The electrical supply infrastructure is designed to serve consumers directly from energy sources. The latter can be either autonomous generators or complete thermal, hydrological, and nuclear plants. At the same time, backbone networks are rarely used to power end consumers. The energy distribution is used to supply transport nodes with a traction substation with characteristics suitable for a particular object.
Substation device
The technical support of the substation in most cases focuses on the reception of electricity of the order of 110-220 kV. There are also low-power installations designed for networks with a voltage of 35 kV. Depending on the potential, they can have from 2 to 6 entry points - these are small dead-end stations included in the structure of one complex. For the distribution of energy are responsible step-down transformers and converters. Moreover, the distribution devices do not have to be responsible for supplying energy to consumers. Some of them work to maintain the capacity of local facilities. In addition, the device traction substations provides for the presence of inverters and rectifiers. Their tasks are reduced to rectifying the current for the needs of a particular consumer. They can also provide a return to the general energy network, which is generated as a result of regenerative braking of the local line. To ensure the communication of the distribution infrastructure of the substation with consuming facilities, feeder installations are used.
Varieties
One of the basic classifications involves the separation of substations by the method of connection to the main power supply line. In particular, nodal, terminal and intermediate objects are distinguished. Nodal support the reception and distribution of energy through three channels in the range of 110-220 kV. They can also act as a current source for other traction stations. End objects work with two lines, and intermediate objects are designed to connect a divided circuit - between an energy source and the same substation. According to the electric traction system, direct and alternating current stations are allocated. The differences between them are that the DC traction substation is necessarily equipped with distribution devices. Installations working with alternating current serve networks with a voltage of about 27 kV and can be installed from each other at distances up to 50 km.
Substation Applications
The main direction of the use of traction distribution substations is electrified transport and related infrastructure. The main sources of such energy supply are stations that distribute direct current. They are installed along transport lines and provide energy for electric locomotives, trolleybuses, trams and railway complexes. In turn, AC traction substations are more often used for servicing telemechanics and automation, which is part of the same infrastructure. For example, it can be signal arrows, traffic lights and communication lines. This does not mean that a less responsible task lies at the AC station. In terms of power potential, they lose to analogues with direct current, but their energy potential is more stable and resistant to loads.
Substations for Railways
Most facilities of this type serve railways. They serve for the distribution, transformation and direct energy supply of electric rolling stock and non-rail consumers. Installations for DC distribution are mounted along lines with a distance of about 10-15 km. This interval may vary depending on the congestion of the paths and their destination. External trunk networks also act as a source of energy, after which the energy is directed to a transformer. This is followed by the conversion stage, after which electricity is sent to the contact network. It is important to note that the traction substation of the railway is characterized by large volumes of regenerative braking energy. That is, there is a need to organize technical means that are also able to stably transfer energy back to the main lines. Inverters perform this task - as a rule, through the switches of the contact network in automatic mode.
Complete equipment
In addition to the main electrical filling in the form of converters, rectifiers and other devices serving the contact network, substations are supplemented with protective equipment and fire fighting equipment. Moreover, these funds are required not only for the local maintenance of protective functions, but also to ensure the possibility of providing first-aid medical care. The protective equipment of traction substations can include relay devices, circuit breakers, signaling equipment, etc. Sensors are used in the structure of modern substations that record the facts of overloads, overheating, and failure of individual telemechanics segments.
Substation Operation
Substations can be controlled in several ways. Modern objects of this type are serviced through remote controls or using automated equipment. The traditional method of control through personnel is also applied. This management method is often used at small stations in small cities - due to the impossibility of organizing automated support. However, large metropolitan areas can also be equipped with a traction substation with direct servicing by personnel due to the risk of their emergency shutdown. In order to increase reliability, a combined control scheme is used, in which both automated means with remote control and personnel are involved. In this case, all processes are monitored by a supervisor, who takes measures regardless of automation in emergency situations.
Substation Maintenance Instructions
Maintenance is carried out in accordance with the schedule of the routine inspection intended for a specific object. A typical set of measures included in the maintenance program includes equipment revision, testing, minor troubleshooting and identifying problem areas that will be examined in more detail during the scheduled repair. For a long-term perspective, a journal is kept in the framework of equipment condition accounting, in which the dynamics of the results of the inspection are recorded. Without fail, during preventive maintenance, traction transformer substations are cleaned of contaminants, consumables are updated in some areas, and more modern equipment is installed.
Repair work
At the time of the overhaul, the responsible person receives a document indicating the results of previous tests. Based on his analysis, the engineer makes a conclusion indicating the problem areas where repair operations will be carried out. At the basic level, bolt, contact and welded joints are updated. During the current repair, the fasteners are restored, cracks in the insulation are eliminated, and seals and joints are reinforced. In extreme cases, the traction substation can undergo reconstruction with the replacement of the main equipment. Typically, such events are carried out after changing the network parameters, when the voltage values increase or decrease. Modernization is also widespread as part of the expansion of the range of tasks of the station.
Conclusion
To date, traction means of electricity distribution are the best tool for supplying transport infrastructure. This primarily concerns the railways. A traction substation connected to a stable external network is capable of serving several consumers at once, including distribution equipment. In terms of technological modernization, these are flexible facilities that allow you to make changes both in the hardware infrastructure and in the management tools. The most modern sets of traction units support fully automated control, which reduces the cost of their operation and maintenance.