Method for analyzing sub-synchronous resonance of alternating-current system

Abstract

The invention discloses a method for analyzing the sub-synchronous resonance of an alternating-current system in the technical field of running and control of a power system. The method comprises the following steps of: calculating the natural frequency of each decoupling modal of a multi-mass-block model of a generator shaft system, and scanning the frequency of a power transmission system to beresearched by using a frequency scanning method to acquire the resonance frequency feA of an asynchronous generator effect and the resonance frequency feC of a transient torque amplification function; if the feA and/or the feC accords with a condition shown in the specifications, determining that f0(i) is partial main resonance frequency of the sub-synchronous resonance, calculating a line seriescompensation degree KS according to the feA and the feC and determining the minimum value KSmin of the line series compensation degree; establishing a full system equation, and calculating a curve ofeach modal electric damp which is changed with the series compensation degree in a range of between 0 and KSmin by using a characteristic value method; and further obtaining all the main resonance frequencies of the sub-synchronous resonance and a secure series compensation region. By the method, a characteristic of quickness of the frequency scanning method and a characteristic of the precision of characteristic value method are combined, the shortcoming of low precision of the frequency scanning method and the shortcoming of large calculation quantity of the characteristic value method are overcome, and the obtained secure series compensation region has a great significance for engineering practice.

Description

technical field [0001] The invention belongs to the technical field of power system operation and control, and in particular relates to an analysis method for subsynchronous resonance of an AC system. Background technique [0002] With the implementation of the west-to-east power transmission strategy and the acceleration of the national interconnection grid, long-distance large-capacity power transmission is imperative. In my country's power generation industry, thermal power generation dominates, and most of the transmission lines where generators are connected to large systems use series capacitance compensation to improve line transmission power and increase transient stability. However, the series capacitor compensation will cause subsynchronous resonance when the series compensation degree is not set properly, which will damage or even destroy the shafting of the turbogenerator, causing great losses to the stable operation of the system. Since the occurrence of subsyn...

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Problems solved by technology

[0005] Aiming at the shortcomings of the existing method for detecting subsynchronous resonance mentioned in the above background technology that the...

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