Use Case 1 – Peak Shaving

Use Case 1 – Peak shaving and ancillary services in the market

One main use case is to connect a high-capacity storage system to the medium voltage grid on Borkum in order to make the grid function more efficiently and stably.

This storage device will be used to perform peak shaving and to avoid problems concerning rapid power changes of the renewable energy sources (RES). Furthermore, the system is able to provide primary and instantaneous reserve for the electrical grid.

The core of this use case is the Hybrid Energy Storage Solution (HESS). The electrical part of the HESS consists of the three main elements: Inverter, Li-Ion System and UltraCaps System which are linked together in the Connection Box. The Energy Management Platform (EMP) or the Distribution System Operator (DSO) communicates the HESS by means of the intelligent Node Management System (iNMS). The EMS gathers all HESS information via the iNMS and is able to communicate with the three main elements of the HESS System.
Objectives and activities:
Peak shaving (see figure 1) is used for reducing the maximum load of the German island of Borkum or any other Distribution System Operator (DSO) or industry company located in other places. During a low load in the grid, the HESS would store energy which is released at times of peak demand.
The main benefits of peak shaving lies, on one hand, in lower need of resource generation which would just be created for the peak demand (lower investment needs) and, on the other hand, in the grid connection that can be designed smaller.
For the organization performing peak shaving, there is another economic benefit: The energy absorbed by the storage system is bought at low demand times which usually coincide with a cheaper market price, and it is consumed at peak demand times when energy bought from market is usually more expensive.

Figure 1: Power profile for peak shaving

Primary and instantaneous reserve
For controlling the grid frequency (see figure 2 ) and therefore the balance between electrical energy production and consumption, most grids in the world have a grid control based on four patterns: (Inertia, primary reserve, secondary reserve, tertiary reserve, see figure 1). All patterns consist of energy injection or absorption into / from the grid to regulate the frequency, while the difference between each pattern lies in the response time and the duration of the service.

Figure 2: Grid frequency

NETfficient will execute instantaneous reserve services (synthetic Inertia with immediate reaction), performed mainly by the UltraCaps which are part of the HESS and offer a very fast reaction on frequency deviations. Furthermore, the HESS will perform primary reserve (reaction time up to 30s) performed mainly by the Li-Ion Battery.
Due to the limited energy storage capacity of the HESS system we cannot participate in the official market for primary reserve. Nevertheless, it will be tested in the Borkum grid.
RES Integration
The increasing integration of renewable energy sources such as PV and wind generators can provoke rapid power changes caused by the variation of the weather conditions. The MV HESS, controlled by the EMP and its forecasting algorithms, can provide a dual service for a grid-connected PV plant based on Smoothing/Ramp rate and Time Shifting. Islands can be connected to the backbone of the power system on the mainland by a certain connection, such as in Borkum. Considering the generation capacity of Borkum, and the possibility of installing more power based on RES (PV or Wind), a global net-zero energy island would be a future objective to explore. From the technical point of view, this off-grid scenario may be solved by configuring the power system as an off-grid microgrid.