ECE 476 POWER SYSTEM ANALYSIS Lecture 26 Distribution Systems Muhammad Abdul Retha lefte Al-Badri Department of Electrical and Computer Engineering

Announcements Be reading Chapter 14 Last homework is 12.3, 12.11, 14.15. Needs to be done before the final, but not graded. Final exam is as given on the UIUC website. That is, Tuesday Dec 13 from 7 to 10pm here (218 Ceramics). Final is comprehensive, with more emphasis on material since exam 2. Three note sheets allowed (e.g., ones from previous two exams and one new note sheet)

Electricity Delivery Generation: 50-1300MVA, up to 20kV Transmission: 400MVA @ 230kV up to 4000MVA @ 765kV Can include: HVDC, ac-dc links Subtransmission: 69-138kV Can include: taps for large single customer Primary distribution substations: 15-200MVA, 2.2-46kV Can include: LTC, capacitor banks, reclosers Distribution feeders: 4MVA @ 4.16kV up to 30MVA @ 34.5kV Secondary distribution: 5-5000kVA, 120-480V Meters

Electricity Delivery

Electricity Delivery

Primary Distribution 15kV class, 4 wire multigrounded is most common

Primary Distribution Includes everything from the distribution substation to the distribution transformers Rural areas served by overhead lines Urban areas served by underground systems 3 common topologies Radial Loop Network

Primary Radial Systems

Primary Radial Systems Three phase feeder mains of length 1 to 30 miles Single phase laterals branch off main feeder Try to balance the load on the 3 phases Economical and widely used in low load density areas Reclosers are used on overhead lines to minimize loss of load Typically have 3 shots before lockout Sectionalizing fuses also reduce downtime