A single phase grounding failure relay protection method based on negative electrical impedance relay

Abstract

The invention belongs to electric power system field, in particular to a single-phase grounding failure relay protection method based on a negative sequence reactance relay. The method includes: Measure the circuit's failure phase voltage Uphi, phase current Iphi, zero sequence voltage U0, zero sequence current I0, and negative sequence current I2 at the installation place of transformer station as the input values; calculate the residual voltage phasor of the failure point through measuring voltage, measuring current, negative sequence current at the place of protection installation, and circuit impedance angle; constitute the action voltage phasor Uop through measuring voltage, measuring current, residual voltage phasor of failure point, and impedance value within the scope of circuit protection; calculate the angle that the action voltage phasor Uop leads the negative sequence current iU2. If the angle is within the range of [180 DEG, 360 DEG], the protection action sends a signal of tripping operation; contrarily, the protection will not take any action. The method is suitable for the electricity transmission side of ultra / super high voltage electric circuit, particularly ultra / super high voltage heavy load electric circuit. The invention can meet requirements for selection, reliability, sensitivity, and speediness of relay protection.

Description

technical field [0001] The invention belongs to the field of power systems, in particular to a single-phase grounding fault relay protection method based on a negative sequence reactance relay. Background technique [0002] Distance protection is one of the excellent protection principles based on single-ended electrical quantity, which is less affected by the system operation mode, and the protection area is stable; because only the information of the protection installation site is used, no need for communication equipment, and the electrical quantity used is the full amount of faults, It always exists after the fault, so the protection is stable and reliable, and it has been widely used in high-voltage and ultra-high-voltage transmission lines, especially as a backup protection. [0003] Impedance relay is the measurement element of distance protection. Traditional impedance relay does not consider the distributed capacitance of the line. In the case of metallic faults, t...

AI Technical Summary

Problems solved by technology

The main ones that are widely used are zero-sequence reactance relays, but the traditional zero-sequence reactance relays are designed based on the centralized parameter model of the transmission line, without considering the influence of distributed capacitance; and although the heavy load current will not affect the logic of the relay operation, it will Affect the sensitivity of the protection; the most important thing is that the design of the zero-sequence reactance relay assumes that the zero-sequence current flowing through the protection installation is in phase with the zero-sequence current of the fault branch. For traditional high-voltage and ultra-high-voltage lines less than 400km, this The error caused by this assumption can be accepted by the field, but for the ultra / ultra-high voltage long lines with a voltage level above 750kV, this error will hardly meet the requirements of the field application

Images