simulator: Add power loss to SimPdu

This change adds a model for power loss to the Power Distribution Unit
(PDU) model in OpenDC.

2 files changed, 50 insertions, 2 deletions

diff --git a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt
index 365f3435..ed3175c7 100644
--- a/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt
+++ b/opendc-simulator/opendc-simulator-power/src/main/kotlin/org/opendc/simulator/power/SimPdu.kt
@@ -28,8 +28,14 @@ import org.opendc.simulator.resources.*
  * A model of a Power Distribution Unit (PDU).
  *
  * @param interpreter The underlying [SimResourceInterpreter] to drive the simulation under the hood.
+ * @param idlePower The idle power consumption of the PDU independent of the load on the PDU.
+ * @param lossCoefficient The coefficient for the power loss of the PDU proportional to the square load.
  */
-public class SimPdu(interpreter: SimResourceInterpreter) : SimPowerInlet() {
+public class SimPdu(
+    interpreter: SimResourceInterpreter,
+    public val idlePower: Double = 0.0,
+    public val lossCoefficient: Double = 0.0,
+) : SimPowerInlet() {
     /**
      * The [SimResourceDistributor] that distributes the electricity over the PDU outlets.
      */
@@ -40,11 +46,41 @@ public class SimPdu(interpreter: SimResourceInterpreter) : SimPowerInlet() {
      */
     public fun newOutlet(): Outlet = Outlet(distributor.newOutput())
 
-    override fun createConsumer(): SimResourceConsumer = distributor
+    override fun createConsumer(): SimResourceConsumer = object : SimResourceConsumer by distributor {
+        override fun onNext(ctx: SimResourceContext): SimResourceCommand {
+            return when (val cmd = distributor.onNext(ctx)) {
+                is SimResourceCommand.Consume -> {
+                    val duration = cmd.work / cmd.limit
+                    val loss = computePowerLoss(cmd.limit)
+                    val newLimit = cmd.limit + loss
+
+                    SimResourceCommand.Consume(duration * newLimit, newLimit, cmd.deadline)
+                }
+                is SimResourceCommand.Idle -> {
+                    val loss = computePowerLoss(0.0)
+                    if (loss > 0.0)
+                        SimResourceCommand.Consume(Double.POSITIVE_INFINITY, loss, cmd.deadline)
+                    else
+                        cmd
+                }
+                else -> cmd
+            }
+        }
+
+        override fun toString(): String = "SimPdu.Consumer"
+    }
 
     override fun toString(): String = "SimPdu"
 
     /**
+     * Compute the power loss that occurs in the PDU.
+     */
+    private fun computePowerLoss(load: Double): Double {
+        // See https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        return idlePower + lossCoefficient * (load * load)
+    }
+
+    /**
      * A PDU outlet.
      */
     public class Outlet(private val provider: SimResourceProvider) : SimPowerOutlet(), AutoCloseable {
diff --git a/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt
index cef9a97a..b7f51ad3 100644
--- a/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt
+++ b/opendc-simulator/opendc-simulator-power/src/test/kotlin/org/opendc/simulator/power/SimPduTest.kt
@@ -54,6 +54,7 @@ internal class SimPduTest {
         val pdu = SimPdu(interpreter)
         source.connect(pdu)
         pdu.newOutlet().connect(SimpleInlet())
+
         assertEquals(50.0, source.powerDraw)
     }
 
@@ -89,6 +90,17 @@ internal class SimPduTest {
     }
 
     @Test
+    fun testLoss() = runBlockingSimulation {
+        val interpreter = SimResourceInterpreter(coroutineContext, clock)
+        val source = SimPowerSource(interpreter, capacity = 100.0)
+        // https://download.schneider-electric.com/files?p_Doc_Ref=SPD_NRAN-66CK3D_EN
+        val pdu = SimPdu(interpreter, idlePower = 0.015, lossCoefficient = 0.015)
+        source.connect(pdu)
+        pdu.newOutlet().connect(SimpleInlet())
+        assertEquals(87.515, source.powerDraw, 0.01)
+    }
+
+    @Test
     fun testOutletClose() = runBlockingSimulation {
         val interpreter = SimResourceInterpreter(coroutineContext, clock)
         val source = SimPowerSource(interpreter, capacity = 100.0)