特高压直流接地极邻近新能源厂站变压器直流偏磁影响研究

Study on DC Magnetic Bias Effect of Transformer Near UHV DC Ground Electrode in New Energy Plants

构建以新能源为主体的新型电力系统,服务碳达峰、碳中和,急需特高压输电这一载体。我国清洁能源呈资源与需求逆向分布,结合特高压输电技术远距离、大容量、低损耗、少占地的特征,使得特高压输电技术成为实现“双碳”目标的有效途径。特高压直流输电在确保新能源基地电力可靠外送的同时,也会对邻近变压器造成直流偏磁影响。首先,通过建立地上电网-地下土壤耦合模型,求得不同站点直流偏磁电流;然后,研发直流偏磁多站同步检测系统,对接地极邻近站点直流偏磁电流进行实测;最后,分析仿真数据与实测数据偏差原因,提出多维函数多项式逼近方法,构建山西电网直流偏磁精确计算模型,计算结果与实测值相差小于15%,可用于指导后续新建站点选址和直流偏磁治理。

To build a new power system with new energy as the main body and serve carbon peaking and carbon neutralization,UHV transmission is urgently needed as the carrier.Moreover,China’s clean energy is inversely distributed between resources and demand.With the characteristics of long-distance,large capacity,low loss and less land occupation of UHV transmission technology,UHV transmission technology has become an effective way to achieve the goal of“Carbon Peaking and Carbon Neutrality”.UHV DC transmission will not only ensure the reliable external transmission of power in the new energy base,but also have DC bias impact on adjacent transformers.Therefore,firstly,by establishing the coupling model of aboveground power grid and subsurface soil,the DC bias current at different stations is obtained.Then,multi-station synchronous detection system for DC magnetic bias is developed to measure the DC bias current at the station near the ground electrode.Finally,the reasons for the deviation between the simulation data and the measured data are analyzed,a polynomial approximation method of multidimensional function is proposed,and the accurate calculation model of DC magnetic bias of Shanxi power grid is constructed.Since the difference between the calculated results and the measured values is less than 15,this way can be used to guide the subsequent site selection and DC magnetic bias control.