Embed Size (px)
Citation preview
Journal of Electrical Engineering & Technology Vol. 7, No. 3, pp. 297~303, 2012 http://dx.doi.org/10.5370/JEET.2012.7.3.297
297
Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant
Sang-Min Yeo† and Chul-Hwan Kim*
Abstract – This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.
Keywords: Surge, Transient Overvoltages, Switching, Lightning, Gas Insulated Switchgear, EMTP
1. Introduction
Power systems consist of various facilities such as power stations, substations, transmission lines and various loads, etc. Transient overvoltages may occur within a power system when a system status change occurs due to an event such as a fault, lightning or even normal operation.
Generally, modeling of switching devices, such as circuit breakers and disconnector switches, are implemented by ideal switches for analysis within a switching transient simulation. However, the contacts of a disconnector switch move slowly during opening and closing operations, which causes numerous pre-strikes between the contacts. Pre-strikes occur when the dielectric strength between the contacts of the disconnector switch are exceeded by overvoltages. Therefore, the effects of pre-strikes due to disconnector switching continue for a relatively long time compared to the time in a circuit breaker [1-5].
Specifically, in gas insulated switchgear (GIS), a large number of restrikes across the switching contacts will occur when disconnector switches or circuit breaker operation occurs. Each restrike generates very fast transient overvoltages (VFTO), which enter the substation and may propagate inside depending on the substation layout. VFTOs typically have a very short rise time, in the range of 4 to 100 ns, and are followed by high frequency oscillations, in the range of 1 to 50 MHz. Therefore, the analysis of switching transients and very fast transients in GIS is extremely important [6-11]. Also, when lightning hits a nearby tower or the shield wire of an incoming line, this can cause a backflashover, which is when the resultant lightning surge enters the substation and may propagate inside depending on the substation layout. Hence, as in the
case of switching transients, the transients caused by a lightning surge also need to be analyzed.
In 2005, when a disconnector closed within a 345kV Korean thermal plant, the circuit breakers for the exciter protection of two generators tripped except the operation of any protective relay. The tripping of the circuit breakers caused inoperation to occur for two generators, which then caused a productivity decrease for the entire plant. Thus, analysis is required in order to discover the trip cause for the circuit breakers due to disconnector switching. In this paper, the authors analyze the VFTOs due to disconnector switching, including the switching transient and lightning overvoltages.
This paper shows the simulation results of transient overvoltages within a GIS. Also, both a 345kV thermal plant and a pre-strike model of a disconnector switch are modeled by EMTP and then it is further simulated to analyze the transient overvoltages via various transients.
2. Background Theory The components in a GIS have already been previously
modeled by the authors via several transient simulations [12, 13]. The previous papers include more details about modeling as follows, except for in the case of lightning surges. Therefore, these factors are described briefly within this paper.
2.1 Very fast transients
VFTs may occur within a GIS at any time and will cause
an instantaneous voltage change, one example being the change caused by disconnector switching. These transient over-voltages are generally below the basic insulation level (BIL) of the GIS and are connected to equipment with
† Corresponding Author: Power & Industrial Systems R&D Center, Hyosung Corporation, Korea. ([email protected])
* School of Information and Communication Engineering, Sungkyunkwan Univerity, Korea. ([email protected])
Received: April 29, 2011; Accepted: February 3, 2012
Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant
298
lower voltage classes. However, they frequently contribute to the life reduction of the insulation within the system [9].
The propagation of VFT through the GIS can be analyzed by representing GIS sections as low-loss distributed parameter transmission lines. The main frequencies depend on the length of the GIS sections affected by the disconnector operation and are in the range of 1 to 50MHz. Also, an internally generated VFT will propagate throughout the GIS and reach the bushing where it will cause both a transient enclosure voltage and a traveling wave that will propagate along the overhead transmission line.
2.2 Pre-strike
The pre-strike phenomena of the switches are considered
in order to simulate the switching transients. In this paper, the authors refer to references 4 and 5 for modeling the pre-strike, which consists of a calculation for the withstand voltage (Vw), a comparison of the withstand voltage, the switch voltage, a controlled switch, and a probe for measuring the switch terminal voltage. Fig. 1 shows the model of a pre-strike in EMTP [14].
Compare21
Csw?s
PROD12
Fm4
PROD12
Fm5
DIV1
2
Fm6
c
C4
1
++-
sum2
Gain2
#KVr#
ABS1
Fm7
v(t)
Vsw
scopeVw
+Inf
?s
0
1
lim2
Csw
Vsw
sg2
f(t)
c_gfun
c
t#toper#
C1
Fig. 1. Model of a pre-strike by EMTP
It is confirmed via the simulation results that the
verification of the pre-strike model is properly implemented.
2.3 Grounding system
The operational safety and proper functioning of electric
systems are influenced by their earth terminations. Local inequalities of reference potential for a grounding
system are sources of malfunction and may cause the destruction of components that are electrically connected to the grounding system. Therefore, ground system modeling is necessary in order to analyze the effects of reference potential disturbances during various operation abnormalities.
The presented methodology extends the validity range of well-known grounding system models towards higher frequencies, in the range of a few MHz. The approach is based on the three basic concepts that have been developed [15, 17].
This paper uses a grounding system model via the circuit approach method, as mentioned in [18] and shown in Fig. 2.
+ 570
R
1
+
0 .0463nF C9
+1.2uH
L2
P2P1
Fig. 2. Equivalent model of the grounding system per unit
length
2.4 Lightning surge
Generally, lightning strikes that occur directly on a
substation are ignored because it is safely assumed that the substation is shielded appropriately. On the contrary, lightning strikes to the tower or shield wire can cause backflashover due to line insulation flashover between the tower and the phase conductor, and can enter the substation and propagate inside according to the substation layout [9].
In this paper, the standard 1.2x50us impulse waveform is used for the lightning surge model, as shown in Fig. 3.
+R1 ?i
0.0001
+
Icramp1
1.2us/63kA
+R2 ?v
400BUS1
a
a
Fig. 3. Lightning surge model
3. Simulation and Results
3.1 System Model This paper models a 345kV thermal plant via EMTP.
The modeled system, as shown in Fig. 4, is comprised of six generators and six transformers, and connects to other systems via six transmission lines.
Fig. 4. System Model
3.1.1 Very fast transients and lightning surge section
In order to successfully simulate VFT overvoltage, accurate models are needed for various equipment devices in the range of zero hertz to a few megahertz. However,
Sang-Min Yeo and Chul-Hwan Kim
299
component modeling within all frequency ranges is very difficult and impracticable. Thus, for reasons of practicality, the modeling of frequency-dependent power system components is implemented within a specific frequency range [9]. The equivalent GIS model consists of various pieces of equipment that function differently for varying frequency ranges. Therefore, equivalent typical equipment models for very fast transients are used [6-8, 10-13, 17].
