Hybrid back-to-back direct-current power transmission device and fault processing method

Abstract

The invention discloses a hybrid back-to-back direct-current power transmission device and a fault processing method. The method comprises the following steps of: 1, collecting a direct voltage and a direct current of the direct-current power transmission device, an alternating voltage of an alternating power grid connected with a voltage source type converter, and a voltage of a voltage source type converter sub-module capacitor; 2, judging whether the direct-current power transmission device breaks down according to analog quantities collected in the step 1; and 3, if yes, changing the power transmitted by the voltage source type converter, and simultaneously changing the direct voltage generated by the voltage source type converter and / or the output alternating current. According to the invention, the direct current overvoltage problem caused when the alternating power grid connected with voltage source type converter at an inversion side in the direct-current power transmission device can be effectively solved, a direct-current bus and the sub-module capacitor are prevented against the overvoltage, the alternating fault is reliably crossed, and the safety of equipment is better protected.

Description

technical field [0001] The invention relates to a hybrid back-to-back DC power transmission device and a fault handling method, in particular to a DC power transmission device and a fault handling method which are composed of at least one end being a current source converter and one end being a voltage source converter. Background technique [0002] HVDC systems can be divided into two types: conventional DC transmission systems (LCC-HVDC) based on thyristor technology and flexible HVDC systems based on fully controlled power electronic device technology (Flexible-HVDC). Among them, the conventional direct current transmission system (LCC-HVDC) has low cost, low loss, and mature operation technology. The inverter side is prone to commutation failure, strong dependence on the AC system, absorbing a large amount of reactive power, and large area occupied by the converter station. The new generation of flexible direct current transmission system (Flexible-HVDC) can realize the...

AI Technical Summary

Problems solved by technology

But this method for figure 1 The direct current transmission device in is not applicable, figure 1 The rectification side of the DC transmission device shown is a current source converter, and the speed of its power current regulator is much slower than that of the flexible DC transmission device. By reducing the reference value of active power on the DC side, the DC voltage cannot be prevented in time. Further increase, the voltage on the DC side will still greatly exceed the acceptable range

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