SimulinkMATPOWER - A Simulink to MATPOWER interface

This toolbox called SimulinkMATPOWER enables you to use MATPOWER in Simulink. Furthermore, it adds a control layer for tap changers if this feature is activated.

The idea is the following: MATPOWER provides us with a power flow solver. Simulink provides a graphic interface. Let's bring these two together and enable people to use MATPOWER in Simulink.

Note: SimulinkMATPOWER is part of MATPOWER Extras, which is included in MATPOWER zip distributions in the extras/simulink_matpower directory.

How it works

What this toolbox does is that it enables you to manipulate a MATPOWER casefile (mpc) from Simulink, run a power flow solver on the mpc from Simulink and then extract the power flow solution in Simulink. Given that the toolbox purely interconnects MATPOWER with Simulink everything is based on the standard MATPOWER casefile. We write values into the mpc from Simulink, we run the power flow on the mpc from Simulink and read values from the mpc to Simulink.

A Simulink Library was created for this toolbox. The library is called SimulinkMATPOWERbase.slx and can be found in the root folder of the library. In there you can find the block that enables using MATPOWER's power flow solver in Simulink (the block "ACPF"). There are also other blocks that help you interconnect your own blocks with MATPOWER (e.g. blocks that get voltage magnitudes etc).

Setup

1. Install MATPOWER.

2. Add the toolbox directory with sub-directories to the Matlab path.

   Note: Step 2 is necessary only if SimulinkMATPOWER was not already included with your MATPOWER distribution (in extras/simulink_matpower).

3. Go into ac_testbed_setup.m and change the code in line 16 to load the MATPOWER case file you want to work with.

4. Run ac_testbed_setup (in example.slx it is automatically run by Simulink as an install_function).

5. Run the example example.slx to see whether it works and to get a first idea of how this toolbox works.

How to Use the Toolbox

1. Drag and drop or copy the ACPF block from the library to your Simulink model. This block calls the MATPOWER power flow solver from Simulink.

2. Writing data into the MATPOWER casefile from Simulink. The ACPF block has inputs. These inputs correspond to the structure of a mpc file. For example,

   • active_power_generation_in is written into mpc.gen(:,PG)
   • voltage_magnitude_in is written into mpc.bus(:,VM)

   You can use these inputs to parametrise the mpc as you want. Everything that you do not want to actively change will still need to be given to the ACPF block every time the power flow is solved.

   Check the example how you can write these values into the ACPF block easily (take the output of the ACPF block, store it by one time step and then send that to the inputs).

   For example, this enbales you to simulate a closed-loop control system in which a controller changes reactive power setpoints of generators. Then the power flow is solved to model the power grid and the solution of the power flow is given to the controller which then again updates the setpoints and so on.

3. Running the MATPOWER power flow solver on the mpc.

   This is done automatically at every timestep when you run the Simulink model.

   (optional) In line 30 of ac_testbed_setup.m you can enable tap changer control by setting mpm.oltc.enable=1. The default is 0. When enabled the following happens: The power flow is solved using MATPOWER, then for all generators with tap changers it is checked whether or not the secondary voltage is outside the deadband. When the voltage is outside the deadband the tap ratio is changed (which is exactly what a tap changer would do) and the power flow is solved once more. Again all secondary voltages are checked and if needed the tap changer position are changed again. This repeats until not more tap changes occur. Overall, this calculates the steady-state power flow solution including tap changer behaviour.

4. Getting data from the solved power flow into Simulink (aka reading values from the mpc file after the power flow was solved).

   For this there are several different blocks in the library. For example, blocks that extract the voltage magnitudes, the power flows, the losses, etc. Drag and drop or copy them into your Simulink file. Check the example to see where they should be located (in the triggered subsystem "Extracting Power Flow Results").

Checkout the example.slx to get your project going.

Important Information

1. DEFINE TAP CHANGERS. The file find_OLTC_indexes creates a vector idx_branches_in_oltc with the indexes of the branches that are transformers with on-load-tap-changers (OLTCs). Adjust and parametrize this file to make it find the indexes of the OLTCs in your grid model.

2. If idx_branches_in_oltc is empty, then the Simulink subsystem extracting the tap ratios must be commented out.

3. The MATPOWER case file mpc is inside the mpm structure (mpm.mpc).

Citing SimulinkMATPOWER

We request that publications derived from the use of the SimulinkMATPOWER toolbox explicitly acknowledge that fact by citing the following paper which initiated the development of this toolbox.

Lukas Ortmann, Jean Maeght, Patrick Panciatici, Florian Döfler, Saverio Bolognani, "Online Feedback Optimization for Transmission Grid Operation," 2022. doi: 10.48550/arXiv.2212.07795

Questions

If you have any questions or are facing difficulties, then please reach out to Lukas Ortmann at lukas.ortmann@web.de.

License

SimulinkMATPOWER is distributed under the 3-clause BSD license.

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