Advanced AC and DC Transmission Systems

Coursework 1 -Part A

Case Studies with Computer Aided Simulations

This is an individual-based assessment where you are expected to carry out the tasks with Matlab/Simulink and write a technical report. You would have to keep to the maximum word limit for this part of the coursework (2500 words).

Case study: Control and Operation of HVDC Lines

A: Explain in detail aided with illustrations and schematics as appropriate the use of the following DC fault protection methods (Comment on the efficacy of each method):

(i) Artificial AC Fault protection method.
(ii) Solid state DC circuit breaker
(iii) Hybrid DC circuit breaker
(iv) Full Bridge MMC

B: Using an appropriate Simulink model for a modular multilevel converter (MMC) station connected to an HVDC line, explain (aided with suitable waveforms exported to your report):

(i) The DC fault current profiles (with no MMC protection) in each DC pole upon a pole to pole DC fault occurring at different distances from the MMC station. Comment on the change in AC currents and DC current peaks.

(ii) Compare the DC fault current profiles at 20km distance from the MMC station with and without the ACCB tripping 50ms after DC fault detection.

(iii) The impact of using any of the DC fault protection methods in (a) on the DC fault current profile. Consider the ACCB trips 50ms after DC fault detection.

(Note: you must clarify key parameters used in (i), (ii), and (iii) such as distance from MMC station, DC fault resistance, DC choke inductance, etc).