This paper deals with the simultaneous calculation of the series compensation degrees of multiple lines in a transmission grid, in order to achieve the desired active power flows in the compensated lines, using an analytical approach based on the compensation theorem. The paper extends to the case of multiple compensated lines the methodological approach already proposed by the authors for a single compensated line. The mathematical basis beneath the proposed method is first presented and later the method is applied and validated using two test networks. The first network is a 10 buses, 14 lines customization of a portion of an existing 400 kV – 50 Hz transmission network. The second network represents a 400 kV – 50 Hz large real network consisting of 78 nodes and 109 overhead lines for a total extension of 10,900 km, including 17 series-compensated lines. The results show the robustness and accuracy of the analytical method proposed, which has the advantage to be simpler than the classical approach based on power flow procedures. Accordingly, the novel method proposed proves to be an interesting alternative to the classical calculation procedures.
