Editing Single-line diagram (section)

== Buses ==
The lines in the single-line diagram connect ''nodes'' – points in the system that are "electrically distinct" (i.e., there is nonzero [[electrical impedance]] between them). For sufficiently large systems, these points represent physical [[busbar]]s, so the diagram nodes are frequently called ''buses''. A bus corresponds to a location where the power is either injected into the system (e.g., a generator) or consumed (an [[electrical load]]).{{sfn|Meier|2006|p=197}} A steady-state of each bus can be characterized by its voltage [[phasor]]; the ''system state'' is defined by a vector<ref name="Ahmad2013">{{cite book | author = Mukhtar Ahmad | date = 2013 | title = Power System State Estimation | publisher = Artech House | page = 166 | isbn = 978-1-60807-511-9 | oclc = 1259189630 | url = https://books.google.com/books?id=T5Pq6Z8h8vsC&pg=PA166}}</ref> of voltage phasors for all the buses.<ref name="PadiyarKulkarni2019">{{cite book | author1 = K. R. Padiyar | author2 = Anil M. Kulkarni | date = 4 February 2019 | title = Dynamics and Control of Electric Transmission and Microgrids | publisher = John Wiley & Sons | page = 12 | isbn = 978-1-119-17338-0 | oclc = 1043202630 | url = https://books.google.com/books?id=9i97DwAAQBAJ&pg=PA12}}</ref> In a physical system the state is calculated through [[power system state estimation]], since the end of the 20th century this process involves direct simultaneous measurements ([[synchrophasor]]) using the [[phasor measurement unit]]s.<ref name="Dagle2018">{{cite book | title = Power Electronics and Power Systems | last1 = Dagle | first1 = Jeff | chapter = Importance of Synchrophasor Technology in Managing the Grid | date = 30 May 2018 | pages = 1–11 | publisher = Springer International Publishing | issn = 2196-3185 | eissn = 2196-3193 | doi = 10.1007/978-3-319-89378-5_1 | isbn = 978-3-319-89377-8 | s2cid = 115678159 | url = }}</ref>