For the simulation of the lightning surges, the system model is derived from plant layout drawings and should include the lightning surge characteristics. For this reason, the modeling method is similar to the method used for the case of VFT. Though the plant modeling for VFT is more complicated rather than typical modeling for a lightning surge, when the lightning surge is simulated the authors use the modeled system for the VFT in order to reduce effort and time due to repeated modeling.
Fig. 5 shows the equivalent model of the circuit breaker from the equivalent model of GIS components. The other components are modeled by similar procedure [4, 6-13].
(a) Open status (b) Close status
Fig. 5. The equivalent model of the circuit breaker In order to simulate the effect of various transients on
control circuit, the model of control circuit is shown in Fig. 6. Based on the feature of real control circuit, the model of control circuit is simplified.
386E
TRIP_E TRIP_R
D1
D2
D3
D4
D5
D6
D7
+1 2
Tr0_1
0.192
v (t)
p2
v (t) p6
scopeDC_125V
scopeDC_24V
IN_SGNv (t)
p13
scopeIn_Sgn
7.794e-3
Gain1
scopeDC_125VPU
0.039
Gain2
scopeDC_24VPU
+
Trip
_R
?vi
+
Trip
_E
?vi
VM+
?v
386E
_V
IN_VAC
GN
D
+
15600uF!vC5
+
C6!v
2uF
+
C7!v
2uF
Compare21
?sDetect_125
v(t) p14
scope386E_VLL
+
386E
_SW
Out_Sgn++-
sum1
c125
C8
v(t)
p1
BUS1BUS1
cba
a
Fig. 6. The model of control circuit
In addition, the entire grounding system is modeled by
the layout of real grounding system and the equivalent model in Figs. 2 and 7 shows the model of the entire grounding system used in this paper.
Fig. 8 shows the layout of the 345kV thermal plant, also shown in Fig. 4, when modeled by EMTP.
(a) The layout of real grounding system
tml_
5_0
tml_
6_0
tml_
5_1
tml_
6_1
tml_
5_2
tml_
6_2
tml_
5_3
tml_
6_3
P2P1DEV1
P2P1DEV2
P2P1
DEV3
P2P1
DEV4
P2
P1DE
V5 P2
P1DE
V6
P2
P1DE
V7 P2
P1DE
V8
P2P1
DEV9
P2P1
DEV10
P2
P1DE
V13
P2
P1
DEV
14
P2P1
DEV1 5
P2P1
DEV1 6
P2P1
DEV21
P2P1
DEV22
P2P1DEV2 3
P2P1
DEV2 5
P2
P1DE
V27
P2
P1
DEV
28
P2P1
DEV2 9
P2P1
DEV3 1
P2P1
DEV3 2
P2
P1DE
V33
P2
P1
DEV
34
P2P1
DEV35
P2P1
DEV36
P2
P1DE
V41
P2
P1
DEV
42
P2P1
DEV4 3
P2P1
DEV52
P2P1
DEV5 3
P2P1
DEV55
P2P1
DEV56
P2P1
DEV6 0
P2P1
DEV61
P2
P1
DEV
67
P2
P1DE
V70
P2
P1DE
V72
P2
P1
DEV
74 P2
P1
DEV
75 P2
P1
DEV
76P2
P1
DEV
77
P2
P1DE
V78
P2
P1DE
V79
P2
P1DE
V80
P2
P1DE
V83
P2
P1DE
V84
P2
P1DE
V87
P2
P1DE
V88
P2
P1DE
V89
P2
P1
DEV
90 P2
P1
DEV
93 P2
P1
DEV
94P2
P1
DEV
95
P2
P1
DEV
96 P2
P1
DEV
98 P2
P1
DEV1
00P2
P1
DEV1
10
P2
P1
DEV1
12 P2
P1
DEV1
14 P2
P1
DEV1
15P2
P1
DEV1
17
P2
P1
DEV
118
P2
P1
DEV
119
P2
P1
DEV
120
P2
P1
DEV
121
P2P1
DEV1 22
P2P1
DEV12 3
P2P1
DEV1 24
P2P1
DEV12 5
P2P1
DEV1 27
P2P1
DEV12 9
P2P1
DEV1 30
P2P1
DEV1 31
P2P1
DEV13 2
P2P1
DEV1 33
P2P1
DEV1 40
P2P1
DEV14 3
P2P1
DEV14 4
P2P1
DEV1 45
P2P1
DEV14 6
P2P1
DEV14 7
P2
P1
DEV
148
P2
P1
DEV1
52
P2
P1
DEV1
53
P2
P1
DEV
154
P2
P1
DEV
155
P2
P1
DEV
156
P2
P1
DEV
162
P2
P1
DEV
164
P2
P1
DEV
165
P2
P1
DEV1
66
P2
P1
DEV1
67
P2
P1DE
V16
8
P2P1
DEV17 2
P2P1
DEV1 73
P2P1
DEV17 4
P2P1
DEV1 75
P2P1
DEV1 76
P2P1
DEV17 7
P2P1
DEV17 8
P2P1
DEV1 79
P2P1
DEV18 0
P2
P1
DEV
183
P2
P1
DEV1
84
P2
P1
DEV
185
P2P1
DEV1 87
P2P1
DEV19 0
P2P1
DEV1 94
P2P1
DEV19 6
P2
P1
DEV
201
P2
P1
DEV
206
P2P1
DEV21 6
P2
P1
DEV2
20
P2
P1
DEV2
21
P2
P1
DEV
224
P2
P1
DEV
225
P2
P1
DEV
226
P2
P1
DEV
229
P2
P1
DEV2
30
P2
P1
DEV2
40
P2
P1
DEV2
41
P2
P1
DEV
242
P2
P1
DEV
243
P2
P1
DEV
244
P2P1
DEV24 5
P2P1
DEV24 6
P2
P1
DEV
247
P2
P1
DEV2
48
P2P1DEV24 9
P2
P1
DEV
250
P2P1
DEV2 51
P2
P1
DEV
252
P2
P1
DEV2
53 P2
P1
DEV2
54
P2
P1
DEV
256
