【目的】随着新能源的迅速发展,新能源逆变器的弱抗扰性加剧了其在故障扰动后发生连锁性脱网的风险,对现有保护风险防控技术提出了新的挑战。针对有源中点钳位(ANPC)逆变器交流侧短路的故障工况,本文对逐波限流控制方法进行了研究。【方法】在传统的逐波限流控制方法中,当电流大于过流阈值时,会断开逆变器所有开关器件。但这会频繁触发限流控制,开关器件的电流变化率di/dt很高,且有过电流流过绝缘栅双极型晶体管(IGBT)的反并联二极管,无法有效保护逆变器中的开关器件。在强制关断所有开关器件的控制与放任过电流发展导致新能源脱网事故发生之间,本文提出了一种控制逆变器介于中间状态的技术,即开关部分关断的逐波“软”限流控制技术。当触发控制时,关断指定开关器件,导通剩余开关器件。最后使用MATLAB/Simulink建立仿真模型,对本文提出的逐波限流控制方法进行验证。【结果】结果表明,该方法可有效减少触发次数,降低开关器件的di/dt,并且降低逆变器内部开关器件的电流峰值,提高逆变器的可靠性。与全关断逐波限流相比,逐波“软”限流的触发周期更长,触发次数更少,且将开关器件电流峰值限制在更低水平,有利于提高逆变器的可靠性,优化了逐波限流控制方法。【结论】本文提出的有源中点钳位型逆变器逐波“软”限流控制方法,在短路故障情况下,能够有效减小逆变器开关器件电流应力,提升逆变器短路故障穿越能力,为新能源并网安全运行提供技术支撑。

[Objective] With the rapid development of new energy, the weak anti-interference capability of new energy inverters intensifies the risk of cascading grid disconnection after fault disturbances, posing new challenges to current risk prevention and control technologies for protection. This paper investigates the cycle-by-cycle (CBC) current limiting control methods for the fault condition of active neutral point clamped (ANPC) inverters when an AC side short circuit occurs. [Methods] In traditional CBC current limiting control methods, all switching devices of the inverter were turned off when the current exceeded the over-current threshold. However, this frequently triggered current limiting control, resulting in high current change rate di/dt of switching devices, and excessive current flowing through the anti-parallel diode of the insulated gate bipolar transistor (IGBT), which failed to effectively protect the switching devices in the inverter. Between the control strategy of forcibly turning off all switching devices and the new energy grid disconnection accidents caused by allowing over-current to develop, this paper proposed a technology that controlled the inverter in an intermediate state—partial-switching-off CBC "soft" current limiting control technology. When the control was triggered, the specified switching devices were turned off while the remaining ones were kept on. Finally, a simulation model was established using MATLAB/Simulink to verify the proposed CBC current limiting control method. [Results] The results indicated that this method could effectively reduce the number of triggers, lower the di/dt of the switching devices, and decrease the current peak value of the internal switching devices in the inverter, thereby enhancing the reliability of the inverter. Compared with the full-switching-off CBC current limiting method, the trigger cycles of the partial-switching-off CBC "soft" current limiting were longer, and the trigger frequency was lower. Moreover, the CBC "soft" current limiting method limited the peak current of the switching devices to a lower level, which was beneficial for improving the reliability of the inverter and optimizing the CBC current limiting control method. [Conclusion] The proposed CBC "soft" current limiting control method for ANPC inverters can effectively control inverter current under short-circuit faults, improve the inverter’s short-circuit fault ride-through capability, and provide technical support for the safe operation of new energy grid connection.

广东省自然科学基金海上风电联合基金重点项目(2024B1515250001);广东省自然科学基金面上项目(2025A1515010058)