Multi-direct-current feed-in city power transmission network harmonic wave amplification characteristic analysis method

Abstract

The invention discloses a multi-direct-current feed-in city power transmission network harmonic wave amplification characteristic analysis method. Through an established high-voltage long-cable distribution parameter model and a direct-current power-transmission droppoint harmonic wave emission frequency scope, a city power transmission network node admittance matrix is acquired. And then a harmonic wave amplification inductance and capacitance coupling relationship is decoupled so as to determine a harmonic wave amplification key modal. Based on the above condition, a node observation factor, a harmonic wave source excitation factor and sensitivity of a modal impedance to a network component parameter are calculated. In the invention, a harmonic wave amplification frequency scope of a multi-infeed city power transmission network can be accurately determined, a node which is greatly influenced by harmonic wave amplification can be accurately determined too, and an effect of each direct-current droppoint harmonic wave disturbance source can be well assessed. An idea of reducing the harmonic wave amplification through reversely adjusting a component parameter according to a component modal sensitivity is provided, which is good for searching a solution scheme of restraining the harmonic wave amplification.

Description

technical field [0001] The invention relates to the technical field of harmonic analysis of multiple DC feed-in grids, in particular to a method for analyzing harmonic amplification characteristics of multiple DC feed-in urban transmission grids. Background technique [0002] In recent years, due to the increasing scale of urban power grids and the rapid development of power electronics technology, urban power grids have shown the characteristics of a large number of harmonic sources, high cable coverage, and high power supply density. The feed-in of multiple DC transmission systems makes the harmonic source of the urban power grid more complicated; the extensive use of cables causes harmonic amplification in the local power grid; the high density of power supply makes harmonic pollution serious, causing serious damage to the low-voltage distribution network Abnormal power consumption of a large number of household appliances. [0003] At present, the research on the influe...

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Problems solved by technology

The feed-in of multiple DC transmission systems makes the harmonic source of the urban power grid more complicated; the extensive use of cables causes harmonic amplification in the local power grid; the high density of power supply makes harmonic pollution serious, causing serious damage to the low-voltage distribution network Abnormal power consumption of a large number of household appliances

[0003] At present, the research on the influence of cables on harmonic amplification is mainly focused on urban distribution networks, which usually use low-voltage short cables ranging from several hundred meters to several kilometers, and harmonics only occur at high-order harmonics (such as above 29th) Amplification, considering the isolation effect of the transformer, the amplification effect of the cable on the harmonic is usually limited to the voltage level to each low voltage level

The cables used in the urban transmission network have the characteristics of high voltage level and long length, which may cause harmonic amplification within the frequency range (such as 11th and 13th) of the DC drop point harmonic emission, and the characteristics of long cable distribution parameters cannot be ignored. Parametric models no longer apply

[0004] The methods for analyzing harmonic amplification mainly include frequency analysis method and modal analysis method. Spectrum analysis method can determine the existence of harmonic amplification and the resonance frequency point, but it cannot provide important components that are easily affected by harmonic amplification, such as busbars and harmonic amplification. Associative information, the modal analysis method provides a certain solution to this problem. For example, the proposed participation factor can reflect the excitability and observability of the node to the resonance. The above analysis method only analyzes the system structural parameters, and does not Considering the Interaction of Multiple DC Falling Point Harmonic Disturbance Sources

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