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TRANSCRIPT
Hello and welcome to this lesson on microgridcontrol in islanded mode.
In the last lesson you learned how to easilycreate a simple microgrid model using Typhoon's
generic DER components.
You also used predefined widgets from a userwidget library to create a SCADA panel.
The previous lesson made use of a VirtualHIL device, which means that the simulation
was not truly running in real time.
In this lesson, you will see a fully functionalterrestrial microgrid model based on DER switching
components.
First, let's open the model using the ExampleExplorer.
Go to microgrid, microgrid example and selectthe Plug-and-play microgrid library and testing
of microgrid controller example.
Open this example by clicking the "Open model"button.
In order to run in real time, this model requiresa 6-series HIL device, such as the Typhoon
HIL602+, HIL603, HIL604, or HIL606.
For this lesson, we will use a HIL606 device.
The reason this model requires a 6-seriesHIL device can be better understood by looking
at the message console.
From the resource perspective, this modelutilizes four standard processing cores and
a machine solver.
If you look at the device configuration table,you can see how the different configurations
allocate these resources.
As you can see for the HIL606, most configurationssupport this combination of four SPCs and
one machine solver.
Only configurations four and seven do notsatisfy this requirement.
If you look at the configuration table fora 4-series HIL device, however, you can see
that there are no such configurations.
The HIL606 combines the speed of the HIL404with the capacity of the HIL604.
With this in mind, the HIL606 enables youto increase model complexity and add more
DER components than ever before.
You can find more information about this examplein the application note.
This example demonstrates a microgrid controllerand its ability to handle a microgrid islanding
event.
Net power flow is observed at the point ofcommon coupling or PCC and system resources
are commanded as necessary to prepare forand respond to islanding.
In two separate cases, a battery inverterand a diesel generator are used as the primary
grid-forming DER in order to compare theirdynamic responses when islanding.
The microgrid model consists of four DER components:an Energy Storage System, a Wind Plant, a
PV Plant, and a Diesel Genset.
The microgrid also has three types of loads:a constant load, an interruptible load, and
a variable load.
All elements of the microgrid are connectedto the same point of common coupling.
All components except the interruptible loadare plug-and-play, directly introduced from
the Typhoon Microgrid Library.
Each DER has its own transformer with ratio12.5 kV/480 V. The ESS, the Wind Plant, and
the PV Plant are all converter-based models.
While this example is implemented using switchedcomponents, the same model can be implemented
using generic or average components if preferred.
In this way, the model would be able to runon 4-series devices.
The microgrid controller is the brain of themicrogrid.
It can monitor and issue commands to the DERsand command the synchronization relay to connect
or disconnect the microgrid from the maingrid, depending on the operating mode requested
by the microgrid operator and any grid faults.
The microgrid controller also handles powerflow regulation through the PCC.
By sending power references to the grid-formingDER, the active and reactive power flowing
through the PCC can be zeroed, allowing forsmooth intentional islanding.
In microgrids, the microgrid controller oftencommunicates with DERs using communication
protocols, for example IEC 61850, DNP3, orModbus.
All DERs can be commanded through the DERcontrol signal coming from the microgrid controller,
but only the ESS and the diesel genset haveextra inputs/outputs.
Since they are the only two DERs not basedon an intermittent energy source, they can
be selectively engaged by the microgrid controlleras a grid-forming source.
They provide information about power to themicrogrid controller and receive power references
in return.
The microgrid controller is fully implementedusing the signal processing toolbox.
At its core, the microgrid controller logicis built around state machines implemented
using C Function components.
These two state machines are SM and SM2.
These state machines issue commands to thecircuit breaker inside of the PCC monitor
subsystem and to the grid-forming DERs, withthe support of PI Controllers, Signal Routing,
and Rate Transition components.
Inside of the PCC monitor subsystem, you cansee that the PCC monitor oversees the power
flow through the PCC and keeps the microgridcontroller informed of the main breaker status.
The breaker status signal serves as a triggerfor the microgrid controller to start controlling
the power flow by managing the DERs.
