Device and method for controlling fault ride-through of power grid of flexible direct-current transmission system

Abstract

A grid fault ride-through control device for a flexible direct current transmission system, including a control unit, a detection unit, a switchable braking resistor unit, a power voltage adjustment unit, and a full-bridge braking unit; the switchable braking resistor unit is used for outputting the rectifier terminal A device for first-level power release; power voltage adjustment unit: a device for second-level power release on the output of the switchable braking resistor unit; full-bridge braking unit: used for third-level power release on the output of the inverter terminal Level power release device. The method of the present invention detects the bus voltage on the DC side and the bus voltage on the AC side in real time, and when a fault signal is detected, the DC switching switch is disconnected, the second full-control switch is closed, and the first full-control switch is dynamically turned on to perform dynamic voltage regulation. Realize the maximum release of remaining power. The method can effectively suppress the overvoltage of the direct current bus, avoid the blockage of the equipment of the direct current transmission system, ensure the maximum transmission of the remaining power, and can work normally during the fault period.

Description

technical field [0001] The invention relates to the technical field of power transmission and transformation, in particular to a power grid fault ride-through control device and method for a flexible DC power transmission system. Background technique [0002] For flexible DC power transmission, in order not to affect the stable operation environment of the AC grid and the safety and reliability of the DC equipment itself, it is required that when the grid has a serious grid voltage drop fault (such as a three-phase short-circuit fault, etc.), the DC transmission equipment should not be damaged as much as possible. Fault blocking, DC fault blocking and re-investment after fault recovery will have a great impact on the entire AC-DC parallel system, and at the same time, the damage to the flexible DC transmission system is also huge. Therefore, it is required that the flexible DC transmission system can continue to operate when a fault occurs, and realize the fault ride-through...

AI Technical Summary

Problems solved by technology

These technologies have serious limitations, and they have not been able to improve the level of flexible DC-AC fault ride-through and suppress DC bus voltage fluctuations.

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