Magnetic saturation iron core direct current fault current limiter capable of performing secondary active current limiting and current limiting method

Abstract

The invention relates to a magnetic saturation iron core type direct-current fault current limiter technology, in particular to a magnetic saturation iron core direct-current fault current limiter capable of performing secondary active current limiting and a current limiting method, and the current limiter comprises an iron core, two direct-current main branch windings, two coupling branch windings, a coupling branch and two permanent magnets; the iron core is square-shaped and comprises a left iron core column, a right iron core column, an upper transverse yoke and a lower transverse yoke, the upper transverse yoke and the lower transverse yoke are located at the upper end and the lower end respectively, and the permanent magnets are embedded in the middles of the upper transverse yoke and the lower transverse yoke respectively; the two direct-current main branch windings are wound on the left and right iron core columns respectively and are connected in series to a direct-current power grid, and the two coupling branch windings are wound on the outer sides of the two direct-current main branch windings in a tight coupling manner and are connected with the coupling branch; and the coupling branch is formed by connecting n sub-modules in parallel. The current limiter can effectively limit the fault current of a direct-current power grid, reduces the time that the fault current acts on the winding of the current limiter in the current drop stage, reduces the energy absorption and overvoltage of a direct-current circuit breaker, and achieves the secondary utilization of short-circuit fault energy.

Description

technical field [0001] The invention belongs to the technical field of a magnetically saturated core type DC fault current limiter, in particular to a magnetically saturated core DC fault current limiter capable of secondary active current limiting and a current limiting method. Background technique [0002] The rapid rise of the fault current in the HVDC system has always threatened the safe operation of the HVDC system, so the fault current limiter system that limits the rising speed of the fault current is essential for the safe operation of the HVDC system. At the same time, the DC circuit breaker will automatically reclose after removing the fault for the first time. Due to the unknown type of fault, the DC circuit breaker may automatically reclose on a permanent fault, causing the system to withstand the second short-circuit impact. Due to the time interval between the two impacts Short, the secondary impact will cause superimposed damage to the entire system, so the c...

AI Technical Summary

Problems solved by technology

But its disadvantage is that the inductance value is small and the current limiting effect is limited

Existing fast-response DC current limiter topologies such as image 3 As shown, it adopts the method of coupling a resistance energy-absorbing branch with a traditional magnetically saturated core-type DC fault current limiter. The advantage is that it can absorb fault energy, but the disadvantage is that the energy absorption speed is slow, and the direct consumption of fault energy cannot be carried out. secondary use

The topology of the existing fast energy storage type magnetically saturated iron core DC fault current limiter is as follows: Figure 4 , which adopts the method of coupling an energy storage branch with a traditional magnetically saturated core-type DC fault current limiter. Its advantage is that it can store fault energy, but its disadvantage is that it can only be used to supply energy to secondary equipment, and the fault energy cannot be used as active current limiting

at the same time image 3 and Figure 4 The primary and secondary windings of the two current limiters are wound separately on the left and right columns, and are in a loosely coupled state. The magnetic flux leakage presented to the outside is relatively large, the efficiency of energy transfer is low, and there is a certain loss.

Finally, the above four current limiters are all passive current limiters. When the DC circuit breaker mistakenly closes on a permanent fault, the entire DC system will face the second impact caused by the short-circuit fault. Due to the short interval, the two The second impact will cause superimposed damage to the DC system

The above-mentioned current limiters can only play a passive current limiting role, and the current limiting effect is limited, which cannot effectively alleviate the damage caused by the secondary impact of the short-circuit fault to the entire DC system.

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