P2
P1
DEV
257
P2
P1
DEV
259
P2
P1
DEV
260
P2
P1
DEV2
61
P2
P1
DEV2
69
P2
P1DE
V27
0
P2P1
DEV27 1
P2
P1
DEV
272
P2
P1
DEV
273
P2P1
DEV27 4
P2
P1
DEV
275
P2
P1
DEV2
76
P2
P1
DEV2
77
P2
P1
DEV
278
P2P1
DEV2 79
P2P1
DEV2 80
P2P1
DEV28 2
P2P1
DEV2 85
tml_
3_0
tml_
4_0
tml_
3_1
tml_
4_1
tml_
3_2
tml_
4_2
tml_
3_3
tml_
4_3
P2P1DEV28 6
P2P1DEV3 08
P2P1
DEV31 5
P2P1
DEV3 16
P2
P1
DEV
317
P2
P1
DEV
318
P2
P1
DEV
323
P2
P1
DEV
324
P2P1
DEV33 0
P2P1
DEV3 31
P2
P1
DEV
332
P2
P1
DEV
333
P2
P1
DEV
334
P2
P1
DEV
335
P2
P1
DEV
345
P2
P1
DEV
346
P2P1
DEV34 7
P2P1
DEV34 8
P2P1
DEV34 9
P2P1
DEV35 0
P2P1DEV35 3
P2P1DEV3 54
P2P1
DEV35 5
P2P1
DEV3 57
P2
P1
DEV
368
P2
P1
DEV
373
P2
P1
DEV
377
P2
P1
DEV
378
P2P1
DEV37 9
P2P1
DEV3 96
P2P1
DEV3 99
P2P1
DEV4 00
P2
P1
DEV
401
P2
P1
DEV
402
P2P1
DEV40 3
P2P1
DEV40 4
P2
P1
DEV
406
P2
P1
DEV
407
P2
P1
DEV
409
P2
P1
DEV
410
P2
P1
DEV
413
P2
P1
DEV
415
P2P1
DEV41 7
P2P1DEV4 18
P2P1
DEV41 9
P2P1
DEV42 0
P2P1
DEV42 2
P2P1P2P1
DEV4 24
P2
P1
DEV4
26
P2
P1
DEV4
27
P2
P1
DEV4
28
P2
P1
DEV4
29
P2
P1
DEV4
30
P2
P1
DEV4
31
P2
P1
DEV4
32 P2
P1
DEV4
34 P2
P1
DEV4
36
P2
P1
DEV4
37
P2
P1DE
V43
8
P2
P1DE
V43
9
P2
P1DE
V44
0
P2
P1DE
V44
1
P2
P1DE
V44
2
P2
P1DE
V44
3
P2P1
DEV44 4
P2P1
DEV4 45
P2P1
DEV44 6
P2P1
DEV4 48
P2P1
DEV44 9
P2P1
DEV4 50
P2P1
DEV4 51
P2
P1
DEV
453
P2
P1
DEV
454
P2
P1
DEV
455
P2
P1
DEV
456
P2
P1
DEV4
57 P2
P1
DEV4
58 P2
P1
DEV4
59 P2
P1
DEV4
60P2
P1
DEV4
61
P2
P1
DEV4
62 P2
P1
DEV4
63 P2
P1
DEV4
64 P2
P1
DEV4
65P2
P1
DEV4
66
P2
P1
DEV
467
P2
P1
DEV
468
P2
P1
DEV
469
P2
P1
DEV
470
P2
P1
DEV
471
P2
P1
DEV
472 P2
P1
DEV
473 P2
P1
DEV
474 P2
P1
DEV
475P2
P1
DEV
476
P2
P1
DEV4
77 P2
P1
DEV4
78 P2
P1
DEV4
79 P2
P1
DEV4
80P2
P1
DEV4
81
P2
P1
DEV4
82 P2
P1
DEV4
83 P2
P1
DEV4
84 P2
P1
DEV4
85P2
P1
DEV4
86
P2
P1
DEV
487
P2
P1
DEV
488
P2
P1
DEV
489
P2
P1
DEV
490
P2
P1
DEV
491
P2
P1
DEV
492
P2
P1
DEV
493
P2
P1
DEV
494
P2
P1
DEV
495
P2
P1
DEV
496
P2
P1
DEV4
97
P2P1
DEV49 8
P2P1
DEV4 99
P2P1
DEV50 0
P2P1
DEV5 02
P2P1
DEV50 3
P2P1
DEV5 04
P2P1
DEV5 05
P2P1
DEV50 7
P2P1
DEV5 08
P2P1
DEV50 9
P2P1
DEV51 0
P2P1
DEV51 2
P2P1
DEV5 13
P2P1
DEV5 14
P2P1
DEV51 5
P2P1
DEV51 6
P2P1
DEV5 17
P2P1
DEV51 8
P2P1
DEV51 9
P2P1
DEV52 1
P2P1
DEV5 22
P2P1
DEV5 23
P2P1
DEV52 4
P2P1
DEV52 5
P2P1
DEV5 26
P2P1
DEV52 7
P2P1
DEV52 8
P2P1
DEV53 0
P2P1
DEV5 31
P2P1
DEV5 32
P2P1
DEV53 3
P2P1
DEV53 4
P2P1
DEV5 35
P2P1
DEV53 6
P2P1
DEV53 7
P2P1
DEV53 9
P2P1
DEV5 40
P2P1
DEV5 41
P2P1
DEV54 2
P2P1
DEV5 43
P2P1DEV5 44
P2P1
DEV5 45
P2P1
DEV5 46
P2P1
DEV5 47
P2P1
DEV5 48
P2P1
DEV5 49
P2P1
DEV5 50
P2
P1
DEV
551
P2
P1
DEV5
52
P2
P1
DEV5
53
P2
P1
DEV
554
P2
P1
DEV
555
P2
P1
DEV
556
P2
P1
DEV
557
P2
P1
DEV
559
P2
P1
DEV5
61
P2
P1
DEV5
62
P2
P1DE
V56
3
P2P1
DEV56 4
P2P1
DEV5 65
P2P1
DEV56 6
P2P1
DEV56 7
P2P1
DEV56 9
P2P1
DEV5 70
P2P1
DEV5 71
P2P1
DEV57 2
P2P1
DEV5 73
P2
P1
DEV
574
P2
P1
DEV5
75
P2
P1
DEV
576
P2
P1
DEV5
77
P2
P1
DEV
578
P2
P1
DEV5
79
P2
P1
DEV
580
P2
P1
DEV5
81
P2
P1
DEV
582
P2
P1
DEV
583
P2P1DEV5 84
P2P1
DEV58 5P2P1
DEV5 86
P2P1
DEV5 87
P2P1
DEV5 88
P2P1
DEV58 9
P2
P1
DEV
590
P2
P1
DEV
591
P2P1
DEV5 92
P2P1DEV5 93
P2P1
DEV5 94
P2P1
DEV5 95
P2P1
DEV5 96
P2
P1
DEV
597
P2P1
DEV5 98
P2P1
DEV5 99
P2
P1
DEV6
00
P2
P1
DEV6
01
P2
P1
DEV
602
P2
P1
DEV
603
P2
P1
DEV
604
P2
P1
DEV
605
P2
P1
DEV6
06
P2
P1
DEV6
07
P2P1
DEV6 08
P2P1
DEV60 9
P2P1
DEV61 0
P2
P1
DEV
611
P2
P1
DEV6
12
P2
P1
DEV6
13
P2
P1
DEV
614
P2
P1
DEV
615
P2P1
DEV61 6
P2P1
DEV61 7
P2
P1
DEV6
18
P2P1
DEV6 19
P2P1
DEV6 20tm
l_1
_0
tml_
2_0
tml_
1_1
tml_
2_1
tml_
1_2
tml_
1_3
tml_
2_3
P2P1
DEV62 2
P2P1DEV6 23
P2P1DEV62 4
P2
P1
DEV6
25 P2
