电力系统中的传统电压互感器有绕组或铁芯,可导致暂态响应不能跟随一次电压变化,易产生铁磁谐振过电压,且响应频带窄、体积大,测量过程需要与高压导体进行接触。文章基于D-dot测量原理,提出一种新的互感器结构,可作为非接触的电压互感器。D-dot互感器是通过电场耦合原理对导体电位进行无接触测量,通过差动输入结构和多重电极并联结构,避免负载电阻、积分电路及引线寄生电感的影响的同时,可减小互感器的相位误差。通过有限元仿真计算对传感器结构进行优化,并将传感器制成印刷电路板在10 kV电压等级下进行误差和暂态性能试验。试验结果表明,互感器可满足准确测量要求并具有良好的暂态特性,符合智能电网测量传感器智能化、小型化、便捷化的发展需要。
Traditional voltage transformers in power system contain windings or iron cores, which can make transient response fail in following the change of primary voltage and leads to ferroresonance overvoltage. These transformers also have disadvantages in narrow bandwidth and large size. Morever, these devices need to be contacted to high voltage conductors during measuring process. A new voltage transformer was proposed as a kind of non-contacting voltage transformer based on the measuring principle of D-dot probe. D-dot probe can realize non-contact measurement of conductors according to the priciple of electric-field coupling. With the differential input circuit and multi-electrode structure, the voltage transformer can avoid spurious inductance brought by load resistances and integrators, and reduce phase errors. The finite element simulation was operated to get the optimal configuration of the voltage transformer. The probe was manufactured into printed circuit board (PCB) for testing its error and transient behaviors in 10 kV voltage level. The results show that the voltage transformer not only meets the requirement of high accuracy but also has a good transient response. The voltage transformer can meet the requirement of smart grid, which needs sensors to be intelligent, miniature and convenient.