Control and Operation of HVDC

study the operation of a VSC HVDC station based on modular multilevel technology (MMC) and fed from a 300km HVDC transmission line. Use the provided MMC HVDC model for the tasks in this part of the coursework. System parameters are listed in the given matlab model. Follow the steps indicated inside the model file to activate the pole-to-pole DC fault at 60km from the HVDC station.
(a) Export plots of MMC arm currents and capacitor voltages, DC current, DC voltage at the MMC station, AC currents and voltages.
(b) Change the fault distance to 10km and 15km, respectively, and in each case export plots of DC current and voltage as well as arm currents.
(c) Comment on the following:
1- The arm voltage profiles (capacitor voltages) in both cases (a) and (b) in comparison to steady state operation (i.e. the case of no fault)
2- The DC fault current profile and peak magnitude in both cases (a) and (b).
3- TheimpactoftheDCsmoothingreactoronDCfaultandarmcurrentsinbothcases(a) and (b).
4- State in clear points why the MMC station needs protection in this case
5- EnumerateatleastthreemethodsofprotectingtheMMCstation.Explainbrieflytwoof these methods with neat schematics.
(d) Now for 10km fault distance, enable the AC circuit breaker (generate the AC circuit breaker trip signal 50ms after DC fault inception). Export plots of AC currents and DC current ONLY and show whether or not the AC circuit breaker tripping is sufficient to protect the MMC.
(e) Select a DC fault protection circuit that is built at the AC terminals of the MMC station. Model the protection circuit to trip 5ms after DC fault detection. Export plots of DC current and DC voltage and ACCB current, protective circuit internal currents, and show whether it offers sufficient protection for the MMC or not. Comment on the waveforms and performance of the protective method.