Enel-Codensa operates a transmission substation at a hydroelectric power plant along the Bogota River. In 2019, they decided to upgrade their substation from high-impedance to low-impedance busbar differential protection for greater system awareness and flexibility. Traditionally, this upgrade would require the installation of several new copper cables in order to link the bays in the substation yard to the relays in the control room. However, that endeavor presented a serious challenge for Enel-Codensa due to the unique layout of their substation.
At their site, the control room and substation yard are located on opposite sides of the Bogota River, which means Enel-Codensa must rely on suspended raceways to run all their cables between the two locations. When they decided to upgrade, their existing raceways were already heavily used and couldn’t support any additional copper cables. Rather than constructing new raceways across the Bogota River—an expensive and time-consuming task—Enel-Codensa decided to look for alternative solutions that would be simpler and more cost-effective to implement.
Enel-Codensa has the largest coverage of any distribution utility in Colombia. They supply electricity to more than 3.4 million customers in the capital of Bogota and provide coverage for over 100 municipalities throughout the Department of Cundinamarca.
After comparing several alternatives, Enel-Codensa decided to partner with SEL Colombia to develop a customized solution for their substation. SEL’s proposal featured the SEL-487B Bus Differential and Breaker Failure Relay integrated with Time-Domain Link (TiDL) technology.
With TiDL technology, the SEL-487B can be housed in the control room and communicate with the substation yard using only fiber-optic cables—thereby eliminating the expense and hazard associated with running high-energy copper cables into the control room. SEL accomplishes this by installing remote TiDL nodes in the substation yard, which digitize discrete I/O and analog signals from primary equipment and then transmit the data directly to the relay via fiber optics.
In addition to reducing copper cabling, the simple point-to-point architecture of TiDL technology has a number of other benefits. Thanks to the direct fiber connections and nonroutable protocol, TiDL communications are deterministic, cybersecure, and independently time-synchronized. A TiDL-enabled system requires no Ethernet switches, network engineering, or external time sources—which drastically simplifies installation and commissioning. Additionally, TiDL technology is compatible with the standard SEL-400 series protection algorithms and schemes, so there’s no need to modify system configurations and settings.
Enel-Codensa installed an SEL-487B in their control room, which gave them the advantage of high-speed internal and external fault detection as well as directional current elements. They utilized fiber-optic cabling and six remote TiDL nodes, housed in a NEMA 4X cabinet, to connect the relay to secondary current and disconnect switch positions from several bays in the substation yard.
Enel-Codensa ultimately chose SEL’s solution for busbar differential protection because it was more secure, more cost-effective, and easier to implement than the alternatives. The TiDL-enabled solution eliminated their need to construct additional raceways for new copper cables, while also improving the safety of their control house for personnel.
When Enel-Codensa field-tested their upgraded busbar protection scheme using GPS equipment for time reference, the TiDL-enabled system demonstrated reliable performance with precise data synchronization. Additionally, the TiDL fiber-optic communications had no significant impact on tripping speeds—less than one millisecond of difference, compared to the traditional copper cabling solution—ensuring the same reliably fast protection that SEL-400 series relays are known for.
At Enel-Codensa, we use SEL protection relays in most substations, and our engineers are familiar with the traditional configuration. With the installation of this bus differential protection, we feel safer understanding that the only difference is in the data acquisition and there is nothing different in terms of configuration.