调相机与STATCOM协调抑制直流送端暂态过电压的控制策略

A Control Strategy for Transient Overvoltage Suppression at DC Supply Terminal by a Coordination of Condenser and STATCOM

  • 摘要: 1直流换相失败导致的送端系统暂态过电压严重影响了直流送端新能源基地的安全稳定运行,新能源基地往往通过在附近安装调相机和STATCOM来抑制过电压,但抑制效果还有待于提高。分析了调相机和STATCOM在由直流换向失败引起的送端暂态过电压过程中无功输出能力方面的缺陷和局限性,针对STATCOM的无功响应速度低于电压变化速度,会出现反调加重过电压的缺陷,提出了通过闭锁定电压控制抑制STATCOM反调的控制策略;针对调相机励磁调节控制动作时间慢,在故障初期仅依靠其内电势不突变提供有限无功支援能力的局限性,提出了在过电压时调相机采用零励磁以及STATCOM采用增加电压变化倍数的调相机与STATCOM协调控制抑制过电压的控制策略。最终通过PSCAD仿真验证了所提控制策略的合理性和有效性。

     

    Abstract: The transient overvoltage caused by DC commutation failure seriously affects the safe and stable operation of the DC transmission terminal new energy base. The suppression effect of new energy bases is not satisfactory and needs to be improved. In this paper, we analyze the deficiencies and limitations in the reactive power output capability of the condenser and STATCOM in the transient overvoltage process caused by DC commutation failure. To address the issue that the reactive power response speed of STATCOM is lower than the voltage change speed, which will result in overshoot and exacerbation of overvoltage, a control strategy is proposed to suppress STATCOM overshoot through closed lock voltage control. In response to the limitation of slow action time of the excitation regulation control of the condenser and limited reactive power support ability,which solely only relies on the internal potential not changing suddenly in the early stage of faults, a control strategy is proposed. It employs zero excitation for the condenser during overvoltage situation and coordinates control with STATCOM to suppress overvoltage by increasing the voltage change multiple for both the condenser and STATCOM. Finally, the rationality and effectiveness of the proposed control strategy are verified through PSCAD simulation.

     

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