基于电容式电压互感器暂态误差估计的自适应距离保护

针对电容式电压互感器(CVT)暂态过程引起距离保护超越的问题，通常采用简单延时的方法，来防止保护的超越。这对电力系统的安全稳定运行是很不利的。该文提出了CVT暂态误差的实时估计方法，即根据所选用的基波算法和CVT的额定参数求出误差系数，然后根据二次电压的大小实时估计出电压幅值的测量误差。据此提出了一种自适应距离保护方法，根据误差的大小调整动作门槛。仿真计算表明，文中提出的方法对于普通线路，其动作性能几乎不受影响；对于短线路，也能够在近处故障时快速动作。其整体性能较常规的距离保护方案有了很大的提高。

AN ADAPTIVE DISTANCE RELAY BASED ON TRANSIENT ERROR ESTIMATION OF CVT

Simple delay approach is usually used to prevent transient overreach caused by the transient error of CVT. It is very harmful to the safety and stability of power system. A proposed real-time CVT transient error estimation approach based on the chosen fundamental wave algorithm and the rated CVT parameters consists of two stages. The first stage obtains the error coefficient. The second stage estimates the measured error of the voltage amplitude according to the secondary side voltage. A novel adaptive distance relay approach which can adjust action thresholds according to the error is proposed. The approach hardly affects the action performance for normal lines and acts rapidly for short lines with close-in faults, which is verified by the results of simulations. The whole performance is improved greatly compared with common distance relay approach.