Starting method of hybrid multi-terminal direct-current power transmission system

Abstract

The invention discloses a starting method of a hybrid multi-terminal direct-current transmission system, and belongs to the technical field of power systems. The method comprises: arranging at least one series LCC on a rectification side, arranging at least one series LCC on an inversion side, arranging at least one parallel VSC on the inversion side, closing LCC alternating-current lines on the rectification side and the inversion side, and disconnecting each VSC alternating-current line on the inversion side; selecting an appropriate LCC converter station for constant current control, adopting constant extinction angle control for the inversion side LCC, and charging the inversion side LCC and the inversion side VSC through the rectification side LCC; making each VSC on the inversion side be not locked in the charging process, and simultaneously carrying out capacitance voltage-sharing control or wheel touch control on a multi-level MMC; closing the alternating-current line of each VSC on the inversion side at the same time, and carrying out initialization assignment on the controller of each VSC on the inversion side; rising the VSC power reference value adopting constant powercontrol on the inversion side to a rated value according to a slope, and rising the LCC current reference value adopting constant current control to a rated value according to a slope, wherein the rising speeds of the two reference values are kept the same; and inputting alternating current systems connected with the VSCs adopting amplitude-phase control in batches.

Description

technical field [0001] The invention belongs to the technical field of electric power systems, relates to a safety and stability analysis technology of electric power systems, and in particular relates to a starting method of a hybrid multi-terminal direct current transmission system. Background technique [0002] Flexible direct current transmission (VSC-HVDC) has been more and more widely used because of its advantages such as realizing active and reactive power decoupling control, supplying power to passive networks, and providing reactive power support. However, limited by the withstand voltage and current levels of IGBTs, VSC-HVDC is not suitable for high-voltage, large-capacity DC transmission. While traditional direct current transmission (LCC-HVDC) meets the needs of high-voltage and large-capacity transmission, it is difficult to achieve flexible control and distribution of power. Therefore, LCC-HVDC and VSC-HVDC will coexist and complement each other for a long ti...

AI Technical Summary

Problems solved by technology

At present, the following problems still exist in the existing technology: 1) when the VSC is actively started through the AC network, a current limiting resistor needs to be connected in series; 2) the start-up when the hybrid DC system is connected to the passive network cannot be realized; 3) the traditional DC side is adopted When starting, the bridge arm overcurrent is caused by the voltage halving at the moment of unlocking the MMC; 4) Both the traditional AC start and DC start need to block the VSC, and the overcurrent will occur due to the state mismatch at the moment of unlocking

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