50Hertz operates the electricity highways which serve to transport electrical energy over long distances with minimal power losses. With the energy transition, the system of energy supply has changed fundamentally. Increasingly, renewable energies are fed directly or via the distribution networks into our grid and transported via our lines. Renewable energies already account for 60 percent of electricity consumption in the 50-Hertz grid region. This share will continue to grow. Like traffic, electricity flows across borders. The 50Hertz transmission grid is part of the European interconnected grid and is directly connected to neighbouring countries Poland, the Czech Republic and Denmark. We want to continue optimizing this international flow of electricity. Due to our central location in Europe, we are predestined for this. We are working consistently on successfully shaping the energy transition - as grid owner, system controller, market facilitator and trustee.
As a transmission system operator, we transport electrical energy over long distances with maximum voltages of 150, 220 and 380 kilovolts (kV). Our high voltage grid has a power circuit length of approximately 10,490 kilometres - that is the distance from Berlin to Rio de Janeiro. In 74 substations and switching stations we exchange electricity with the distribution network operators - transformers convert the voltage level between high and extra-high voltage. Large generating plants, pump storage facilities and highly energy-intensive industrial plants such as steel production are directly connected to our extra-high voltage grid.
We are constantly adapting and expanding our transmission grid to according to needs, keep it in operating condition and repairing damage caused by age or, for example, severe weather. When expanding the grid, 50Hertz acts sustainably and conserves the natural and environmental resources. We only build as many new lines as are actually necessary. With our responsibility for nature and environment, we compensate necessary interventions in nature with appropriate compensation measures and give habitat and cultural landscapes back to Society. In 2017, we fully commissioned the newly built South-West Interconnector from Saxony-Anhalt via Thuringia to Bavaria together with our neighbouring transmission system operator Tennet. It is primarily used to transport renewable energy from the North-East to the consumption centres in southern Germany. Thanks to the transmission capacity of this line, expensive interventions due to grid congestion have been significantly reduced.
Moreover, 50Hertz is planning the high-voltage direct current (HVDC) power link in a joint project with Tennet. The grid connection points are Wolmirstedt near Magdeburg (federal state of Saxony-Anhalt) and Isar near Landshut (federal state of Bavaria), where converters will transform alternating current (AC) into direct current (DC) and vice versa. In addition, 50Hertz connects offshore wind farms in the Baltic Sea with its grid. To this end, we build and operate offshore substations, partly in cooperation with the wind farm operators, which convert wind energy to a higher voltage for onshore transport level with minimal power losses. From there, the electricity is transported to our onshore substations through our submarine cables.
More about our grid
Our colleagues in our Control Center keep the production and consumption of electrical energy in balance at all times in our grid area, we ensure an optimal power flow and a smooth transition to our neighbouring transmission system operators and distribution grids. This is a particularly challenging task in our grid area because more generation capacity from renewable energy sources is installed than from conventional power plants. In particular, wind power plays a major role. The infeed quantity is constantly changing at short intervals. The same is true for the infeed from photovoltaic systems to our grid. This differs from hour to hour and depends on the weather. Through constant control, infeed and consumption are kept in balance and the security of the electrical system as a whole is ensured.
Electricity is freely tradable. Traders, power distributors, producers and grid operators are assigned to difference balancing groups in the 50Hertz grid area. Within each individual balancing group, power infeed and consumption are held in balance on a quarter-hourly basis. If balancing groups are not balanced, deviations from the overall balance arise, which we balance. To do so, we take excess amounts of electricity from or add balancing energy to the balancing group. Corresponding balances are invoiced monthly with those responsible for the balancing group. We maintain the balance between infeed and consumption for the sum of all balancing groups at all times. We use balancing energy to do so.
More on Balancing groups
50Hertz is not only part of the German transmission grid, but it is also directly connected to the extra-high-voltage grids of Denmark, Poland and the Czech Republic. We also plan a connection, an interconnector, to Sweden – the HansaPower Bridge.
We have been working together with neighbouring grid operators and market participants in a spirit of trust for a long time. Together with our neighbours and the market participants, we develop energy market products that facilitate the efficient use and control of the grids and the energy system. We also take on new challenges: Thus, the increased infeed of wind energy in the 50Hertz grid area placed an increasingly heavy load on the interconnectors to Poland and the Czech Republic. This resulted in loop flows in which power from the north of Germany sought a way to Bavaria and Austria via Poland and the Czech Republic. 50Hertz agreed with the transmission system operators PSE in Poland and CEPS in the Czech Republic to better control these cross-border power flows: Therefore, phase shifter transformers (PST) were installed at the coupling points to these neighbours’ control zones. This has allowed us to efficiently control the power flows in the 50Hertz grid area, exploit transmission potential as fully as possible and significantly improve free power trading in Europe.
We are committed to the development of a European internal energy market and are working to achieve this in numerous initiatives, collaborations and projects. 50Hertz also has shares in the European Energy Exchange (EEX) in Leipzig and thus indirectly also in the European Power Exchange (EPEX) in Paris.
More on the electricity market
50Hertz is already a pioneer for the integration of volatile renewable energies. That is why we are developing solutions with over 70 partners in the "WindNODE" project, with which large quantities of renewable energies can be integrated into the system while keeping the electricity grids stable.
In addition, the German legislator has transferred the responsibility for coordinating and processing legal levy systems to promote environmentally-friendly technologies to the transmission system operators. These include, among others, the Renewable Energies Act (EEG) levy and the Power and Heat Cogeneration Act (KWKG) levy. We collect these levies as a trustee, administrate these and coordinate their distribution to the recipients. If the producers do not market electricity from renewables directly, we sell this electricity on the power exchange. By doing so, we integrate renewable energies in the electricity market transparently.