P1
DEV6
26
P2
P1DE
V627
P2P1
DEV6 29
P2
P1
DEV6
31
P2
P1DE
V632
P2
P1
DEV6
33
P2
P1DE
V634
P2
P1
DEV6
35
P2
P1DE
V636
P2
P1
DEV6
37
P2
P1DE
V638
P2P1DEV6 39
P2P1
DEV6 40
P2P1DEV64 3
P2P1
DEV64 4
P2P1
DEV6 45
P2P1DEV6 47
P2P1DEV6 48
P2
P1
DEV6
49 P2
P1
DEV6
50
P2
P1DE
V652
P2P1
DEV6 54
P2P1DEV65 5
P2
P1
DEV6
57
P2
P1DE
V658
P2P1DEV6 59
P2
P1
DEV6
62 P2
P1
DEV6
65 P2
P1
DEV6
68 P2
P1
DEV6
71
P2
P1
DEV
675
P2
P1
DEV
681
P2
P1
DEV
684
P2
P1
DEV
687
P2P1
DEV68 9
P2P1
DEV6 90
P2P1
DEV6 93
P2P1
DEV6 94
P2P1 P2P1
DEV6 97
P2
P1
DEV
698
P2
P1
DEV
700
P2
P1
DEV
702
P2
P1
DEV
705
P2
P1
DEV
706
P2
P1
DEV
708
P2
P1
DEV
709
P2
P1
DEV
710
P2
P1
DEV
711
P2
P1
DEV
712
P2
P1
DEV
713
P2
P1
DEV
714
P2
P1
DEV
715
P2
P1
DEV
717
P2P1
DEV7 18
P2P1
DEV7 19
P2P1
DEV72 0
P2P1
DEV7 23
P2P1
DEV72 4
P2P1
DEV7 27
P2
P1
DEV7
29 P2
P1
DEV7
30 P2
P1
DEV7
31 P2
P1
DEV7
32 P2
P1
DEV7
33 P2
P1
DEV7
38
P2P1
DEV7 39
P2P1
DEV74 0
P2P1
DEV7 41
P2P1
DEV74 2
P2P1
DEV7 43
P2P1
DEV7 44
P2P1
DEV7 45
P2P1
DEV74 6
P2P1
DEV7 47
P2P1
DEV7 48
P2P1
DEV7 49
P2P1
DEV75 0
P2P1
DEV7 51
P2P1
DEV7 52
P2P1
DEV7 53
P2P1
DEV7 54
P2P1
DEV75 5
P2P1
DEV7 56
P2
P1
DEV
757
P2
P1
DEV
758
P2
P1
DEV
759
P2
P1
DEV
760
P2
P1
DEV
761
P2
P1
DEV
762
P2
P1
DEV
763
P2
P1
DEV
764
P2
P1
DEV
765
P2
P1
DEV
766
P2
P1
DEV
767
P2
P1
DEV
768
P2
P1
DEV
769
P2
P1
DEV
770
P2
P1
DEV
771
P2
P1
DEV
772
P2
P1
DEV
773
P2
P1
DEV
774
P2
P1
DEV
775
P2
P1
DEV
776
P2
P1
DEV
777
P2
P1
DEV
778
P2
P1
DEV
779
P2
P1
DEV
780
P2
P1DE
V781 P2
P1DE
V782 P2
P1DE
V783 P2
P1DE
V784 P2
P1DE
V785 P2
P1DE
V786 P2
P1DE
V787P2
P1DE
V788
P2
P1
DEV
789
P2
P1
DEV
790
P2
P1
DEV
791
P2
P1
DEV
792
P2
P1
DEV
793
P2
P1
DEV
794
P2
P1
DEV
795
P2
P1
DEV
796
P2
P1
DEV
797
P2
P1
DEV
798
P2
P1
DEV
799
P2
P1
DEV
800
P2
P1
DEV
801
P2
P1
DEV
802
P2
P1
DEV
803
P2
P1
DEV
804
P2
P1
DEV
805 P2
P1
DEV
806 P2
P1
DEV
807 P2
P1
DEV
808 P2
P1
DEV
809 P2
P1
DEV
810 P2
P1
DEV
811P2
P1
DEV
812
P2
P1DE
V813 P2
P1DE
V814 P2
P1DE
V815 P2
P1DE
V816 P2
P1DE
V817 P2
P1DE
V818 P2
P1DE
V819P2
P1DE
V820
P2
P1
DEV
821
P2
P1
DEV
822
P2
P1
DEV
823
P2
P1
DEV
824
P2
P1
DEV
825
P2
P1
DEV
826
P2
P1
DEV
827
P2
P1
DEV
828
P2
P1
DEV
829
P2P1
DEV8 30
P2P1
DEV83 1
P2P1
DEV8 32
P2P1
DEV83 3
P2P1
DEV8 34
P2P1
DEV8 35
P2P1
DEV83 6
P2P1
DEV8 37
P2P1
DEV8 38
P2P1
DEV83 9
P2P1
DEV8 40
P2P1
DEV84 1
P2P1
DEV8 42
P2P1
DEV8 43
P2P1
DEV8 44
P2P1
DEV84 5
P2P1
DEV8 46
P2P1
DEV8 47
P2P1
DEV84 8
P2P1
DEV8 49
P2P1
DEV85 0
P2P1
DEV8 51
P2P1
DEV8 52
P2P1
DEV8 53
P2P1
DEV85 4
P2P1
DEV8 55
P2P1DEV8 56
P2P1DEV85 7
P2P1DEV8 58
P2P1DEV85 9
P2P1DEV8 60
P2P1DEV8 61
P2P1DEV8 62
P2P1DEV86 3
P2P1DEV8 64
P2P1
DEV8 65
P2P1
DEV86 6
P2P1
DEV8 67
P2P1
DEV86 8
P2P1
DEV8 69
P2P1
DEV8 70
P2P1
DEV8 71
P2P1
DEV87 2
P2P1
DEV8 73
P2P1
DEV8 74
P2P1
DEV87 5
P2P1
DEV8 76
P2P1
DEV87 7
P2P1
DEV8 78
P2P1
DEV8 79
P2P1
DEV8 80
P2P1
DEV88 1
P2P1
DEV8 82
P2P1
DEV8 83
P2P1
DEV88 4
P2P1
DEV8 85
P2P1
DEV88 6
P2P1
DEV8 87
P2P1
DEV8 88
P2P1
DEV8 89
P2P1
DEV89 0
P2P1
DEV8 91
P2P1
DEV8 92
P2P1
DEV8 93
P2P1
DEV8 94
P2P1
DEV8 95
P2P1DEV89 6
P2P1
DEV89 7
P2P1
DEV89 8
P2P1
DEV89 9
P2P1
DEV90 0
P2P1DEV90 1
P2P1
DEV90 2
P2P1
DEV90 3
P2
P1
DEV
904
P2
P1
DEV
905
P2
P1
DEV
906
P2
P1DE
V907
P2
P1
DEV
908
P2
P1
DEV
909
P2
P1
DEV
910
P2
P1DE
V911
P2
P1
DEV
912
P2
P1
DEV
913
P2
P1
DEV9
14
P2
P1DE
V915
P2
P1
DEV
918
P2
P1
DEV
919
P2
P1
DEV
920
P2P1
DEV9 22
P2P1
DEV92 3
P2P1
DEV9 24
P2P1
DEV92 5
P2P1
DEV9 26
P2P1
DEV9 27
P2P1
DEV9 28
P2P1
DEV92 9
P2P1
DEV9 30
P2P1
DEV93 1
P2
P1
DEV
932
P2
P1
DEV
933
P2
P1
DEV
934
P2
P1
DEV
935
P2
P1
DEV
936
P2
P1
DEV
937
P2
P1
DEV
938
P2
P1
DEV
939
P2
P1DE
V940P2
P1DE
