Ahmed Sunjaq Electrical engeneering

Ahmed Sunjag is a PhD student in the research group powergrids and components, division of Electric power egineering.

Discussion leader for the seminar is professor Olof Samuelsson from Lund University.

Examiner is professor Massimo Bongiorno, division of power engineering.

Abstract: This study explores various converter-based solutions with storages to address grid
capacity bottlenecks and enhance the resiliency of medium-voltage microgrids. Main contributions of the work include: 1) Illustrating drivers for interconnection of microrids via multiport
converter for alleviation of grid capacity bottleneck, 2) Identifying key factors for dimensioning
a multiport converter (MPC) equipped with a storage for grid capacity bottleneck alleviation of
interconnected microgrids and integration of a DC load , and 3) Proposing a frequency controller using a PI-based droop for voltage-source inverter-based technologies to enable smooth
island transition in a hydro-powered microgrid with critical demand. Steady-state analysis
shows that the size of one AC Port of the MPC depends on three main factors: 1) The maximum
power deficiency of the microgrid where the AC Port is interfaced, 2) The maximum power deficiency in the other microgrid when it coincides with available capacity in the microgrid where
the AC Port is interfaced, and 3) Maximum DC load demand when it coincides with available
capacity in the microgrid where the AC Port is interfaced. Moreover, the sizing of the power and
energy capacities of the storage is primarily determined by the maximum power deficiency and
maximum accumulated energy deficiency of the aggregated microgrids. Dynamic simulation
results show that the proposed PI-based droop and tuning strategy meet desired frequency quality requirements for smooth island transition without over-sizing the storage capacity compared
to the traditional proportional droop controller.