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TRANSIENT ELECTROMAGNETIC ENVIRONMENT OF 500KV SUBSTATIONS IN CHINA
XIANG CUI1* XIONG WU2 WEIDONG ZHANG1 JIWEI SUN3
BAOQUAN WAN2 BINXIAN LU1 GUANGZHOU ZHANG2 XUESONG GU1 XIAOWU ZHANG2
1 : North China Electric Power University 2 : Wuhan High Voltage Research Institute, State Grid Corporation of China 3 : North China Grid Company Limited, State Grid Corporation of China
(China)
SUMMARY In high voltage substations, secondary equipments placed in the switchyard and inside the control house can be highly sensitive to the transient electromagnetic disturbances due to switching operations. In order to evaluate transient electromagnetic environments and provide guidance for better immunity design of secondary equipments, it is necessary to measure and analyze these transient electromagnetic disturbances. During the last 5 years, many transient electromagnetic disturbances were measured and recorded inside nine air-insulated 500kV substations in China. An analysis program was developed and used to analyze characteristics of the disturbances. The typical characteristic parameters are summarized. Assessing the agreement between the measured transient waveforms and the characteristics of the immunity test standard waveforms in IEC61000-4-10 and IEC61000-4-12, the authors suggest that for the damped oscillatory magnetic field immunity test, adding test items with higher oscillatory frequencies, e.g. 5MHz and 10MHz, for the damped oscillatory waves immunity test, adding test items with higher common mode voltage 4kV and higher oscillatory frequencies, e.g. 6MHz and 10MHz. KEYWORDS Transient Electromagnetic Disturbance - High Voltage Substation - Electromagnetic Environment - Switching Operation
* [email protected] This work is supported by the Scientific Funds for Outstanding Young Scientists of China (No. 50325723).
1. Introduction In high voltage substations, secondary equipments placed in the switchyard and inside the control house can be highly sensitive to the transient electromagnetic disturbances due to switching operations. A lot of researchers have paid more attentions to this problem and contributed their studies for several decades [1-4]. Most of the study results were drawn on the CIGRE Guide No.124 [5]. After the publication of the Guide, new measurement campaigns were conducted and the measured data can be use to upgrade the EMC immunity standards [6-9]. With the rapid growth of China economy, the electric power generation, transmission and distribution have been speeding up in these years. The 500kV power network has become main trunk of electric power transmission in China. There are a lot of 500kV substations to be running and to be built in China now. Many new technologies especially micro electronic components, microprocessors and distributed control systems have been widely used in the secondary system of the high voltage substations. Because the micro electronic components and microprocessors are more sensitive to the transient electromagnetic disturbance due to switching operation, such as the closing/opening of circuit breaker and disconnector, and short circuit faults or lightning strikes in the substation. The electromagnetic compatibility of the secondary system has become an important problem in the design, construction and run of the substations. It is necessary to measure and understand the transient electromagnetic environment including electromagnetic radiated and conducted emissions not only to enhance the immunity of the secondary devices but also to determine the immunity requirements or EMC standards of the relay and control devices in high voltage substations. This paper summarizes some measurement campaigns conducted by the authors. Several typical transient waveforms are provided, and the characteristics of the transient waveforms are analyzed in this paper.
