3. Examples
To get a better understanding of the setup and usage of IMTB, following couple of examples based on the HVDC MMC point-to-point connection from [1] are demonstrated. Only the grid frequency is adjusted to 50 Hz (global substitution variable) in original model. If not otherwise stated, all other parameters are left as in the original. The examples with the results can also be found in the distribution folder.
Warning
The HVDC MMC example will only work with GFortran compilers and Intel Fortran compilers <=v15 (32-bit). IF15 (64-bit) and later versions are not supported by the MMC example from [1]. In this case you can still try the IMTB functionality on simple RLC example in the same folder/workspace.
To set up the frequency scan on the AC side of Terminal 1 MMC, the IMTB is inserted between the grid representation and the MMC as shown in figure below. The parameters of the IMTB PSCAD component are adjusted to the DUT ratings. Note that the component needs to be mirrored vertically for the alignment of DUT and NET terminals. Because the Terminal 1 controls the AC voltage, the scan works better with a shunt current injection instead of a series voltage injection.
Figure 1. Setup of PSCAD model on the AC terminal.
Two exemplarily scans are done to showcase the use and functions:
In this example a MIMO impedance in the low frequency range is scanned on the AC side. The settings of the GUI and the results (alpha-beta frame) are depicted in figures below.
Figure 2. Setup of GUI settings for AC MIMO Example.
Figure 3. Results of the AC MIMO Example as impedance in alpha-beta frame.
In the multi-scenario example, only the positive sequence of the MMC is calculated. In this example only the active power reference of the Terminal 2 is varied in steps of 600 MW per pole. The setup of the GUI, the model parameter list and the results are depicted in figures below. Theoretically all other parameters can be varied in the same way.
Figure 4. Setup of GUI settings for multi-scenario example.
Figure 5. Setup of the multi-scenario list for the example.
Figure 6. Results of the multi-scenario example as impedance in positive sequence.
To scan the DC side impedance the IMTB is inserted between the MMC and the DC line as depicted in figure below. In the example the DC MIMO impedance is scanned. The settings and the results are shown in figures below.
Figure 7. Setup of PSCAD model on the DC terminal.
Figure 8. Setup of GUI settings for DC MIMO scan example.
Figure 9. Results of the DC MIMO scan example.
[1] MHI PSCAD Knowledge Base; Modular Multi-Level Converter (MMC) (February 26, 2015); link: https://www.pscad.com/knowledge-base/article/234