Enhancing Wind Power Plant Integration Using a T-NPC Converter with DR-HVDC Transmission Systems

Abstract

This paper introduces an innovative control technique tailored for the seamless integration of wind power plants (WPP) into onshore grids. Our approach utilizes Diode-Rectifier-based High Voltage Direct Current (HVDC) system and incorporates a T-type Neutral Point Clamped (T-NPC) converter on the HVDC back, providing solutions for current challenges in wind power integration. While the use of Diode Rectifier (DR) as the Offshore converter for HVDC transmission has proven advantageous in terms of cost and loss reduction, it also introduces new challenges, such as maintaining AC grid voltage and frequency on the Offshore side and achieving the synchronization of the wind energy conversion system (WECS). This paper proposes a comprehensive control strategy to adresse these challenges by developing frequency and AC voltage control loops, ensuring the synchronization of WECS with the DR AC side. A notable distinctive feature of our proposed technique is to ensure the regulation of the DC voltage of the HVDC cable, accomplished through the onshore inverter. This crucial aspect ensures stable and efficient power transmission from wind power plants to the onshore grid.