Hybrid DC power transmission system having DC fault blocking capacity and control method thereof

Abstract

The invention discloses a hybrid DC power transmission system. The power transmission system comprises a phase controlled rectifier which is arranged at a transmitting end and a self-resistance modularized multilevel converter which is arranged at a receiving end, or comprises the self-resistance modularized multilevel converter which is arranged at the transmitting end and the phase controlled rectifier which is arranged at the receiving end. The transmitting end and a first AC system are connected at the AC bus of the transmitting end, the receiving end and a second AC system are connected at the AC bus of the receiving end through an AC transformer, and the controlled rectifier and DC port of the self-resistance modularized multilevel converter are connected through a corresponding DC power transmission line. The invention also discloses a corresponding control method of the hybrid DC power transmission system. The problems that a phase controlled converter cannot connect a weak AC power grid and is liable to fail in phase commutation can be solved; or the phase controlled converter can directly connect a wind power plant with no requirement for installing of a reactive power compensation device so that the hybrid power transmission system is enabled to have a DC fault isolation function at the minimum cost.

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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