page1 deppon protection system. page2 deppon objectives to isolate a faulty equipment from other...
TRANSCRIPT
Page1 Deppon
Protection System
Page2 Deppon
OBJECTIVES
• To isolate a faulty equipment from other healthy parts of the system
• To minimise effects of abnormal operating conditions in the system (e.g. High / Low Voltage, High / Low Frequency, overloading of parts of the network etc.)
Page3 Deppon
EXPECTATIONS
• Sensitivity
• Selectivity
• Speed
• Reliability
Page4 Deppon
COMPONENTS
• Circuit Breakers
• Fuses
• Instrument Transformers
• Relays
• Control Logic
Page5 Deppon
RELAYING TECHNOLOGIES
• Electro-mechanical
»Electro-magnetic Induction
»Electro-magnetic Attraction
•Static – Analogue
•Numerical - Digital
Page6 Deppon
PROTECTION TYPES
• Current• Voltage• Frequency• Directional• Power• Distance • Differential
Page7 Deppon
PROTECTION SYSTEM DESIGN
• Network Study
• Calculation of fault currents for different system conditions
• Protection Coordination
Page8 Deppon
Source
Line Impedanc
e Transforme
r Data 3-Ph 1500 MVA X 1.5ohms X 11.5%
Voltage 33 KV R 1 ohms MVA 20 MVA HV 33 KV LV 11 KV Neutral 0 ohms
Typical NetworkA B C
Page9 Deppon
TYPICAL TIME GRADING DIAGRAM
1.4SBus ABus A
0.6S
0.2SBus BBus B
1.0S
Page10 Deppon
0.6S 0.6S
0.2S 0.2S
1.2 s 0.8 s
0.6 s
0.2 s
TYPICAL TIME GRADING DIAGRAM (contd.)
1.2S
Page11 Deppon
Transformer Ratio = nTurns Ratio = k = n * 1.732
Side 1 Currents :Ir = IF / k;Iy = IF /k;Ib = 0;In = 0;
Side 2 Currents :Ir = IF;Iy = 0;Ib = 0;In = IF;
F
FAULT CURRENT FLOW
Page12 Deppon
Transformer Ratio = nTurns Ratio = k = n * 1.732
Side 1 Currents :Ir = IF / k;Iy = 2 * IF /k;Ib = IF / k;In = 0;
Side 2 Currents :Ir = IF ;Iy = IF ;Ib = 0;In = 0;
F
FAULT CURRENT FLOW (contd.)
Page13 Deppon
Transformer Ratio = nTurns Ratio = k = n / 1.732Side 1 Currents :
Ir = IF / 3 / k;Iy = 0;Ib = IF / 3 / k;In = 0;
Side 2 Currents :Ir = IF ;Iy = 0 ;Ib = 0;In = IF;
IF/3
IF
IF
2 * IF/3
FAULT CURRENT FLOW (contd.)
Page14 Deppon
Vr
Vry
Vyb
Vbr
Ir
Iy
Ib
VyVb
R Y B R Y B
Source Load
LOAD CURRENT VECTOR DIAGRAM
Page15 Deppon
Vr
Vry
Vyb
Vbr
Ir
VyVb
R YB R YB
Source Load
F
If = 3 x Vph /(Z1 + Z2 +Z0)
Where Z1, Z2 & Z0 are sequence Impedances upto the point of fault
If
FAULT CONDITION VECTOR DIAGRAM
Page16 Deppon
VrVry
Vyb
Vbr
Ir
VyVb
R Y B R Y B
Source Load
F
If = 1.732 x Vph /(Z1 + Z2)
Where Z1, Z2 are sequence Impedances upto the point of fault
If
Iy
Ib
FAULT CONDITION VECTOR DIAGRAM (contd.)
Page17 Deppon
VrVry
Vyb
Vbr
Ir
Iy
Ib
VyVb
R Y B R Y B
Source Load
F
If = Vph /(Z1)
Where Z1 is +ve sequence Impedance upto the point of fault
If
FAULT CONDITION VECTOR DIAGRAM (contd.)
Page18 Deppon
VrVry
Vyb
VbrIy
Ib
VyVb
R Y B R YB
Source Load
F
Ig = 3 * Vph * Z2 / (Z1*Z2+Z2*Z0+Z0*Z1)
Where Z1, Z2 & Z0 are sequenceImpedances upto the point of fault
If Ig
FAULT CONDITION VECTOR DIAGRAM (contd.)
Page19 Deppon
SEQUENCE NETWORKS - A RECAP
1-Ø TO GROUND FAULT
1-Ø TO GROUND FAULT
Z1
Z2
I1
I1 = - I2
~
I2
Ø-Ø FAULTØ-Ø FAULT
~
IR = I1 + I2 + I0 IY = a2 I1 + aI2 + I0
IB = aI1 + a2 I2 + I0
Page20 Deppon
SEQUENCE NETWORKS - A RECAP (contd.)
~
3Ø FAULT
~
Ø-Ø - E FAULTØ-Ø - E FAULT
~Vph Vph
Page21 Deppon
SEQUENCE NETWORKS - A RECAP (contd.)
V1+
= (V1 + aV2 + a2V3 ) / 3
V1- = (V1 + a2 V2 + aV3 ) / 3
V10 = (V1 + V2 + V3 ) / 3
V2+ = a2 V1
+
V3+ = aV1
+
V2- = aV1
-
V3- = a2 V1
-
V10 = V2
0 = V30
Thank You