HVDC topology structure using existing ac cable lines for integrating renewable energy sources

• Published in: Journal of engineering (Stevenage, England) England), 2017, Vol.2017 (13), p.729-733
• Main Authors: Xu, Feng, Xuan, Xiaohua, Lu, Yi, Qiu, Peng, Jiang, Daozhuo, Chen, Qian
• Format: Article
• Language: English
• Subjects: ac lines; control; conventional bipolar HVDC; current modulation strategy; current regulation; design/electro‐magnetic transient design; effective implementation; existing ac cable lines; high‐voltage dc; HVDC power convertors; HVDC power transmission; HVDC topology structure; maximum power transmission capacity; power cables; power systems computer; power transmission control; power transmission topology; renewable energy sources; space charge; space charge accumulation; square wave ac; SWAC‐HVDC; transmission mode
• ISSN: 2051-3305; 2051-3305
• DOI: 10.1049/joe.2017.0427

To solve the problem of the space charge accumulation of ac cable and upgrade the transmission capacity in the conversion of ac lines to dc, a new power transmission topology which is called the square wave ac (SWAC)-based high-voltage dc (HVDC) is proposed. In this topology, the voltage of each phase is changed in a certain frequency to weaken the accumulation of the space charge. For the effective implementation of this transmission mode, a voltage and current modulation strategy is proposed, which can upgrade the maximum power transmission capacity of the SWAC-HVDC to 1.41 times of the conventional bipolar HVDC. For the variable resistor used for current regulation, the resistance distribution scheme is studied, and a general formula is derived. The steady and transient simulation results in power systems computer-aided design/electro-magnetic transient design and control show the feasibility of the SWAC-HVDC and its control strategy.