【摘要】 零序方向元件测得的零序电压实际为变压器的零序分压。随着电力系统的发展,变压器容量越来越大,其零序阻抗越来越小,导致保护上零序电压很小,不满足灵敏度要求,零序方向元件误动或者拒动。针对这一缺陷,通过分析变压器中性点零序电流和保护零序电流的相位关系,提出一种基于变压器中性点零序电流的方向元件。该元件以变压器中性点零序电流为参考,与保护零序电流进行比相,进而判断故障方向。经仿真验证,该方向元件动作准确、可靠。更多还原

【Abstract】 The zero sequence voltage measured by zero sequence direction element is in fact the zero sequence voltage of the transformer.As the development of power system,the capacity of transformer becomes larger and its zero sequence impedance becomes smaller,so does the zero sequence voltage,which can not meet the sensitivity requirement of the protection.This leads to malfunction of the protection.By analyzing the phase’s relationship between transformer neutral zero sequence current and zero sequence current of the protection,a novel direction element based on zero sequence current of the transformer neutral point is proposed to overcome the above shortcoming.This element uses the zero sequence current of the transformer neutral point as a reference,and compares with the zero sequence current of the protection.Then their phase’s difference is taken as evidence to determine direction of the fault.The simulations show that this element is correct and reliable.更多还原