From direct sources of generation to the consumer, electrical energy goes through many technological points. Moreover, its carriers themselves in the form of lines with conductors are essential in this infrastructure. In many ways, they form a multi-level and complex system of electric power transmission, where the consumer is the final link.
Where does the electricity come from?
At the first stage of the general process of energy supply, generation occurs, that is, the generation of electricity. For this, special stations are used that produce energy from its other sources. As the latter, heat, water, sunlight, wind and even earth can be used. In each case, generator stations are used that convert natural or artificially generated energy into electricity. It can be both traditional nuclear or thermal power plants, and windmills with solar panels. For the transmission of electricity to most consumers, only three types of stations are used: nuclear power plants, thermal power plants and hydroelectric power stations. Accordingly, nuclear, thermal and hydrological installations. About 75–85% of energy is generated on them all over the world, although due to economic and especially environmental factors, the tendency to reduce this indicator is growing. One way or another, it is these main power plants that produce energy for its further transmission to the consumer.
Electric Power Transmission Networks
The transportation of generated energy is carried out by the network infrastructure, which is a combination of various kinds of electrical installations. The basic structure of power transmission to consumers includes transformers, converters and substations. But the leading place in it is occupied by power lines that directly connect power plants, intermediate installations and consumers. At the same time, the networks can differ from each other - in particular, by purpose:
- Social networks. Supply household, industrial, agricultural and transport facilities.
- Network communications for autonomous power supply. Provide power to autonomous and mobile facilities, which include aircraft, ships, non-volatile stations, etc.
- Networks for power supply of the objects performing separate technological operations. In addition to the main electricity supply, a line may be provided at the same production facility to maintain the operability of specific equipment, conveyor, engineering installation, etc.
- Contact lines of power supply. Networks designed to deliver electricity to directly moving vehicles. This applies to trams, locomotives, trolleybuses, etc.
Classification of electricity transmission networks by size
The largest include trunk networks that connect energy generation sources with consumption centers across countries and regions. Such communications are characterized by high rates of power (in the amount of gigawatts) and voltage. At the next level are regional networks, which are branches from trunk lines and, in turn, themselves have smaller-sized departures. These channels transfer and distribute electricity to cities, regions, large transport hubs and remote deposits. Although networks of this caliber can boast of high power indicators, the main thing is that their advantage is not in the volume supply of energy resources, but in the transportation distance.
At the next level are district and domestic networks. For the most part, they also perform the functions of energy distribution between specific consumers. District channels feed directly from regional channels, serving urban quarter zones and settlement networks. As for internal networks, they distribute energy within a quarter, village, factory and smaller facilities.
Substations in power supply networks
Between separate sections of electric power transmission lines, transformers are installed in the format of substations. Their main task is to increase the voltage against the background of a decrease in current strength. And there are also lowering settings that reduce the output voltage index in the conditions of increasing amperage. The need for such regulation of the parameters of electricity on the way to the consumer is determined by the need to compensate for losses on the active resistance. The fact is that electricity is transmitted through wires with an optimal cross-sectional area, which is determined solely by the absence of a corona discharge and amperage. The inability to control other parameters also leads to the need for additional regulatory equipment in the form of the same transformer. But there is another reason why the voltage should increase due to the substation. The higher this indicator, the farther, maybe, the distance of energy transfer while maintaining a high power potential.
Features of Digital Transformers
A modern type of substation, allows the possibility of digital control. So, a standard transformer of this type provides for the inclusion of the following components:
- Operational dispatch center. The working personnel through a special terminal connected via remote (sometimes wireless) communication, controls the work of the station in heavy and normal modes. Ancillary automation devices may be used, and the command rate varies from a few minutes to hours.
- Emergency Control Unit. This module is included in the work with strong disturbances on the line. For example, if the transmission of electricity from a power plant to a consumer occurs under the conditions of transient electromechanical processes (when the power supply, generator are suddenly turned off, a significant load is dumped, etc.).
- Relay protection. As a rule, an automatic module with an independent power supply source, the list of tasks of which includes local control of the power system by quickly detecting and separating faulty parts of the network.
Auxiliary electrical installations on power lines
The substation, in addition to the transformer block, provides for the presence of disconnectors, separators, measuring and other complementary devices. They are not directly related to the management complex and work by default. Each of these settings is designed to perform specific tasks:
- The disconnector will open / close the power circuit if there is no load on the power wires.
- The separator automatically disconnects the transformer from the network for the time required for emergency operation of the substation. Unlike the control module, in this case, the transfer to the emergency phase of the work is done mechanically.
- Measuring devices determine the vector of voltages and currents at which electric power is transferred from a source to a consumer at a particular point in time. These are also automatic tools supporting and accounting for metrological errors.
Problems in the transmission of electrical energy
When organizing and operating power supply networks, many difficulties arise that are of a technical and economic nature. For example, the aforementioned current power losses due to resistance in conductors are considered the most important problem of this kind. This factor is compensated by transformer equipment, but it, in turn, needs maintenance. Maintaining the network infrastructure through which electricity is transmitted over a distance is, in principle, costly. It requires both material and organizational resource costs, which ultimately affects the increase in tariffs for energy consumers. On the other hand, the latest equipment, materials for conductors and optimization of control processes can still reduce part of the operating costs.
Who is the consumer of electricity?
To a large extent, the requirements for energy supply are determined by the consumer himself. And in this capacity, industrial enterprises, public utility organizations, transport companies, owners of suburban cottages, residents of multi-apartment city houses, etc. can act as the principal sign of the difference between different groups of consumers can be called the power of its supply line. According to this criterion, all transmission channels of electricity to consumers of different groups can be divided into three types:
- Up to 5 MW.
- From 5 to 75 MW.
- From 75 to 1 thousand MW.
Conclusion
Of course, the above-described energy supply infrastructure will be incomplete without a direct organizer of the processes of energy resource distribution. Participants in the wholesale energy market, who have the appropriate provider license, act as the supplying company. An agreement on electricity transmission services is concluded with an energy sales organization or other supplier that guarantees supply during the specified billing period. At the same time, the maintenance and operation of the network infrastructure, which provides a specific consumer object under the contract, may be in the department of a completely different third-party organization. The same applies to the source of energy generation.