Introduction to Substation Design TADP 542 Design Principles- General Framework Instructor: Richard Snell Transmission & Distribution Program
Module 2 Outline Presentation 1: General Framework Presentation 2: Defining a Project Presentation 3: Project Authorization Presentation 4: Substation Site Issues Presentation 5: Time Issues
General A substation is an integral part of the overall power system. Its design should minimize adverse impacts to substation equipment, transmission and distribution system, and also to customers. The design should minimize costs while providing the required functionality.
General (cont.) A substation can be a very complex facility as can be seen in this picture of the transmission bus in an existing substation.
General (cont.) A substation is analogous to a large commercial or small industrial facility in complexity. It has several subsystems and can have hundreds or thousands of different parts. A substation is usually operated and maintained while it is in service.
General (cont.) Drawings used to depict site development, equipment and structure placement; physical and/or electrical characteristics of structures and equipment and electrical interconnections between and within equipment. The number of drawings for a substation can range from a few to several hundred.
General (cont.) Substations may be owned by exempt wholesale generators; electric transmission companies; integrated, transmission and/or distribution electric utility companies; large commercial facilities or industrial complexes. A substation design must conform to applicable electrical codes as well as some federal, state and local laws and regulations.
General (cont.) Most substation projects are for additions or modifications to existing substations. The number of new substations constructed nationally each year is less than five percent of the total number of existing substations. In rapidly growing areas, the number of new substations being constructed annually may be greater with respect to the number of existing substations in that area than the national average.
General
Design Personnel A substation project should be designed by one or more professional engineers. This is usually a legal requirement set by the state or province where the project is located for the protection of the public. Those engineers may supervise others in the design of all or portions of the project. However, the professional engineers are legally responsible for the design.
National Electrical Safety Code National Electrical Safety Code-ANSI C2 (NESC) establishes minimum requirements for construction, operation and maintenance of electric and communications facilities. Purpose is the safety of persons during installation, operation, or maintenance of electric supply and communication lines and associated equipment.
National Electrical Safety Code (cont.) NESC developed as a voluntary standard. A majority of states have adopted some form the NESC as either law or regulations. A 2007 IEEE survey shows which edition or parts of the NESC has been adopted by each state. The survey results can be seen at: http://grouper.ieee.org/groups/nesc/pucsurvey2007.pdf
National Electrical Safety Code (cont.) Section 9, Grounding Methods for Electric Supply and Communication Facilities covers substation grounding. Part 1, Rules for the Installation and Maintenance of Electric Supply Stations and Equipment covers generating plant and substations.
National Electrical Safety Code (cont.) Part 2, Safety Rules for the Installation and Maintenance of Overhead Electric Supply and Communication Lines covers overhead lines entering, leaving, and within a substation. Part 3, Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines addresses underground lines entering, leaving and within a substation.
National Electrical Safety Code (cont.) Part 4 Rules for Operation of Electric Supply and Communications Lines and Equipment is applicable to operation and maintenance of the supply and communications lines within a substation.
National Electric Code The National Electric Code NFPA 70 (NEC), a modified version of it or a similar code has been adopted by states to regulate the installation of electrical systems and equipment in buildings and structures. Many states exempt low voltage wiring in substations from meeting the NEC or equivalent when it is covered by the NESC.
National Electric Code NEC requirements for medium and high voltage installations are those of the NESC which are included by reference to the NESC.
Federal Regulations Environmental Protection Agency (EPA) has implemented regulations for controlling and preventing effluents from flowing into waterways. Primary effluent in a substation is the insulating oil in power transformers and/or other oil-insulated equipment.
Federal Regulations (cont.) Substation will require containment structures or devices if distance to waterway is less than proscribed by regulations and effluent could flow into waterway. Includes oil sumps near or impenetrable berms around oil-filled equipment, fence curbing around a crushed rock surface or other containment methods.
Federal Regulations (continued)
Federal Regulations (cont.) FCC Part 15 regulations requires incidental radio frequency radiators to maintain their radio frequency emissions to levels that do not adversely impact other FCC regulated services. A substation will become an incidental radiator if its design or construction creates a corona discharge on its transmission voltage conductors, connectors or equipment.
Federal Regulations (cont.) Corona occurs when an electric field at a point on the surface of an energized conducting object exceeds the breakdown voltage of the air. Corona is most prevalent at transmission voltages of 230 kv and above. See EPRI AC Transmission Line Reference Book 200 kv and Above for further corona information.
Corona
State Laws and Regulations Some states have regulations for control of storm water runoff both during construction of a substation and after its completion. Catch Basins
State Laws and Regulations (cont.) Many states have implemented audible noise limits for substations. Purchasing power transformers with lower sound levels is one method of reducing substation audible noise. Installation of sound reducing barriers is another method of reducing substation audible noise.
State Laws and Regulations (cont.) State laws may require substations be designed to withstand anticipated seismic forces at their locations.
Local Ordinances and Regulations Local jurisdictions may require building permits for substations and/or substation control houses. Local zoning ordinances or decisions may specify requirements for the substation enclosure and/or the landscaping.
Design Software Currently, there is no commercially available software for designing a complete substation. There are software products available to design portions of a substation.
Design Software (cont.) Most substations designs are created by copying existing substation designs and modifying them as needed. Substation designs are mostly presented graphically using drawings. CAD software is used to create, copy and modify substation drawings.
Design Software (cont.) Many utilities and engineers have developed software and/or spreadsheets to accomplish certain tasks. Word processing software can be used to create specifications and contracts related to the substation design. Materials management software can be used for ordering materials for a substation project.
Image Acknowledgements Transmission Bus 115kV Richard Snell Example Drawing List Public Utility District of Grant County Circuit Breaker Addition One-line Diagram Public Utility District of Grant County Corona Discharge Public Utility District of Grant County Catch Basins Public Utility District of Grant County