Ship direct-current networking electric propulsion system and short-circuit fault rapid protection method

Abstract

The invention discloses a ship direct-current networking electric propulsion system which comprises a larboard direct-current bus and a starboard direct-current bus. A generator branch composed of a rectification unit and a generator set, a load branch composed of a frequency conversion unit and a load, and a transformer branch composed of a frequency conversion unit and a daily transformer are respectively led out from the larboard direct current bus and the starboard direct current bus, and a main circuit fuse is connected between the larboard direct current bus and the starboard direct current bus. The larboard direct-current bus and the starboard direct-current bus are each provided with a rapid protection unit, and the rapid protection units, the frequency conversion unit and the rectification unit are connected with the direct-current bus through branch fuses. The invention also discloses a short-circuit fault rapid protection method. When direct-current bus short-circuit fault and branch short-circuit fault happens in the system, a faulty half board or faulty branch is quickly cut off, so that the non-faulty half board or the non-faulty branch is prevented from undervoltage fault, and the system is prevented from shutdown and power failure.

Description

technical field [0001] The invention relates to a marine DC networking electric propulsion system and a short-circuit fault rapid protection method, which is suitable for the rapid protection of busbar short circuit and branch circuit short circuit of a DC networking system powered by a diesel unit, a battery, or a hybrid power supply of a diesel unit and a battery. Background technique [0002] In order to realize the selective protection of the system and reduce the cost in the DC networking system, fuses are used as protection devices for each branch circuit and bus tie. [0003] The characteristic of the DC networking system is that the capacitor capacity on the DC bus is large. When a short-circuit fault occurs, all the capacitors will quickly discharge to the short-circuit point. The discharge current is large and the time is short. If the fault point cannot be quickly isolated and the capacitor discharge is blocked, once the capacitor voltage Below a certain threshold...

AI Technical Summary

Problems solved by technology

[0003] The characteristic of the DC networking system is that the capacitor capacity on the DC bus is large. When a short-circuit fault occurs, all the capacitors will quickly discharge to the short-circuit point. The discharge current is large and the time is short. If the fault point cannot be quickly isolated and the capacitor discharge is blocked, once the capacitor voltage Below a certain threshold, the equipment on the DC bus will be shut down instantaneously due to undervoltage, causing the entire ship to lose power and the system cannot work

[0004] Due to the small line impedance in the DC system, the size and time of capacitor discharge current are closely related to parameters such as capacitor internal resistance, distribution parameters on the line, switch contact resistance, and internal resistance of fuses and other components. The values ​​of these parameters are extremely small , and the dispersion is large, it is difficult to calculate accurately in engineering

[0005] The selection of conventional protective element fuses requires a more accurate calculation of the capacitive discharge current, so there is a certain degree of difficulty in coordination, and the key parameters of the fuse itself (the pre-arc Joule integral and the melting Joule integral) also have certain dispersion. Increased difficulty of project implementation

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