How do switchgears work

Substations are the nodes of our transmission network. You take on various tasks that are crucial for the smooth operation of our network. Their main tasks: "Switching on and off" the power lines and transforming the electrical energy to another voltage level. Technicians therefore speak of "switchgear and transformer stations", which we will simply refer to here as "transformer stations".

Highly available digital protection and control technology devices are used to control and monitor the systems. The transmission of the data to the head office or to the system takes place extremely securely via our own communications network, which we operate independently of the public information network.

Tension up or down - reclamping

Our systems connect the transmission network with the distribution networks, the facilities of large industrial companies and the power generation systems. In order for the electricity transport to function smoothly, the voltage must be adapted to the requirements of the customers. Powerful transformers are responsible for the so-called “reclamping” - for example from 380 to 110 kilovolts.

Line on or off - switching

Overhead lines and underground cables converge in our switchgear and can be switched on or off as required.

The switching is done by so-called circuit breakers, which in normal operation - automatically in the event of a fault - enable the electrical current to be switched off safely. We control and monitor our systems from a central point. Our engineers in the network control centers in Rommerskirchen and Hoheneck take on this task. They receive measured values ​​from all systems, which, among other things, provide information on how busy individual lines are. With this data, we can ensure that the electricity reaches its destination without overloading our network. We also monitor the voltage level and set it to permissible values.

Switchgear has been part of the extra-high voltage network for more than 80 years. Its structure and its individual components have fundamentally developed since then. Today we work with innovative technologies and circuit concepts that offer us numerous advantages. This includes equipping our systems with several busbars. So we have created reserves or redundancies.

This gives us several options for connecting the incoming and outgoing power lines to the system. This flexibility also leads to a higher reliability of our network. Because in the event of an error, we can fall back on a reserve rail and route the electricity via an alternative route. Another advantage: the flexible wiring of the lines allows the flow of electrical energy in the network to be controlled within certain limits. This helps us to avoid overloading individual line sections. Since our switchgear also contains an additional bypass rail, we can keep the line in operation during maintenance and repair work within the system. This increased effort in our transformer stations ensures that we always operate the required overhead lines and thus avoid bottlenecks in the transmission network. These bottlenecks trigger high costs, which are known in technical terms as redispatch.

Keeping the reactive power stable

Our systems increasingly have another important function: They stabilize the voltage level in the network. When alternating current is transported, magnetic and electric fields build up and down permanently - this is a physical property of alternating current lines. The so-called reactive power is required for this. However, the transport of reactive power loads the power lines and reduces the usable transmission power, the so-called active power.

So far, reactive power has mainly been provided by the generators of conventional large power plants. Because many of these power plants are going offline in the course of the energy transition, Amprion is increasingly building so-called reactive power compensation systems. This includes reactors, which are already installed in many Amprion substations. Reactors are similar to large transformers. We always connect them to the grid when the voltage on a line is too high. The choke coils compensate for reactive power and thus reduce the voltage on the line again. In the opposite case, i.e. if the voltage on a line is too low, capacitor banks are used. In the future, we will also use power electronic compensation systems as well as synchronous generators (so-called rotating phase shifters), which provide reactive power flexibly and thus can both raise and lower the voltage.

The construction of a substation

Although there are different designs, all Amprion substations have a modular structure based on a similar principle. This ensures the efficient construction and operation of our systems. In principle, the required switching devices and measuring devices for each line circuit and transformer are arranged close to one another within the substation. We are talking about the so-called control panel. The switchgear panels are connected by busbars and couplings. Specifically, a substation consists of the following essential components:

The path of electricity in the substation

From the incoming line to the outgoing line, the current flows through various switching devices, busbars and transformers that change the voltage. Each line circuit has three conductors. When the electricity reaches the substation, it is therefore passed on via three switching devices arranged next to each other.