteria related to functional, technical and economic various load demand can be served. Magnetic coils, super capacitors and super conductors are very costly and are not widely adopted in ESS [31].

Distribution grid management
Distribution Automation (DA) devices are robust and reliable, act as a source of planning data and offer higher computing power. DA is the atomization of the whole distribution system. Therefore, the devices like Phasor Measurement Units (PMUs), Remote Telemetry Units (RTUs), Supervisory Control and Data Acquisition (SCADA), Energy management system (EMS), smart meters and Distribution management system (DMS) are used in distribution system [32]. The DA schemes for electrical power distribution systems is depicted in Figure 1. Intelligent grid automation has several advantages such as network restoration/switching, optimal operation, distributed generation for emergency use (through intelligent controls and demand reduction), distribution system management (DSM), fault and stability diagnosis, self-healing, network switching and control, i.e., intelligent control schemes and device management, and reactive power control by managing the control coordination. The part of electrical power system involves the delivery of energy to consumers and the associated features. DA deployments highlighted several continuing challenges for grid modernization [33]:  Improved cyber security and interoperability standards, protocols, tools, and techniques for safe, rapid, and cost-effective DA implementation.  Faster simulation methods and more robust control approaches to operate modern grid systems with large amounts of variable generation.  High-resolution, low-cost sensors that report real-time conditions along feeders to enhance distribution system operator visibility beyond the substation assets.  Integration between smart grid DMS and Distributed Energy Resources Management System (DERMS).

Local opportunities for SG development
The basic research and development and the fundamental technologies that will move the SG forward are as follows:  Integrated Communications: To connect the components to open architecture to drive the real-time control and information allowing each and every part of electrical grid to both "talk" and "listen" at the same time.  Advanced Control Methods: To monitor essential components that enable rapid diagnostics and precise solutions appropriate for any event.  Sensing and Measurement Technologies: To support more accurate ad faster responses, like time-of-use pricing, remote monitoring, and demand-side management.  Advanced Components: To apply recent research in storage, superconductivity, power electronics, and diagnostics.

Regional and national opportunities for SG development
Before looking at the particular technologies for moving forward, the government and utilities have shared input about basic functions they require of the smarter grid. The opportunities for regional and national level include the features, such as resist attack and self-healing, provide higher quality power that will save money lost on outages, motivate consumers to actively participate in grid operations, and accommodate all generation and energy storage options.

Global opportunities for SG development
The global energy challenges that are policy and technical will require efficient analysis for the SG to operate the grid more efficiently, enable electricity markets to flourish and also enable higher penetration of RERs.

CONCLUSIONS
This paper has presented a detailed review of challenges, issues and opportunities for the development of smart grid (SG). The main issue with smart grid is adoption and lack of awareness of those standards by people involved in designing the SG systems. Another challenge is to integrate the interchangeable parts from a variety of different providers throughout the world, i.e., standards and interoperability. Various challenges for smart grid include the capturing the benefits of storage, distributed generation and plug-in hybrid electric vehicles (PHEVs), enhanced intelligence and communications, integrating intermittent renewable power generation, and strengthening the grid. From this paper, it can be concluded that the smart grid has numerous issues and challenges that need to be handled, but there is a great opportunity to explore it. Smart grid technology will help to save money, reduce demand, and improve reliability and efficiency.