V941 P2P1
DEV94 2
P2P1
DEV9 43P2P1
DEV94 4
P2P1
DEV94 5
P2P1
DEV94 6
P2P1
DEV9 47
P2
P1
DEV
948
P2
P1
DEV
949
P2P1
DEV95 0
P2P1
DEV9 51
P2P1
DEV9 52
P2P1
DEV9 53
P2P1
DEV9 54
P2
P1
DEV
955
P2P1
DEV95 6
P2P1
DEV9 57
P2P1
DEV6 5
P2P1
DEV66
P2P1
DEV18 1
P2P1
DEV18 2
P2P1
DEV28 4
P2P1
DEV9 58
P2P1
DEV9 59
P2P1
DEV96 0
P2P1
DEV9 61
P2P1
DEV9 62
P2P1
DEV96 3
P2P1
DEV96 4
P2P1
DEV9 65
P2P1
DEV96 6
P2P1
DEV9 67
P2P1
DEV96 8
P2P1
DEV9 69
P2P1
DEV9 70
P2P1
DEV9 71
P2P1
DEV97 2
P2P1
DEV97 3
P2P1
DEV64
+
1
R9
+
1
R23
+
1
R24
+
1
R2 5
+
1
R2 6
+
1
R2 7
+
1
R28
+
1
R30
+
1
R49
v (t)
p 1
scopeGnd 56
v(t)
p 2
scopeGnd 34
v (t)
p3
scopeGn d1 2
P2P1
DEV1 7
P2P1
DEV18
P2P1
DEV4 0
P2P1
DEV44
P2P1
DEV4 5
P2P1
DEV4 6
P2P1
DEV47
P2P1
DEV48
P2P1
DEV4 9
P2P1
DEV50
P2P1
DEV5 1
P2P1
DEV5 7
P2P1
DEV58
P2P1
DEV6 3
P2P1
DEV68
P2P1
DEV6 9
P2P1
DEV8 1
P2P1
DEV8 2
P2P1
DEV85
P2P1
DEV8 6
P2P1
DEV91
P2P1
DEV92
P2P1
DEV9 7
P2P1
DEV99
P2P1
DEV1 01
P2P1
DEV1 02
P2P1
DEV10 3
P2P1
DEV10 4
+
1
R2
P2
P1
DEV1
05
P2
P1
DEV
106
P2
P1
DEV1
07
+
1
R1
+
1
R3
(b) the model of the entire grounding system
Fig. 7. Model of the grounding system
disconnector
DS_CRpLp
7071DS_C
PI+
PI1 PI
+PI
2 CP+
55.4
3
TLM
1
CP+
6.16
TLM
2
PQ
Load
1
54
5MW
29M
VAR
PQ
Load
2
29
2MW
46M
VAR
PQ
Load
3
34
2MW
46M
VAR
PQ
Load
4
54
9MW
32M
VAR
PQ
Load
5
54
5MW
41M
VAR
CP+
55.4
3
TLM
3
CP+
6.16
TLM
4
CP+
77.4
3
TLM
5
CP+
8.60
TLM
6
CP+
77.4
3
TLM
7
CP+
8.60
TLM
8D
S_C R
pLp
7622
DS
_C Rp
Lp75
22
DS
_C Rp
Lp73
22
DS
_C Rp
Lp72
22
DS
_C Rp
Lp7A
22
DS
_C Rp
Lp7B
22
DS
_C Rp
Lp71
21
DS
_C Rp
Lp72
21
DS
_C Rp
Lp73
21
DS
_C Rp
Lp74
21
DS
_C Rp
Lp76
21
BUS2BUS1GIS Bus Bar
GISbusbar
7B7A_2
BUS2BUS1GIS Bus Bar
GISbusbar
7A71_2
BUS2BUS1GIS Bus Bar
GISbusbar
7172_2
BUS2BUS1GIS Bus Bar
GISbusbar
7273_2
BUS2BUS1GIS Bus Bar
GISbusbar
7B7A_1
BUS2BUS1GIS Bus Bar
GISbusbar
7A71_1
BUS2BUS1GIS Bus Bar
GISbusbar
7172_1
BUS2BUS1GIS Bus Bar
GISbusbar
7273_1
BUS2BUS1GIS Bus Bar
GISbusbar
7374_1
BUS2BUS1GIS Bus Bar
GISbusbar
7576_1
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SIN
GO
SUN
G2
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SIN
GO
SUN
G1
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SAM
CH
EON
PO2
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SAM
CH
EON
PO1
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SAM
HAE
1
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
SAM
HAE
2
BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
1 BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
2 BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
3 BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
4 BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
5 BU
S2B
US
1G
IS B
us B
ar
GIS
busb
ar
Gen
6
BUS2BUS1GIS Bus Bar
GISbusbar
7475_2
BUS2BUS1GIS Bus Bar
GISbusbar
7475_1
Rp
LpDS
_O
DSO
pen
7521
pinst./pu
7576DS_R
12
MAI
NTR
1
21
/345
SM
GEN
1
22kV
660M
VA
12
MAI
NTR
2
21
/345
SM
GEN
2
22kV
660M
VA
12
MAI
NTR
3
21
/345
SM
GEN
3
22kV
660M
VA
12
MAI
NTR
4
21
/345
SM
GEN
4
22kV
660M
VA
12
MAI
NTR
5
20
.9/3
45
pinst./pu
Gen4
pinst./pu
Gen3
pinst./pu
AUXTR4_2ND
pinst./puSSUBTR4_2ND
pinst./pu
SSUBTR6_2ND
+
0.05
nF C
3
BUS2BUS1GIS Bus Bar
GISbusbar
7576_2
+
0.05
nF C
4
+
0.05
nF C
5
+
0.05
nF C
6
+
0.05
nF C
7
+
0.05
nF C
8
LpR
pC
B_C
CBC
lose
7B00
BUS
2B
US
1G
IS B
us B
ar
GIS
busb
ar
7BG
IS
LpR
pC
B_C
CBC
lose
7A00
BUS
2B
US
1G
IS B
us B
ar
GIS
busb
ar
7AG
IS
Rp
LpDS_
C
DSC
lose
7B52
Rp
LpDS_
C
DSC
lose
7B01
Rp
LpDS_
C
DSC
lose
7A52
Rp
LpDS_
C
DSC
lose
7A01
LpR
pC
B_C
CBC
lose
7400
BUS
2B
US
1G
IS B
us B
ar
GIS
busb
ar
74G
IS
Rp
LpDS_
