PhD Gianni BAKHOS: “Management of AC & DC Hybrid Power Systems’ Security: Assessment and Enhancement”

Abstract

With the multiple opportunities offered by HVDC links for power transmission and control, a new challenge for maintaining and improving power system stability is emerging. The main objective of this thesis is to study the opportunities for improving the stability of hybrid AC and DC networks by means of active power control. This control sends active power references to the system’s single actuator, the power converter, in order to regulate several stability aspects simultaneously while taking into account the physical constraints of AC and DC networks. The time scales considered in the studies range from a few milliseconds to tens of seconds.

Therefore, the main objective of this thesis is to study the possibilities of improving AC and DC stability using the active power exchanged via AC/DC power converters. Emphasis is made on the ancillary services that an HVDC system can offer. A controller tuning methodology and two active power control coordination strategies are proposed to improve the stability aspects considered simultaneously (frequency, rotor angles, DC voltage). Combining several controllers on the only actuator available is not straightforward, as improving one stability criterion may degrade another. Consequently, a compromise was found through an optimization approach also proposed in the thesis.

Director of thesis:Prof. Seddik BACHA

Co-directors of thesis: Prof. Luigi VANFRETTI, Dr. Abdelkrim BENCHAIB