A method for distance protection of transmission line with series capacitance compensation

Abstract

The invention provides a series capacitor compensation power transmission line distance protection method. The method comprises the following steps that: the voltage and current of a power transmission line can be acquired in a real-time manner, and the voltage sampling value and the current sampling value of a power transmission line protection installation position (circuit breaker) at each sampling time point can be obtained; and at the same time, power transmission line fault detection is performed, if a fault occurs on the power transmission line, fault location is performed so as to judge the position of the fault point. With the series capacitor compensation power transmission line distance protection method of the invention adopted, over tripping caused by series compensation capacitor short-circuit faults occurring in a forward direction can be avoided, and incorrect tripping can be also avoided due to series compensation capacitor short-circuit fault protection in a reverse direction, and therefore, the influence of series compensation capacitors on distance protection can be eliminated. According to the series capacitor compensation power transmission line distance protection method of the invention, a pi-shaped equivalent circuit of a series compensation line forward-direction fault is adopted; an iterative algorithm is used for distance measurement; and the position of the fault point with respect to the series compensation capacitors can be judged according to the discrete degree of the distance measurement. Thus, with the series capacitor compensation power transmission line distance protection method adopted, the over tripping and incorrect tripping of the distance protection can be reliably prevented, and the sensitivity of the protection can be improved.

Description

technical field [0001] The invention belongs to the relay protection technology of electric power system, and in particular relates to a distance protection method of series capacitance compensation transmission line. Background technique [0002] Series compensation capacitor compensation is an effective means to improve the economy and reliability of transmission lines. Its main functions are: to improve the transmission capacity of the power system by controlling the flow; to improve the stability of the power system; to improve voltage quality and reactive power balance; to reduce system Reduce the line loss and increase the transmission capacity of the line; when used in long-distance and large-capacity power transmission, it can reduce the number of transmission line circuits and save investment. It also has the function of improving the transient stability of the system, optimizing the power flow of the transmission line and reducing the loss of the system. [0003] ...

AI Technical Summary

Problems solved by technology

[0003] However, the series compensation capacitor destroys the linear relationship between the transmission line impedance and distance, which brings great difficulties to the design of series compensation capacitor compensation line protection, especially distance protection.

The traditional distance protection applied to the series compensation line has the problem of overrunning action, and the distance I section must consider the capacitance of the series compensation capacitor in the series compensation line (Z C ), according to line impedance (Z L ) and the sum of the capacitive reactance of the series compensation capacitor (Z L -j|Z C |) for setting, when the series compensation capacitor is large, the protection sensitivity may be very low, which cannot meet the requirements of line protection; PT, when a short-circuit fault occurs through the series compensation capacitor in the reverse direction, the protection will malfunction

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