C
DSC
lose
7401
LpR
pC
B_C
CBC
lose
7100
BUS
2B
US
1G
IS B
us B
ar
GIS
busb
ar
71G
IS
Rp
LpDS_
C
DSC
lose
7152
Rp
LpDS_
C
DSC
lose
7101
LpR
pC
lose
Blo
ck7B
71
LpR
pC
lose
Blo
ck7A
71
LpR
pC
lose
Blo
ck71
71
LpR
pC
lose
Blo
ck72
71
LpR
pC
lose
Blo
ck72
00
LpR
pC
lose
Blo
ck72
72
LpR
pC
lose
Blo
ck73
71
LpR
pC
lose
Blo
ck73
00
LpR
pC
lose
Blo
ck73
72
LpR
pC
lose
Blo
ck74
71
LpR
pC
lose
Blo
ck75
71
LpR
pC
lose
Blo
ck75
00
LpR
pC
lose
Blo
ck76
71
LpR
pC
lose
Blo
ck76
00
LpR
pO
pen
Blo
ck
SWBl
ock_
Ope
n
7572
LpR
pO
pen
Blo
ck
SWBl
ock_
Ope
n
7672
2 3
1
6.9/
6.9/
21
AUXT
R5
2 3
1
6.9/
6.9/
21
AUXT
R4
2 3
1
6.9/
6.9/
21
AUXT
R3
2 3
1
6.9/
6.9/
21
AUXT
R2
2 3
1
6.9/
6.9/
21
AUXT
R1
BUS2BUS1GIS Bus Bar
GISbusbar
DEV1
BUS2BUS1GIS Bus Bar
GISbusbar
DEV2
BUS2BUS1GIS Bus Bar
GISbusbar
DEV3
pinst./pu76BUS_E
BUS2BUS1GIS Bus Bar
GISbusbar
DEV4
BUS2BUS1GIS Bus Bar
7374_2
GISbusbar
pinst./pu
7576DS_L
pinst./pu7576DS_C
Rp
LpDS
_CD
EV8
DSC
lose
DS_CRpLp
DEV9
12
0.48
/0.1
5
DY_
2
12
0.48
/0.1
5
DY_
1
12
0.48
/0.1
5
DY_
3
12
0.48
/0.1
5
DY_
4
12
0.48
/0.1
5
DY_
5pinst./pu
SUBTR4_2ND
pinst./puSSUBTR3_2ND
126.9/
0.48
YY6
126.9/
0.48
YY5
126.9/
0.48
YY4
126.9/
0.48
YY3
126.9/
0.48
YY2
+
20us|1E15|0
?vi
SW1
pinst./pu
Gen6
pinst./pu
AUXTR6_2ND
pinst./pu
SUBTR_2ND
pin
st./
puD
EV10
2 3
1YgYg
D_n
p1
6.
9/6.
9/21
12
0.48
/0.1
5
DY_
7
126.9/
0.48
YY1
12
20.9
/345
DY_
6
v(t)
i(t)
p3
v(t)
i(t)
p4
v(t)
i(t)
p6
v(t)
i(t)
p5
scopeTR1N_VscopeTR1N_C
scopeTR2N_VscopeTR2N_C
scopeTR4N_VscopeTR4N_C
scopeTR6N_VscopeTR6N_C
v(t)
i(t)
p7
scopeCTR1N_VscopeCTR1N_C
v(t)
i(t)
p8
scopeCTR2N_VscopeCTR2N_C
v(t)
i(t)
p9
scopeCTR3N_VscopeCTR3N_C
v(t)
i(t)
p10
scopeCTR4N_VscopeCTR4N_C
v(t)
i(t)
p11
scopeCTR5N_VscopeCTR5N_C
v(t)
i(t)
p12
scopeCTR6N_VscopeCTR6N_C
v(t)
i(t)
p1
scopeTR5N_VscopeTR5N_C
v(t)
i(t)
p2
scopeTR3N_VscopeTR3N_C
+
0.05nF C9
+
0.05nF C1
SM22
kV62
0MVA
SM1SM
22kV
620M
VA
SM2
LF Load7
184MW2MVAR
LF Load6
154MW2MVAR
LF Load8
164MW2MVAR
tml_
1_0
tml_
1_1
tml_
1_2
tml_
1_3
tml_
2_0
tml_
2_1
tml_
2_2
tml_
2_3
tml_
3_0
tml_
3_1
tml_
3_2
tml_
3_3
tml_
4_0
tml_
4_1
tml_
4_2
tml_
4_3
tml_
5_0
tml_
5_1
tml_
5_2
tml_
5_3
tml_
6_0
tml_
6_1
tml_
6_2
tml_
6_3
DEV5
full_gnd
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL1
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL2
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL3
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL4
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL5
IN_SGNIN_VAC
GND Out_Sgn
Control & DC Part
CTRL_Block
CTRL6
c
b
a
Fig. 8. 345kV thermal plant for very fast transients and lightning surges
Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant
300
3.1.2 A switching transients section In order to simulate switching transients due to a pre-
strike on the disconnector switch, the system model uses the pre-strike model mentioned previously. Fig. 9 shows the GIS part of the system model applied to the pre-strike model. The system model is same except the GIS part with the pre-strike model.
3.2 Simulation conditions
In order to analyze very fast transients, switching
transients, which occur due to disconnector switching within the system model, and lightning surges, the simulation conditions are fixed, as shown in Table 1, 2, and 3, respectively.
PI
+
PI1 PI
+
PI3 C
P+
TLM
9 55
.43
CP
+
TLM
10
6.
16
PQ
545M
W29
MVA
R
Load
9
PQ
292M
W46
MVA
R
Load
10
PQ
342M
W46
MVA
R
Load
11
PQ
549M
W32
MVA
R
Load
12
PQ
545M
W41
MVA
R
Load
13
CP
+
TLM
11 55
.43
CP
+
TLM
12
6.
16
CP
+TLM
13
77.4
3
CP
+
TLM
14
8.
60
CP
+
TLM
15 77.4
3
CP
+
TLM
16
8.
