Self-adaptive Positive-sequence Current Quick-break Protection Method for Petal-shaped Power Distribution Network Trunk Line

A self-adaptive positive-sequence current quick-break protection method for a petal-shaped power distribution network trunk line, comprising the following steps:

• step 1, calculating a positive-sequence voltage phasor {dot over (U)}1 and a positive-sequence current amplitude I1 of a protection installation position when a fault occurs based on the obtained voltage power frequency quantity {dot over (U)}apre, {dot over (U)}bpre, {dot over (U)}cpre of each phase during normal operation, voltage power frequency quantity {dot over (U)}a, {dot over (U)}b, {dot over (U)}c of each phase and current power frequency quantity İa, İb, İc of each phase when a fault occurs;
• obtaining and storing the positive sequence impedance value ZL1 of the protected line;
• and utilizing the fault component of each phase current at the protection installation position to determine the fault type;
• at the same time, utilizing the power directional element adopting a 90° wiring mode to determine the fault direction based on the obtained fault type;
• step 2, electing a self-adaptive positive sequence quick-break current protection setting formula according to the fault type when the fault directional element is judged to have a fault in the forward direction, and judging that the protected line has short-circuit fault and making a circuit breaker trip quickly when the protection detects that the positive sequence current is greater than the protection setting value.