Method for determining single-phase ground fault of small current grounding system

Abstract

The invention discloses a method for determining a single-phase ground fault of a small current grounding system. A plurality of transformer station outgoing lines located in the small current grounding system are included. Each transformer station outgoing line is provided with a zero-sequence current transformer. The method is characterized by comprising the following steps of: A, acquiring secondary zero-sequence current values generated by the zero-sequence current transformers and reducing the secondary zero-sequence current values to primary zero-sequence current values by variable-ratioamplification; B, transmitting the primary zero-sequence current values to a main station scheduling desk through telecontrol, and displaying the primary zero-sequence current value of each transformer station outgoing line at the main station scheduling desk; and C, determining a faulty line according to the magnitudes of the primary zero-sequence current values. The method realizes purposes ofaccurately searching for a small current grounding line, avoiding power outage of non-faulty lines, shortening the abnormal-state time of a power grid, reducing labor intensity of a scheduler and improving work efficiency.

Description

technical field [0001] The invention relates to the technical field of small current grounding systems, in particular to a method for judging single-phase ground faults in small current grounding systems. Background technique [0002] Single-phase grounding refers to single-phase grounding of small current grounding systems. Single-phase grounding faults are the most common faults in power distribution systems. They mostly occur in wet and rainy weather. It is caused by many factors such as disconnection and small animal hazards. Single-phase grounding not only affects the normal power supply of users, but also may generate overvoltage, burn out equipment, and even cause phase-to-phase short circuit to expand accidents. [0003] Single-phase grounding faults account for more than 80% of the total faults in small current grounding systems. When a fault occurs, the voltage of the faulted phase is zero, and the voltage of the non-faulted phase increases by 1.73 times, which en...

AI Technical Summary

Problems solved by technology

[0004] At present, for the small current grounding system, in order to identify the grounding line as soon as possible, it is usually selected to install the grounding line selection device, but because some plants are old and do not have the conditions for transformation, it cannot be installed; when the substation is not connected to the grounding line selection device, or When there is a false alarm, the dispatcher can only search for the grounding line one by one according to the relevant regulations, resulting in a power outage of the non-faulty line, increasing the time of equipment abnormal state and the number of times of trying to pull the line

When the substation is equipped with a grounding line selection device, not only the investment cost will increase, but also due to its single algorithm and a large number of grounding signals uploaded, it is difficult to maintain and monitor later, and false positives often occur.

Images