60
BUS2BUS1GIS Bus Bar
GISbusbar
DEV1+
cSW1
+
cSW2
+
cSW3
PQ
554M
W8M
VAR
Load
1
V0 mag rad
zseq1
scopeBUS_Vmag
scopeBUS_Vrad
pinst./puDEV19p
inst./puDEV20
PrestrikeCswVsw
DEV6
PrestrikeCswVsw
DEV2
PrestrikeCswVsw
DEV3
pinst./puGISBUS
BUS2BUS1GIS Bus Bar
GISbusbar
DEV7
BUS2BUS1GIS Bus Bar
GISbusbar
DEV8
a
b
c
a
b
c
Fig. 9. System model for the switching transients
Table 1. Simulation conditions for very fast transients
Time step 3ns Maximum simulation time 30us
System condition 76BUS have been de-energized Simulation condition 75-76 DS close when simulation starts
Table 2. Simulation conditions for switching transients
Time step 125ns Maximum simulation time 1.3s
System condition 76BUS have been de-energized Simulation condition 75-76 DS close when simulation starts
Table 3. Simulation conditions for switching transients
Time step 3ns Maximum simulation time 100us
Simulation condition Lightning strike transmission lines at 20us
3.3 Simulation results
3.3.1 Very fast transients (1) Analysis of the transients in the time domain Fig. 10 shows the voltage waveform, which has a 1.9pu
maximum value and a high speed oscillation, of the energized 76BUS after closing the disconnect switches (DS).
Fig. 11 shows voltage waveforms, which are different at each measuring point, for each generator. The voltage at the #4 generator terminals, close to the 75-76 DSs that caused the overvoltage, is more affected by the VFTOs than the voltage at the terminals of the other generators. Therefore, the voltage for the #4 generator is higher than
the voltages for the others. As shown in Figs. 10 and 11, overvoltages from the disconnector switching propagate through the GIS and are reflected and refracted at every transition point.
(2) Analysis of transients in the frequency domain Fig. 12 shows the frequency spectrum of the measured
voltages at each generator terminal. Due to the main frequencies of the VFT overvoltages being in the range of 100kHz to 50MHz, the simulation results shown in Fig. 12 are the same as in the theoretical studies. Additionally, since the propagation route of the traveling wave is different from the GIS layout and length, the main frequency is different from the frequency at the measuring point. Therefore, both an accurate GIS layout and length are very important for obtaining exact simulation results when a VFT is simulated with disconnector switching within a GIS. Tables 4 and 5 show the summarized the simulation results.
(a) #4 Generator (b) #6 Generator
Fig. 12. Voltage waveforms for some generators in the frequency domain
Fig. 10. Voltage waveform at 76BUS
(a) #4 Generator (b) #6 Generator
Fig. 11. Voltage waveforms for some generators in the time domain
Sang-Min Yeo and Chul-Hwan Kim
301
As shown in the simulation results below, it is clear that the overvoltages generated by disconnector switching propagate through the GIS. The propagated overvoltages affect transformers, generators and buses, especially for a bus that is energized. As mentioned before, VFTOs caused by disconnector switching have very high frequencies and propagate through the GIS and reach all pieces of equipment. Hence, these high frequency overvoltages may cause improper operation of low-voltage control circuits.
Table 4. Measured voltage at each generator
Voltage at each generator (unit : p.u.) Measured Point #1 Gen. #2 Gen. #3 Gen. #4 Gen. #6 Gen.
Max. voltage 1.184 1.311 1.377 1.336 1.111Max. voltage
deviation 0.432 0.651 0.729 0.787 0.270
Table 5. Measured voltage at each bus
Voltage at each bus (unit: p.u.) Measured Point 70BUS 71BUS 75BUS 76BUS
Max. voltage 1.27937 1.11887 1.22162 1.89149 Max. voltage
deviation 0.55189 0.29512 0.49931 1.67597
3.3.2 A switching transients
Fig. 13 shows the 3-phase instantaneous voltage waveforms and frequency spectrum for the GIS bus bar
after the disconnector switching occurred. Also shown is the slight difference in the overvoltage magnitude at the GIS bus bar, of approximately 7kV, from the magnitude of the normal voltage during disconnector switching. The dominant frequency of the transient overvoltages is 60Hz, which is the power frequency, but the disconnector switching within the GIS creates high frequency components rather than the dominant one, even if they have a relatively small magnitude.
Moreover, voltages and currents at the neutral point of the main transformer have a large magnitude due to the phase unbalance. Fig. 14 shows the voltage waveforms at the neutral points of the main transformers.
Fig. 14. Voltage waveforms at the neutral point of the main
transformer Even if the magnitudes are different at each measuring
point, the average of the neutral voltage magnitudes is approximately 15kV. As a result of the neutral voltages, the grounding system is affected and the ground voltage is temporarily changed to a non-zero voltage value.
Fig. 15 shows the waveforms of the ground voltages for the low-voltage control circuits. The duration is short, about 0.5 seconds, but the voltages have large magnitudes and high frequencies and, because of this, the control circuits would be damaged if they did not have appropriate protection devices, such as a surge protection device.
Fig. 15. Ground voltage at low-voltage control circuits
3.3.3 A lightning surge Fig. 16 shows the phase voltages at the terminals of each
generator when lightning strikes the BB #2 transmission line. The simulation results for the other transmission lines are slightly different from the results shown in Fig. 16.
As shown in Fig. 16, when the lightning surges
(a) Instantaneous voltages
(b) Frequency Spectrum
Fig. 13. 3-phase voltage at the GIS bus bar
Analysis of Transient Overvoltages within a 345kV Korean Thermal Plant
302
propagate through the GIS, the generator transformers also experience overvoltages, approximately 140kVpeak, due to lightning surges. Figs. 17-18 show the voltage waveform at the neutral point of the main transformer and ground voltage of the low-voltage control circuits, respectively.
Fig. 16. The voltage waveforms at each generator when the
lightning strikes BB #2 T/L
Fig. 17. Voltage waveforms at the neutral point of the main
transformer
Fig. 18. Ground voltage of the low-voltage control circuits
The voltages of the neutral point of the main transformer
and at the ground point of the low-voltage control circuits should be close to zero. However, each voltage has a large magnitude during a lightning surge strike, as in the case of switching transients. The magnitude at the neutral point of the transformers and at the ground point of the control circuits is approximately 250Vpeak, -580Vpeak, respectively. These magnitudes are smaller than the magnitudes of the switching transients, but the lightning surges and the magnitudes have significantly high frequencies. Therefore, several control circuits may be damaged by the overvoltages.
5. Conclusions This paper demonstrates an equivalent model for various
pieces of equipment implemented via EMTP in order to accurately simulate VFTOs by disconnector switching within GIS. Also, calculated voltages are shown in both the time and frequency domains at various measuring points.
