Decentralized Frequency Regulation of Hybrid MTDC-linked Grids
This
paper proposes a new strategy for optimal grid frequency regulation (FR) in an
interconnected power system where regional ac grids and an offshore wind farm
are linked via a multi-terminal high voltage direct-current
(MTDC) network.
In the proposed strategy, decentralized H∞
controllers are developed to coordinate the operations of ac synchronous
generators and hybrid MTDC converters, thus achieving optimal power sharing of
interconnected ac grids and minimizing frequency deviations in each grid. To
develop the controllers, robust optimization problems are formulated and solved
using a dynamic model of the hybrid MTDC-linked grids with model parameter uncertainty
and decentralized control inputs and outputs. The model orders of the resulting
controllers are then reduced using a balanced truncation algorithm to eliminate
unobservable and uncontrollable state variables while preserving their
dominant response characteristics. Sensitivity
and eigenvalue analyses are conducted focusing on the effects of grid
measurements, parameter uncertainty levels, and communication time delays.
Comparative case studies are also carried out to verify that the proposed strategy
improves the effectiveness, stability, and robustness of real-time FR in MTDC-linked
grids under various conditions characterized mainly by load demands,
communications systems, and weighting functions.
History
Email Address of Submitting Author
powersys@postech.ac.krSubmitting Author's Institution
Pohang University of Science and TechnologySubmitting Author's Country
- South Korea