Refactor discrete voltage control

src/main/java/com/powsybl/openloadflow/ac/equations/AcEquationSystemUpdater.java

@@ -32,7 +32,8 @@ private void updateVoltageControl(VoltageControl voltageControl) {
             // we only support one controlling static var compensator without any other controlling generators
             // we don't support controller bus that wants to control back voltage with slope.
             if (!firstControllerBus.isVoltageControlEnabled()) {
-                equationSystem.createEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V_WITH_SLOPE).setActive(false);
+                equationSystem.getEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V_WITH_SLOPE)
+                        .orElseThrow().setActive(false);
             }
         } else {
             if (voltageControl.isVoltageControlLocal()) {
@@ -47,7 +48,8 @@ private void updateVoltageControl(VoltageControl voltageControl) {
 
     private void updateVoltageControl(LfBus controllerBus, boolean newVoltageControllerEnabled) {
         // active/de-activate bus target reactive power equation to switch bus PV or PQ
-        equationSystem.createEquation(controllerBus.getNum(), AcEquationType.BUS_TARGET_Q)
+        equationSystem.getEquation(controllerBus.getNum(), AcEquationType.BUS_TARGET_Q)
+                .orElseThrow()
                 .setActive(!newVoltageControllerEnabled);
 
         updateVoltageControl(controllerBus.getVoltageControl().orElseThrow());
@@ -62,11 +64,13 @@ private void updateDiscretePhaseControl(DiscretePhaseControl phaseControl, Discr
         boolean on = newMode != DiscretePhaseControl.Mode.OFF;
 
         // activate/de-activate phase control equation
-        equationSystem.createEquation(phaseControl.getControlled().getNum(), AcEquationType.BRANCH_TARGET_P)
+        equationSystem.getEquation(phaseControl.getControlled().getNum(), AcEquationType.BRANCH_TARGET_P)
+                .orElseThrow()
                 .setActive(on);
 
         // de-activate/activate constant A1 equation
-        equationSystem.createEquation(phaseControl.getController().getNum(), AcEquationType.BRANCH_TARGET_ALPHA1)
+        equationSystem.getEquation(phaseControl.getController().getNum(), AcEquationType.BRANCH_TARGET_ALPHA1)
+                .orElseThrow()
                 .setActive(!on);
     }
 
@@ -75,81 +79,26 @@ public void onDiscretePhaseControlModeChange(DiscretePhaseControl phaseControl,
         updateDiscretePhaseControl(phaseControl, newMode);
     }
 
