How do i tune my STATCOM to fit my model?

I have built a 3 machine 9 bus system. I am trying to analyse STATCOM's behaviour during fault conditions. I'm trying to minimise the line voltage dips whicih would occur during the fault and also try to improve post fault disturbance by using a STATCOM. I was successful in building a 3 machine 9 bus model. These were the line voltage graphs for different buses.

Later, i added a 48 pulse VSC STATCOM to the model. Intially i used a 100MVAR system and later tried to increase the rating based on the demand. But no matter how many times i try to tune it, the final waveforms are even more unstable than when i simulated them without STATCOM. I'm getting a lot of overshoot and the voltage dip is also not improved. I have tried tuning the PI gains inside the STATCOM. The ripples in the waveform are getting smooth but the main problem, which is the voltage dip and post-fault disturbance remains the same. I suspect the overshoot is because there is both PSS and STATCOM in my model, so both of them combined, reactive power injection post-fault is very high. I have provided the line voltage waveforms for all the buses below along with the MATLAB file. How do I get an improved voltage profile?

Answer 1

[Sabin]

Tuning the PI gains in the STATCOM can help with waveform ripples but may not address the core issue if both controllers are acting independently and aggressively. To improve the voltage profile, consider coordinating the control strategies of the PSS and STATCOM - for example by limiting the STATCOM’s response during certain conditions, implementing a hierarchical control scheme, or adjusting the setpoints and response times to prevent both devices from overcompensating simultaneously. Additionally, verify the STATCOM’s placement and sizing relative to the fault location and system demand, and ensure that your controller parameters are not causing resonance or instability.