适用于风电经柔性直流并网系统的柔性耗能装置及控制策略

A flexible energy dissipation device with control strategy for an HVDC wind power integration system

高压柔性直流输电技术可实现有功功率的双向控制,且无换相失败问题,是实现风电并网外送的重要手段之一。风电经柔性直流并网系统易发生交直流故障,故障期间风电系统持续输出功率,过剩的暂态能量危害系统的安全运行。针对风电经柔性直流并网系统的暂态能量耗散问题,提出了一种基于全桥子模块的柔性耗能装置(flexible energy dissipation device,FEDD)。为解决子模块充放电无法准确控制的难题,提出了柔性耗能装置的动态电压控制策略和暂态能量耗散策略,并兼顾了子模块电容能量平衡。根据FEDD的工作原理和控制策略,提出了设备主要参数设计方法。最后通过RTDS实验结果验证了柔性耗能装置能够准确吸收暂态能量,保证换流站平稳穿越交直流故障。

HVDC transmission technology is one of the main ways to realize bidirectional control of active power,avoid commutation failure and achieve wind power integration.However,HVDC wind power integration systems are prone to AC&DC faults.As the wind turbines continuously output power during the fault,the transient surplus energy endangers the safe operation of the system.Given this transient energy dissipation problem of an HVDC wind power integration system,this paper proposes a full-bridge sub-module-based flexible energy dissipation device(FEDD).To accurately control the charging and discharging of the sub-module,a dynamic voltage control strategy and transient energy dissipation strategy are proposed,and the capacitance energy balance of the sub-module is taken into account.In addition,based on the working principle and control strategy of the FEDD,the design methods of its main parameters are proposed.Finally,the RTDS simulation results verify that the FEDD can realize transient energy dissipation of the HVDC wind power integration system and ensure the converter stations smoothly ride-through AC and DC faults.