Using this mechanism, the PCC monitor canperform synchronization, control, and protection
including over and under voltage and overand under frequency protection.
As you can see, it is possible to use theHIL device as a controller or rapid control
prototyping platform for real microgrid controllerdevelopment.
Microgrid RCP applications are further supportedby the wide selection of connectivity options
and communication protocols inside of thecommunication protocols toolbox.
Connectivity and communication protocols areaddressed in greater detail in the Communication
protocols module.
Typhoon HIL also supports C code export functionalityallowing you to export the controller model
from Typhoon HIL to another controller developmentenvironment.
Let's compile and load the model.
As mentioned previously, we will use a fourthgeneration HIL606 device.
Let's open the panel file found in model directoryand run the simulation.
If you are using a Virtual HIL device, youwill likely notice that the simulation is
very slow compared to the real-time simulation.
This is another important benefit of usinga HIL device.
Large power electronics models like thesedemonstrate the added value of using HIL devices
not only to test controllers but also to allowteaching naturally and conveniently, in real
time.
Let's begin with the scenario where all DERsare enabled and connected to the main grid.
In this configuration, all DERs operate ingrid-following mode.
The microgrid operator may choose to issuea command to change the operation mode from
"Grid Tied" to "Islanded."
The microgrid operator can also decide whichgrid forming capable DER will be used as the
primary DER.
Here the Battery Inverter is chosen.
As you can see in the PCC monitor group, themicrogrid is consuming around 900 kW of active
power and 216 kVA of reactive power.
Statuses of the PCC circuit braker, microgriddead bus, Utility nominal voltage, microgrid
nominal voltage, and utility nominal frequencyare indicated by LEDs.
You can also see plots of active and reactivepower as well as a synch check phasor graph.
First, let's run the Battery ESS.
The ESS is injecting 200 kW of active power.
As you can see, the power supplied from utilityto the microgrid has been reduced.
Let's run the other three DERs the same way.
With the other DERs enabled and connected,the net power that flows through the PCC has
become negative.
This means that the microgrid is supplyingpower back to the utility.
Now, let's test an intentional islanding scenario.
Do this by changing the Operation mode combobox from Grid Tied to Islanded.
The active power offset and reactive poweroffset graphs provide information on the active
and reactive power which needs to be eithersupplied or absorbed by the grid-forming DER
in order to reach net zero flow through thePCC.
The microgrid is now in islanded mode, disconnectedfrom the utility with the Battery ESS forming
the grid.
This means the Battery ESS is setting thenominal voltage and nominal frequency in the
microgrid.
Any power that is injected into the grid byother DERs now charges the battery.
Similarly, any power absorbed from the gridis now supplied by the Battery ESS.
The process of intentional islanding usingthe Battery ESS happens rather quickly.
It's important to note, however, that differentelements in a microgrid have different dynamics.
This can be illustrated by conducting thesame intentional islanding experiment using
the diesel genset as the grid forming DER.
Let's switch back to grid tied mode in theoperation modes combo box.
The microgrid controller, with help of thePCC monitor sync check, will provide new voltage
and frequency references to the ESS in orderto synchronize with the utility.
When the microgrid and utility are synchronized,the circuit breaker in the PCC can be closed.
Once connected to the main grid, the ESS willswitch to grid following mode as it did before
islanding.
Once again, you can see this process happenedquickly with the battery ESS in charge of
grid synchronization.
The PCC circuit breaker is now closed, meaningthe microgrid is back in grid tied mode.
To make the Diesel Genset the grid formingDER, select Diesel Genset in the grid-forming
DER combo box.
Now run the intentional islanding scenarioagain to see the Diesel Genset's dynamic response.
The graphs in the microgrid controller groupshows the active/reactive power offset commands
sent by the microgrid controller to the genset.
Due to the inertia of the genset and the differentdynamics of the genset controller, the response
is slower compared to battery.
You can find more information about this microgridin the application note provided in the materials
tab.
Thank you for your attention.
