Stabilization of MT-HVDC grids via passivity-based control and convex optimization.

• This paper addresses the stabilization of DC resistive networks with multiple RERs. • A port-Hamiltonian model and PBC theory are used for designing nonlinear controllers. • The proposed controller does not require cross measures (the main paper contribution). • The operative point is obtained by a convex reformulation of the optimal power flow. • The proposed model is solved via semidefinite programming approach. This paper presents a model for stabilizing multi-terminal high voltage direct-current (MT-HVDC) networks with constant power terminals (CPTs) interfaced with power electronic converters. A hierarchical structure of hierarchical control is developed, which guarantees a stable operation under load variations. This structure includes a port-Hamiltonian formulation representing the network dynamics and a passivity-based control (PBC) for the primary control. This control guarantees stability according to Lyapunov's theory. Next, a convex optimal power flow formulation based on semidefinite programming (SDP) defines the control's set point in the secondary/tertiary control. The proposed stabilization scheme is general for both point-to-point HVDC systems and MT-HVDC grids. Simulation results in MATLAB/Simulink demonstrate the stability of the primary control and the optimal performance of the secondary/tertiary control, considering three simulation scenarios on a reduced version of the CIGRE MT-HVDC test system: (i) variation of generation and load, (ii) short-circuit events with different fault resistances and (iii) grid topology variation. These simulations prove the applicability and efficiency of the proposed approach. [ABSTRACT FROM AUTHOR]