基于电流互感器线性传变区检测的母线采样值差动保护

根据电流互感器(TA)饱和时每工频周期内线性传变区和饱和区存在周期性间隔重复，且线性传变区之间的间隔通常短于1/2工频周期的规律，提出基于TA线性传变区检测的母线采样值差动保护新方法：首先利用采用值差动原理确定线性传变区的位置，如果在差流1/2周期里没有出现线性区，则开放保护，否则说明TA发生饱和，闭锁保护1/2周期。在后续的工频周期中，同样的判断重复进行，直至保护动作或者启动退出。该方法提高了保护对发展性故障的动作速度和灵敏度，动模验证表明多数情况下可以在1/2周期内快速判断，区外故障时具有很强的抗TA饱和能力。

Busbar Sampled Value Differential Protection Based on Linear Transfer Section Checking of TA

When TA is saturated,its linear transfer section and saturated section repeat periodically and alternatively during each power frequency perid,and the interval between linear transfer sections is shorter than half power cycle.According to this regularity,a new busbar sampled value differential protection based on linear transfer section of TA is proposed.In this method,firstly by use of samled value differential principle the linear transfer section of TA is determined.When linear section does not appear in half cycle of differential current,it shows TA is not satuated,the protection is unblocked;when linear section appears in half cycle of differential current,it shows TA is saturated,the protection is blocked for half power cycle.At the following power cycles,the same procedure is repeated,until the protection acts or is out of service.The proposed method can improve the sensitivity of busbar sampled value differential protection.The dynamic simulation results show that using the proposed method most of transitional faults can be quickly judged in half cycle and this method possesses strong anti-saturation ability for external faults.