Tubular bus current differential protection method applicable to direct-current ice melting system rectifying device
A rectifier device, DC ice melting technology, applied in emergency protection circuit devices, electrical components and other directions, can solve problems such as unreliability and protection misoperation, and achieve the effect of protection from misoperation and high sensitivity
Active Publication Date: 2015-07-29
EXAMING & EXPERIMENTAL CENT OF ULTRAHIGH VOLTAGE POWER TRANSMISSION COMPANY CHINA SOUTHEN POWER GRID
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The rectifier is the core equipment of the DC ice-melting system. The 12-pulse rectifier is widely used. Therefore, it is necessary to configure a complete relay protection to ensure the safety and reliability of the ice-melting process. Overstress, the DC ice melting system is equipped with valve short-circuit protection as the main protection of the rectification device. The valve short-circuit protection mainly uses the fault phenomenon that the rectification device's AC side current is greater than the DC side current as a protection criterion, and then protects the rectification device. However, it is not reliable enough to protect the rectifier according to the protection criterion in the existing protection method, for example, when the current transformer has an unbalanced current, it is easy to cause the protection to malfunction
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[0040] figure 1 This is a schematic diagram of the circuit topology of the 12-pulse DC ice melting system. Its topology and working principle are basically the same as those of the rectifier in the HVDC transmission project, but there are differences between the two, mainly due to the different location of the grounding point. The grounding point is generally selected at the midpoint of the two poles, that is, the midpoint of the series circuit of two groups of 12-pulse rectifier circuits, while the grounding point of the rectifier device of the DC ice melting system is selected at the midpoint of one group of 12-pulse rectifier circuits, that is, two groups of three-phase The series connection point of the bridge rectifier circuit is directly grounded, and the ground point of the rectifier device of the DC ice melting system only acts to clamp the neutral point potential, and does not provide a DC path. figure 1①-⑨ are marked as various types of fault points that may occur in...
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Disclosed is a tubular bus current differential protection method applicable to a direct-current ice melting system rectifying device. According to the method, corresponding differential protection actions are performed by judging whether three-phase current of the alternating-current side in the direct-current ice melting system rectifying device and anode and cathode current on the direct-current side meet a protection action equation or not, the protection action equation effectively reflects various faults in the rectifying device protection area, and a fault bridge positioning function is realized. The protection braking function further considers influence of unbalance current of two measurement circuit current transformers, the traditional valve short-circuit protection braking function is improved and changed into a two-broken-line type braking function, and reliability in protection is improved.
Description
technical field [0001] The invention mainly relates to a current differential protection method of a rectifier device, in particular to a tube bus current differential protection method suitable for a DC ice melting system. Background technique [0002] The DC ice melting system system mainly uses DC voltage to the transmission line and short-circuits the end of the transmission line, so that the wire is heated to melt the ice on the transmission line, so as to avoid the line falling down due to icing, which is of great significance to the safety of power grid transmission. . The rectifier is the core equipment of the DC ice melting system. The 12-pulse rectifier is widely used. Therefore, it is necessary to configure a complete relay protection to ensure the safety and reliability of the ice melting process. Over stress, the DC ice melting system is equipped with valve short-circuit protection as the main protection of the rectifier. The valve short-circuit protection main...
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IPC IPC(8): H02H7/125
Inventor 顾保全唐金昆张楠李博通李斌邱宏严喜林梁宁
Owner EXAMING & EXPERIMENTAL CENT OF ULTRAHIGH VOLTAGE POWER TRANSMISSION COMPANY CHINA SOUTHEN POWER GRID