Dispatching Power Plants
One of the fundamental aspects of the power system is the fact that energy cannot be easily stored for later use like other commodities. Therefore, the power grid must be continuously adjusted in order to meet the demand for electricity. This process is called, "dispatch" of power plants.
There are two main stages of the dispatching process that occur at different times:
- The first stage, referred to as "unit commitment," usually occurs a day before (referred to as day-ahead) the time needed to meet real-time electricity demand. In most European markets, an auction takes place to determine the price and amount of power required.
- The second stage, known as "dispatch," occurs when the plants that have been committed are chosen to operate at a specific level to meet total electricity demand. Economic factors drive the dispatch choice. In addition, ramp rates and minimum run times are taken into account in the dispatch decision.
The transmission system operator determines which of its power plants to turn on or off in preparation for demand when the unit is committed. We refer to a plant as "committed" or "scheduled" to create energy if it is turned on during the unit commitment process.
- Every hour, the grid operator must meet a certain amount of electricity demand known as "base load."
- Demand is typically greater during the day than at night. As a result, the grid operator will need to arrange some forms of power plants to operate around the clock, but not others.
- Finally, there are times each day when demand is especially high. These are known as "peak" hours, and the grid operator would need to plan some forms of power plants to be "on-demand," running only during these peak demand periods. While these plants can be turned on and off quickly, they are also more expensive to operate.
Balancing the grid with a virtual power plant
Virtual power plants allow for centralized dispatching. This ensures that the total demand for electricity in the region is met while also taking into account factors such as the availability of energy sources and the cost of energy. The system also tracks the current and projected load on the power grid and adjusts the output of power plants to ensure that the necessary energy is generated to meet the demand. This helps minimize the potential for power outages and helps reduce the overall cost of energy in the region.
What is Redispatch?
Redispatch is a request made to power plants by the transmission system operator to modify the actual power they input in order to reduce or prevent congestion. This can be done while maintaining the total real power in the grid near to constant. The way to do that is by decreasing the real power output of one or more power plants while simultaneously boosting the real power output of one or more other power plants.
Redispatch is typically employed in areas like California or Germany that produce a large amount of renewable energy. In other areas, it is less typical. Redispatch takes place after the initial scheduling of committed power plants on the day-ahead auction. The grid operators perform what is known as a load flow or grid load calculation as soon as the schedules are received to generate a summary of the grid's anticipated feed-in and consumption for the next day.
To get an idea of whether areas of the power grid might be adversely affected and to what extent, they study the dispatch schedule. The transmission system operator can advise plant operators to postpone planned power output based on the next day's load flow calculation to avoid grid bottlenecks, hence reducing the amount of short-term, grid-stabilizing interventions the next day.
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Nano Energies operates a dispatching center that manages power plants in central and Eastern Europe. Our dispatchers are working 24/7 and are constantly monitoring the situation in the energy market, to be able to adjust at a moment's notice. Because dispatching is centralized in our international headquarters in Prague, asset owners can benefit from letting Nano Energies remotely manage their devices. Finding reliable staff to work around the clock is challenging, let us do it for you.