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直流电压稳定是关系到电压源型直流输电系统可靠运行的关键问题之一。文中首先分析了在电压源型直流输电系统中直接电流控制和直流电压偏差控制的工作原理,然后提出了在电压源型多端直流输电系统中采用基于直流电压偏差控制的多点直流电压控制策略。控制器采用该策略后,能实现定有功功率控制模式与定直流电压控制模式之间的自动转换,确保定直流电压控制的换流站故障退出后,仍能实现对直流电压的控制和有功的平衡。以一个5端系统为例进行仿真验证,结果表明多端直流输电系统的运行可靠性得到提高,且获得良好的动态性能。
DC voltage stability is one of the key issues that are related to the reliable operation of the voltage source type DC transmission system. In this paper, the working principle of direct current control and DC voltage deviation control in voltage source HVDC system is firstly analyzed. Then a multi-point DC voltage control strategy based on DC voltage deviation control is proposed in voltage source HVDC system. After the controller adopts this strategy, it can realize the automatic conversion between active power control mode and constant DC voltage control mode to ensure that the DC voltage control and active balance. A five-terminal system is used as an example to verify the simulation results. The results show that the operational reliability of the multi-terminal HVDC system is improved and good dynamic performance is obtained.