Active/passive damping method for suppressing high-frequency oscillation of HVDC flexible transmission system

Abstract

The invention discloses a method for suppressing high-frequency oscillation of a flexible direct current transmission system with active / passive damping. The method includes the following steps: establishing an alternating current system, calculating the typical working conditions of the power grid on the alternating current side, and determining the MMC in the The maximum phase of the high frequency band; a filter is added to the voltage feedforward channel of the MMC control system; a second-order high-pass passive filter is connected in parallel at the PCC node where the MMC is connected to the AC system, according to the stability margin requirements of the flexible DC transmission system, comprehensive Considering the capacity and loss of the second-order high-pass passive filter, the parameters of the second-order high-pass passive filter are designed to realize the high-frequency resonance suppression of the flexible DC transmission system. The invention can improve the economy of the resonance suppression scheme on the premise of ensuring the stability of the high frequency and wide frequency band of the flexible direct current transmission system, and has certain significance in practical engineering.

Description

technical field [0001] The invention belongs to the technical field of grid stability control of power systems, and in particular relates to a method for suppressing high-frequency oscillation of a flexible direct current transmission system with active and passive damping. Background technique [0002] For the flexible DC transmission system based on Modular Multilevel Converter (MMC), compared with low-level converters such as two-level and three-level converters, MMC has more modules and better internal dynamic characteristics. Due to the complexity, it brings more stability problems to the flexible DC transmission technology. The two back-to-back flexible DC projects that have been put into operation in China both have the phenomenon of high frequency resonance. The long-delay characteristics of the control link will cause the AC side impedance of the MMC to have inductive negative damping in the high frequency band, and the AC side power grid may exhibit a capacitive pr...

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Problems solved by technology

[0004] The purpose of the present invention is to aim at the limited range that the control strategy based on active damping can adjust the MMC impedance, adopt the method for passive damping to have the capacity of filter bigger, the cost of passive device is higher, propose a kind of based on active damping The method of source / passive damping to suppress the high-frequency oscillation of the flexible direct current transmission system improves the economy of the resonance suppression scheme under the premise of ensuring the stability of the high frequency band and wide frequency band of the flexible direct current transmission system based on MMC

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