From 1b2301a5d7eea4a5c7baae4fb1da4cac1530dfc0 Mon Sep 17 00:00:00 2001
From: joda9 <jonas.danke@rl-institut.de>
Date: Thu, 25 Jul 2024 09:00:16 +0200
Subject: [PATCH] source of formula added

---
 edisgo/tools/tools.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/edisgo/tools/tools.py b/edisgo/tools/tools.py
index 76a7cd64..dea5d673 100644
--- a/edisgo/tools/tools.py
+++ b/edisgo/tools/tools.py
@@ -226,9 +226,10 @@ def calculate_voltage_diff_per_line(
         Voltage difference in kV.
     """
     sin_phi = np.sqrt(1 - cos_phi**2)
+    # Calculate the voltage difference using the formula from VDE-AR-N 4105
     voltage_diff = np.abs(
         (s_max * 1e6 / (v_nom * 1e3)) * (r_total * cos_phi + sign * x_total * sin_phi)
-    )
+    )  # in V
     return voltage_diff / 1e3  # Convert to kV