"Postes Intelligents" Design, Test and Commissioning of Rte's first completely Digital Substation

Authors: J-Y. Astic, V. Leitloff, T. Buhagiar, A. Kurtz Rte, and P. Brun, S. Vigouroux, J-P. Cayuela, GE

Rte's “Postes Intelligents” project (Smart substation in French) consists of the refurbishment of two substations (Blocaux 225 kV / 90 kV and Alleux 90 kV, see page 46) and the upgrading of other substations, located in the same area in northern France. This area features a large amount of wind generation prone to occasional transmission line congestions. It is worth exploring what a smart substation should be, at least in Rte’s view.

First, we consider that the traditional protection, communication, control, and automation services can be more effective in terms of time response, selectivity, accuracy, interoperability, electrical safety and reliability. For the "Postes Intelligents" project, Parallel Redundancy Protocol (PRP) for the station bus and High Availability Seamless Redundancy (HSR) protocol for the process bus has been selected (see page 46). Low Power Instrument Transformers (LPIT) have been installed on some feeders. This implies safer conditions for maintenance and a good linearity in the transient dynamic response when a fault occurs.

Rte has also experimented a new functional design: all the protection devices are installed in a same cubicle instead of the traditional “feeder oriented design" of cubicles. This enables the possibility to connect an on-line spare Intelligent Electronic Device (IED) that can replace any faulted IED of the same type upon request. The final aim is to obtain self-healing or N-1 failure resilient protection and automation functions, giving more time for maintenance personnel to intervene.

Then, most of the primary apparatus were equipped with embedded or external monitoring systems, based on a huge variety of sensors. For instance, in the “Postes Intelligents” project, disconnectors are equipped with a measurement of the actuator supply current during the rotation of the arms: a loose or blocked arm can thus be detected and warnings or alarms may be initiated. To achieve this, it is required that the sensors are compliant with IEC 61850 or connected to the PACS via a multi-field protocols gateway. The monitoring data then has to be processed locally for immediate or adaptive remedial actions or sent to some distant maintenance or monitoring centers.

Finally, combining real time information (Sampled values, GOOSE messages, logical information, measurements, etc.), and monitoring data, a state estimation of all the components of the substation may be established and advanced automated area functions may be implemented (locally or remotely). For instance, the “Poste Intelligents” will enable a Dynamic Line Rating (DLR) calculation based on weather information from surrounding substations. Furthermore, it is designed to operate an adaptive and coordinated wide area protection scheme. Summing up, “Poste Intelligents” substation is a mix of the following different features:

  • Fully digitalized protection and automation system
  • Extensive monitoring system
  • Advanced functions implemented using local computing resources
  • Reliable and resilient telecommunication networks with Cybersecurity (see here)
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