Active Power Distribution: better reports severities when residual mismatch remains

src/main/java/com/powsybl/openloadflow/ac/outerloop/DistributedSlackOuterLoop.java

@@ -77,9 +77,12 @@ public OuterLoopResult check(AcOuterLoopContext context, ReportNode reportNode)
         );
         double remainingMismatch = resultWbh.remainingMismatch();
         double distributedActivePower = slackBusActivePowerMismatch - remainingMismatch;
-        if (Math.abs(remainingMismatch) > ActivePowerDistribution.P_RESIDUE_EPS) {
+        if (Math.abs(remainingMismatch) > slackBusPMaxMismatch / PerUnit.SB) {
             Reports.reportMismatchDistributionFailure(iterationReportNode, remainingMismatch * PerUnit.SB);
         } else {
+            if (Math.abs(remainingMismatch) > ActivePowerDistribution.P_RESIDUE_EPS) {
+                Reports.reportResidualDistributionMismatch(reportNode, remainingMismatch * PerUnit.SB);
+            }
             ActivePowerDistribution.reportAndLogSuccess(iterationReportNode, slackBusActivePowerMismatch, resultWbh);
         }
         DistributedSlackContextData contextData = (DistributedSlackContextData) context.getData();

src/main/java/com/powsybl/openloadflow/dc/DcLoadFlowEngine.java

@@ -228,9 +228,12 @@ public DcLoadFlowResult run() {
             );
             double remainingMismatch = resultWbh.remainingMismatch();
             distributedActivePower = initialSlackBusActivePowerMismatch - remainingMismatch;
-            if (Math.abs(remainingMismatch) > ActivePowerDistribution.P_RESIDUE_EPS) {
+            if (Math.abs(remainingMismatch) > context.getParameters().getSlackBusPMaxMismatch() / PerUnit.SB) {
                 Reports.reportMismatchDistributionFailure(reportNode, remainingMismatch * PerUnit.SB);
             } else {
+                if (Math.abs(remainingMismatch) > ActivePowerDistribution.P_RESIDUE_EPS) {
+                    Reports.reportResidualDistributionMismatch(reportNode, remainingMismatch * PerUnit.SB);
+                }
                 ActivePowerDistribution.reportAndLogSuccess(reportNode, initialSlackBusActivePowerMismatch, resultWbh);
             }
             if (resultWbh.failed()) {

src/main/java/com/powsybl/openloadflow/util/Reports.java

@@ -162,7 +162,15 @@ public static void reportMismatchDistributionFailure(ReportNode reportNode, doub
         reportNode.newReportNode()
                 .withMessageTemplate("mismatchDistributionFailure", "Failed to distribute slack bus active power mismatch, ${mismatch} MW remains")
                 .withTypedValue(MISMATCH, remainingMismatch, OpenLoadFlowReportConstants.MISMATCH_TYPED_VALUE)
-                .withSeverity(TypedValue.ERROR_SEVERITY)
+                .withSeverity(TypedValue.WARN_SEVERITY)
+                .add();
+    }
+
+    public static void reportResidualDistributionMismatch(ReportNode reportNode, double remainingMismatch) {
+        reportNode.newReportNode()
+                .withMessageTemplate("residualDistributionMismatch", "Remaining residual slack bus active power mismatch after active power distribution, ${mismatch} MW remains")
+                .withTypedValue(MISMATCH, remainingMismatch, OpenLoadFlowReportConstants.MISMATCH_TYPED_VALUE)
+                .withSeverity(TypedValue.DEBUG_SEVERITY)
                 .add();
     }
 

src/test/java/com/powsybl/openloadflow/dc/DcLoadFlowTest.java

@@ -553,6 +553,17 @@ void testDcApproxIgnoreG() {
         assertEquals(-307.436, line2.getTerminal2().getP(), 0.01);
     }
 
+    @Test
+    void testDcResidualMismatchRemaining() {
+        Network network = IeeeCdfNetworkFactory.create9();
+        network.getGenerator("B1-G").setTargetP(67.99); // Setting target P to have an initially almost balanced network
+        ReportNode reportNode = ReportNode.newRootReportNode().withMessageTemplate("test", "test").build();
+        System.out.println(network.getGenerator("B1-G").getId() + " has P = " + network.getGenerator("B1-G").getTargetP());
+        loadFlowRunner.run(network, network.getVariantManager().getWorkingVariantId(), LocalComputationManager.getDefault(), parameters, reportNode);
+        // DC loadflow succeeds but the initial residual mismatch still remains
+        assertReportContains("Remaining residual slack bus active power mismatch after active power distribution, [-+]?0\\.\\d* MW remains", reportNode);
+    }
+
     @Test
     void testDcSlackDistributionFailureBehavior() {
         Network network = IeeeCdfNetworkFactory.create57();