A distance protection method for transmission lines with series equipment

Abstract

The invention discloses a distance protection method for a power transmission line with serial connection equipment. The method comprises the steps that voltage drop between the two ends of the serial connection equipment as well as the voltage and current in a protective installation position are collected; 2) an equivalent impedance of the serial connection equipment is calculated in real time; 3) a measuring resistance of the power transmission line including the serial connection equipment is calculated accurately according to the equivalent impedance of the serial connection equipment; 4) whether distance protection is carried out is determined by comparing the positional relation between the measuring impedance with a distance protection motion area. The equivalent impedance of the serial connection equipment is calculated in real time, the measuring impedance of the power transmission line including the serial connection equipment is calculated accurately according to the calculated equivalent impedance, and the finally whether distance protection is carried out is determined by comparing the positional relation between the measuring impedance with the distance protection motion area. Influence of the serial connection equipment on line distance protection is eliminated, it is ensured that the practical protection range of distance protection is the set protection range, and the reliability and sensitivity of distance protection are improved.

Description

technical field [0001] The invention relates to a distance protection method for a power transmission line with series equipment. Background technique [0002] The installation of series equipment on transmission lines is an important measure to improve the stable operation of the system. The series equipment changes the potential characteristics of the head and end of the line, thereby further changing the potential phase and amplitude distribution in the system, and plays a role in regulating the power flow distribution in the entire area. Although the installation of series devices on transmission lines has obvious economic benefits, the existence of series devices destroys the uniformity of transmission line impedance, which brings great difficulties to the design of line protection, especially distance protection. When the series device is capacitive, the measured impedance of the distance protection is reduced, and the fast distance protection set according to the rou...

AI Technical Summary

Problems solved by technology

[0003] The Chinese patent with the application number CN200910034668.7 discloses a series capacitor compensation line distance protection method combined with a phase ratio relay. Its shortcoming is that it is only suitable for transmission lines where the series equipment is a capacitive series equipment.

Its disadvantage is that the maximum equivalent impedance of UPFC is not an accurate equivalent impedance, and the equivalent impedance of UPFC during normal operation is not strictly equal to the equivalent impedance of UPFC during system failure

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