PhD presentations in April 2021: Muhammad-Ali-Khan Virdag & Ala Qawasmi
Thursday April 15, 2021
Via video stream. Dial-in data are available by e-mail. Please register at firstname.lastname@example.org
4:00 p.m.[Time zone UTC +1:00 Berlin] Muhammad-Ali-Khan Virdag, M. Sc.
“Design, Implementation and Analysis of Hybrid DC Circuit-breaker with Counter-current Injection Principle“
Faults in DC systems are difficult to interrupt due to absence of natural current-zero crossing and high rate-of-rise of DC current. In this thesis, a prototype of hybrid DC circuit-breaker based on the counter-current injection principle to perform zero current switching is developed and analyzed. Use of thyristor as the main switch and auxiliary circuit in parallel consisting of RLC elements enable fast switching of fault current at minimum arcing. The work focuses on modeling of DC circuit-breaker elements to interrupt a fault current up to 100A with prospective fault current up to 10kA in 380VDC grids. Improvements in the design are made by optimizing the number of semiconductor devices, designing a dedicated gate driver circuity and designing the snubber circuit for over-voltage limitation. Effect of inductive and capacitive loads on the circuit-breaker performance was determined.
5:00 p.m.[Time zone UTC +1:00 Berlin] Ala Qawasmi, M. Sc.
“Fault Current Interruption Analysis and Development of a Power Semiconductor Switch for a Medium-Voltage DC Hybrid Circuit Breaker”
The multiterminal medium-voltage dc grid technology promises an efficient and flexible integration of renewable energy generation and electromobility. Fast isolation of faulty network segments is a key requirement that ensures an uninterrupted power flow and guarantees the safety of the grid components.
This work analyzes faults in MVDC networks and the contribution of the different grid components to the fault current. It investigates different circuit breaker technologies and their capability to interrupt fault currents
The work proposes a new power semiconductor switch specifically designed for the hybrid circuit breaker. The switch is based on the gate turn-off thyristor, which has a high current interruption capability. The switch uses a small package, a reduced number of components, simple driving and control circuits to guarantee high reliability.