Details of Electricity Transmission
Context:
- Like light, sound, heat, and other types of energy, power and the transmission of power also come in a variety of forms. However, because electric current flows in several phases and because of other elements like voltage, impedance, frequency, etc., electric power transmission is more complex.
Energy source:
- The three main parts of any power supply system are distribution, transmission, and generation.
- Power plants and smaller renewable energy facilities both produce electricity.
- Then, among other components, a dispersed network of stations, substations, switches, overhead and subterranean cables, and transformers is used to transport it.
- Ultimately, it is supplied to customers in a uniform manner that satisfies the requirements of diverse devices and uses.
Electricity transmission fundamentals:
- First, with higher voltages and lower currents, the transmission efficiency of any wire carrying electric current increases.
- This is due to the fact that energy loss during gearbox rises as the current squares, yet the amount of voltage increase varies in direct proportion to the drop in current.
- In other words, if voltage is raised by five units, current will decrease by five units but energy loss will be decreased by twenty-five units.
- Transformers serve this function: while receiving current to be supplied to consumers, they reverse the process of increasing voltage and decreasing current before feeding into transmission lines.
- Second, there is still some resistance in the cables that carry the current, which causes some energy to be lost.
- The cable’s thickness can be changed to reduce the amount of loss; the thicker the cable, the less energy is lost, but the cost goes up. Therefore, the cables are thinner when the cost of the material is high.
- Third, the cost of gearbox decreases with increasing gearbox distance.
- The usage of alternating current (AC) significantly complicates all these problems.
- Compared to direct currents (DC), alternating current (AC) is more easily adjusted in transformers and has a higher transmission efficiency.
- However, the more resistance the current faces in the material, the higher the AC frequency.
- To calculate the amount of electrical energy that will be lost between generation and consumption, engineers simulate each of these variables for a specific network.
Transmission of power:
- Each wire in a three-phase AC circuit carries an AC current in a distinct phase.
- The cables are sent from a power plant to transformers, which increase the voltage.
- They then travel great distances while suspended from gearbox towers, which need to be sturdy and wired correctly.
- If there is a surge in the line, insulators in contact with the wires absorb part of the current; if there is too much, circuit-breakers “break” the circuit.
- In order to shield the cables from abrupt spikes in voltage, such as those caused by lightning strikes, the towers are additionally grounded and fitted with arresters.
- In a similar vein, dampers stop cable vibrations from impairing the stability of the towers. Switches are used to transfer electricity across lines and regulate the amount of current available.
Grid operation:
- Transmission is located in between production and distribution, as was previously mentioned.
- Since a national grid consists of all three parts, transmission must also take into consideration the specifics of power production from diverse sources at different places, as well as the where and how of that power consumption.
- Certain energy sources, such as nuclear or coal-fired reactors, have a continuous energy production capability, while renewable energy sources have intermittent energy production.
- In order to store electrical energy during periods of excess supply and release it during periods of deficiency, grids also feature storage facilities.
- In addition, grids must control the AC frequency, enhance the power factor, modify voltages in response to demand, and react to failures in one area of the network and stop them from spreading to other areas.
Way Forward:
- If every generator linked to a grid is generating AC current at the same frequency, then the grid is said to be wide-area synchronous. A wide-area synchronous grid is also the national grid of India. Although these systems reduce electricity costs, precautions must be taken to avoid cascading power supply outages.
