不考虑剩磁非同步合闸技术的混合变压器励磁涌流治理策略研究

Research on Excitation Inrush Current Management Strategy of Hybrid Transformer Without Considering Remanence Asynchronous Closing Technology

当电力变压器接入电网时,由于剩磁和电压暂态分量等原因,变压器一次侧会产生较大的励磁涌流,容易引起差动保护误动作,造成大面积停电。针对以上问题,该文提出一种基于混合变压器模型的非同步合闸励磁涌流治理方法。首先,通过合理设计混合变压器拓扑,建立辅助绕组实现变压器电磁双耦合机制,为励磁涌流治理奠定磁路基础;其次,利用辅助绕组建立一种阶梯型调制磁场,在调制磁场的作用下铁芯磁通呈正弦式线性增加并趋于稳定;最后,通过电网采样电路获得一次侧电压信号,在磁通稳定后非同步合闸,可以有效地缓解励磁涌流的产生。搭建非同步合闸混合变压器样机平台验证所提方案的有效性,为当前电力系统躲“剩磁”、避“涌流”的现状,提供一定的参考依据。

When a power transformer is connected to power grid,due to the remanence and voltage transient components,the primary side of the transformer will generate large inrush current,which is easy to cause misoperation on differential protection,resulting in a large area of power outage.In view of the above problems,this paper proposed an asynchronous inrush current treatment method based on the hybrid transformer model.Firstly,through rational design of hybrid transformer topology,the auxiliary winding was established to realize the electromagnetic coupling mechanism of the transformer,thus laying the magnetic circuit foundation for inrush current management.Secondly,a step synchronous magnetic field was established with auxiliary winding.Under the effect of the synchronous magnetic field,the magnetic flux of the core increases linearly in a sinusoidal manner and tends to be stable.Finally,the voltage signal of the primary side was obtained by the sampling circuit of the grid,and the excitation current can be effectively alleviated by asynchronously closing after stabilizing the flux.An asynchronous closing hybrid transformer prototype platform was built to verify the effectiveness of the proposed scheme,providing certain reference for the current situation of avoiding“remanence”and“insurge current”in the current power system.