An On-line Setting Self-adaptive Distance Protection Scheme for 110kV Transmission Line

The traditional three section distance protection is widely used in transmission lines with voltage level of 110kV and above, and the setting of impedance and time is the key. At present, the setting of three-section distance protection depends on manual calculation or off-line setting by professional software, which requires a lot of work and often leads to insufficient sensitivity or lack of coordination. In this paper, a distance protection scheme based on adaptive on-line setting method is proposed. This scheme does not need to set the impedance setting value and time setting value of the distance protection, instead, it only needs to calculate the fault distance using the local current and voltage information. On the basis of the calculated fault distance, the operation time limit can be calculated online by using the time limit calculation formula proposed in this paper. The protection operation time of the upper and lower lines can be adaptively coordinated and has an ultra-long protection range. This scheme can not only greatly improve the performance of distance protection, but also realize the cost reduction and efficiency improvement of relay protection setting, which brings considerable practical and economic benefits.