2. Measurement
Under the support of the State Grid Corporation of China, we have measured the transient electromagnetic environment produced during the switching operation including breaker and disconnector operations in nine 500kV substations since 2001. Some substations are conventional substations, which the relay and control devices are installed in a concentrative control room, and others are new ones where the relay and control devices are installed inside the relay cell located in 500kV switchyard. The sites visited where measurements were undertaken are listed in Table 1. The typical 500kV configuration in substation is shown in Fig. 1. Table 1: Substations visited and Line #1
500kV busbar #2 measurements undertaken. Substations Ⅰ Ⅱ Ⅲ Ⅳ
Fuxing 525/230/36 1×750 D 4/6 Xiaogan 525/230/36 1×750 D 3/5 Binhai 500/230/36 2×750 D 3/8 Baobei 500/230/36 2×750 C 6/8 Xinan* 500/-/- - D 3/-
Angezhuang 515/230/36 1×750 C 4/4 Luofang 525/230/36 1×750 D 1/7 Wujiang 505/230/36 2×750 D 2/7 Wanquan 525/230/36 1×800 C 6/4
5053 5032 5012
Transformer #1
50522
5031 5052 5011
50521
Notes:Ⅰ-System voltage, kV; Ⅱ- Transformer rate, MVA; Line #2 500kV busbar #1 Ⅲ- Conventional concentrative control substations (C) or new distributed control substations (D); ; Circuit breakers: 5011, 5012, 5031, 5032, 5052, 5053 Ⅳ- Number of 500kV/220kV output lines Disconnectors: 50521, 50522 *: Switching substation. Fig. 1 The typical 500kV configuration in substation. The measured parameters include transient electric fields, transient magnetic fields, transient voltages and transient currents. The measurement systems and the measured locations are the following: (1) Transient electric fields: The measurement system consists of a three-dimensional spherical probe, 50 meters optical fiber and a receiver. The frequency range of the system is 15Hz ~100MHz,
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the measurement range of electric field strength is beyond 30kV/m. Under the operated 500kV busbars the probe was mounted 1.5m above ground. The recorded operations are circuit breaker closing/opening 500kV power transformer, energizing and de-energizing 500kV lines without load, and disconnector closing/opening 500kV busbars without load. (2) Transient magnetic fields: The measurement system consists of a one-dimensional loop probe, 50 meters optical fiber and a receiver. The frequency range of the system is 40Hz ~100MHz, the measurement range of magnetic flux density is beyond 1100A/m. Under the operated 500kV busbars the probe was mounted 1.5m above ground. The recorded operations are circuit breaker closing/opening 500kV power transformer, energizing and de-energizing 500kV lines without load, and disconnector closing/opening 500kV busbars without load, and circuit breaker closing/opening 35kV reactors. (3) Transient voltages: The digital storage oscilloscopes were used to record the transient voltages via dividers with wide frequency range. The measured voltages were the following:
Common mode voltages at the output of the current transformer (CT) and the capacitance voltage transformer (CVT) in 500kV switchyard;
Differential mode voltages at the output of the CVT in 500kV switchyard; Common mode voltages at the terminals of CT and CVT secondary cables inside control room or
inside the relay cell located in 500kV switchyard; Differential mode voltages at the terminals of CVT secondary cables in control room or inside the
relay cell located in 500kV switchyard; Common mode voltages at the terminal of DC power supply inside the relay cell located in 500kV
switchyard. (4) Transient currents: The current clamps with wide frequency range were used to measure the
transient current transferred to the secondary coil of the CT in 500kV switchyard.
3. Measured waveforms and characteristics
Several typical measured waveforms and their spectrums are given and their characteristics are analyzed. The characteristics of the transient disturbances are mainly transient duration, rise time, peak-peak value, frequency range and dominant frequency.
3.1 Electric fields
There are 47 waveforms of transient electric fields to be measured. Among these, there are 15 waveforms due to circuit breaker operations, including closing/opening power transformer, and 500kV lines energizing /de-energizing under no-load conditions.Fig. 2 shows a waveform of electric field as a circuit breaker closing operation for energizing a power transformer. The dominant frequencies are 0.73kHz and 1.22kHz respectively.
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
-12
-10
-8
-6
-4
-2
0
2
4
6
t (ms)
E (k
V/m
)
103 104 105
10-6
10-5
10-4
10-3
10-2
f (Hz)
E (k
V/m
/Hz)
(a) Waveform (b) Spectrum
Fig. 2 Electric field as a circuit breaker closing operation for energizing a power transformer.
Fig. 3 shows a waveform of electric field as a closing operation for energizing 500kV lines. The dominant frequency is 0.27kHz.There are 32 waveforms being respect to disconnector closing/opening 500kV busbars. Several waveforms recorded repeated transients, and the number of the transient pulses is 46. Fig. 4 shows a waveform of electric field as disconnector opening 500kV busbars. Due to the restriking of the arc, there are many micropulses (about 200/s) within a waveform, i.e. macroburst. The transient electric field strength becomes stronger and stronger during the opening operations.
2
0 5 10 15 20 25 30 35 40 45 50
-15
-10
-5
0
5
10
15
t (ms)
E (k
V/m
)
0 10 20 30 40 50 60 70 80 90 100
-10
-5
0
5
10
t (ms)
E (k
V/m
)
Fig. 3 Electric field as a closing operation Fig. 4 Electric field as a disconnector opening 500kV busbar.
for energizing 500kV line.
Fig. 5 shows a transient waveform as a disconnector opening a short-section 500kV busbar. The transient duration is about 10.1μ s, the rise time is about 1.1 μ s. The peak-peak value is 10.3kV/m. The frequency range is 0~25MHz, the dominant frequencies are 0.3MHz and 1MHz.
