DERSG Course Notes
Overview of Traditional and Evolving Electricity Grids
Distributed Energy Resources and Smart Grids 4 (DERSG)
Document Comments
This document provides a summary of traditional and evolving electricity grids. Subsequent course
documents will provide increased depth and analysis of the listed topics in section 2. Each document
will contain recommended literature references and where applicable, useful conclusions obtained from
literature which is provided as extra content.
The material is summarised course notes from ‘Distributed Energy Resources and Smart Grids 4’,
completed at The University of Edinburgh. Full credit goes to Dr Michael Merlin for delivering an
extremely engaging and relevant course. This course is a SCFQ level 10 course (year 4 undergraduate)
and accounts for 20 credits.
The course is relevant to students with interests within electrical and mechanical engineering, with a
focus on power systems and energy networks. If you have any questions concerning the content within
this course series, please contact me. I wish you all the best in your studies!
1: Traditional Electricity Grids
1.1: History and Motivation
The electricity grid has evolved continually from the late 1800’s to meet rising customer demands.
Some of the first power stations are summarised below:
1. 1879: Dolgeville Dynamo. One of the first hydro power plants which supplied power to local
mills using a DC dynamo.
a. https://edisontechcenter.org/Dolgeville.html
2. 1881: Niagara Falls AC to DC conversion. Small DC dynamo supplying lighting loads. This
was later converted to AC.
a. https://teslaresearch.jimdofree.com/niagara-falls-power-project-1888/
For reference, a DC dynamo is simply an older term to describe a generator that produces DC power.
DC power is only sent in one direction and creates DC current using a commutator. Nowadays, a simpler
alternator is used for large scale power generation as it is more efficient and reliable.
The first grids were constructed at a similar period, as summarised below:
1. 1882: Edison illuminating company (DC). A DC cogeneration plant by distributing steam.
2. 1886: Great Barrington (AC). Full AC power distribution system at 500V using transformers,
Siemens generator and Edison’s incandescent lights.
3. 1891: Greater London (AC). Remote AC power station at 11kV supplying central London.
The first transmissions were also constructed at a similar period, as summarised below:
1. 1882: Miescbach, Germany (DC): Large DC transmission at 1.4kV over 57km. This was only
for industrial clients.
2. 1884: Lanzo Torinese to Torino (AC). Uses Gaulard and Gibbs transformer to transmit 2kV
over 40km on an experimental line.
3. 1889: Lauffen-Frankfurt Germany (AC). Another experimental line which was 175km long at
40Hz. Voltage was initially 8kV but lowered to 55V for a power efficiency of 75%. This line
cemented 3-phase systems for future applications.
From these initial developments, it was concluded that DC systems have limited range. AC systems
were preferred as they use transformers to boost voltage for low-loss transmission which is then reduced
1
Overview of Traditional and Evolving Electricity Grids
Distributed Energy Resources and Smart Grids 4 (DERSG)
Document Comments
This document provides a summary of traditional and evolving electricity grids. Subsequent course
documents will provide increased depth and analysis of the listed topics in section 2. Each document
will contain recommended literature references and where applicable, useful conclusions obtained from
literature which is provided as extra content.
The material is summarised course notes from ‘Distributed Energy Resources and Smart Grids 4’,
completed at The University of Edinburgh. Full credit goes to Dr Michael Merlin for delivering an
extremely engaging and relevant course. This course is a SCFQ level 10 course (year 4 undergraduate)
and accounts for 20 credits.
The course is relevant to students with interests within electrical and mechanical engineering, with a
focus on power systems and energy networks. If you have any questions concerning the content within
this course series, please contact me. I wish you all the best in your studies!
1: Traditional Electricity Grids
1.1: History and Motivation
The electricity grid has evolved continually from the late 1800’s to meet rising customer demands.
Some of the first power stations are summarised below:
1. 1879: Dolgeville Dynamo. One of the first hydro power plants which supplied power to local
mills using a DC dynamo.
a. https://edisontechcenter.org/Dolgeville.html
2. 1881: Niagara Falls AC to DC conversion. Small DC dynamo supplying lighting loads. This
was later converted to AC.
a. https://teslaresearch.jimdofree.com/niagara-falls-power-project-1888/
For reference, a DC dynamo is simply an older term to describe a generator that produces DC power.
DC power is only sent in one direction and creates DC current using a commutator. Nowadays, a simpler
alternator is used for large scale power generation as it is more efficient and reliable.
The first grids were constructed at a similar period, as summarised below:
1. 1882: Edison illuminating company (DC). A DC cogeneration plant by distributing steam.
2. 1886: Great Barrington (AC). Full AC power distribution system at 500V using transformers,
Siemens generator and Edison’s incandescent lights.
3. 1891: Greater London (AC). Remote AC power station at 11kV supplying central London.
The first transmissions were also constructed at a similar period, as summarised below:
1. 1882: Miescbach, Germany (DC): Large DC transmission at 1.4kV over 57km. This was only
for industrial clients.
2. 1884: Lanzo Torinese to Torino (AC). Uses Gaulard and Gibbs transformer to transmit 2kV
over 40km on an experimental line.
3. 1889: Lauffen-Frankfurt Germany (AC). Another experimental line which was 175km long at
40Hz. Voltage was initially 8kV but lowered to 55V for a power efficiency of 75%. This line
cemented 3-phase systems for future applications.
From these initial developments, it was concluded that DC systems have limited range. AC systems
were preferred as they use transformers to boost voltage for low-loss transmission which is then reduced
1
