Eq. 3.49 typo in list of variables

### Type of suggestion

Equation

### Printed book or PDF?

Printed book (softcover)

### Version number

v1.2 2023

### Location

p144, list of variables below Eq. 3.49

### Description

a_n mentioned twice. Second mention (phase angle of component n) should be an alpha_n instead to be consistent with 3.49

### Contact details (optional)

s.g.pearson@tudelft.nl