0 2 4 6 8 10 12
0
2
4
6
8
10
t (µ s)
E (k
V/m
)
104 105 106 107 108
10-8
10-7
10-6
10-5
10-4
f (Hz)
E (k
V/m
/Hz)
(a) Waveform (b) Spectrum Fig. 5 Electric field as a disconnector opening a short- section busbar.
In order to get the statistical characteristics, all of the 46 transient spectrums are put together. In every frequency point the highest amplitude is remained to make an envelope, shown in Fig. 6. Then 20% higher values are eliminated, an envelope for the 80% remained values is also gotten and shown in Fig.6. In order to get the distributed characteristics, the probability (P) of peak-peak values (Epp) and rise times are shown in Fig. 7.
104 105 106 107 10810-7
10-6
10-5
10-4
10-3
f (Hz)
E (k
V/m
/Hz)
100% Value Envelope 80% Value Envelope
Fig. 6 100% highest value envelope and 80% value envelope.
0 2 4 6 8 10 12 14 16 18 200
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Epp (kV/m)
P
0 1 2 3 4 5 6 7 8 9 100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
tr (µs)
P
(a) Peak-peak value (b) Rise time
Fig. 7 The probability (P) of Epp and rise time in respect to disconnector operation.
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3.2 Magnetic fields
There are 48 waveforms of transient magnetic fields to be measured. Among these, there are 35 waveforms due to circuit breaker operations of 500kV lines energizing /de-energizing under no-load conditions. Typical waveform indicates the transient duration is about 25μs, the rise time is about
0.5 μ s. The peak-peak value is 84.6A/m. The frequency range is 0~25MHz, the dominant frequencies are 0.83MHz, 1.32MHz and 4.53MHz respectively.
There are 7 waveforms due to disconnector closing/opening 500kV busbars. Fig. 8 shows the waveform of magnetic field as a disconnetor closing 500kV busbars. The transient duration is about 20μs, the rise time is about 0.25μs. The peak-peak value is 149A/m. The frequency range is 0~40MHz, the dominant frequencies are 0.55MHz, 1MHz and about 10MHz respectively.
2 4 6 8 10 12 14 16-150
-100
-50
0
50
100
150
t (µ s)
H (A
/m)
105 106 10710-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
f (Hz)
H (A
/m/H
z)
(a) Waveform (b) Spectrum
Fig. 8 Magnetic field as a disconnetor closing 500kV busbar.
There are 6 waveforms due to circuit breaker closing/opening 35kV reactors. Fig. 9 shows the waveform of magnetic field as a circuit breaker closing 35kV a reactor. The transient duration is about 2μs, the rise time is about 0.07μs. The peak value is 40A/m. The frequency range is 0~60MHz, the dominant frequencies are 5~8MHz and 20~40MHz respectively.
0 0.5 1 1.5 2 2.5-30
-20
-10
0
10
20
30
40
t (µ s)
H (A
/m)
106 107 108 10910-10
10-9
10-8
10-7
10-6
10-5
10-4
f (Hz)
H (A
/m/H
z)
(a) Waveform (b) Spectrum
Fig. 9 Magnetic field as a circuit breaker closing 35kV a reactor.
3.3 Voltages
There are 125 waveforms of transient voltages to be measured at the outputs of CVT and CT in 500kV switchyard. We also obtained 112 waveforms of transient voltages at the terminals of secondary cables in the control room. All of the measured waveforms were analyzed as the following: (1) The 21 waveforms are differential mode voltages measured at the outputs of CVT in 500kV switchyard for taking 500kV lines energizing under no-load conditions. The typical peak value is 160V. (2) The 104 waveforms are common mode voltage measured at the outputs of CVT and CT in
4
500kV switchyard: Fig. 10 shows a waveform of taking 500kV lines energizing under no-load conditions. The transient duration is about 10μs. The peak-peak value is 6.31kV. The frequency range is 0~11MHz, the dominant frequencies are 0.63MHz, 3.22MHz and 6.34MHz respectively. Also, in order to get the statistical characteristics, all of the 104 transient spectrums are put together. In every frequency point the highest amplitude is remained to make an envelope, shown in Fig. 11. Then 20% higher values are eliminated, an envelope for the 80% remained values is also shown in Fig. 12. In order to get the distributed characteristics of the measured data, the probability versus peak-peak values is shown in Fig. 12. (3) The 9 waveforms are differential mode voltage measured at the terminals of the CVT secondary cables inside the control room or inside the relay cell located in 500kV switchyard. Fig. 13 shows a waveform of energizing 500kV lines under no-load conditions. The transient duration is about 10μs. The peak-peak value is 256V. The Frequency range is 0~10MHz, the dominant frequencies are 0.31MHz, 1.16MHz and 4.34MHz respectively. (4) The 91 waveforms are common mode voltage measured at the terminals of the CVT and CT secondary cables in the control room or inside the relay cell located in 500kV switchyard. Fig. 14 shows a waveform of energizing 500kV line under no-load condition. The transient duration is about 10μs. The peak value is 906.8V. The frequency range is 0~4MHz, the dominant frequencies are 0.49MHz, 1.32MHz and 2.34MHz respectively. (5) The 12 waveforms are common mode voltage measured at the terminals of the DC and AC power supply for secondary cable inside the relay cell located in 500kV switchyard. Fig. 15 shows a waveform of energizing 500kV line under no-load condition. The transient duration is about 10μs. The peak-peak value is 13V. The frequency range is 0~20MHz, the dominant frequencies are 0.88MHz, 6MHz and 13.6MHz respectively.
