Why MMC-HVDC control works with ideal AC source but fails with synchronous generator input

I am a student trying to build matlab model on gird-following and grid-forming control in MMC-HVDC system. For grid-forming method, I am trying to build control method of 1. virtual synchronous generator control and 2. Capacitor Energy synchronization control which I have read on some journal papers for reference models. However, when I use three-phase voltage ac source as an input for both sides, it simply works fine. The problem is when I connect Synchronous Generator with Disel Engine GFovernor as input, both GFL and GFM control does not work and gives me nearly zero output even though I use the same model and same control method. If there is someone who had similar issue or are working on similar research on this field, please kindly help.

[Sabin]

Can you share the model to better understand the issue?

Answer 1

[Sabin]

Without a model it is not easy to point to a specific root cause. However, the issue you are experiencing likely comes from the interaction between the synchronous generator and MMC-HVDC control schemes. Unlike a three-phase voltage source, a synchronous generator introduces more complex dynamics, such as frequency and voltage variations, inertia, and governor response, which can affect the stability and performance of both grid-following and grid-forming controls. Your control algorithms, especially virtual synchronous generator and capacitor energy synchronization, may require tuning or adaptation to properly synchronize and share power with a real generator source. Check model parameters, initialization, and controller settings to ensure compatibility with the dynamic behavior of the synchronous generator, and consider implementing more robust synchronization and control loops to handle these interactions.