Technical Presentations

Application of single phase tripping and re-closing to 380KV double circuit transmission line896

Abstract
Faults within a transmission system can greatly impact the capability for power transfer. Isolating a fault by removing the line from service can further diminish the power transfer capacity, compromi... see moresing the system`s stability margin. Single-phase-to-ground faults, which are the most frequent, can be effectively isolated by taking only the affected phase out of service, while keeping the remaining two phases active. This approach, referred to as single-pole switching (SPS), permits the line to carry two-thirds of its power and preserve synchronization between the sources at both ends of the line, However, it presents distinct challenges. In a long line, a small AC current can still sustain even after the breakers open. This current is called the secondary arc current and it is due to electromagnetic coupling between the phase conductors. If the breaker pole is reclosed before this current extinguishes, the fault will reoccur, leading to unsuccessful reclosure. The aim of this work is to identify the key factors that significantly influence the secondary arc current and to evaluate different methods to reduce its amplitude. For successful reclosure, the circuit breaker`s dead time must be longer than the secondary arc`s extinction time. This study models the secondary arc using the EMTP program to simulate its interaction with the transmission system and estimate the necessary dead time for the circuit breaker. The study analyzes the self-extinguishment of the secondary arc by monitoring its magnitude and the recovery voltage using EMTP. It concludes with recommendations for reducing the secondary arc current and determining the minimum dead time required for the successful reclosure of a 380KV transmission line.

Tag(s): Fault Analysis, Transmission System, Secondary Arc Current, Circuit Breaker

Secondary arc in hybrid AC DC overhead lines872

Abstract
This presentation covers a specific issue related to hybrid AC / DC overhead transmission lines: the extinction of the secondary arc current of a faulted DC pole. As a result of a pole-to-ground fault... see more, breaker openings interrupt the short-circuit current. Because of the inductive and capacitive coupling between the AC circuit and the faulted pole, a small AC current (a few 10ths Amps) keeps flowing in the fault. This current is known as the secondary arc current and it may disappear after some time.

Tag(s): AC/DC Lines, Secondary Arc, Sensitivity Analysis, Frequency Scan, Shunt Reactors, High-Speed Earthing Switches

Stability analysis of the CCS power plant769

Abstract
This work shows the simulations performed using EMTP before and after tuning the PSS of the Coca Codo Sinclair hydro power plant (1500 MW) of the National Interconnected System of Ecuador. Each machin... see moree in the plant is modeled and its control systems (AVR and PSS) are represented by models created by the user and by library models. The results obtained are compared with real signals taken by the Wide Area Monitoring Systems.

In addition, the analyzes performed are shown, from a point of view of the transient stability of the plant, to determine the adjustment of the single-phase reclosing dead time of the San Rafael – El Inga transmission line, at 500 kV, taking into account the secondary arc model of the EMTP library.