A backup protection method and device for a converter fault in a flexible direct current transmission system
A flexible DC and power transmission system technology, which is applied to emergency protection circuit devices, circuit devices, parts of emergency protection devices, etc., can solve the problems of difficult identification and location of minor phase-to-phase short-circuit faults of voltage source converters
Active Publication Date: 2022-03-29
NR ELECTRIC CO LTD +1
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Problems solved by technology
[0005] The purpose of the present invention is to provide a flexible direct current transmission system converter fault backup protection method and device, which can solve the problem of difficult identification of internal phase-to-phase short-circuit faults in voltage source converters, especially minor phase-to-phase short-circuit faults
A further optimal solution also solves the problem of difficulty in locating faults
Method used
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Embodiment example 2
[0058] as if figure 1 For example, assuming that the DC current command is 1000A, the DC voltage is 500KV, and the line voltage on the secondary side of the connection transformer is 300KV, then it is calculated according to the flexible DC current conversion formula:
[0059] The peak value of the three-phase upper arm current when there is no fault is equal to:
[0060]
[0061] The peak value of the three-phase lower arm current when there is no fault is equal to:
[0062]
[0063] When there is no fault, the peak value of the three-phase voltage source converter and the connecting variable lead current is equal to:
[0064]
[0065] When the F3AB fault occurs, the A-phase current of the upper arm, the B-phase current of the upper arm, the A-phase current of the lower arm, the B-phase current of the lower arm, the A-phase current of the voltage source converter and the connecting lead, the voltage source The current of phase B of the inverter and the connecting l...
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The invention discloses a fault backup protection method for a converter of a flexible direct current transmission system, comprising: step 1: collecting the three-phase upper and lower bridge arm currents flowing through a voltage source converter unit, and the three-phase voltage source converter unit Connect with the variable lead current; step 2: extract and calculate the phase-to-phase short-circuit characteristics of the converter area based on the analog quantities collected in step 1, and determine whether a phase-to-phase short-circuit fault occurs in the converter area. The invention also simultaneously discloses a corresponding fault backup protection device for the converter of the flexible direct current transmission system. By adopting the technical scheme of the invention, the internal phase-to-phase short-circuit fault of the voltage source type converter can be effectively detected.
Description
technical field [0001] The invention belongs to the field of flexible direct current power transmission, and particularly relates to a fault protection method and device for a converter of a flexible direct current power transmission system. Background technique [0002] Flexible-HVDC can realize active power and reactive power decoupling control, can supply power to passive network, compact structure and small footprint, and there is no commutation failure problem on the inverter side, so the application is more and more. More and more, there are more and more flexible DC transmission projects. [0003] At present, there are two structures of voltage source converters in flexible DC transmission systems: the first is that the bridge arm reactor is generally located between the AC connection point and the converter valve, and the three-phase upper and lower bridge arm current transformers It is located between the bridge arm reactor and the converter valve, and the three-ph...
Claims
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IPC IPC(8): G01R31/52H02H1/00H02H7/122H02H7/125
CPCH02H1/0007H02H7/1225H02H7/1255
Inventor 杨建明李广宇张庆武王杨正俞翔
Owner NR ELECTRIC CO LTD