Smart Grid1. Concept of Smart GridSmart Grid is basically an intelligence added to the power grid by enabling bidirectional flow of information through supporting communication infrastructure. Thus, Smart Grid is interconnection of communication and information systems, modern technologies along with control and automation process across entire electricity sector comprising of generation, transmission, distribution and the consumer. The aim of smart grid is to make existing infrastructure more robust, reliable and efficient by using intelligent tools and technologies, encourage active demand side participation, ensuring sustainability of supply through renewable integration, promoting green and clean environment and provide incentives for efficient production, transmission, distribution and consumption of electricity across the value chain of electricity.

Figure 1: Smart Grid NetworkThe Key features that may be offered by a Smart Grid include: Extensive real time observability in the network enabled by bidirectional communication between utility and consumers Easy programmability for utility as well as consumer to optimize consumption pattern Extensive participation of different stake holders in real time energy market Stable, reliable and self-healing grid. Easy integration of renewables at distribution level; enable islanded operation Real time energy audit and fault clearance Increased utilization of power infrastructure without risk of overloadingThe benefits of a Smart grid have been described in the following table.Benefits of Smart Grid

AreaBenefits

Improved reliabilityUtility: Reduced operational cost Increased employee & customer safety Increased revenue

Consumer: Improved level of service with fewer inconveniences Reduced out-of-pocket costs resulting from loss of power

Society: Virtual elimination of blackouts Improved infrastructure boosts economic development

Improved EconomicsUtility: Increased revenues as theft of service is reduced A flatter load profile will reduce operating and maintenance (O&M) costs Improved cash flow from more efficient management of billing and e revenue management processes

Consumer: Downward pressure on energy prices and total customer bills Opportunity to interact with the electricity markets through home area e network and smart meter connectivity Opportunity to sell consumer-produced electricity back to the grid Huge savings by eliminating the need for DG backup

Society: A more robust transmission grid will accommodate larger increases in wind and solar generation i.e. green energy Creation of new electricity markets enabling society to offer its electricity resources to the market and creating the opportunity to earn a revenue stream on such investments as demand response, distributed generation, and storage

Improved EfficiencyUtility: Increased asset utilization Reduction in lines losses on both transmission and distribution Reduction in transmission congestion costs Reduced use of inefficient generation to meet system peaks

Consumer: Increased capability, opportunity, and motivation to be more efficient on the consumption end of the value chain Increased influence on the electricity market

Society: Deferral of capital investments as future peak loads are reduced Reduced Energy losses

Improved EnvironmentUtility: Increased capability to integrate intermittent renewable resources Reduction in emissions as a result of more efficient operation, reduced system losses, and energy conservation Increased capability to support the integration of electric-powered vehicles Reduction in frequency of transformer fires and oil spills through the use of advanced equipment failure / prevention technologies

Consumer: Increased capability, opportunity, and motivation to shift to electric vehicle transportation Increased opportunity to purchase energy from clean resources, further creating a demand for the shift from a carbon-based to a green economy

Society: Reduced CO2 emissions Improved public health

A brief description for the attributes of Smart Grid that help in harnessing the benefits including those mentioned above is being provided in the following sections.2. Attributes of Smart GridAs mentioned before, a smart grid network imparts intelligence based on the Information and Communication Technologies (ICT) colocated with the power system elements. Hence, Smart Electricity Meters serve as the building block of a smart grid. Once the complete communication infrastructure is made available and the smart meters at consumer premises and distribution transformer level start communicating with the utility control centre in real time, various programmable features, auditing, dash boards etc. may be developed. The fundamental attributes of such a network are as follows:2.1 Advanced Metering Infrastructure (AMI)AMI requires installation of smart meters having two way communications with control centre. The energy consumption data from DT and Customers is sent at one-defined duration to control centre which could be audited to regulate theft & pilferages and also help in automatic billing. Through these meters various signals for demand response, load dis/re-connection, operation of critical & non-critical loads alerts can also be sent from control centre to consumers and Vice-versa. Tampering events are reported on-line to control centre. An AMI system is comprised of a number of technologies and applications that have been integrated to perform as one: Smart meters Wide-area communications infrastructure Home (local) area networks (HANs) Meter Data Management Systems (MDMS) Operational Gateways

Figure 2: Scheme for AMI2.2 Outage Management System (OMS)To increase reliability of the power supply and reduce outage frequency & duration, Outage Management System is installed. The system is integrated with other systems, and ensures that as soon as the outage is reported or detected, it predicts the fault location, identifies the consumers affected and initiates consumer interaction, until the outage is restored. The intelligent system suggests network reconfiguration options to the operator immediately to restore as many consumers as possible. Meanwhile, the maintenance crew management system dispatches maintenance team directly to fault location. Also various monitoring devices are installed which helps in checking healthiness of lines & distribution transformer to enable predictive maintenance practices. A complete Outage Management System comprises of the following elements: Field devices like Fault Passage Indicators (FPI), Distribution Transformer Monitoring units (DTMU), remote terminal units (RTUs and FRTUs) etc. Smart switching devices such as auto reclosures, sectionalizers, Ring Main Units (RMUs) etc. for network reconfiguration and self-healing. Softwares for OMS, crew management etc integrated with the SCADA.The basic configuration and integration scheme for OMS is shown in Figure 2

Figure 3: Outage Management System Integration Scheme2.3 Peak Load Management (PLM)Peak Load management is one of the Smart grid initiative through which utility can reduce the peak demand. This plays significant role in reducing the purchasing cost of power. By managing load at the peak timing utility can minimize its Unscheduled interchange (UI) and higher purchasing cost of power at peak time. The goal of peak load management is to encourage the consumer to use less energy during peak hours, or to move the time of energy use to off-peak times such as night-time and weekends. It is the modification of consumer demand for energy through various methods such as financial incentives and partial curtailment. Figure 3 shows the peak load shifting. Peak Load Management works in two ways:a) Demand Response: Consumers are motivated to shift there load voluntarily by implementing Dynamic / ToU pricing.b) Demand Side Management: Consumer load is segregated as critical / non critical and during peak hours, if the consumer load is beyond a settable limit the switch for non-critical loads is open. Thus, the utility owns the switch in demand side management.

Figure 4: Peak Load Management2.4 Renewable Integration Apart from technical challenges for integration of Distributed Generation (primarily solar PV) in the distribution network (modified protection schemes, anti-islanding, voltage stability etc.), Smart Grid encourages consumers to participate in RE generation through commercial mechanisms such as net metering. Net metering (i.e. Import Energy Export energy) is a facility available in Smart Meters. When installed at consumers premise having distributed renewable generation resources like rooftop solar PV etc., it facilitates metering of import energy from distribution grid (in case consumption is higher than own generation) and export of energy to distribution grid (in case own generation is higher than consumption) and net is recorded. Schematic of net metering arrangement is shown in Figure 4 below.

Figure 5: Net Metering Arrangement2.5 Power Quality Management (PQM)Power Quality Management attribute of Smart Grid takes care of Harmonics & Voltage quality of the system. Voltage profile & Harmonics of the system are continuously monitored. Active Harmonic Filter, Var Compensator, Surge suppressors etc. installed in the system to take any remedial action if power quality deviates