Hybrid AC/DC Power System Stability: An Attempt of Global Approach

Abstract

In this paper, a new control coordination strategy is proposed to address multiple stability problems that may arise
in HVAC/HVDC power systems. The stability issues studied in this paper include small-signal, rotor angle,
frequency, and DC voltage. A benchmark composed of two 2-area AC systems inspired by Kundur system
connected through a Modular Multilevel Converter-based (MMC) multi-terminal DC (MTDC) system is proposed
to study multiple stability issues. To enhance the global security of the considered benchmark power system,
supplementary power converter controllers are designed and implemented as ancillary HVDC services. The
combination of these services may not always result in satisfactory dynamic performance due to system constraints
and control interactions. Therefore, a coordinated strategy is proposed and evaluated through a comparative study.
The advantages of this method are mainly: 1) AC & DC stability phenomena – usually studied separately – are
considered and enhanced in a global approach, simultaneously, and 2) the coordination strategy guarantees
minimal control interactions during operation without the need of modifying the tuning of the controller
parameters.