Conventional substations have been replaced by digital substations, which increasingly incorporate the communications benefits of the IEC 61850 standard, which defines the process bus network in which packets are sent with generic object-oriented signals from the substation (GOOSE) and sampled data packets of analog current and voltage signals called "SAMPLED VALUES". For this reason, HMV Ingenieros installed control and protection systems with a process bus under the IEC 61850-9 standard for the 110 kV line output bays that connect the San Miguel (42MW) and El Molino (20MW) hydroelectric plants with the interconnected system.
The line protections at the end of the San Miguel hydroelectric power plant were designed with two systems, one main with the process bus concept under the IEC 61850-9-2LE standard, where copper wiring is replaced by fiber optic between patio equipment and control and protection IEDs, and another backup system with the conventional concept where copper wiring is used for analog and digital signals. On the other hand, line protections at the end of the El Molino plant were designed with the complete implementation of two process bus systems under the IEC61850-9 standard; a system under switched network technology (IEC61850-9-2LE) and the other system with point-to-point network (IEC61850-9-1).
Line Protection with Process Bus One of the main elements that appear in the process bus systems are the Merging Units (MU), which process the analog and digital signals and transmit them by fiber optic communication over switched networks or point to-point to the different IEDs, these MUs are designed to be located outside the control room, as close to the primary equipment, and receive in copper wiring all signaling instrumentation transformers and patio equipment.
The majority of the tests for the process bus system are made in the factory and can be divided into 3 types: (i) Communications compliance tests determine whether the IEDs meet the IEC 61850 standard specification. (Ii) interoperability testing of devices connecting two or more IEDs to the LAN of a different manufacturer and (iii) testing of devices. For testing on process bus systems it includes at least the following checks:
• Tests on individual components related to the IEC61850 protocol
• Tests on Merging Units
• Tests on distributed applications at bay level
• Tests on distributed applications a substation level In addition, new tools are required for IED process bus tests:
• Testing software on configuration files in IEC61850.
• Analog Variation Simulation Tool
• Merging Unit Simulator:
• IED Simulator:
• Evaluation Tool: Allows the monitoring of the elements integrated to the data networks by performing a permanent monitoring on the same
• Tool for the generation of detailed reports of the tests to be performed on the network devices. Digital substations based on the IEC 61850 standard have been replacing conventional control and protection systems, taking advantage of the benefits of communications systems to reduce conventional copper wiring, associated civil works, and take advantage of their benefits in operation and maintenance .