Multiple HVDC Research Articles

Coordinated control design of multiple HVDC links based on model identification

This paper presents a method for designing a centralized coordinated controller for several HVDC links. The controller increases the damping of the power oscillations by modulating the current through the HVDC links in a coordinated fashion. To design a centralized coordinated controller a reduced order open system model is estimated. The open system model of the power system is estimated using the Numerical Algorithms for Subspace State-Space System Identification (N4SID) algorithm which is a black-box system identification technique. The current set-point change through the HVDC links is the set of input signals and the speeds of the generators are the set of outputs. This controller design method increases the damping significantly, which is shown for a small power system.

A fast corrective load shedding control scheme to prevent AC/DC systems voltage collapse

AbstractThis paper proposes a corrective load shedding algorithm to restore power flow solvability of AC/DC systems after severe contingencies. Firstly, contingency parameterization power flow is constructed to describe a set of multiple contingencies, including generators, HVDC links, ac lines and transformers. The post‐contingency critical point is quickly determined through optimal multiplier power flow and a simple optimization‐based outage parameter updating procedure. The updating strategy is better improved by the analysis of stability surface. At the nose point, the sensitivity analysis is performed to select the most effective control measure. Then, the corrective load shedding sensitivity‐based linear programming model is constructed to improve the stability margin. The numerical simulations on a practical 1621 bus system testify that the proposed method can prevent system from voltage collapse effectively and efficiently. Copyright © 2008 John Wiley & Sons, Ltd.

Expandable multiterminal DC systems based on voltage droop

This paper introduces a decentralized control scheme for the parallel connection of multiple rectifiers feeding a DC network with numerous inverters. The coordination of multiple HVDC power systems without explicit communication is accomplished by the use of DC-side voltages as a "droop" mechanism. The DC side voltage serves the role of frequency in an ordinary AC system. The approach is most suitable to superconducting DC systems and to DC systems that span small distances and where voltage is relatively uniform throughout the DC system. This paper presents the concept in the context of a high capacity superconducting 10 kV urban infeed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>