DC protection system combined with DC bus voltage

Abstract

The invention discloses a DC protection system combined with DC bus voltage. The system comprises a DC circuit breaker, a current divider, an isolation-amplification unit and a DC protection device, wThe invention discloses a DC protection system combined with DC bus voltage. The system comprises a DC circuit breaker, a current divider, an isolation-amplification unit and a DC protection device, wherein the DC circuit breaker is positioned on an output line of a DC power source; the current divider is positioned on the output line of the DC power source and can convert DC of a DC system into wherein the DC circuit breaker is positioned on an output line of a DC power source; the current divider is positioned on the output line of the DC power source and can convert DC of a DC system into weak-voltage signals; the isolation-amplification unit is connected with the current divider and can amplify the weak-voltage signals output by the current divider; and the DC protection device is conneak-voltage signals; the isolation-amplification unit is connected with the current divider and can amplify the weak-voltage signals output by the current divider; and the DC protection device is connected with the isolation-amplification unit, comprises a data processing unit, and can set various types of current protection, analyze input signals, judge whether DC line faults exist and sent out tected with the isolation-amplification unit, comprises a data processing unit, and can set various types of current protection, analyze input signals, judge whether DC line faults exist and sent out tripping instructions. The system is characterized in that a voltage signal led out from a DC bus is connected to the input end of the isolation-amplification unit through a voltage conversion unit. Thripping instructions. The system is characterized in that a voltage signal led out from a DC bus is connected to the input end of the isolation-amplification unit through a voltage conversion unit. The system has the advantages of taking the DC bus as an auxiliary criterion, effectively excluding noise and interfering signals and accurately cutting off fault current.e system has the advantages of taking the DC bus as an auxiliary criterion, effectively excluding noise and interfering signals and accurately cutting off fault current.

Description

technical field [0001] The invention relates to a relay protection system, in particular to a DC current protection system combined with a DC bus voltage which can be applied in a DC power supply system, and belongs to the field of electrotechnical technology. Background technique [0002] The DC power supply system usually adjusts the voltage of the AC power supply system to the voltage required by the rectifier device through a rectifier transformer, and then outputs it to the rectifier device. After being rectified by the rectifier device, the output of the rectifier device is the DC power required by the DC power supply system. [0003] Usually, a shunt is installed on the output line of the DC power supply. This shunt converts the DC current of the DC system into a weak voltage signal, and after the transformation of the isolation amplifier unit, it is output to the DC protection device as the original signal input by the DC protection device. Based on the analysis of t...

AI Technical Summary

Problems solved by technology

[0004] First of all, unlike the AC system, the DC system is a power frequency signal, which is easy to extract the characteristic signal and filter out the interference. Since the DC system does not have the power frequency signal as the basic characteristic quantity, it is difficult to distinguish the fault current from the sudden load current and interference.

[0005] Secondly, the shunt converts the DC current signal into a voltage signal. The signal is very weak. Although it is transformed by the isolation amplifier unit, the noise and interference are also amplified, so it is difficult to distinguish the fault signal.

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