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21 April 2023
DelftUniversity ofTechnology
Electrical Power System Essentials
ET2105 Electrical Power System Essentials
Prof. Lou van der Sluis
The Transmission of Electric Energy
23. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Introduction (1)
• Transmission and Distribution• Advantages of interconnected systems
• Better reliability• Smaller frequency deviations• Better overall system efficiency• Facilitates power exchange
• Disadvantages of interconnected systems• Limitations to interconnection transport capacity• Power losses because of energy exchange• Unwanted parallel power flows• More complex system operation
33. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Introduction (2)Rated voltage for AC – power system
43. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Introduction (3)Voltage levels in the Dutch Power System
53. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Dutch High-Voltage Network
Introduction (4)
63. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Network Structures
Radial structure Loop structure Multi-loop structure
73. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Substations (1)Open-air substation
Courtesy of TenneT TSO B.V.
83. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Substations (2)High-Voltage Circuit Breakers and Pantograph Disconnector
Courtesy of TenneT TSO B.V.
93. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Substations (3)SF6-insulated substation
Courtesy of Eaton Holec
103. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Substations (4)Bus system
Single bus system
Double bus system
113. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The TransformerThe ideal transformer
123. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Transformer Model (1)
• Not ideal• Permeability is not infinity
• Finite self inductance
• Leakage flux• Winding losses (copper losses)• Core losses
• Hysteresis
• Eddy-current losses
133. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Transformer Model (2)
Copper lossesLeakage reactance
Iron losses (core) Magnetizing susceptance
Efficiency = Pout / Pin = 1 – Ploss / Pin
143. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Three-Phase Transformer (1)
• Three single-phase transformers
• Three phase transformer
• Complex turns ratio 1 : a*ej
• Amplitude• Phase shift: multiple of 30°
153. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Three-Phase Transformer (2)Single-phase equivalent
163. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Three-Phase Transformer (3)Out of the tank
Courtesy of TenneT TSO B.V.
173. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Yy-4 Transformer
183. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Yd-11 Transformer
193. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
The Magnetization CurrentThe magnetization current contains a third harmonic
203. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Overhead Transmission Lines (1)380 kV River crossing
Courtesy of TenneT TSO B.V.
213. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Overhead Transmission Lines (2)The power carriers in the Dutch power system
223. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Overhead Transmission Lines (3)150kV transmission line tower
233. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transmission Line Conductors (1)
• Material• Al• Cu
• ACSR (Aluminum Conductor Steel Reinforced)
243. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transmission Line Conductors (2)
Courtesy of TenneT TSO B.V.
253. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transmission Line Conductors (3)Advantages and disadvantages of bundled conductors
263. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Galloping Lines
• Counter measures
273. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Shield Wires
283. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transposition (1)
• Unbalanced system
• Solution: transposition
293. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transposition (2)
303. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
High-Voltage Cable
Courtesy of Prysmian Cable Holding B.V.
• 6/10 kV cable • 220/380 kV cable
313. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Transmission of PowerPoynting Vector: S = E x H
VV
HH
HH
HHEE
EE
EE
SS
SS
SS
EE
SS
SS
HH
HHEE
SS
SS
323. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Conductor Modeling
• L : H-field• C : E-field• R : Ohmic losses• G : Insulator and corona losses
RL
G C
333. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Line / Cable
• Line, 150 kV• R = 0.125 /km• XL = 0.425 /km
• C = 7.7 nF/km• Sth = 130 MVA
• Cable, 150 kV• R = 0.12 /km• XL = 0.166 /km
• C = 210 nF/km• Sth = 135 MVA
343. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
1 km Line / Cable
• Line, 132 kV• R = 0.178 • XL = j0.40 • XC = -j350 k• I = 450 A
• Cable, 400 kV• R = 9 m• L = 0.4 mH• C = 0.38 µF• I = 1.9 kA
353. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Line Models
• Short(<80 km)
• Medium(80 km..240 km)
• Long(>240 km)
VR
IRIS
VS
Z
IRIS
VS Y/2Y/2 VR
Z
IRIS
VS VR
/kmH/kmF/km
363. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Short Line
VR
IRIS
VS
R+jX
Vr
Vs
jIrX
IrIrR
Vr
VsjIrX
IrIrR
Vr
Vs jIrX
Ir
IrR
373. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Series-Compensation
• Z = R + jX = R + j (L - 1/C)
Hydro-Quebec / 735 kV
383. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Long Line: Distributed Elements
zx
yx V(x)
x
V(x+x)
I(x)I(x+x)
393. The Transmission of Electric Energy | 39
Electrical Power System Essentials ET2105
Equivalent Circuits of Lines
• Short
• Medium
• Long
VR
IRIS
VS
Z
IRIS
VS
Z
Y/2
Y/2 VR
IRIS
VS
Z'
Y'/2
Y'/2 VR