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Fix DcEquationSystem with disabled non impedant branch #663

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merged 5 commits into from
Nov 30, 2022
Merged

Fix DcEquationSystem with disabled non impedant branch #663

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147e38b
Add a test that shows the bug.
annetill Nov 29, 2022
307d1a0
Fix proposal.
annetill Nov 29, 2022
00199b2
Merge branch 'main' into fix-disabled-non-impedant-branch
geofjamg Nov 29, 2022
b1c41d1
Merge
geofjamg Nov 29, 2022
07f5c7e
Fix
geofjamg Nov 29, 2022
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1 change: 1 addition & 0 deletions src/main/java/com/powsybl/openloadflow/dc/DcTargetVector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ public static void init(Equation<DcVariableType, DcEquationType> equation, LfNet
break;

case BUS_TARGET_PHI:
case DUMMY_TARGET_P:
targets[equation.getColumn()] = 0;
break;

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21 changes: 13 additions & 8 deletions src/main/java/com/powsybl/openloadflow/dc/equations/DcEquationSystem.java
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Expand Up @@ -31,10 +31,10 @@ private DcEquationSystem() {

private static void createBuses(LfNetwork network, EquationSystem<DcVariableType, DcEquationType> equationSystem) {
for (LfBus bus : network.getBuses()) {
var p = equationSystem.createEquation(bus.getNum(), DcEquationType.BUS_TARGET_P);
var p = equationSystem.createEquation(bus, DcEquationType.BUS_TARGET_P);
bus.setP(p);
if (bus.isSlack()) {
equationSystem.createEquation(bus.getNum(), DcEquationType.BUS_TARGET_PHI)
equationSystem.createEquation(bus, DcEquationType.BUS_TARGET_PHI)
.addTerm(equationSystem.getVariable(bus.getNum(), DcVariableType.BUS_PHI).createTerm());
p.setActive(false);
}
Expand All @@ -48,22 +48,27 @@ public static void createNonImpedantBranch(EquationSystem<DcVariableType, DcEqua
if (!(hasPhi1 && hasPhi2)) {
// create voltage angle coupling equation
// alpha = phi1 - phi2
equationSystem.createEquation(branch.getNum(), DcEquationType.ZERO_PHI)
equationSystem.createEquation(branch, DcEquationType.ZERO_PHI)
.addTerm(equationSystem.getVariable(bus1.getNum(), DcVariableType.BUS_PHI).createTerm())
.addTerm(equationSystem.getVariable(bus2.getNum(), DcVariableType.BUS_PHI).<DcEquationType>createTerm()
.minus());

// add a dummy active power variable to both sides of the non impedant branch and with an opposite sign
// to ensure we have the same number of equation and variables
var dummyP = equationSystem.getVariable(branch.getNum(), DcVariableType.DUMMY_P);
equationSystem.getEquation(bus1.getNum(), DcEquationType.BUS_TARGET_P)
.orElseThrow()
.addTerm(equationSystem.getVariable(branch.getNum(), DcVariableType.DUMMY_P)
.createTerm());
.addTerm(dummyP.createTerm());

equationSystem.getEquation(bus2.getNum(), DcEquationType.BUS_TARGET_P)
.orElseThrow()
.addTerm(equationSystem.getVariable(branch.getNum(), DcVariableType.DUMMY_P).<DcEquationType>createTerm()
.minus());
.addTerm(dummyP.<DcEquationType>createTerm().minus());

// create an inactive dummy active power target equation set to zero that could be activated
// on case of switch opening
equationSystem.createEquation(branch, DcEquationType.DUMMY_TARGET_P)
.addTerm(dummyP.createTerm())
.setActive(branch.isDisabled()); // inverted logic
} else {
throw new IllegalStateException("Cannot happen because only there is one slack bus per model");
}
Expand All @@ -88,7 +93,7 @@ private static void createImpedantBranch(EquationSystem<DcVariableType, DcEquati
EquationTerm<DcVariableType, DcEquationType> a1 = equationSystem.getVariable(branch.getNum(), DcVariableType.BRANCH_ALPHA1)
.createTerm();
branch.setA1(a1);
equationSystem.createEquation(branch.getNum(), DcEquationType.BRANCH_TARGET_ALPHA1)
equationSystem.createEquation(branch, DcEquationType.BRANCH_TARGET_ALPHA1)
.addTerm(a1);
} else {
//TODO
Expand Down
3 changes: 2 additions & 1 deletion src/main/java/com/powsybl/openloadflow/dc/equations/DcEquationType.java
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Expand Up @@ -16,7 +16,8 @@ public enum DcEquationType implements Quantity {
BUS_TARGET_P("bus_target_p", ElementType.BUS), // bus active power target
BUS_TARGET_PHI("bus_target_\u03C6", ElementType.BUS), // slack bus voltage angle target
BRANCH_TARGET_ALPHA1("branch_target_\u03B1", ElementType.BRANCH), // phase shifter constant shift
ZERO_PHI("zero_\u03C6", ElementType.BRANCH); // zero impedance branch, voltage angle equality
ZERO_PHI("zero_\u03C6", ElementType.BRANCH), // zero impedance branch, voltage angle equality
DUMMY_TARGET_P("dummy_target_p", ElementType.BRANCH);

