Utility: Substation Automation

PECO Energy

PECO Energy is a Fortune 500 electric utility company that services the metropolitan Philadelphia area. Like many utilities today, PECO needed a better way to remotely monitor, maintain, and diagnose equipment at their substations to reduce operating costs and provide improved services to customers.  The substation automation design team developed a very detailed specification outlining PECO’s expectations for such a system, emphasizing maximum functionality for minimal costs.
Project Requirements

The project scope was a complete substation automation solution from system design through installation and commissioning.  Requirements included distribution line protection and real-time monitoring of substation equipment such as circuit breakers and transformers.  Microprocessor-based relays were to replace existing electromechanical relays.  PLC-based systems were to be installed for monitoring distribution transformers and high-voltage circuit breakers.  The overall project included (87) substations over seven to ten years.  One of the significant benefits of the project is remote access to the substations from PECO’s central office.  This functionality provides the ability to remotely configure and control relays and diagnose equipment problems so that repair crews are dispatched with the proper tools and information.
Benefits of ACC’s Solution

ACC partnered with industry leader Schweitzer Engineering Laboratories (SEL).  The ACC Team proposed an innovative, streamlined system architecture which met PECO’s requirements and was ultimately selected as the winning solution by PECO.  

The benefits of ACC’s solution include:
  • Seamless integration with and remote access to PECO’s existing information systems
  • Flexibility to accommodate future system requirements, such as additional substations and enhanced functionality, such as power quality monitoring
  • Open-architecture, off-the-shelf components which eliminate proprietary design
  • Excellent diagnostic tools to aid in the analysis of faults
  • Common user interface which facilitates training of PECO personnel
  • Clean design with minimal number of components - increases system throughput and MTBF and reduces installation requirements
  • Reduced outage time through simplified wiring and installation
“PECO Energy wishes to commend the entire ACC team ... for their professionalism ... and thoroughness in responding to the numerous requests”

PECO Energy
Sourcing Consultant
Substation Automation System Architecture

PECO Energy’s Substation Automation System offers either remote or local control of the substation.  Each substation contains a PC-based HMI as the substation HMI.  Remote communication to PECO’s SCADA systems occurs via RTU-based protocols.  Local communication occurs through SEL-2020 communications processors to SEL-relays and through spread spectrum RS-232 modems to PLCs.


ACC has been implementing substation automation systems for PECO since the mid-90’s.  While the components have changed over time in order to leverage new technology, the overall architecture remains constant.   The substation automation solution designed and implemented by ACC provides both remote and local control.  Each substation has a PC-based HMI as the local substation operator interface.  Remote communication to PECO’s SCADA systems occurs via RTU-based protocols.  Local hardwired communication occurs between SEL 2032 communications processors and SEL solid state relays that handle protection and control.  Spread spectrum wireless modems are used to communicate between the HMI and the PLCs that monitor substation equipment such transformers and circuit breakers.  Equipment health data, collected onto the local HMI PC, is polled by PECO’s main Historian at a central station.