基于暂态零序能量的配电网故障选线方法研究

针对中性点经消弧线圈接地系统发生单相接地故障时因故障边界复杂、随机,故障稳态分量小,零序瞬时功率倒相而导致传统的单一特征量选线方法失效问题,提出了一种新的基于暂态零序能量的选线方法。该方法通过一种数字滤波器来滤除暂态零序电流中的不对称分量和稳态工频分量,得到各条线路零序电流和母线零序电压的暂态纯故障分量,由此构造暂态零序能量,并根据暂态零序能量的大小和方向判断故障类型及线路,即发生单相接地故障时,非故障线路暂态零序能量的方向为正,故障线路暂态零序能量的方向为负,且其绝对值为其余线路暂态零序能量之和;发生母线接地故障时,母线暂态零序能量的大小为其余线路暂态零序能量之和。针对母线暂态零序能量受噪声影响大而导致选线灵敏度低的问题,提出将自动重合闸技术应用到该选线方法中的方案。Matlab仿真结果表明,该选线方法的准确性、可靠性较高。

Research of Fault Line Selection Method of Distribution Network Based on Transient Zero-sequence Energy

For problem of ineffectiveness of traditional line selection methods by use of single feature value caused by complex and random fault borderline,small steady component of fault and reverse phase of instantaneous zero-sequence power when single-phase grounding fault happens in power system connected to earth through an arc suppression coil,the paper proposed a new method of line selection based on transient zero-sequence energy.The method filters nonsymmetrical component and steady component of transient zero-sequence current through a digital filter and gets zero-sequence current of each line and pure transient fault component of zero-sequence voltage of bus in order to get transient zero-sequence energy.Then the method judges fault type and line according to the value and direction of transient zero-sequence energy.When single-phase grounding fault happens,the direction of transient zero-sequence energy of non-fault line is positive,the direction of transient zero-sequence energy of fault line is negative,and absolute value of transient zero-sequence energy of fault line is the sum of the ones of other lines.When the bus grounding fault happens,the value of transient zero-sequence energy of the bus is the sum of the ones of other lines.Meanwhile,in order to solve the problem of low sensitivity of line selection caused by influence of noise on transient zero-sequence energy of the bus,the paper proposed a scheme of usting auto-reclosing technique in the line selection method.The Matlab simulation result showed that the line selection method has high accuracy and reliability.