Early fault warning method for shunt capacitor bank based on differential current

Abstract

The invention discloses an early fault warning method for a shunt capacitor bank based on differential current. The method comprises the following steps: monitoring the current of capacitor units in the shunt capacitor bank; sending the current of the capacitor units to a data center; obtaining differential current according to collected current data of the capacitor units and a pre-established mathematical analysis model; comparing the obtained differential current with rated differential current values corresponding to faults of different degrees; judging the fault severities of internal elements; comparing the fault severities with the rated differential current values at the same time; and sending an alarm signal when the rated values are exceeded. By monitoring the differential current, the reliability and sensitivity of a fault early warning device are taken into account, and the fault degrees of the internal elements can be reflected. Moreover, a differential current initialization function is added, so that initial errors caused by different factory defaults of electric capacity are eliminated; the accuracy of alarm is further improved; false alarm and missed alarm are prevented; and unnecessary waste of manpower and material resources is reduced.

Description

technical field [0001] The invention relates to the field of on-line monitoring, in particular to an early warning method for parallel capacitor banks based on differential current. Background technique [0002] The complete set of shunt capacitors is widely used in reactive power compensation of power systems, and is generally installed in substations for centralized compensation. With the increasing scale of the power grid and the increasing load demand, the system adjusts its voltage and reactive power more and more frequently. The safe operation of the complete set of shunt capacitors plays an important role in the reactive power balance and supply voltage stability of the entire power system. very important role. [0003] The complete set of shunt capacitors includes shunt capacitor banks, series reactors, discharge coils, lightning arresters, isolating switches, grounding switches and other electrical equipment ( image 3 , Figure 4 ), connected to each other by har...

AI Technical Summary

Problems solved by technology

At the same time, fluctuations in grid voltage, harmonics, and temperature may also cause various state variables including capacitance to change within a certain range. How to eliminate interference and confirm that the change is caused by capacitor failure, thereby preventing false alarms or leaks Alarming has always been a difficulty in early warning of parallel capacitor failures

[0007] Various existing early warning methods are often based on the ideal condition that the capacitance value of each capacitor is the rated value, and predict the change of each state quantity when its internal components fail. However, because the calculation process does not take into account the The ex-factory deviation of the unit and the influence of operating conditions on the capacitance value, or the interference factors cannot be ruled out, false alarms when the external conditions fluctuate and the capacitor is operating normally, or artificially increase the alarm threshold in order to avoid the fluctuation, resulting in early failures Missing alarms, so that reliability and sensitivity cannot be taken into account, resulting in unnecessary waste of manpower and material resources

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