-    private void updateTransformerVoltageControl(TransformerVoltageControl voltageControl, DiscreteVoltageControl.Mode newMode) {
-        LfBus controlledBus = voltageControl.getControlled();
-        if (newMode == DiscreteVoltageControl.Mode.OFF) {
-
-            // de-activate transformer voltage control equation
-            equationSystem.createEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V)
-                    .setActive(false);
-
-            for (LfBranch controllerBranch : voltageControl.getControllers()) {
-                // activate constant R1 equation
-                equationSystem.createEquation(controllerBranch.getNum(), AcEquationType.BRANCH_TARGET_RHO1)
-                        .setActive(true);
-
-                // clean transformer distribution equations
-                equationSystem.removeEquation(controllerBranch.getNum(), AcEquationType.DISTR_RHO);
-            }
-        } else { // newMode == DiscreteVoltageControl.Mode.VOLTAGE
-
-            // activate transformer voltage control equation
-            equationSystem.createEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V)
-                    .setActive(true);
-
-            // add transformer distribution equations
-            AcEquationSystem.createR1DistributionEquations(voltageControl.getControllers(), equationSystem);
-
-            for (LfBranch controllerBranch : voltageControl.getControllers()) {
-                // de-activate constant R1 equation
-                equationSystem.createEquation(controllerBranch.getNum(), AcEquationType.BRANCH_TARGET_RHO1)
-                        .setActive(false);
-            }
-        }
-    }
-
-    private void updateShuntVoltageControl(ShuntVoltageControl voltageControl, DiscreteVoltageControl.Mode newMode) {
-        LfBus controlledBus = voltageControl.getControlled();
-        if (newMode == DiscreteVoltageControl.Mode.OFF) {
-
-            // de-activate transformer or shunt voltage control equation
-            equationSystem.createEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V)
-                    .setActive(false);
-
-            for (LfBus controllerBus : voltageControl.getControllers()) {
-                controllerBus.getControllerShunt().ifPresent(shunt -> {
-                    // activate constant B equation
-                    equationSystem.createEquation(shunt.getNum(), AcEquationType.SHUNT_TARGET_B)
-                            .setActive(true);
-
-                    // clean shunt distribution equations
-                    equationSystem.removeEquation(shunt.getNum(), AcEquationType.DISTR_B);
-                });
-            }
-        } else { // newMode == DiscreteVoltageControl.Mode.VOLTAGE
-
-            // de-activate transformer or shunt voltage control equation
-            equationSystem.createEquation(controlledBus.getNum(), AcEquationType.BUS_TARGET_V)
-                    .setActive(false);
-
-            // add shunt distribution equations
-            AcEquationSystem.createBDistributionEquations(voltageControl.getControllers(), equationSystem);
-
-            for (LfBus controllerBus : voltageControl.getControllers()) {
-                controllerBus.getControllerShunt().ifPresent(shunt ->
-                        // de-activate constant B equation
-                        equationSystem.createEquation(shunt.getNum(), AcEquationType.BRANCH_TARGET_RHO1)
-                                .setActive(false));
-            }
-        }
-    }
-
     @Override
     public void onDiscreteVoltageControlModeChange(DiscreteVoltageControl voltageControl, DiscreteVoltageControl.Mode newMode) {
         if (voltageControl instanceof TransformerVoltageControl) {
-            updateTransformerVoltageControl((TransformerVoltageControl) voltageControl, newMode);
+            AcEquationSystem.updateTransformerVoltageControlEquations((TransformerVoltageControl) voltageControl, equationSystem);
         } else if (voltageControl instanceof ShuntVoltageControl) {
-            updateShuntVoltageControl((ShuntVoltageControl) voltageControl, newMode);
+            AcEquationSystem.updateShuntVoltageControlEquations((ShuntVoltageControl) voltageControl, equationSystem);
+        }
+    }
+
+    @Override
+    public void onDisableChange(LfElement element, boolean disabled) {
+        if (element.getType() == ElementType.BUS) {
+            LfBus bus = (LfBus) element;
+            bus.getVoltageControl().ifPresent(this::updateVoltageControl);
+            bus.getTransformerVoltageControl().ifPresent(voltageControl -> AcEquationSystem.updateTransformerVoltageControlEquations(voltageControl, equationSystem));
+            bus.getShuntVoltageControl().ifPresent(voltageControl -> AcEquationSystem.updateShuntVoltageControlEquations(voltageControl, equationSystem));
+        } else if (element.getType() == ElementType.BRANCH) {
+            LfBranch branch = (LfBranch) element;
+            branch.getTransformerVoltageControl().ifPresent(voltageControl -> AcEquationSystem.updateTransformerVoltageControlEquations(voltageControl, equationSystem));
+            // TODO phase control.
         }
     }
 }

src/main/java/com/powsybl/openloadflow/ac/equations/AcEquationType.java

@@ -27,7 +27,7 @@ public enum AcEquationType implements Quantity {
     ZERO_V("zero_v", ElementType.BRANCH), // zero impedance branch, voltage magnitude equality
     ZERO_PHI("zero_\u03C6", ElementType.BRANCH), // zero impedance branch, voltage angle equality
     DISTR_RHO("distr_\u03C1", ElementType.BRANCH), // remote transformer voltage control ratio distribution
-    DISTR_B("distr_b", ElementType.SHUNT_COMPENSATOR); // remote transformer voltage control ratio distribution
+    DISTR_SHUNT_B("distr_b", ElementType.SHUNT_COMPENSATOR); // shunt remote voltage control susceptance distribution
 
     private final String symbol;
 

