View
225
Download
0
Category
Tags:
Preview:
Citation preview
Nov. 2003 1
Voltage Collapse in Electrical Power Systems
by
Zivan ZabarECE Dept
Nov. 2003 2
Voltage collapse
Voltage collapse of an electric distribution network means that the system can no longer maintain voltage at the load site.
Nov. 2003 3
Electrical grid (system)
Electrical grid consists of three main components:
• Generating plants• Transmission and distribution networks• Customer loads
Nov. 2003 4
Transmission of electric power(Bonneville Power Adm.)
Nov. 2003 5
Basic Components of Power System (H. Saadat)
Nov. 2003 6
Subtransmission Grid & Low-Voltage Secondary Ntwk (W)
Nov. 2003 7
Voltage Collapse (DC circuit)
From
€
P = I2R and
€
V =E
R +r R we get:
€
V =12
E ± E2 − 4 ⋅P ⋅r( )
and
€
I =E − V
r
Nov. 2003 8
Voltage Collapse (DC circuit); cont.
Max powerat r = R
Load power
Loadvoltage Current
r1
r2 < r1
Nov. 2003 9
AC power
€
Apparent = Active + j ⋅Reactive
where:
€
S = P + jQ
€
P = V ⋅I⋅cos ϕ [W]
€
Q = V ⋅I⋅sinϕ [VAr]
€
ϕ − the phase angle between
the current and the voltage
Nov. 2003 10
Power transfer over a transmission line
Active power:
€
P =E ⋅V
Xsinθ [W]
Reactive Power:
€
Q =E ⋅V
Xcosθ−
V2
X [VAr]
Nov. 2003 11
Power transfer curves
ReactivePower
ActivePower
ReactivePower
Nov. 2003 12
Voltage collapse (AC circuit)
Power [W]:
€
PL =VS ⋅VL
Xsinθ
Reactive power [VAr]
€
QL =VS ⋅VL
Xcosθ−
VL2
X
Defining:
€
β=tanϕ
€
VL =VS
2
2− β ⋅PL ⋅X±
VS4
4− PL ⋅X PL ⋅X+ β ⋅VS
2( )
Nov. 2003 13
Voltage collapse (AC circuit) cont.
Load powerCriticalvoltage
Loadvoltage Current
€
β1=0.18PF1 = 0.98€
β2=0PF2 = 1
Nov. 2003 14
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 15
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 16
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 17
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 18
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 19
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 20
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Summary of the situation at 4:10:38
Nov. 2003 21
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 22
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 23
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 24
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 25
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 26
August 14, 2003 Blackout--Sequence of events[US/Canada Outage Task Force; 9/12/03]
Nov. 2003 27
Nov. 2003 28
Recommended