diff --git a/open-reac/src/main/resources/openreac/acopf.mod b/open-reac/src/main/resources/openreac/acopf.mod
index 85bfb991..4c3e35c7 100644
--- a/open-reac/src/main/resources/openreac/acopf.mod
+++ b/open-reac/src/main/resources/openreac/acopf.mod
@@ -109,27 +109,27 @@ var branch_Ror_var{(qq,m,n) in BRANCHCC_REGL_VAR}
 var Red_Tran_Act_Dir{(qq,m,n) in BRANCHCC } =
     V[n] * branch_admi[qq,m,n] * sin(teta[m]-teta[n]+branch_dephor[qq,m,n]-branch_angper[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])
-  + V[m] * (branch_admi[qq,m,n]*sin(branch_angper[qq,m,n])+branch_Gor[1,qq,m,n])
+  + V[m] * (branch_admi[qq,m,n]*sin(branch_angper[qq,m,n])+branch_Gor_mod[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])**2
   ;
 
 var Red_Tran_Rea_Dir{(qq,m,n) in BRANCHCC } =
   - V[n] * branch_admi[qq,m,n] * cos(teta[m]-teta[n]+branch_dephor[qq,m,n]-branch_angper[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])
-  + V[m] * (branch_admi[qq,m,n]*cos(branch_angper[qq,m,n])-branch_Bor[1,qq,m,n])
+  + V[m] * (branch_admi[qq,m,n]*cos(branch_angper[qq,m,n])-branch_Bor_mod[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])^2
   ;
 
 var Red_Tran_Act_Inv{(qq,m,n) in BRANCHCC } =
     V[m] * branch_admi[qq,m,n] * sin(teta[n]-teta[m]-branch_dephor[qq,m,n]-branch_angper[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])
-  + V[n] * (branch_admi[qq,m,n]*sin(branch_angper[qq,m,n])+branch_Gex[1,qq,m,n])
+  + V[n] * (branch_admi[qq,m,n]*sin(branch_angper[qq,m,n])+branch_Gex_mod[qq,m,n])
   ;
 
 var Red_Tran_Rea_Inv{(qq,m,n) in BRANCHCC } =
   - V[m] * branch_admi[qq,m,n] * cos(teta[n]-teta[m]-branch_dephor[qq,m,n]-branch_angper[qq,m,n])
     * (if (qq,m,n) in BRANCHCC_REGL_VAR then branch_Ror_var[qq,m,n]*branch_cstratio[1,qq,m,n] else branch_Ror[qq,m,n])
-  + V[n] * (branch_admi[qq,m,n]*cos(branch_angper[qq,m,n])-branch_Bex[1,qq,m,n])
+  + V[n] * (branch_admi[qq,m,n]*cos(branch_angper[qq,m,n])-branch_Bex_mod[qq,m,n])
   ;
 
 
diff --git a/open-reac/src/main/resources/openreac/commons.mod b/open-reac/src/main/resources/openreac/commons.mod
index 776cb080..9d0f6d18 100644
--- a/open-reac/src/main/resources/openreac/commons.mod
+++ b/open-reac/src/main/resources/openreac/commons.mod
@@ -103,6 +103,23 @@ param branch_X_mod{(qq,m,n) in BRANCHCC} :=
   else branch_X[1,qq,m,n];
 check {(qq,m,n) in BRANCHCC}: abs(branch_X_mod[qq,m,n]) > 0;
 
+# If in BRANCHZNULL, then set Gor/Gex/Bor/Bex to 0
+param branch_Gor_mod{(qq,m,n) in BRANCHCC} :=
+    if (qq,m,n) in BRANCHZNULL then 0
+    else branch_Gor[1,qq,m,n];
+
+param branch_Gex_mod{(qq,m,n) in BRANCHCC} :=
+    if (qq,m,n) in BRANCHZNULL then 0
+    else branch_Gex[1,qq,m,n];
+
+param branch_Bor_mod{(qq,m,n) in BRANCHCC} :=
+    if (qq,m,n) in BRANCHZNULL then 0
+    else branch_Bor[1,qq,m,n];
+
+param branch_Bex_mod{(qq,m,n) in BRANCHCC} :=
+    if (qq,m,n) in BRANCHZNULL then 0
+    else branch_Bex[1,qq,m,n];
+
 # Busses with valid voltage value
 set BUSVV := {n in BUSCC : bus_V0[1,n] >= min_plausible_low_voltage_limit};