For the TUNES project, we need a way to describe a usage rate of a storage device. In the S2 world, this corresponds to a FRBC.UsageForecast message, which, in turn, is composed of FRBC.UsageForecastElements.

Model the input and useful extraction of energy from a buffer.
For non-electric storages of energy, where a usage signal for direct extraction exists (e.g. heating, or other use cases like water tanks).

Two things that need consideration here:

• Input (and transformation) of energy
• Storing energy for direct extraction

Some more technical considerations:

• Time series with elements. Fill value 0.0 for empty data points.
• Non-negative values.
• A positive value makes the stock decrease.
• Values should not exceed min power.
• Potentially, think about the case of charge (using one power) -> discharge (using another port).

How to approach this?

• Add the term $UsageForecast(d,j)$ to the the state dynamics equation:

$$ \Delta Stock(d,j) = \frac{P_{down}(d,j)}{\eta_{down}(d,j) } + P_{up}(d,j) \cdot \eta_{up}(d,j) - UsageForecast(d,j) $$

Note:

The idea of adding the term $-UsageForecast(j)$ to the min and max values of the device constraint dataframe would lead to a wrong result:

This will leave the Stock constraint as follows:

$$ Stock_{min}(j) \leq Stock(j) - UsageForecast(j) \leq Stock_{max}(j) $$

Example $soc_{min} = 0$, $soc_{max} = 100$, $soc(-1) = 30$, $UsageForecast(10) = 20$

$$ 20\leq Stock(10) \leq 120 $$