Open

39-Bus New England System

Location

This example model can be found in the HYPERSIM under the category "How To" with the file name "PowerFactory_Import_39_Bus.ecf".

Open

The folder structure of this demo is as follows:

├───PowerFactory_Import_39_Bus
│ │ PowerFactory_Import_39_Bus.csv
│ │ PowerFactory_Import_39_Bus.svt
│ …
│ │
│ └───PowerFactory_ref_model
│ PowerFactory_Import_39_Bus.xml
│ PowerFactory_Import_39_Bus_Results.csv

The folder PowerFactory_ref_model contains the XML export of the PowerFactory model, and the simulation results from PowerFactory which can be used for comparison purposes.

Description

This model is a modified version of the 39 Bus System example provided by PowerFactory 2023:

A new Study Case was created in the original project, which is partially based on the EMT Simulation Fault Bus 03 one. This new Study Case was in turn associated to 4 modified network variations.

All together, this set of network variations results in a network model with the following modifications:

• PH-E connected constant impedance, 100% static loads.

• Yg-connected synchronous machines.

• ESST1A excitation system models associated to all synchronous machines.

• 2-winding transformers without saturation, nor sequence data.

• Explicit reference angle definition = -30 deg, as a setpoint of the machine connected to the swing bus.

The events in the modified Power Factory Study Case are as follows:

• A 2-Phase Short-Circuit event in Bus 03 at t = 0.3 s (phases A-B):

• An immediate clearing of the short circuit in Bus 03 at t = 0.5 s:

Note that these two events are imported to HYPERSIM using a custom fault block () with the following parameters:

Import the PowerFactory model

The PowerFactory import tool aims to enhance efficiency by automatically converting models from PowerFactory to HYPERSIM. This feature not only saves time but also reduces the risk of errors associated with manual imports.

The PowerFactory import tool comprises a parser, mapper, and exporter:

• The parser analyzes and interprets PowerFactory model components and parameters. It converts the PowerFactory xml file into a list of objects.

• The mapper performs a mapping between PowerFactory and Unified Database (UDB) components and parameters.

• The exporter creates the HYPERSIM model after a successful database import.

To import the example model, start by creating a new HYPERSIM model and continue by following the steps described in PowerFactory | Importing a Network .

As explained in https://opal-rt.atlassian.net/wiki/spaces/PDOCHS/pages/889028859/Examples+PowerFactory+Import+39-Bus+New+England+System#Location , the xml input file for the example can be found under the PowerFactory_ref_model folder.

Wait until the end of the import process. A message “Import successful” in the Import Panel interface indicates that the import is completed.

Simulation and Results

Load Flow Test

It is highly recommended to start a validation process by conducting a comparison of load flow results.

In the Load Flow Calculation window from PowerFactory, select “AC Load Flow, balanced, positive sequence” as the calculation method. Also, make sure the Consider Voltage Dependency of Loads option is selected. Then Execute the command.

The Network Model Manager will now display the updated load flow results. For instance, voltage magnitude and angle at each bus can be obtained from the Flexible Data table of the Busbar element, as shown below:

Load flow calculation must also be carried out in HYPERSIM (see the steps in Quick Start | Load Flow). The table below shows the absolute errors in voltage magnitude and angle for all buses in the network model. Please notice that even though in general all error values are negligible, there is a relatively large mismatch in the voltage angle at bus 34 (i.e., 2.5 deg).

The large voltage angle mismatch at bus 34 can be explained by the value of the parallel Transformers parameter in Trf 20 - 34 (see the figure below). As pointed out in https://opal-rt.atlassian.net/wiki/spaces/PDOCHS/pages/875528410/PowerFactory+Supported+Features+and+Limitations#Transformers , this feature is not yet supported by the PowerFactory Network Import function.

Fortunately, the discrepancy observed above does not have significant effects on the validation of the EMT simulation results which will be discussed later.

EMT Simulation Test

Record HYPERSIM results with Datalogger

In HYPERSIM, the model time step needs to be set to 50 µs to align with the PowerFactory Initial Conditions for EMT Simulation. The https://opal-rt.atlassian.net/wiki/spaces/HDI/pages/3548177 is employed to record the desired sensor measurements from t = 0 s to t = 2 s, with a Decimation factor of 1 applied. Additionally, for the chosen Signal Groups, the Number of frames to record is set to 1, the Frame length is adjusted to 2 seconds, and the Output file auto naming checkbox is unticked. A predetermined set of sensors is provided in this example. However, users may record additional sensors by following the instructions from https://opal-rt.atlassian.net/wiki/spaces/PDOCHS/pages/150077741.

The provided ScopeView template, PowerFactory_Import_39_Bus.svt, facilitates the comparison of simulation recordings between PowerFactory and HYPERSIM.

To load the plots, play the recorded data as shown in the figure below:

Results

To demonstrate the consistency between HYPERSIM and PowerFactory results, the following variables are compared:

• Phase voltages at bus 02.

• Field voltage in generator 10.

• Speed in generator 10.

• Active power in generator 10.

• Reactive power in generator 10.

Plots showing the comparison of phase voltages are available in the first page of the ScopeView template:

Plots can be zoomed in to better verify how close each pair of variables match after each event:

Plots showing the comparison of a selected set of generator 10 variables are available in the second page of the ScopeView template:

The plots can be zoomed in to better observe the mismatches, specially when it comes to speed and field voltage.

These errors can be explained by the following reasons:

• Differences in the implementation of the mechanical dynamics of the synchronous machine models in HYPERSIM and PowerFactory (i.e., the swing equation). This has a particular impact on the Speed of the machines, which is what can be observed in the second plot of the first row. Differences in the speed might in turn explain differences in other variables.

• Different implementation of the ESST1A excitation system model in the native model of HYPERSIM with respect to the PowerFactory one.

References

[1] DIgSILENT PowerFactory, “39 Bus New England System”, benchmark model documentation.