Study on fault ride-through control of islanded wind farm connected to VSC-HVDC grid based on the VSC converter AC-side bus forced short circuit

• Published in: Journal of engineering (Stevenage, England) England), 2019-03, Vol.2019 (16), p.3325-3328
• Main Authors: Li, Yan, Liu, Chao, Tian, Xinshou, Wang, Zhibing
• Format: Article
• Language: English
• Subjects: AC-side bus; fault responding feature; fault ride-through; forced short circuit; grid fault conditions; HVDC fault; HVDC power convertors; HVDC power transmission; islanded wind farms; offshore installations; power generation control; power generation faults; power grids; protection equipment; short-circuit resistance; The 14th IET International Conference on AC and DC Power Transmission (ACDC 2018); voltage source converter-based high-voltage direct current system; voltage-source convertors; VSC; VSC converter; VSC station; VSC-HVDC system; wind farm collection network; wind farm side converter; wind power plants
• ISSN: 2051-3305; 2051-3305
• DOI: 10.1049/joe.2018.8421

Wind farms integrated to an AC power system through a voltage source converter-based high-voltage direct current system (VSC-HVDC) are viewed as islanded wind farms. The wind farm side converter of VSC-HVDC maintains a constant frequency of the wind farm collection network and also controls its voltage. However, the transient responding time of VSC-HVDC is very short, and its fault responding feature is at the millisecond (ms) level. As a result, under grid fault conditions, the VSC station could be overloaded and even operation could be quitted because of blocking if islanded wind farms fail to limit their power generation in time. This study proposes a fault ride through control method for VSC-HVDC connected with islanded wind farms based on the forced short circuit of the AC-side bus of the VSC station. When there is a fault in the VSC-HVDC and the protection equipment is not able to cut off the excessive power at the ms level, the short-circuit resistance installed on the AC side of the VSC station would be switched to make a forced short circuit. That would activate the low-voltage ride through mode of islanded wind farms, and therefore reduce the power flowing into the VSC quickly. The HVDC fault and short circuit on the AC side would be cleared at the same time. The VSC-HVDC system accomplishes fault ride through.