I understand that you are facing issues when using a Synchronous generator as a source for VSC Rectifier based system to observe frequency changes due to load variations.
You can try the below steps to rectify the issue:
- Ensure that the parameters of the synchronous generator (e.g., inertia, damping, reactance) are accurately set to reflect the real system as incorrect parameters can cause instability.
- Ensure that the control loops and the control parameters of the VSC, such as the Proportional-Integral (PI) controllers for current and voltage regulation are properly tuned.
- Ensure that the VSC is correctly synchronized with the generator's output, especially during startup and load changes.
- Sudden or large load changes can cause significant disturbances. Implement a smoother transition or ramping of load changes as they help in maintaining system stability.
- If a phase-locked loop (PLL) is used in the VSC, make sure it is properly tuned to lock onto the generator's frequency, as an improperly tuned PLL can lead to detuning.
- Use a solver with smaller time step to capture the dynamics of the system accurately. Consider using a variable-step solver if the system shows stiff behaviour.
- Ensure the simulation time is sufficient to observe the transient and steady-state behaviour after load changes.
- Perform a stability analysis of the system. Tools like eigenvalue analysis or Bode plots can help us in identifying the stability issues and guides us in making necessary adjustments.
- Test both the synchronous generator and VSC rectifier separately to ensure each component is functioning correctly before integration.
In this way you can obtain tuning between Synchronous generator and VSC based Rectifier system.
