Start-Up Control and Grid Integration Characteristics of 300 MVar Synchronous Condenser With Voltage Sourced Converter-Based SFC

Synchronous condenser (SC) is generally used as the devices for reactive power support for the ultra-high-voltage direct current (UHVDC) transmission at the receiving end. When a SC is started, it will have a large surge on the interconnected system and the SC itself. In severe cases, it will endanger the operation of SC and related equipment. The start-up control of a 300 MVar SC using voltage source converter (VSC)-based static frequency converter (SFC) is proposed in this paper. Dynamic behaviors of interconnected system during the start-up period with three different criterions of grid integration constraint of the SC, including initial falling speed, frequency difference and phase difference, are analyzed. Firstly, topological structure and control strategy of the VSC-based SFC are proposed. Secondly, a mathematical model of the SFC-based SC is established. The surge of the start-up and grid integration of the SC with three different constraint criterions on the interconnected system is analyzed in sequence. Thirdly, a simulation system of a 300 MVar SC with VSC-based SFC is established in the time-domain simulation software PSCAD/EMTDC™. Dynamic behaviors and surge of the overall system with different criterions of grid integration constraint are demonstrated and studied. Finally, a comprehensive starting control strategy of the SC with optimized initial falling speed, optimized frequency difference and optimized phase difference is proposed based on the theoretical analysis and simulation experiments. Simulation results justify the effectiveness of the start-up and grid integration control strategy proposed.