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

@@ -139,20 +139,6 @@ private static double getReactivePowerDistributionTarget(LfNetwork network, int
         return target;
     }
 
-    private static double getRho1DistributionTarget(LfNetwork network, int num, DistributionData data) {
-        LfBranch controllerBranch = network.getBranch(num);
-        LfBranch firstControllerBranch = network.getBranch(data.getFirstControllerElementNum());
-        // as a first and very simple ratio distribution strategy, we keep the gap between the 2 ratios constant
-        return controllerBranch.getPiModel().getR1() - firstControllerBranch.getPiModel().getR1();
-    }
-
-    private static double getBDistributionTarget(LfNetwork network, int num, DistributionData data) {
-        LfShunt controllerShunt = network.getShunt(num);
-        LfShunt firstControllerShunt = network.getShunt(data.getFirstControllerElementNum());
-        // as a first and very simple B distribution strategy, we keep the gap between the 2 B constant
-        return controllerShunt.getB() - firstControllerShunt.getB();
-    }
-
     private static double createBusWithSlopeTarget(LfBus bus) {
         // take first generator with slope: network loading ensures that there's only one generator with slope
         double slope = bus.getGeneratorsControllingVoltageWithSlope().get(0).getSlope();
@@ -220,11 +206,8 @@ public static void initTarget(Equation<AcVariableType, AcEquationType> equation,
                 break;
 
             case DISTR_RHO:
-                targets[equation.getColumn()] = getRho1DistributionTarget(network, equation.getElementNum(), equation.getData());
-                break;
-
-            case DISTR_B:
-                targets[equation.getColumn()] = getBDistributionTarget(network, equation.getElementNum(), equation.getData());
+            case DISTR_SHUNT_B:
+                targets[equation.getColumn()] = 0;
                 break;
 
             default:

src/main/java/com/powsybl/openloadflow/equations/EquationUtil.java

@@ -9,9 +9,11 @@
 import com.powsybl.openloadflow.network.ElementType;
 import com.powsybl.openloadflow.network.LfBranch;
 import com.powsybl.openloadflow.network.LfBus;
+import com.powsybl.openloadflow.network.LfShunt;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
@@ -64,6 +66,27 @@ public static <V extends Enum<V> & Quantity, E extends Enum<E> & Quantity> void
                     deactivatedEquationTerms.add(equationTerm);
                 }
             }
+
+            List<LfShunt> shunts = new ArrayList<>(2);
+            bus.getShunt().ifPresent(shunts::add);
+            bus.getControllerShunt().ifPresent(shunts::add);
+            for (LfShunt shunt : shunts) {
+                // deactivate all equations related to a shunt
+                for (Equation<V, E> equation : equationSystem.getEquations(ElementType.SHUNT_COMPENSATOR, shunt.getNum())) {
+                    if (equation.isActive()) {
+                        equation.setActive(false);
+                        deactivatedEquations.add(equation);
+                    }
+                }
+
+                // deactivate all equation terms related to a shunt
+                for (EquationTerm<V, E> equationTerm : equationSystem.getEquationTerms(ElementType.SHUNT_COMPENSATOR, shunt.getNum())) {
+                    if (equationTerm.isActive()) {
+                        equationTerm.setActive(false);
+                        deactivatedEquationTerms.add(equationTerm);
+                    }
+                }
+            }
         }
     }
 

src/main/java/com/powsybl/openloadflow/network/AbstractElement.java

@@ -11,7 +11,7 @@
 /**
  * @author Geoffroy Jamgotchian <geoffroy.jamgotchian at rte-france.com>
  */
-public abstract class AbstractElement {
+public abstract class AbstractElement implements LfElement {
 
     protected final LfNetwork network;
 
