Method for measuring the resistance and the inductance of a line
AssigneeABB Research Ltd.
InventorsMichael Stanimirov, Bernhard Deck, Walter Rueegg
Life of this patent
Estimating the term…
Abstract
The method described here makes it possible to determine the impedance of a line (1) by measuring the voltage (u) applied across the line and the time derivative of the current (i) flowing through the line. The measured values of the differentiated current are not integrated in this case, but rather are substituted directly, together with the measured voltage values, into an equation system from which the values of the inductance (L) and the resistance (R) of the line (1) can be estimated. In this way, integration of the values of the differentiated current is obviated.
Claims10
A method for measuring the resistance R and the inductance L of a line, in which a voltage u across the line and a time derivative ι of a current through i through the line are measured at a rate 1/TA in order to obtain a series of N voltage values u0, u1, . . . uN and a series of N values ι0, ι1, . . . ιN of the differentiated current, wherein the first derivative of the current ι of the current i is measured using a Rogowski coil, N≧3 and the voltage values and the values of the differentiated current are substituted directly into an equation system with N−1 equations of the form
- un=un−1+α0·ιn+α1·ιn−1,
- with parameters α 0 = R A + L α 1 = R A - L
- where
- A≅2/TA
- or A = ω 0 · cot ( ω 0 2 · T A 2 ) ,
- and wherein the resistance R and the inductance L are found from the equation system.
Dependencies are inferred from the claim text.