Case Study of a Large Transmission and Distribution Substation Automation Project

In this paper, the author describes a case study of a large substation integration design project. The project involves complete integration and automation of distribution and transmission within the substation. The critical design factors that the customer required are discussed, followed by system designs presented to the customer. The author steps through the project with the aid of lessons learned along the way to explain how and why a particular system architecture was chosen. System reliability, redundancy of protection and communications and no single point of failure were essential. The author next presents analysis tools and uses them to quantify attributes of the PECO Energy Company system design. The reader is told how to use these tools to quantify aspects of any system. Review of the progression of this successfully installed system will present the reader with a comprehensive discussion of available technologies, quantification of system attributes, and the implementation of a multivendor system. The project consisted of a protection and control design for a retrofitted substation, recently renovated for PECO Energy Co., which exploits many of the advanced capabilities of microprocessor relays. For the protection and distribution automation schemes, a completely integrated microprocessor-based design was envisioned, primarily to provide supervisory control and data acquisition (SCADA), distribution automation (DA), and automation of the transmission system through a substation integration system. In addition, this scheme would minimize maintenance cost through the use of self-checking and relay setting verification. The new economical, streamlined design allows for primary and backup redundancy for all single contingency fault conditions, while intuitively replicating existing electromechanical protection philosophies. The microprocessor relays’ new digital communications capabilities, incorporated into a substation integration (SI) system, allow exceptionally fast and reliable SCADA control, status and metering for all interrupting devices, lockout relays, and motor operated disconnects (MOD)s.