Chapter1
Electrical power grid
Definition
Electrical power grid is an interconnected network of power lines and related equipment for supply of electrical energy from producers to consumers.
Most electricity production is usually done in power plants (e.g. coal, nuclear or hydro) but they are often far away from consumers. The distance is caused by several factors such as economy, health, safety and environmental. Delivery usually takes place at two levels: transmission and distribution. Transmission part transmits energy over long distances (e.g. hundreds of kilometers) and uses higher voltages for more effective transmission. Distribution is focused on delivery for individual consumers and uses lower voltages for safer and easier distribution.
Note
In generally, the energy chain is production -> transmission -> distribution -> consumption.
Besides this traditional concept, there exist concept of distributed energy resources (DER).
Note
In DER concept, energy is generated near the point of consumption, e.g. in the same building.
DERs are usually small and environment friendly. They usually use solar energy, natural gas or wind. The location of all mentioned concepts is shown on the Fig. 1.
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1. Basic scheme of electric grid with energy generation, transmission, distribution, consumption
Fig. 1. Basic scheme of electric grid with energy generation, transmission, distribution, consumption
A clear separation of the transmission and distribution levels is also visible. This separation is also present in the operation of the power grid. The transmission part is operated by the transmission system operators (TSO) and distribution by the distribution system operators(DSO). Distribution operators can be regional or local.
Interesting
In Europe, there are above 3500 DSO companies. In some countries (e.g. as Czechia, Slovakia, Hungary), the three largest DSO deliver more than 60% of power.
Interesting
Maps and schemes of transmission parts published by TSOs are publicly available, e.g. in [1] a scheme for whole Central Europe is available. Here we present here a partial view on Fig. 2.
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2. Power systems of central east Europe [1], zoomed to Slovak-Ukraine border, provided with permission SEPS a.s.
Fig. 2. Power systems of central east Europe [1], zoomed to Slovak-Ukraine border, provided with permission SEPS a.s.