并联型四端直流输电系统实时数字仿真分析

Analysis on a Parallel Four-terminal HVDC Transmission System Based on Real Time Digital Simulation

利用实时数字仿真器(RTDS)建立了并联型四端±500kV,5 000MW双极直流输电仿真模型,直流控制保护模型采用所开发的多端直流输电控制保护样机,与RTDS构成实时闭环仿真试验环境。控制策略采用多端直流电流裕度控制,控制系统架构按多端控制、极控制2级进行设置。多端控制包含多端直流输电系统各换流站功率指令分配、功率升降协调、直流电压控制和多端通信等功能。极控制包含常规直流控制功能,主要实现各换流站功率控制。利用该仿真系统对并联型四端直流输电系统稳态运行工况、单站闭锁功率补偿、直流线路故障进行仿真研究,结果表明所提出的控制策略和开发的控制保护样机可以满足多端直流输电要求。

The simulation model of a ＋500 kV/5 000 MW four-terminal direct current transmission system is proposed based on the real time digital simulator （RTDS）. The multi-terminal DC （MTDC） control and protection equipment is developed to form a real time closed loop simulation environment with RTDS. The control strategy employed for the system is the MTDC current margin method. The structure of control system is configured according to the MTDC master control and the converter station pole control. The MTDC master control coordinates the control of terminals with some functions such as power orders distribution, power ramping coordination, DC voltage control and MTDC communication. The converter station pole control contains conventional DC control functions and mainly realizes the power control in each station. The steady state operation, power compensation after single station blocking and DC line fault of the parallel four-terminal HVDC system are simulated using this simulation system. The simulation results show that the proposed control strategy and the developed MTDC control protection equipment can meet the requirement of the MTDC power transmission.