Move cleanContingencies from DC sensitivity analysis to utility method

src/main/java/com/powsybl/openloadflow/network/impl/PropagatedContingency.java

@@ -540,4 +540,58 @@ public Optional<LfContingency> toLfContingency(LfNetwork network) {
                            new DisabledNetwork(busesToLost, branchesToOpen, lostHvdcs), shunts, loads, generators,
                            connectivityLossImpact.hvdcsWithoutPower()));
     }
+
+    /**
+     * In general, a {@link PropagatedContingency} is translated to a {@link LfContingency}. During the translation,
+     * cleans are performed to deal with branches connected at one side and slack bus loss. But in some fast DC computations,
+     * we don't want to use {@link LfContingency} object, so a dedicated clean method directly available on a {@link PropagatedContingency}
+     * is needed. It contains:
+     *  - Removing branches out of this synchronous component from branches to open.
+     *  - Removing branches connected at one side from branches to open.
+     *  - Removing slack bus from buses lost (not supported yet).
+     *  - Adding branches connected to buses lost in branches to open.
+     */
+    public static void cleanContingencies(LfNetwork lfNetwork, List<PropagatedContingency> contingencies) {
+        for (PropagatedContingency contingency : contingencies) {
+            // Elements have already been checked and found in PropagatedContingency, so there is no need to
+            // check them again
+            Set<String> branchesToRemove = new HashSet<>(); // branches connected to one side, or switches
+            for (String branchId : contingency.getBranchIdsToOpen().keySet()) {
+                LfBranch lfBranch = lfNetwork.getBranchById(branchId);
+                if (lfBranch == null) {
+                    branchesToRemove.add(branchId); // disconnected branch
+                    continue;
+                }
+                if (!lfBranch.isConnectedAtBothSides()) {
+                    branchesToRemove.add(branchId); // branch connected only on one side
+                }
+            }
+            branchesToRemove.forEach(branchToRemove -> contingency.getBranchIdsToOpen().remove(branchToRemove));
+
+            // update branches to open connected with buses in contingency. This is an approximation:
+            // these branches are indeed just open at one side.
+            String slackBusId = null;
+            for (String busId : contingency.getBusIdsToLose()) {
+                LfBus bus = lfNetwork.getBusById(busId);
+                if (bus != null) {
+                    if (bus.isSlack()) {
+                        // slack bus disabling is not supported in DC because the relocation is done from propagated contingency
+                        // to LfContingency
+                        // we keep the slack bus enabled and the connected branches
+                        LOGGER.error("Contingency '{}' leads to the loss of a slack bus: slack bus kept", contingency.getContingency().getId());
+                        slackBusId = busId;
+                    } else {
+                        bus.getBranches().forEach(branch -> contingency.getBranchIdsToOpen().put(branch.getId(), DisabledBranchStatus.BOTH_SIDES));
+                    }
+                }
+            }
+            if (slackBusId != null) {
+                contingency.getBusIdsToLose().remove(slackBusId);
+            }
+
+            if (contingency.hasNoImpact()) {
+                LOGGER.warn("Contingency '{}' has no impact", contingency.getContingency().getId());
+            }
+        }
+    }
 }

src/main/java/com/powsybl/openloadflow/sensi/DcSensitivityAnalysis.java

@@ -40,6 +40,7 @@
 import java.util.stream.Collectors;
 
 import static com.powsybl.openloadflow.dc.DcLoadFlowEngine.run;
+import static com.powsybl.openloadflow.network.impl.PropagatedContingency.cleanContingencies;
 import static com.powsybl.openloadflow.network.util.ParticipatingElement.normalizeParticipationFactors;
 
 /**
@@ -338,50 +339,6 @@ private void processContingenciesBreakingConnectivity(ConnectivityBreakAnalysis.
                 connectivityAnalysisResult.getElementsToReconnect(), resultWriter, reportNode, partialDisabledBranches, rhsChanged);
     }
 
-    protected void cleanContingencies(LfNetwork lfNetwork, List<PropagatedContingency> contingencies) {
-        for (PropagatedContingency contingency : contingencies) {
-            // Elements have already been checked and found in PropagatedContingency, so there is no need to
-            // check them again
-            Set<String> branchesToRemove = new HashSet<>(); // branches connected to one side, or switches
-            for (String branchId : contingency.getBranchIdsToOpen().keySet()) {
-                LfBranch lfBranch = lfNetwork.getBranchById(branchId);
-                if (lfBranch == null) {
-                    branchesToRemove.add(branchId); // disconnected branch
-                    continue;
-                }
-                if (!lfBranch.isConnectedAtBothSides()) {
-                    branchesToRemove.add(branchId); // branch connected only on one side
-                }
-            }
-            branchesToRemove.forEach(branchToRemove -> contingency.getBranchIdsToOpen().remove(branchToRemove));
-
-            // update branches to open connected with buses in contingency. This is an approximation:
-            // these branches are indeed just open at one side.
-            String slackBusId = null;
-            for (String busId : contingency.getBusIdsToLose()) {
-                LfBus bus = lfNetwork.getBusById(busId);
-                if (bus != null) {
-                    if (bus.isSlack()) {
-                        // slack bus disabling is not supported in DC because the relocation is done from propagated contingency
-                        // to LfContingency
-                        // we keep the slack bus enabled and the connected branches
-                        LOGGER.error("Contingency '{}' leads to the loss of a slack bus: slack bus kept", contingency.getContingency().getId());
-                        slackBusId = busId;
-                    } else {
-                        bus.getBranches().forEach(branch -> contingency.getBranchIdsToOpen().put(branch.getId(), DisabledBranchStatus.BOTH_SIDES));
-                    }
-                }
-            }
-            if (slackBusId != null) {
-                contingency.getBusIdsToLose().remove(slackBusId);
-            }
-
-            if (contingency.hasNoImpact()) {
-                LOGGER.warn("Contingency '{}' has no impact", contingency.getContingency().getId());
-            }
-        }
-    }
-
     @Override
     public void analyse(Network network, List<PropagatedContingency> contingencies, List<SensitivityVariableSet> variableSets,
                         SensitivityFactorReader factorReader, SensitivityResultWriter resultWriter, ReportNode reportNode,