A layman’s guide to power blackouts

A primer on a hot-topic

by Kumar David-April 2, 2016, 8:21 pm 

There is a buzz around this topic for obvious reasons and this brief primer is an attempt to provide a few theoretical insights in laymen’s language. I will deal mostly with general principles or with events of some time ago and not touch on the blackouts of September 2015, February 2016 and March 2016 because of my involvement in some aspects of an ongoing investigation. There are different ways in which to approach the topic and I have chosen to do so under the subheadings ‘The System as a Whole’, ‘Planning and Management’ and ‘Equipment’. Power system blackouts are topics esoteric to non-specialists, so occasionally a didactic tone may creep in – apologies for that.

Not only in recent months but previously too, our system and systems around the world, have shut down. It is the behaviour of the network, that is the functioning of the system as a whole, that holds the key to the problem; it is not the repetition of the same defect time and again. I will make a start by throwing light, as simply as possible, on the cohesion of the network.

The system as a whole

The electricity supply system consists of dozens (in a large country hundreds) of alternating current (AC) generators connected to hundreds of load points by a network. I am referring to high voltage of transmission interconnections. Lower distribution networks that tap power from the transmission network (grid) and convey it to a multitude of individual loads are usually not significant in the security and stability of the system of generators and transmission lines as a whole. Each generator does not service a particular load; rather, the output of all generators is "pooled" into the transmission grid. Individual distribution systems (municipalities, industries, rural regions) tap power from the grid in much the same way as a housing estate taps the water-main and then distributes water to individual housing units. There is one critical difference though; electricity cannot be stored in the grid, therefore there has to be a near instantaneous balance of production and consumption of electric energy.

The crucial point about the grid is that it is the critical structure that binds all the generators and loads into what in the jargon is called a synchronised system. A large-scale blackout is a failure of all or part of the interconnection. Power supply networks are interconnected for three reasons; viz as load varies the cheapest generators can be run and the more expensive ones held back for use at peak time only; second, power from different areas and types of plant (think Laxapana and Norochcholai) can be sent to far flung load centres depending on needs and availability, and third a large strong interconnection is stable against all but the most serious disruptions. Nicola Tesla proved conclusively that AC is superior to direct current (DC) for electricity supply. The reasons will take me too far from my topic today.

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