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Energy management
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Note
The content on this page refers only to the blue'Log XC combined with the Hybrid EMS licence.
About energy management
In addition to power plant control functions that support grid stability (for example, frequency control and active power limitation), the blue’Log also provides energy management features. These help plant operators, especially those using a combination of PV and battery systems, to optimize system efficiency. Energy management functions have the lowest priority among all active power control functions.
You can set the following operation modes under Power Control > Active power > Energy management. The available operation modes depend on the plant type you have configured under Plant data (Hybrid EMS).
Operation mode | Plant type | |
|---|---|---|
| 1 | Default mode |
|
| 2 | PV self-consumption |
|
| 3 | Band shaving |
|
PV only 
PV Default
In Default mode, no energy management functions are active. The blue’Log relies
on external commands from the energy trader to operate the PV and battery system. As long as the energy trader does not send any signals, the PV system is not limited (Psetpoint,PV = 100%) and the battery system neither charges nor discharges (Psetpoint,battery = 0%).
Use case
Default mode is primarily used when the energy trader controls the system to participate in energy markets such as:
Intraday/day-ahead markets.
Balancing services markets: Frequency Containment Reserves (FCR) or Frequency Restoration Reserves (FRR).
PV self-consumption
In PV self-consumption mode, the hybrid system is controlled such that all available solar power is used for self-consumption to cover the local load. Any excess solar energy is used to charge the battery. PV Power is only fed into the grid when the battery is fully charged and the load is covered. If solar energy generation is not sufficient to cover the local load, the battery discharges the stored energy. In this mode, the PV system is never curtailed.
Example
This example shows a plant setup with a PV system (10 MW), a battery system (5 MW), and a connected load. In this chart, the load varies in order to illustrate the behavior of the operation mode.
System behavior in PV self-consumption mode
t0 - t1: No load is present and the battery is fully charged. All available PV power is fed into the grid.
t1 - t2: The load increases, but can still be covered by the PV system. The battery’s SOC remains stable.
t2 - t3: The load exceeds the available PV power. The battery starts discharging to compensate for the missing PV power so that no power must be drawn from the grid.
t3 - t4: The battery is entirely discharged (SOC=0%) and the PV system is no longer able to cover the local consumption. Thus, power is drawn from the grid.
t4 - t5: The load reduces and the PV plant can cover local consumption again (no consumption from the grid).
t5 - t6: The load further decreases. Excess PV power is available to charge the battery.
t6 - t7: The battery is fully charged again. The PV power covers the local load. The excess PV power is fed into the grid.
t7 - t8: No load is present and the battery is fully charged. All available PV power is fed into the grid.
Band shaving
The goal of Band Shaving mode is to maintain the power exchange at the grid connection point — both feed-in and import — within a specified range. This range is defined by two power thresholds which can be configured:
Lower limit
Upper limit
The system operates such that the power at the grid connection point remains below the upper limit and above the lower limit.
The upper limit triggers the battery to charge or the PV system to be curtailed:
When the power at the grid connection point reaches the upper limit, the battery begins to charge in order to absorb the excess energy and maintain the power at the grid connection point below the upper limit.
If the battery is already full or cannot absorb all the surplus power, the PV system is curtailed to prevent exceeding the upper limit.
Conversely, the lower limit triggers the battery to discharge:
When the power at the grid connection point drops to the lower limit, the battery starts discharging to ensure the power at the grid connection point does not fall below the lower limit.
Info
The upper limit currently triggers both battery charging and PV curtailment with a single threshold value. This will be split in a future release:
Upper limit (Battery): Defines the threshold at which the battery begins charging.
Upper limit (PV): Defines the threshold at which PV curtailment is triggered.