Y/?接线电力变压器直流扰动励磁特性

Excitation Characteristics of Y/Δ Connected Power Transformer with DC Disturbance

针对Y/Δ接线电力变压器在直流扰动下的偏磁饱和问题,通过模型仿真与实验验证相结合的方法,研究了变压器直流扰动下励磁参数的变化规律与励磁特性。首先,利用励磁电感、电流作为单/三相变压器的关键励磁参数,反映直流扰动下的励磁特性。然后,针对变压器遭受直流扰动时励磁饱和特性与关键励磁参数的关联,利用电磁耦合模型进行仿真研究,并总结其励磁参数的变化特性;由220 V三相变压器交直流混杂动模实验平台获取端口量测信息,利用时域差分原理辨识关键励磁参数,从而建立励磁参数与励磁饱和特性的对应关系,并将仿真结果与实验数据进行对比,验证该方法的正确性和有效性。最后,通过现场10 kV变压器试验分析其遭受直流扰动时的励磁特性。结果表明:当直流扰动水平ε超过一定限值(ε≥2.0)时,可能会导致变压器出现较为严重的偏磁失稳问题,高电压等级电力变压器应当具备一定的抗直流扰动能力,从而为进一步研究变压器直流扰动抑制措施与保护策略提供思路。

In order to solve the biasing saturation problem of power transformer with Y/Δwired under DC disturbance,the excitation parameters and variation characteristics of DC disturbance transformer are studied by combining a model simulation and experimental verification.Firstly,the excitation inductance and current are used as the key excitation parameters to characterize the single/three-phase transformer excitation characteristics under DC disturbance.Secondly,the intrinsic relationship between the key excitation parameters and excitation saturation characteristics is simulated based on the electromagnetic coupling principle when the transformer suffers from DC disturbance.Moreover,an AC/DC hybrid experiment platform of 220 V three-phase transformer is built,and the excitation parameters are identified by port measurement information and time domain difference principle.The relationship between the excitation parameters and excitation saturation characteristics is built.The simulation results are compared with the experimental data to verify the correctness and effectiveness of the proposed method.Finally,the DC disturbance excitation characteristics are further analyzed by field 10 kV transformer tests.The results show that when the DC disturbanceεexceeds a certain limit(ε≥2.0),it may lead to more serious biasing instability problem.High-voltage level power transformers should have the capacity to withstand DC disturbance.The conclusion will provide some ideas for the further study of DC disturbance suppression measures and protection strategies.