It can be concluded from the calculated results that the VFT overvoltages via disconnector switching within GIS propagate and reach all pieces of equipment. Also, the high frequencies of the VFT overvoltage can have an impact on the low-voltage control circuits. Due to the pre-strike phenomenon that causes different reactions for each phase, the phase voltage becomes unbalanced during disconnector switching and then the generated zero sequence voltage has a large magnitude. These zero sequence voltages are revealed as neutral voltages at the neutral point of the transformer and they will affect the grounding system. The simulation results show that the switching transient overvoltages occurring via disconnector switching in GIS are smaller than ones from other origins. Also, when the lightning surge enters the various equipment pieces, such as the GIS, generators, transformers and various devices electrically connected to the GIS in thermal plant, they experience significant overvoltages similar to those stated for the previous cases, i.e. VFTs and switching transients.
However, though the magnitudes of the overvoltages are small, it is clear that overvoltages have high frequencies and can cause high voltages in the grounding system and will, therefore, damage low-voltage electronic devices.
References
[1] Salih Carsimamovic, Zijad Bajramovic, Miroslav Ljevak, Meludin Veledar, “Very Fast Electromagnetic Transients in Air Insulated Substations and Gas Insulated Substations due to Disconnector Switching”, International Symposium on Electromagnetic Compatibility, 2005. EMC 2005, vol. 2, pp. 382-387, 8-12 Aug., 2005.
[2] Z. Haznadar, S. Carsimamovic, R. Mahmutcehajic, “More Accurate Modeling of Gas Insulated Substation Components in Digital Simulations of Very Fast Electromagnetic Transients”, IEEE Trans. on Power Delivery, vol. 7, no. 1, pp. 434-441, Jan., 1992.
[3] EPRI, Electromagnetic Transients Program(EMTP) Workbook II, EPRI Final Report, EL-4651, vol. 2, June. 1986.
[4] V. Vinod Kumar, Joy Thomas M., M.S. Maidu, “Influence of Switching Conditions on the VFTO Magnitudes in a GIS”, IEEE Trans. on Power Delivery, vol. 16, no. 4, pp. 539-544, Oct., 2001
[5] Lu Tiechen, Zhang Bo, “Calculation of Very Fast Transient Overvoltages in GIS”, 2005 IEEE/PES
Sang-Min Yeo and Chul-Hwan Kim
303
Transmission and Distribution Conference & Exhibition: Asia and Pacific Dalian, China, pp. 1-5, 2005.
[6] Xuzhu Dong, Sebastian Rosado, Yilu Liu, Nien-Chung Wang, E-Leny Line, Tzong-Yih Guo, “Study of Abnormal Electrical Phenomena Effects on GSU Transformers”, IEEE Trans. on Power Delivery, vol. 18, no. 3, pp. 835-842, July, 2003.
[7] IEEE Working Group 15.08.09, Tutorial on Modeling and Analysis of System Transients using Digital Programs, IEEE PES Special Publication, 1998.
[8] D.A. Woodford, L.M. Wedepohl, “Transmission Line Energization with Breaker Pre-Strike”, 1997 Conference on Communications, Power and Computing WESCANEX '97 Proceedings, pp. 105-108, May 22-23, 1997.
[9] D.A. Woodford, L.M. Wedepohl, “Impact of Circuit Breaker Pre-Strike on Transmission Line Energization Transients”, IPST '97, Seattle, pp. 250-253, June 22-26, 1997.
[10] A. Ametani, T. Goto, S. Yoshizaki, H. Omura, H. Motoyama, “Switching Surge Characteristics in Gas-Insulated Substation”, Universities Power Engineering Conference, 2006. UPEC '06. Proceedings of the 41st International, vol. 3, pp. 941-945, Sept. 2006.
[11] A. Ametani, K. Ohtsuki, N. Nagaoka, “Switching Surge Characteristics in Gas-Insulated Substations in Particular Reference to Low-Voltage Control Circuits”, UPEC 2004, Bristol, UK, Sept., 2004.
[12] S.M. Yeo, H.C. Seo, C.H. Kim, Y.S. Lyu, B.S. Cho, “EMTP Analysis of Very Fast Transients due to Disconnector Switching in a 345kV Korean Thermal Plant”, International Conference of Electrical Engineering, Okinawa, Japan, paper no. P-093, 6-10 July, 2008.
[13] S.M. Yeo, H.C. Seo, C.H. Kim, Y.S. Lyu, B.S. Cho, “Investigation of Switching Transients due to Disconnector Switching”, International Conference of Electrical Engineering, Okinawa, Japan, paper no. O-112, 6-10 July, 2008.
[14] DCG-EMTP(Development coordination group of EMTP) Version EMTP-RV, Electromagnetic Transients Program. [Online]. Avaliable : http://www.emtp.com.
[15] F.E. Menter, L. Grcev, “EMTP-Based Model for Grounding System Analysis”, IEEE Trans. on Power Delivery, vol. 9, no. 4, pp. 1838-1849, Oct. 1994.
[16] L. Grcev, “Modelling of Grounding Systems for Better Protection of Communication Installations
against Effects from Electric Power System and Lighting”, IEE Conference INTELEC 2001, pp. 461-468, 14-18 Oct. 2001.
[17] G. Celli, F. Pilo, “A Distributed Parameter model for Grounding Systems in the PSCAD/EMTDC environment”, IEEE Power Engineering Society General Meeting, 2003, vol. 3, pp. 1650-1655, 13-17 July 2003.
[18] A. Rakotomalala, Ph. Auriol, A. Rousseau, “Lighting Distribution through Earthing Systems”, IEEE International Symposium on Electromagnetic Com- patibility, pp. 419-423, 22-26 Aug., 1994.
[19] I. Uglesic, S. Hutter, V. Milardic, I. Ivankovic, B. Filipovic-Grcic, “Electromagnetic Disturbances of the Secondary Circuits in Gas Insulated Substation due to Disconnector Switching”, International Conference on Power Systems Transients, IPST 2003 in New Orleans, USA, 2003.
Sang-Min Yeo was born in Korea, 1976. He received his B.S., M.S., and Ph.D. degrees in Electrical Engineering from Sungkyunkwan University in 1999, 2001, and 2009, respectively. Since October 2009, he joined Power & Industrial Systems R&D Center, Hyosung Corporation, Korea. His
current research interests include power system transients, modeling and simulation for FACTS/HVDC using EMTP, power system protection and computer application using EMTP, and signal processing.
Chul-Hwan Kim was born in Korea, 1961. He received his B.S., M.S., and Ph.D degrees in Electrical Engineering from Sungkyunkwan University, Korea, 1982, 1984, and 1990 respectively. In 1990 he joined Cheju National University, Cheju, Korea, as a full-time Lecturer. He has been a visiting
academic at the University of BATH, UK, in 1996, 1998, and 1999. Since March 1992, he has been a professor in the School of Information and Communication Engineering, Sungkyunkwan University, Korea. His research interests include power system protection, artificial intelligence application for protection and control, the modelling/ protection of underground cable and EMTP software.