@@ -38,7 +38,12 @@ public boolean isDisabled() {
     }
 
     public void setDisabled(boolean disabled) {
-        this.disabled = disabled;
+        if (disabled != this.disabled) {
+            this.disabled = disabled;
+            for (LfNetworkListener listener : network.getListeners()) {
+                listener.onDisableChange(this, disabled);
+            }
+        }
     }
 
     public LfNetwork getNetwork() {

src/main/java/com/powsybl/openloadflow/network/AbstractLfNetworkListener.java

@@ -50,4 +50,9 @@ public void onGenerationReactivePowerTargetChange(LfBus bus, double oldGeneratio
     public void onDiscretePhaseControlTapPositionChange(PiModel piModel, int oldPosition, int newPosition) {
         // empty
     }
+
+    @Override
+    public void onDisableChange(LfElement element, boolean disabled) {
+        // empty
+    }
 }

src/main/java/com/powsybl/openloadflow/network/BusModeState.java

@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) 2021, RTE (http://www.rte-france.com)
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+package com.powsybl.openloadflow.network;
+
+/**
+ * @author Anne Tilloy <anne.tilloy at rte-france.com>
+ */
+public class BusModeState extends ElementState<LfBus> {
+
+    private final DiscreteVoltageControl.Mode transformerVoltageControlMode;
+    private final DiscreteVoltageControl.Mode shuntVoltageControlMode;
+
+    public BusModeState(LfBus bus) {
+        super(bus);
+        transformerVoltageControlMode = bus.getTransformerVoltageControl().map(TransformerVoltageControl::getMode).orElse(null);
+        shuntVoltageControlMode = bus.getShuntVoltageControl().map(ShuntVoltageControl::getMode).orElse(null);
+    }
+
+    @Override
+    public void restore() {
+        if (transformerVoltageControlMode != null) {
+            element.getTransformerVoltageControl().ifPresent(control -> control.setMode(transformerVoltageControlMode));
+        }
+        if (shuntVoltageControlMode != null) {
+            element.getShuntVoltageControl().ifPresent(control -> control.setMode(shuntVoltageControlMode));
+        }
+    }
+
+    public static BusModeState save(LfBus bus) {
+        return new BusModeState(bus);
+    }
+}

src/main/java/com/powsybl/openloadflow/network/BusState.java

@@ -16,8 +16,6 @@ public class BusState extends BusDcState {
     private final double loadTargetQ;
     private final double generationTargetQ;
     private final boolean voltageControlEnabled;
-    private final DiscreteVoltageControl.Mode transformerVoltageControlMode;
-    private final DiscreteVoltageControl.Mode shuntVoltageControlMode;
     private final boolean disabled;
 
     public BusState(LfBus bus) {
@@ -27,8 +25,6 @@ public BusState(LfBus bus) {
         this.loadTargetQ = bus.getLoadTargetQ();
         this.generationTargetQ = bus.getGenerationTargetQ();
         this.voltageControlEnabled = bus.isVoltageControlEnabled();
-        transformerVoltageControlMode = bus.getTransformerVoltageControl().map(TransformerVoltageControl::getMode).orElse(null);
-        shuntVoltageControlMode = bus.getShuntVoltageControl().map(ShuntVoltageControl::getMode).orElse(null);
         this.disabled = bus.isDisabled();
     }
 
