High Voltage Direct-Current (HVDC) systems based on Modular
Multilevel Converter technology
by I.E.P.G. Ph.D. Candidate: A. PerillaDelft University of Technology. 23 August, 2018.
Welcome to the High Voltage Direct-CurrentVoltage Source Converter (VSC-HVDC) world.
Agenda:
Voltage Source Converters
❑ Definition and relevance
❑ Classification:
• Two & Three level converters.• Modular Multilevel Converters.
❑ General operation’s principles of VSCs.• Space-time vector theory.
❑ Modelling & Control of MMC.
Voltage Source Converter(VSC) technology
“The VSC technology is a technology used in the electrical power networks for
transferring (convert) power from one energy system to another one”.
❑Definition and relevance
Voltage Source Converter(VSC) technology
Energy systems (some examples):
Solar Power Plants
Electricity Grid
Wind Farms
Electricity Grid
In this electrical circuit, What should be the VSC voltage value to obtain the Psystem expecified during steady-state operation?
(The Voltage Sources are DC Voltage sources).
What would happen if the Voltage sources would be nowAC Voltage sources?
?
Voltage Source Converter(VSC) technology
Two levels VSC systems:
❑Classification:
Voltage Source Converter(VSC) technology
Three levels VSC systems:
❑Classification:
Voltage Source Converter(VSC) technology
Modular Multilevel VSC systems
❑Classification:
Modular Multilevel Converter (MMC)
Voltage Source Converter(VSC) technology
“The VSC technology is a technology used in the electrical power networks for
transferring (convert) power from one energy system to another one”.
❑Definition and relevance
Voltage Source Converter(VSC) technology
❑ General operation’s principles of VSC systems.
Space-time “vector” theory.
1929 189719181943
1984
1893 1888
1918
N. TeslaA. Kennelly
C. SteinmetzC. FortescueR. ParkE. Clarke
H. Akagi
Space-Time “Vector”Theory
Active Power
ReactivePower
DCVoltage
Voltage Source Converter
STSTVT has two different perspectives which are based on different
mathematical tools developed by the astonishing world-class mathematicians:
Leonhard EulerJoseph-Louis Lagrange However, for simplicity in this master course
Space-Time “Vector”Theory Leonhard
Euler
𝑒𝑗∗ = cos + 𝑗 ∗ sin 1918C. Fortescue
= 𝑒𝑗∗2∗𝜋3 = cos
2 ∗ 𝜋
3+ 𝑗 ∗ sin
2 ∗ 𝜋
3
Fortescue defined the vector (positive sequence vector) :
1 2
Where
Space-Time “Vector”Theory Leonhard
Euler
The instantaneous-complex alpha-beta transformation (for three phase balanced systems) can be defined as :
1943E. Clarke
1984H. Akagi
𝑣(𝑡)= 1 2 *
𝑣𝑎(𝑡)𝑣𝑏(𝑡)𝑣𝑐(𝑡)
𝑣(𝑡)= Space-time voltage’s “vector”
Space-Time “Vector”Theory Leonhard
Euler
𝑆(𝑡) = 𝑣(𝑡) *conj(𝑖(𝑡))
Instantaneous apparent complex power :
Complex three phase power (Steinmetz-Phasor approach):
𝑆 = 3 𝑉𝑓𝑛 ∗ 𝑐𝑜𝑛𝑗(𝐼𝑙) = 𝑃 + 𝑗𝑄
Where are 𝑉𝑓𝑛 𝑎𝑛𝑑 𝐼𝑙 phasors quantities
Space-Time “Vector”Theory Leonhard
Euler
We can apply another mathematical transformation to our Space-time voltage’s “vector” to simplify our power analysis.
𝑅 𝜃 =cos 𝜃 −sin 𝜃sin 𝜃 cos 𝜃
Apply 2D Rotation transformation
1929R. Park
Hey buddy, Let’s apply a Rotation Transformation !
Space-Time “Vector”Theory Leonhard
Euler
𝑽𝑺𝑪 − 𝑯𝑽𝑫𝑪 𝑬𝒏𝒈𝒊𝒏𝒆𝒆𝒓𝑽𝑺𝑪 −𝑯𝑽𝑫𝑪 𝑬𝒏𝒈𝒊𝒏𝒆𝒆𝒓
𝑅 𝜃 =cos 𝜃 −sin 𝜃sin 𝜃 cos 𝜃
Question 1:
Who is ?
Question 2:
Should be 𝒗 𝒕 aligned
with one rotating axe?
Space-Time “Vector”Theory Leonhard
Euler
Iq
Id
Welcome to the High Voltage Direct-CurrentVoltage Source Converter (VSC-HVDC) world.
BREAK ???
QUESTIONS SO FAR ???
Space-Time “Vector”Theory Leonhard
Euler
Iq
Id
Active Power
ReactivePower
Voltage Source Converter
❑ General operation’s principles of VSC systems.
Space-Time “Vector”Theory Leonhard
Euler
Active Power
ReactivePower
DCVoltage
Voltage Source Converter
❑ General operation’s principles of VSC systems.
Let’s use the whiteboard to explain the last one
Modular Multilevel Converter (MMC)
For simplicity in this master
course
Modelling & Control of MMC
❑ Circulating current suppression control CCSC (modelling) approach.
❑ Internal Energy Balance Control (modelling) approach.
There are two main modelling approach to control and model the MMC:
❑ Modelling & Control of MMC (Cigre
Version)
25
To the AC network
DC Current
AC Currents
MMC internal Reactor (Larm)
Based on CIGRE B4-57 working group report
(2014).
26
To the AC network
DC Current
AC Currents
MMC internal Reactor (Larm)
Based on CIGRE B4-57 working group report
(2014).
❑ Modelling & Control of MMC (Cigre
Version)
In summaryCCSC Modelling approach means:
❑ Modelling & Control of MMC (Cigre
Version)
Power SystemsTheory
Power Electronic
DesignTechniques
Control Systems Theory
(VSC) technology
In Summary…
Delft University of Technology. 23 August, 2018.
Thanks for
your
attentionArcadio Perilla
Intelligent Electrical Power Grids Group