科研之友
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摘要
In order to improve the measurement accuracy of distributed parameters for double circuit HVDC transmission lines on the same tower.The model for double circuit HVDC transmission lines on the same tower has been proposed,the open and short circuit impedance for the positive sequence combination patterns (Combination 1: A1 is shorted by A2 while B1 shorts B2,Combination 2: A1 is shorted by B1 when A2 shorts B2,Combination 3: A1 is shorted by B2 as B1 shorts A2) can be obtained if the equal amplitude and 180 degrees phase of power resource has applied on the head of the transmission.The open and short circuit impedance for the positive sequence combination patterns (A1,A2,B1 and B2 are shorted together) can be achieved while the same amplitude and phase of power resource is applied on the head of transmission lines.Furthermore,the distributed resistance,self-reactance,self-capacitance,coupling reactance and capacitance should be obtained from solving the above equations.Moreover,the maximum relative error of the distributed resistance and reactance are 7.3% and 1.6% for 10 different measurement points with the no interfering signals,50Hz and 300Hz interfering signals based on the equivalent length 1000km of HVDC transmission lines.And the proposed method has been applied to the double circuit HVDC transmission lines on the same tower for Niuzai to Guangdong project.The self-reactance and self-capacitance for the single conductor are less than coupling reactance and capacitance for transmission lines of Niuzai to Guangdong projection,respectively,where coupling capacitance are basically the same.However,the self-reactance for the single conductor are greater than coupling reactance while self-capacitance and coupling capacitance have opposite relative for grounding polar transmission lines of Niuzai to Guangdong projection.Consequently,the presented method can provide the reliable measurement distributed parameters for protection setting,DC system simulation,traveling wave fault location etc.
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