@@ -41,12 +37,6 @@ public void restore() {
         element.setGenerationTargetQ(generationTargetQ);
         element.setVoltageControlEnabled(voltageControlEnabled);
         element.setVoltageControlSwitchOffCount(0);
-        if (transformerVoltageControlMode != null) {
-            element.getTransformerVoltageControl().ifPresent(control -> control.setMode(transformerVoltageControlMode));
-        }
-        if (shuntVoltageControlMode != null) {
-            element.getShuntVoltageControl().ifPresent(control -> control.setMode(shuntVoltageControlMode));
-        }
         element.setDisabled(disabled);
     }
 

src/main/java/com/powsybl/openloadflow/network/LfNetworkListener.java

@@ -26,4 +26,6 @@ public interface LfNetworkListener {
     void onGenerationReactivePowerTargetChange(LfBus bus, double oldGenerationTargetQ, double newGenerationTargetQ);
 
     void onDiscretePhaseControlTapPositionChange(PiModel piModel, int oldPosition, int newPosition);
+
+    void onDisableChange(LfElement element, boolean disabled);
 }

src/main/java/com/powsybl/openloadflow/network/VoltageControl.java

@@ -73,7 +73,7 @@ public void updateReactiveKeys() {
         // no reactive dispatch on PQ buses, so we set the key to 0
         for (int i = 0; i < controllerBuses.size(); i++) {
             LfBus controllerBus = controllerBuses.get(i);
-            if (!controllerBus.isVoltageControlEnabled()) {
+            if (controllerBus.isDisabled() || !controllerBus.isVoltageControlEnabled()) {
                 reactiveKeys[i] = 0d;
             }
         }

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

@@ -161,7 +161,7 @@ private void roundBToClosestSection(double b, Controller controller) {
                 smallestDistance = distance;
             }
         }
-        LOGGER.info("Round B shift of shunt '{}': {} -> {}", controller.getId(), b, controller.getB());
+        LOGGER.trace("Round B shift of shunt '{}': {} -> {}", controller.getId(), b, controller.getB());
     }
 
     @Override

src/main/java/com/powsybl/openloadflow/sa/AcSecurityAnalysis.java

@@ -112,6 +112,8 @@ private SecurityAnalysisResult runSimulations(LfNetwork network, List<Propagated
         List<BranchResult> preContingencyBranchResults = new ArrayList<>();
         List<BusResults> preContingencyBusResults = new ArrayList<>();
         List<ThreeWindingsTransformerResult> preContingencyThreeWindingsTransformerResults = new ArrayList<>();
+        List<BranchState> branchStates = ElementState.save(network.getBranches(), BranchState::save);
+        List<BusModeState> busModeStates = ElementState.save(network.getBuses(), BusModeState::save);
 
         // run pre-contingency simulation
         try (AcloadFlowEngine engine = new AcloadFlowEngine(network, acParameters)) {
@@ -133,7 +135,6 @@ private SecurityAnalysisResult runSimulations(LfNetwork network, List<Propagated
 
                 // save base state for later restoration after each contingency
                 List<BusState> busStates = ElementState.save(network.getBuses(), BusState::save);
-                List<BranchState> branchStates = ElementState.save(network.getBranches(), BranchState::save);
                 for (LfBus bus : network.getBuses()) {
                     bus.setVoltageControlSwitchOffCount(0);
                 }
@@ -145,12 +146,12 @@ private SecurityAnalysisResult runSimulations(LfNetwork network, List<Propagated
                     PropagatedContingency propagatedContingency = contingencyIt.next();
                     LfContingency.create(propagatedContingency, network, connectivity, true)
                             .ifPresent(lfContingency -> { // only process contingencies that impact the network
-                                for (LfBus bus : lfContingency.getBuses()) {
-                                    bus.setDisabled(true);
-                                }
                                 for (LfBranch branch : lfContingency.getBranches()) {
                                     branch.setDisabled(true);
                                 }
+                                for (LfBus bus : lfContingency.getBuses()) {
+                                    bus.setDisabled(true);
+                                }
 
                                 distributedMismatch(network, lfContingency.getActivePowerLoss(), loadFlowParameters, openLoadFlowParameters);
 
@@ -162,6 +163,7 @@ private SecurityAnalysisResult runSimulations(LfNetwork network, List<Propagated
 
                                     // restore base state
                                     ElementState.restore(busStates);
+                                    ElementState.restore(busModeStates);
                                     ElementState.restore(branchStates);
                                 }
                             });