private final String symbol;

Expand Down
52 changes: 49 additions & 3 deletions src/test/java/com/powsybl/openloadflow/ac/NonImpedantBranchDisablingTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,9 @@
*/
package com.powsybl.openloadflow.ac;

import com.powsybl.commons.reporter.Reporter;
import com.powsybl.iidm.network.Network;
import com.powsybl.iidm.network.Switch;
import com.powsybl.loadflow.LoadFlow;
import com.powsybl.loadflow.LoadFlowParameters;
import com.powsybl.math.matrix.DenseMatrixFactory;
Expand All @@ -15,13 +17,20 @@
import com.powsybl.openloadflow.ac.outerloop.AcLoadFlowParameters;
import com.powsybl.openloadflow.ac.outerloop.AcloadFlowEngine;
import com.powsybl.openloadflow.graph.EvenShiloachGraphDecrementalConnectivityFactory;
import com.powsybl.openloadflow.network.LfNetwork;
import com.powsybl.openloadflow.network.NameSlackBusSelector;
import com.powsybl.openloadflow.network.NodeBreakerNetworkFactory;
import com.powsybl.openloadflow.graph.NaiveGraphConnectivityFactory;
import com.powsybl.openloadflow.network.*;
import com.powsybl.openloadflow.network.impl.LfNetworkList;
import com.powsybl.openloadflow.network.impl.LfNetworkLoaderImpl;
import com.powsybl.openloadflow.network.impl.Networks;
import com.powsybl.openloadflow.util.LoadFlowAssert;
import com.powsybl.openloadflow.util.PerUnit;
import org.junit.jupiter.api.Test;

import java.util.Collections;
import java.util.List;
import java.util.Set;

import static com.powsybl.openloadflow.util.LoadFlowAssert.assertActivePowerEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;

/**
Expand Down Expand Up @@ -78,4 +87,41 @@ void testOpenBranch() {
assertEquals(-600.0, network.getLine("L2").getTerminal2().getP(), LoadFlowAssert.DELTA_POWER);
assertEquals(Double.NaN, network.getLine("L1").getTerminal2().getP(), LoadFlowAssert.DELTA_POWER);
}

@Test
void testDisabledNonImpedantBranch() {
Network network = NodeBreakerNetworkFactory.create3Bars();
Switch c1 = network.getSwitch("C1");
c1.setOpen(true);

LoadFlowParameters parameters = new LoadFlowParameters();
OpenLoadFlowParameters olfParameters = OpenLoadFlowParameters.create(parameters)
.setSlackBusSelectionMode(SlackBusSelectionMode.NAME)
.setSlackBusesIds(List.of("VL2_0"));

LoadFlow.run(network, parameters);

assertActivePowerEquals(401.757, network.getLine("L1").getTerminal1());
assertActivePowerEquals(100.878, network.getLine("L2").getTerminal1());
assertActivePowerEquals(100.878, network.getLine("L3").getTerminal1());

AcLoadFlowParameters acLoadFlowParameters
= OpenLoadFlowParameters.createAcParameters(network,
parameters, olfParameters,
new DenseMatrixFactory(),
new NaiveGraphConnectivityFactory<>(LfElement::getNum),
true,
false);
try (LfNetworkList lfNetworks = Networks.load(network, acLoadFlowParameters.getNetworkParameters(), Collections.emptySet(), Set.of(c1), Reporter.NO_OP)) {
LfNetwork largestNetwork = lfNetworks.getLargest().orElseThrow();
largestNetwork.getBranchById("C1").setDisabled(true);
try (AcLoadFlowContext context = new AcLoadFlowContext(largestNetwork, acLoadFlowParameters)) {
new AcloadFlowEngine(context).run();
}
// should be the same as with previous LF
assertEquals(401.740, largestNetwork.getBranchById("L1").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
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@annetill why we don't get exactly the value we had with the initial LF: 401.757 vs 401.740 ?

