1. 1 Challenge the future The Impact of Multi-terminal HVDC Grids on The Transient Behavior in Transmission Systems - Modelling And Analysis Lian Liu PhD Thesis Factsheet

2. 2 Challenge the future Thesis Factsheet Protection Scheme for The Multi-terminal HVDC System Lian Liu 1.10.2013 / 1.10.2017 EWI/ ESE/ IEPG Marjan Popov, Mart van der Meijden China Scholarship Council

3. 3 Challenge the future Thesis content Motivation, background There is a trend for integrating large amount of renewable energies into power grid; Conventional protection methods are insufficient for the MTDC system; The design of DC breaker needs the estimation of short circuit currents. Research question The influence of MTDC topology on the post-fault transient behaviors; The algorithms that are suitable for the fault detection and location (CWT? DWT? SWT? etc.); Signal denoising; Algorithm in PSCAD environment.

4. 4 Challenge the future Expected results The transient studies after DC faults; The algorithm can detect and isolate fault within 0-10ms; The algorithm should be universal method for every converter in the network; The attempt on the design of DC breaker.

5. 5 Challenge the future Thesis challenge The modelling of the whole system in EMT software, e.g. PSCAD/EMTDC; Design of fault tolerable AC/DC converter; Insulation coordination study on the test DC grid; A feasible topology and control of DC breaker.

6. 6 Challenge the future Methodology Modelling of MTDC system : decoupled control, VSC converter modelling, Fault detection method: Wavelet transform, Travelling wave theory, etc. Fault location algorithm: M language of Matlab, Fortran language of PSCAD… Software synchronization: PSCAD and Matlab.