A novel control method for a VSC-HVDC system in a grid-connected wind farm

Abstract

Abstract:The voltage source converter-high voltage direct current (VSC-HVDC) transmission is the ideal integration technology for grid-connected wind farms. A passivity-based control (PBC) method for VSC-HVDC when the wind farm voltage is unbalanced is proposed in this paper. The mathematical model of a VSC with unbalanced voltage is established.The PBC theory including dissipation inequality and system strict passivity is introduced, and then the stability of PBC is proven in light of the Lyapunov stability theory. According to PBC theory, a Euler-Lagrange mathematical model of a VSC is constructed. After that, the strict passivity of the VSC is proven. On the premise of the power factor being 1, the PBC controller for the VSC-HVDC system is designed under d-q coordination. The control law is deduced in detail. In order to accelerate the convergence speed, dampers are added to the PBC controller. The decoupled control of the active power and the reactive power is achieved by this method. The dynamic and steady performances of the VSC-HVDC system in a grid-connected wind farm when the wind farm voltage is unbalanced are significantly improved.Furthermore, the robustness of the system is enhanced. The simulation results verify the feasibility and correctness of the method.

Adaptive sliding mode with time delay control based on convolutions for power flow reference tracking using a VSC-HVDC system

“…Once the control vector µ is obtained, the real control action can be calculated using Eqs. (22) and (25).…”

“…Its various capabilities have been discussed in many papers in areas of power flow control [6][7][8], transient stability improvement, and oscillation damping control [9,10]. Furthermore, in the literature, the HVDC transmission system has been applied in a vast variety of control system investigations, including PI control [11][12][13][14], H ∞ approach method [15], linearization control [11], sliding mode control [16,17], backstepping design [18,19], flatness theory-based control [20], and passivity theory-based control [21,22]. All the aforementioned methods, including linear and nonlinear controllers, guarantee asymptotic stability of the closedloop system.…”

Dynamic Performance Analysis of VSC-HVDC Based Modular Multilevel Converter under Fault

“…The need for high powers range in recent years requires more reliable methods of transporting energy in the event of a breakdown, as well as appropriate equipment and means of production. For this purpose, HVDC transport arouses more interest, mainly for their economic factor for the exploitation of production in offshore deposits, such as wind turbines [1], water pipes and for the connection of asynchronous networks.…”

“…For several years, HVDCs based on thyristor (CSC) were used [2,3]. Supported by the developments in power electronics, semiconductors and control techniques, converters based on IGBT called Voltage Source Converters (VSC) have emerged, which enabled the development of HVDC based on this converter, where several functional commercial projects are listed worldwide [1,4]. This kind of converters presents many advantages compared to the CSC, such as a rapid control of active and reactive powers and provides a high power quality with a minimal environmental impact [5].…”