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Maybe because in the first case, we have a system resolution based on the bus/view and in the second case, we are based on the bus/breaker view.

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Yes right, this is not exactly the same system, so make sense to not have numerically the same solution

assertEquals(100.870, largestNetwork.getBranchById("L2").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
assertEquals(100.870, largestNetwork.getBranchById("L3").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
}
}
}
50 changes: 47 additions & 3 deletions src/test/java/com/powsybl/openloadflow/dc/DcLoadFlowTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,11 @@
*/
package com.powsybl.openloadflow.dc;

import com.powsybl.commons.reporter.Reporter;
import com.powsybl.ieeecdf.converter.IeeeCdfNetworkFactory;
import com.powsybl.iidm.network.Line;
import com.powsybl.iidm.network.Network;
import com.powsybl.iidm.network.Switch;
import com.powsybl.iidm.network.TwoWindingsTransformer;
import com.powsybl.iidm.network.test.EurostagTutorialExample1Factory;
import com.powsybl.iidm.network.test.PhaseShifterTestCaseFactory;
Expand All @@ -17,16 +19,22 @@
import com.powsybl.math.matrix.DenseMatrixFactory;
import com.powsybl.openloadflow.OpenLoadFlowParameters;
import com.powsybl.openloadflow.OpenLoadFlowProvider;
import com.powsybl.openloadflow.network.FourBusNetworkFactory;
import com.powsybl.openloadflow.network.SlackBusSelectionMode;
import com.powsybl.openloadflow.dc.equations.DcEquationSystemCreationParameters;
import com.powsybl.openloadflow.network.*;
import com.powsybl.openloadflow.network.impl.LfNetworkList;
import com.powsybl.openloadflow.network.impl.Networks;
import com.powsybl.openloadflow.util.LoadFlowAssert;
import com.powsybl.openloadflow.util.PerUnit;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.usefultoys.slf4j.LoggerFactory;

import java.util.Collections;
import java.util.List;
import java.util.Set;

import static com.powsybl.openloadflow.util.LoadFlowAssert.assertActivePowerEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

Expand Down Expand Up @@ -257,6 +265,42 @@ void shuntCompensatorActivePowerZero() {
.add()
.add();
loadFlowRunner.run(network, parameters);
LoadFlowAssert.assertActivePowerEquals(0, sc.getTerminal());
assertActivePowerEquals(0, sc.getTerminal());
}

@Test
void testDisabledNonImpedantBranch() {
Network network = NodeBreakerNetworkFactory.create3Bars();
Switch c1 = network.getSwitch("C1");
c1.setOpen(true);

LoadFlowParameters parameters = new LoadFlowParameters()
.setDc(true);
LoadFlow.run(network, parameters);

assertActivePowerEquals(400.0, network.getLine("L1").getTerminal1());
assertActivePowerEquals(100.0, network.getLine("L2").getTerminal1());
assertActivePowerEquals(100.0, network.getLine("L3").getTerminal1());

LfNetworkParameters lfNetworkParameters = new LfNetworkParameters()
.setDc(true)
.setBreakers(true);
DcLoadFlowParameters dcLoadFlowParameters = new DcLoadFlowParameters(lfNetworkParameters,
new DcEquationSystemCreationParameters(true, true, false, true),
new DenseMatrixFactory(),
true,
parameters.getBalanceType(),
false);
try (LfNetworkList lfNetworks = Networks.load(network, lfNetworkParameters, Collections.emptySet(), Set.of(c1), Reporter.NO_OP)) {
LfNetwork largestNetwork = lfNetworks.getLargest().orElseThrow();
largestNetwork.getBranchById("C1").setDisabled(true);
try (DcLoadFlowContext context = new DcLoadFlowContext(largestNetwork, dcLoadFlowParameters)) {
new DcLoadFlowEngine(context).run();
}
// should be the same as with previous LF
assertEquals(400.0, largestNetwork.getBranchById("L1").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
assertEquals(100.0, largestNetwork.getBranchById("L2").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
assertEquals(100.0, largestNetwork.getBranchById("L3").getP1().eval() * PerUnit.SB, LoadFlowAssert.DELTA_POWER);
}
}
}