电压源换流器型直流输电技术综述

电压源换流器型直流输电采用可关断电力电子器件和PWM技术,是新一代直流输电技术,它能弥补传统直流输电的部分缺陷,其发展十分迅速。为了进一步推动电压源换流器型直流输电在电力系统中的研究和应用,结合ABB公司几个典型应用工程,在详细介绍电压源换流器型直流输电的系统结构、基本工作原理和与传统直流输电相比的技术优势的基础上,对电压源换流器的拓扑结构、控制与保护策略、开关调制方式等技术问题的国内外研究现状进行了评述。分析表明:在工程应用中,通常从优化系统运行、可靠性、安全性和经济性等角度出发,选择结构简单的电压源换流器主回路结构,并采用能降低开关损耗的开关调制方式。最后就我国开发电压源换流器型直流输电技术提出了需要重点研究的几个关键领域。

Review and Applications of VSC HVDC

In this paper, the structure and operation principle of Voltage Source Converter based High Voltage Direct Current (VSC HVDC) transmission is described. The main technical issues for VSC HVDC are reviewed, including converter topology, characteristics of two level and three level converters, pulse width modulation pattern, control strategy, protection strategy, switching frequency and loss reduction. The potential application fields of VSC HVDC are also discussed, such as power supply to small isolated loads, power supply to islands, power supply to offshore platforms, infeed to city centers, wind farm connection, interconnecting power systems. Several real projects of VSC HVDC are presented to demonstrate their unique application area, including Gotland of Sweden for connecting wind farm in an environmentally friendly way, Tjaereborg of Denmark for optimal exploitation of wind energy, Direct Link of Australia for power trading, Troll A of Norway for supplying power to compressors in an offshore platform. The key problems in developing VSC HVDC technology are summarized, including main circuit related technology, difficulty in connecting IGBTs in series, parameter selection for commutation reactor and DC side capacitor, control system design strategy, protection system configuration, harmonic filtering and grounding system, VSC HVDC loss analysis. Finally, the technology development trend of VSC HVDC and its impact on conventional HVDC and AC transmission is evaluated.