Research and Application of Multi-level Coordination and Risk Assessment of Rural Distribution Lines

There are some problems in the 10 kV feeder switch and line intelligent switch in the existing substations, such as over-protection or no protection range, and failure of coordination between upper and lower levels. To solve these problems, this paper proposes a method of protection setting calculation based on system parameters and two-phase short-circuit fault types. Taking the single radiation line as an example, it analyses in detail the application of this method in protection coordination, over-current setting of switches at all levels, and the risk of leapfrog trip. The results show that this method can effectively increase the protection range, optimize the switch layout, and greatly simplify the protection setting calculation while ensuring the selectivity of the protection device. Finally, based on the above calculation method, the protection setting calculation software is designed. It can automatically complete setting calculation and verify protection range according to relevant parameters of the system, and automatically generate risk assessment report of original setting value.