Imagine a battery, a couple of wires and a lamp. That, in a nutshell, is a full electrical system. You have the power generation and storage (battery), the transport (the wires) and the user (the lamp). Nothing can be easier. There is a perfect balance between production and consumption.
In a reality, electrical systems are a tad more complicated. You have millions of users, each one with different demands and patterns, meshed transportation networks and a variety of power generation methods (plants) with big issues in capacity storage.
Electrical companies have to juggle production, transport, storage and usage to make everything balance perfectly ensuring availability and quality (constant voltage independently of the demand).
Being old as I am I remember the kitchen lamp dimming from time to time as result of lower voltage (as production did not matched demand) and the not so infrequent power outages fifty years ago. Now, these failures are so unusual that we have taken for granted the continuous availability of electrical power and we perceive it as something "easy", which is not.
As time goes by, electrical systems are becoming ever more complex (not complicated) and balancing production with usage more and more difficult. And yet, all of us expect seamless, perfect service.
The power production plants are becoming both more powerful (but not that much more than in the past decades) and varied in types (clean coal, gas, oil, nuclear, hydro, geo, solar -heating mirrors-, photovoltaic, ...) and most importantly are multiplying in numbers with the explosion of micro-generation plants, most of them privately owned by citizens.
An increasing number of houses today are built with their own power generation system whose production helps the house fulfilling its energy needs but doesn't make it independent of the grid. Actually the grid is used both to provide power when the local production is not sufficient and to absorb extra production. Given that most of these micro-systems are based on photovoltaic and produce power when it is not needed for consumption by the house (during daytime) and cannot deliver when power is needed (evening time) the power grid is acting as storage facility.
The advent of home based energy storage might change a bit the situation but it is not something for tomorrow, may be for the next decade.
In this growing complexity, data seem to be an integral part of the solution for the coming years and a number of companies are already offering their "wares" to the market.