Transformer

Remembering that each transformer may have more than one inverter connected to its inputs, the total input power to each transformer is simply the sum of the powers available from the individual inverters connected to the transformer:

$$P_{trans,in}\left( t \right) = \sum_{i = 1}^{N_{inv,trans}}{P_{inv,trans}(t)}$$

For a single transformer, the output power \(P_{\text{trans,out}}(t)\) is calculated as described in Transformer Efficiency Model.

The Transformer Effect quantifies the amount of energy lost in the transformers at the PV plant. At time t the Transformer Effect for all transformers at a given level is calculated as:

$$\Delta_{trans,level}\left( t \right) = \left( \frac{\sum_{i = 1}^{N_{trans,level}}{P_{trans,out}(t)}}{\sum_{i = 1}^{N_{trans,level}}{P_{trans,in}(t)}} - 1 \right) \bullet 100%$$

Averaged over a longer period:

$$\Delta_{trans,level} = \left( \frac{\sum_{i = 1}^{N_{trans,level}}{\sum_{t}^{}{P_{trans,out}(t)}}}{\sum_{i = 1}^{N_{trans,level}}{\sum_{t}^{}{P_{trans,in}(t)}}} - 1 \right) \bullet 100%$$

If a single Transformer Effect for a PV layout with more than one level of transformer is desired, then:

$$\Delta_{\text{trans}} = \Delta_{trans,level1} \bullet \Delta_{trans,level2}$$