Introduction of Series Capacitors in the Venezuelan EHV-grid

Abstract

ENELVEN, a regional electricity utility in Venezuela, has installed a total of five series capacitors in their grid to increase the capacity of existing overhead transmission lines serving the residential, petroleum and petrochemicals center of Maracaibo. A sixth series capacitor is planned for future extension of the grid in the same area. This paper focuses on the power system engineering efforts that were required in conjunction with the delivery of the five series capacitors banks. In order to assure that grid code criteria was met and that stresses on new and existing equipment was still acceptable, a number of engineering studies were performed. The following subtasks were given the utmost focus in this process: transient stability validation, insulation coordination and switching overvoltage studies, short circuit calculations, line circuit-breaker transient recovery voltage (TRV) determination, line protection coordination and sub synchronous resonance (SSR) studies. When series capacitors are to be introduced, the insulation co-ordination and the line breaker TRV stresses should be examined, as well as the impact the series capacitor will have on the line distance protections. The short circuit calculations are needed as the series capacitors will reduce grid impedances, but also for the rating of the series capacitors themselves. The issue of SSR was apparent in this case, as a thermal power plant was located one bus away from a series capacitor, with a prospective possibility for the grid to be configured in a way known to be prone to SSR. The above-listed engineering efforts are reviewed in the paper. Input conditions, study methodologies and end results are discussed. Overall the paper highlights how the challenges related to series capacitor implementation can be mastered, enabling a critical grid reinforcement to be realized under a fast-track schedule