Hybrid DC power transmission system with DC fault blocking capability and control method

Abstract

The invention discloses a hybrid direct current power transmission system. The power transmission system includes a phase-controlled rectifier at the sending end and a self-resistance modular multilevel converter at the receiving end, or a self-resistance modular multi-level converter at the sending end. Level converter and phase-controlled rectifier at the receiving end. The sending end is connected with the first AC system at the sending end AC bus, the receiving end is connected with the second AC system at the receiving end AC bus through an AC transformer, and the phase-controlled rectifier is connected to the self-resistance modular multi-level converter. The DC ports of the converters are connected through the corresponding DC transmission lines. The invention also discloses a corresponding control method of the hybrid direct current transmission system. The invention can solve the problem that the phase-controlled converter cannot be connected to the weak AC power grid and is prone to commutation failure; or it can be directly connected to the wind farm without installing a reactive power compensation device, so that the hybrid power transmission system can achieve the lowest cost It has the DC fault isolation function.

Description

technical field [0001] The invention belongs to the technical field of electric power transmission and distribution, and more specifically relates to a hybrid direct current transmission system with direct current fault blocking capability and a control method thereof. Background technique [0002] HVDC transmission technology is mainly divided into traditional DC transmission technology using phase-controlled converters, flexible DC transmission technology using voltage source converters, and phase-controlled converters at one end and voltage source converters at the other end. Hybrid DC transmission system. [0003] Traditional DC transmission technology is suitable for high-voltage, long-distance, and high-power transmission of electric energy. When the AC short circuit at the receiving end is relatively low, the inverter side of the traditional DC transmission is prone to commutation failure, and the traditional DC transmission technology requires an external AC system t...

AI Technical Summary

Problems solved by technology

[0007] Aiming at the above defects or improvement needs of the prior art, the present invention provides a hybrid direct current transmission system, which adopts a self-impedance modular multilevel converter as the receiving end or sending end converter station, and it is connected with the phase It can solve the problem that the phase-controlled converter cannot be connected to the weak AC grid and is prone to commutation failure; or it can be directly connected to the wind farm without installing a reactive power compensation device, so that the hybrid transmission system can be used as a power grid. DC Fault Isolation with Minimal Expenses

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