Research on coordinated reactive power control strategy of hybrid-HVDC

• Main Authors: Ying Huang, Chunhua Li, Tao Liu
• Format: Article
• Language: English
• Published: Wiley 2019-04-01
• Series: The Journal of Engineering
• Subjects: power transmission faults; reactive power control; voltage control; power transmission control; HVDC power convertors; HVDC power transmission; commutation; power factor; voltage-source convertors; failure analysis; power transmission reliability; power filters; power system stability; coordinated reactive power control strategy; hybrid HVDC transmission system; line-commutated converter; LCC; voltage source converter; VSC; low load operation; system power factor; system voltage drop; voltage control mode; AC bus voltage stability; emergency power support; transient states; filter switching; de-locking process; AC bus voltage; VSC reactive power controller; commutation failure; AC faults; engineering field test
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8857

Based on the hybrid HVDC transmission system, which is composed by line-commutated converter (LCC) in parallel with voltage source converter (VSC), a coordinated reactive power control strategy of hybrid-HVDC in both steady and transient states is proposed. The operation characteristics in situations like low load operation, filter switching, and de-locking process are analysed. Influence of the method to AC bus voltage and system power factor is taken into account. Three kinds of reactive control methods of VSC and LCC are studied, and the logical relationship between the filter and VSC reactive power controller is also given. Considering both the system voltage drop and the risk of commutation failure caused by AC faults, the VSC in voltage control mode is utilised to maintain AC bus voltage stability by providing emergency power support. Simulation results show the feasibility and effectiveness of presented control strategy, then the proposed strategy is applied in practical DC project, whose results achieve the desired effect by engineering field test.