Fault backup protection method and device for converter of flexible direct-current power transmission system
A flexible DC and power transmission system technology, applied in emergency protection circuit devices, circuit devices, and components of emergency protection devices, etc., can solve the problems of difficulty in identifying minor phase-to-phase short-circuit faults and difficulty in locating faults in voltage source converters
Active Publication Date: 2020-06-12
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 figure 1 As an example, assume that the DC current command is 1000A, the DC voltage is 500KV, and the secondary side line voltage of the coupling transformer is 300KV. After calculation 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 current of the three-phase voltage source converter and the connecting lead wire is equal to:
[0064]
[0065] When the F3AB fault occurs, the phase A current of the upper bridge arm, the B phase current of the upper bridge arm, the A phase current of the lower bridge arm, the B phase current of the lower bridge arm, the phase A current of the voltage source converter and the connecting lead wire, and the voltage source The B-phase current of the type con...
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The invention discloses a fault backup protection method for a converter of a flexible direct-current power transmission system. The method comprises the following steps: step 1, collecting three-phase upper and lower bridge arm currents flowing through a voltage source type converter unit, and three-phase voltage source type converter and connection transformer lead currents; and 2, extracting and calculating the inter-phase short-circuit characteristics of the converter region according to the analog quantities acquired in the step 1, and judging whether an inter-phase short-circuit fault occurs in the converter region or not. The invention further discloses a corresponding fault backup protection device for the converter of the flexible direct-current power 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 transmission, and in particular relates to a method and device for protecting a converter from a fault in a flexible direct current transmission system. Background technique [0002] The Flexible-HVDC system can achieve decoupling control of active power and reactive power, can supply power to passive networks, has a compact structure and occupies a small area, and does not have the problem of commutation failure on the inverter side, so it is more and more widely used. More and more extensive, more and more flexible direct current transmission projects. [0003] At present, there are two structures of the voltage source converter in the flexible DC transmission system: the first one 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 Located between the bridge arm re...
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