多换流器并联特高压直流系统控制策略及仿真

并联高压直流输电系统是多端直流系统的一种特殊方式,并联扩建方案经济性好、运行灵活方便。利用实时数字仿真器(RTDS)建立了±800kV双换流器并联、10GW双极直流输电仿真模型。直流控制保护模型采用所开发的直流输电控制保护样机,与RTDS构成实时闭环仿真试验环境。控制策略采用电流裕度控制,整流侧两个换流器均定电流,逆变侧一个换流器定电压,另一个换流器定电流。控制系统架构按双极/极控制层,换流器层控制进行设置。换流器层控制实现两个换流器的触发控制,双极/极控制层产生电流和电压参考值指令,经分配后,发送至换流器层控制。利用该仿真系统对双换流器并联的直流输电系统启停、稳态运行工况、换流器在线投退、功率分配策略等进行仿真研究,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双换流器并联的高压直流输电要求。

Simulation of Control Strategy for Multi-convertor Parallelled HVDC Transmission System

Paralleled high voltage direct current (HVDC) is a special way of multi-terminal HVDC, the expansion scheme is economical, flexible and convenient. Real time digital simulator (RTDS) is used to develop a ±800 kV paralleled double converter and a 10 GW bipolar HVDC simulation model. The HVDC control and protection model uses control and protection demo machines as the prototype and RTDS to constitute a real-time closed loop simulation test environment. The current margin control is used as the control strategy, and constant current control is adopted for both converters at rectifier side, while at the inverter side, one converter uses constant current control, the other one uses constant voltage control. The control system architecture is set after the bipolar/pole layer control, converter layer control. The converter control layer realizes the two converter triggering control, and bipolar/pole control layer generates current and voltage reference value instructions. After allotment, the instructions are sent to the converter layer control. Start and stop pole, steady state operation and online entry and exit of the converter are simulated using this simulation system. The simulation results show that the proposed control strategy and the developed control protection equipment meet the requirement of dual converter paralleled HVDC transmission.