Electrical Grid 101: All you need to know
You must have seen the endless transmission line running through the countryside or the transformer which is kept outside your office building or the energy meters installed at your home but the question is at how is it all related to the electrical grid?
In this article we are going to learn about electrical grid, right from the basic to the advance level. Also we are going to learn about Smart Grids.
We also have a quiz at the end.
The year 2009 witnessed the fall of 1.5% in the energy consumption level for the first time since World War II !
So what’s Electrical Grid?
It’s an electrical power system network which comprises of generating plant, transmission lines, substations, transformers, distribution lines and finally the end consumers.
In most of the cases the generation units are far away from the consumption centres with the electrical grid connecting the two.
Different components of Electrical Grids
The electrical grid can be broadly divided into three main components:
Generation: This can be further classified into two components: Centralized and Decentralized. So basically centralized refers to large scale e power generation this can be from coal, nuclear, natural gas, hydro, wind farms or huge solar parks which are far away from the population centers or consumption centers. On the other hand decentralized generation happens close to the consumption centers, for example: This could be as simple as rooftop solar. We will learn in more detail as we go along.
Transmission and Distribution: As the name suggests this component is responsible for the transmission of electricity from the generation units to the consumption units. We will discuss about it in details further down the article.
Consumption: This is where all the consumers come in to the picture. These consumers could be industrial, residential or commercial depends on the needs.
Now let’s look into each component of the electrical grid in detail:
Generation: This is where all starts
In this stage of the electrical grid, electricity is produced. Production of electricity could be either by electromechanical generators, heat engines which are fueled by combustion and other ways like kinetic energy of flowing water or wind. Solar and geothermal power is also now widely used for the production of electricity but this are restricted to few geographical locations.
Production of Electricity
It’s interesting to note that most of the electricity production on the earth in generated through a turbine which is either driven by burning gas, steam, water or wind. This turbine when attached to a generator drives it and transforms the mechanical energy to electrical energy by electromagnetic induction.
With most countries still depending on the non-renewable sources of energy this generators are mostly driven by heat engines by combustion of fossil fuels. As a matter of fact the modern steam turbine which was developed in the 19th century produces about 80% of the world’s electric power using variety of heat sources.
The electricity generated from the generator which is generally at a voltage level of 15 to 25KV is then fed to a ‘Generator Step-Up Transformer’ (GSU) in order to increase the voltage and reduce the current and acts as a critical link between the power station and the transmission network. These transformers are operated day and night at full load and are built to withstand extreme thermal loading. They take the generator voltage level up to the suitable transmission voltage level.
Transmission and Distribution
Electric power transmission is the movement of electrical energy from the generating source to an extra high voltage (EHV) substation. This is different from the local wiring between the high voltage substations and customers which is referred to as distribution. The combination of transmission and distribution networks together is known as “the grid” in Northern America or “the national grid” in some other countries.
How does transmission work?
Most of the lines are EHV or Extra High Voltage three phase alternating current. Nowadays HVDC (High Voltage Direct Current) technology is used for the transmission of bulk power over very long distances typically hundreds of kilometers. They are also used in the interchange of power grids which are not synchronized.
Electricity is transmitted at high voltages generally 115KV and above but this varies from countries to countries. They are either transmitted through overhead transmission lines or underground cables. One the the main challenge face in the transmission is that there is no concept of storing the energy; electricity needs to be produced and consumed at the same rate. A sophisticated control system is required in order to balance this out because if the demand exceeds the power supply the imbalance will cause the power stations to shut down to prevent the damage which may result in wide spread blackout in the areas. In order to keep this in check the transmission companies determine the maximum reliable capacity of each line in the event of a failure in another part of the network and power needs to be rerouted.
How does distribution work?
The higher voltages coming from the transmission lines are then step down to lower voltages for the purpose of distribution to the consumers. The higher voltage lines end up in a high voltage substation where the voltage level is dropped to 12 kV. Several distribution lines start from the distribution station either as overhead or underground lines.
The distribution transformer at each consumer block then further steps down the voltage to 230/115 V. It is interesting to note that large industries or factories where the equipments need higher voltages take the supply directly from the substation with the involvement of the distribution transformer.
The electricity energy finally which comes to our home at 230V is what we consume. Electric energy is measured in joules (J) or in watt hours (Wh) which represents a constant power over a period of time. The electricity comes to our home through energy meter which measure the energy being consumed and based on the energy consumed we pay our electricity bills.
Interesting fact: The year 2009 witnessed the fall of 1.5% in the energy consumption level for the first time since World War II.
So in the 21st century what makes a grid smart?
In short, the digital technology that allows for two-way communication between the utility and its customers, and the sensing along the transmission lines is what makes the grid smart. Like the Internet, the Smart Grid will consist of controls, computers, automation, and new technologies and equipment working together, but in this case, these technologies will work with the electrical grid to respond digitally to our quickly changing electric demand.