集成S7桥臂的基频调制电流源型海上换流站及其控制策略OA

The use of IGCT-based current source converters(CSC)as the transmission solution for offshore wind farms can significantly reduce the construction costs of offshore converter stations compared to traditional solutions,making it a more economical choice.However,the existing modulation methods for CSCs use either pulse width modulation(PWM)or fundamental frequency modulation.The former suffers from high switching losses,while the latter,due to having only one control parameter(namely,the triggering angle),cannot achieve flexible control of active and reactive power.To ad-dress these issues,this paper proposes a current-source converter station with integrated S7 bridge arms and its control strategy.First,the S7CSC DC transmission topology is introduced,and its operating model is analyzed in detail.The co-ordination between the switching control of the S7 bridge arms and the fundamental frequency modulation strategy is discussed,and a mathematical model is developed.An offshore AC voltage/frequency control strategy is then proposed.The fault characteristics of offshore AC faults are analyzed,and a low-voltage ride-through strategy under AC faults is in-troduced.Finally,a PSCAD simulation model of the S7CSC is built to simulate and analyze the system structure and control strategy.The results verify that the S7CSC has two degrees of freedom,can stably control the offshore AC voltage,and demonstrates good fault response characteristics,making it capable of adapting to fluctuations in wind power output.