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Variations in installed capacities (MW/period)
======

*indexed by: asset, data_type, energy, period, technology, test_case*

<div style="text-align: justify">


### Description

This KPI displays the variations in installed capacities across a pathway study for assets optimized at least during one
period of the pathway.

Values displayed represent the overall variation in installed capacities during the period which just ended. For 
example, add_2030 gives the capacity added during the period ending in 2030. 

<blockquote class="custom-hint">
  <h4>Modelling hint</h4>

  For the first pathway step, values returned by this KPI can be very high for assets that are scenarized then optimized throughout 
  the pathway as the first step can represent the historical installed capacities in this case.
</blockquote>

### Calculation

All the equations below are valid for any realization and are therefore implicitly indexed by test case. Index 
*Technology* is directly deduced from the asset. 

Let $x_{a, p, data\_type}$ be the value returned by this KPI for a given asset $a$ for pathway's period $p$ optimized during at 
least one period of the considered pathway. Each data type of this KPI is computed as follows :

#### Additional capacity

$$
x_{a, p, add} = add_{a, p} - repow_{a, p}
$$

With:
  
- $add_{a, p}$ : The optimization result for variable representing the added capacity of asset $a$ during the period $p$.
- $repow_{a, p}$ : The optimization result for variable representing the repowered capacity of asset $a$ during the period $p$.

#### Decommissioned capacity

$$
x_{a, p, less} = less_{a, p} - repow_{a, p}
$$

With:
  
- $less_{a, p}$ : The optimization result for variable representing the decommissioned capacity of asset $a$ during the period $p$.

</div>

#### Repowered capacity

$$
x_{a, p, repowering} = repow_{a, p}
$$

### Indexing

To help filtering and aggregating values computed by this KPI, additional indexes are added to computed values:

- **Technology** : this index is directly deduced from assets types of the realization
- **Energy** : The energy index added in this KPI corresponds to the asset main produced energy
- **Node** : The node index added in this KPI corresponds to the node where asset produces this energy