Smart Grid is sophisticated, digitally enhanced power systems where the use of modern communications and control technologies allows much greater robustness, efficiency and flexibility than today’s power systems. The American Electric Power Research Institute (EPRI), an advocator of building the smart grid, gave this grid a definition with self-healing, security, integration, collaborative, forecast, optimization and interaction. While European commission define it as : A grid which could support distributed and renewable energy access, supply more reliable and secure electricity, have a service-oriented architecture and flexible grid applications, possess an advanced automation and distributed intelligent, be able to local interact the load and the power, adhere to customer centric. Obviously, these definitions has been formulated for the future of power industry mainly focusing on world today’s energy generation, transmission, distribution limitation & changing consumer trends. Recently world has observed a series of blackout, partial power failure and this compelled the world’s nations to go for an ideal grid system that is smart enough to face such kind of challenges. This has resulted the unification of power system with the information technology & modren telecommunition setup. And SELF HEALING become the key component of smart grid, as smart grid should possess an intelligent control funtion, which could rapidly isolate and self recover the fault, prevent the occurance of balckout and improve the reliability of grid operation with minimum human intervention & consume distributed generation too.
An especially illuminating event occurred in 1879 when Thomos Edison invented what is considered to be the precursor of modern light bulb. Three years later, in 1882, he flipped the first switch on the first electric grid in lower Manhattan. In less than 100 years, electricity became widely available. It is now delivered by means of expensive electrical grids on every continent on Earth, and is integral to various satellites that orbit her. In the decades following this tremendous achievement, however, much of the electrical grid has grown old and outdated. Sadly, Edison would recognize much of the today’s installation. Too often, we find ourselves looking ahead toward the next technological evolution while our infrastructure is more than a century old. This over exhausted and inefficient electrical grid has left the world susceptible to security threats; inhibited alternative energy/ conservation goals; and contributed to reliability goals such as power quality disturbances and blackouts. Smart grid is the solution we desperately need to solve many global energy problems. It is changing the way we think about and interact with our electrical grid.
Today’s transmission grid was designed with many self-healing features. Auto‐reclosing and auto sectionalizing are common techniques employed to maintain service under adverse conditions. The mesh network design of the transmission system is inherently self‐healing due to its built‐in redundancy and such protective relaying features as high‐speed reclosing and single‐phase tripping. System planners have historically modeled the transmission system to verify that, under a normal system configuration, assumed loads could be met even during expected peak conditions. In addition, planners ensured that these same loads could be met even with the failure of single, and in some cases, multiple lines or components. Sophisticated protective relaying schemes are in place to monitor system conditions and take corrective action should specific parameters exceed limits. Transmission lines and equipment are relayed out (opened) when conditions require. Most loads normally are not impacted by a single transmission line fault because the system can tolerate such a contingency. Substation...