Analytical methods for series compensation of a transmission line

The paper proposes an analytical approach to evaluate the effects of series compensation of an overhead transmission line (OHL) concerning the increase of (1) loadability and (2) practical loading of the line. The first part of the paper focuses only on the line characteristics, and proposes an analytical approach to determine the loadability curves of the line as a function of the compensating capacitive reactance. In the second part of the paper, the perspective shifts to examine the power loading of the selected OHL in a meshed electrical network. The target is to evaluate the compensation degree required to achieve a desired power flow increase in the line. To this purpose a fast analytical method, based on the compensation theorem, is presented. Preserving the linearity of the network model, the proposed method allows computation of the needed compensation degree by means of a closed form equation. Numerical applications performed on two simple test networks allow to compare the method with an ad hoc implemented classical optimal power flow. The results validate the method and highlight its effectiveness as a simple and useful tool to support power system planners and designers.