适应逆变电源并网的工频变化量距离保护动作优化策略OA

Inverter interfaced distributed generation(IIDG),influenced by grid connection requirements and control strategies,can be equivalently represented as a controlled current source externally,leading to unstable internal impedance after faults and resulting in poor adaptability of power-frequency variation distance protection in IIDG grid-connected environments.To address this issue,the reasons for the poor adaptability of power-frequency variation distance protection on the IIDG grid side are thoroughly analyzed.Based on the concept of coordinated control and protection,a positive-sequence fault component current suppression strategy is proposed.This strategy temporarily restores the fault component network under IIDG grid-connected conditions to a passive network similar to that under the influence of synchronous generators.PSCAD/EMTDC simulation results demonstrate that the proposed Strategy enables power-frequency variation distance protection to reliably distinguish between internal and external faults while improving its tolerance to fault resistance.This significantly enhances the operational reliability of power-frequency variation distance protection in IIDG grid-connected scenarios.Moreover,the control objective can be achieved within a very short time window.Once the protection meets the tripping conditions,the conventional IIDG fault ride-through control can be restored,ensuring no impact on its grid-connected capability during faults.