Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

Abstract

A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

Evaluation of a HVDC Interconnection to Improve the Voltage Stability of the Nigerian Transmission Network

“…This control system comprises two controllers. The first controller regulates the DC voltage, while the second adjusts the current flow by balancing DC power and AC power [31,32]. The DC voltage control can be explained with the equations below.…”

“…where Kp is the controller proportional gain, Vd, Vq are the supply voltage dq components and Id, Iq are the ac current dq components [31]. R and L refer to the output filter parameters.…”

Optimal Sharing of Real Power Using Robust Controller in Multi-terminal DC Systems

“…So, multi-terminal DC grids are used to provide a meshedtype interconnection between powers generating stations and far control areas where electricity is required. It is also helpful in maintaining the reliability between AC and DC system networks [1,2]. Hence, multi-terminal DC grids can be used to make system economical and increase its efficiency through transmitting power using terminal converter controls.…”