From 3ef6d519d715efb2aec863f9c09ee2ec605c711b Mon Sep 17 00:00:00 2001
From: Bobby Xiong <36541459+bobbyxng@users.noreply.github.com>
Date: Wed, 14 Aug 2024 10:24:38 +0200
Subject: [PATCH] Fix simplify_network.py to handle more complex topologies
 (#1211)

* Fixed simplify_network.py to handle more complex topologies, i.e. if two links are connected to nearby AC buses separated by an AC line.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 scripts/simplify_network.py | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/scripts/simplify_network.py b/scripts/simplify_network.py
index 558e4cf2..2b759a73 100644
--- a/scripts/simplify_network.py
+++ b/scripts/simplify_network.py
@@ -298,13 +298,24 @@ def simplify_links(
     _, labels = connected_components(adjacency_matrix, directed=False)
     labels = pd.Series(labels, n.buses.index)
 
-    G = n.graph()
+    # Only span graph over the DC link components
+    G = n.graph(branch_components=["Link"])
 
     def split_links(nodes):
         nodes = frozenset(nodes)
 
         seen = set()
-        supernodes = {m for m in nodes if len(G.adj[m]) > 2 or (set(G.adj[m]) - nodes)}
+
+        # Supernodes are endpoints of links, identified by having lass then two neighbours or being an AC Bus
+        # An example for the latter is if two different links are connected to the same AC bus.
+        supernodes = {
+            m
+            for m in nodes
+            if (
+                (len(G.adj[m]) < 2 or (set(G.adj[m]) - nodes))
+                or (n.buses.loc[m, "carrier"] == "AC")
+            )
+        }
 
         for u in supernodes:
             for m, ls in G.adj[u].items():