0 2 4 6 8 10 12 14 16 18 20-4000
-3000
-2000
-1000
0
1000
2000
3000
t (µ s)
u (V
)
104
105
106
107
108
10-8
10-7
10-6
10-5
10-4
10-3
10-2
f (Hz)
U (V
/Hz)
(a) Waveform (b) Spectrum
Fig. 10 Common mode voltage of energizing 500kV lines under no-load condition.
104 105 106 107 10810-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
f (Hz)
U (V
/Hz)
100% Value Envelope 80% Value Envelope
0 2 4 6 8 10 12 14 16 18 200
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Upp (kV)
P
Fig. 11 100% highest value envelope and 80% Fig. 12 The probability (P) of Upp in respect to
value envelope. disconnector operation.
5
0 2 4 6 8 10 12 14 16-200
-150
-100
-50
0
50
100
150
200
t (µ s)
u (V
)
105
106
107
108
10-8
10-7
10-6
10-5
10-4
10-3
f (Hz)
U (V
/Hz)
(a) Waveform (b) Spectrum
Fig. 13 Differential mode voltage of energizing a 500kV line under no-load condition.
0 2 4 6 8 10 12 14 16 18 20-1000
-800
-600
-400
-200
0
200
400
600
800
t (µ s)
u (V
)
104
105
106
107
108
10-7
10-6
10-5
10-4
10-3
10-2
f (Hz)
U (V
/Hz)
(a) Waveform (b) Spectrum
Fig. 14 Common mode voltage of energizing a 500kV line under no-load condition.
0 1 2 3 4 5 6 7 8 9 10-8
-6
-4
-2
0
2
4
6
8
t (µ s)
u (V
)
104 105 106 107 10810-9
10-8
10-7
10-6
10-5
f (Hz)
U (V
/Hz)
(a) Waveform (b) Spectrum
Fig. 15 Common mode voltage of AC power supply for secondary cable inside the relay cell located in 500kV switchyard. In addition, four 350m shielded secondary cables with the shield different grounding forms were set along a cable channel from 500kV switchyard to the control room in order to further compare the difference of different grounding forms of the shield. The transient voltages induced on the cables were measured at the end of the control room, including common mode and differential mode. The grounding forms of the shield of four cables are the following:
No.1: Both the ends in 500kV switchyard and in the control room were grounded; No.2: Only the end in the control room was grounded; No.3: Only the end in 500kV switchyard was grounded; No.4: Both the ends in 500kV switchyard and in the control room were floating.
The operations were circuit breaker energizing/de-energizing 500kV lines under no-load conditions and the operations were repeated three times. Table 2 shows one group of peak-peak values in respect to circuit breaker closing operations. The limited data indicate that for common mode voltages the highest peak-peak value takes place in No.4, i.e. both the ends in 500kV switchyard and in the control
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room were floating. However for differential mode voltages the highest peak-peak value takes place in No.3, i.e. only the end in 500kV switchyard was grounded. From EMI point of view, the No. 1 grounding form should be better and suggest to be selected to prevent the transient disturbance. Table 2: Upp at the ends of the shielded cable in the control room in respect to circuit breaker closing operations.
Voltage (V) No.1 No.2 No.3 No.4 Common mode 700 800 2500 9000
Differential mode 22 24 485 110
3.4 Currents
There are 12 waveforms of differential mode transient currents to be measured at the outputs and CT in 500kV switchyard. Fig. 16 shows a current waveform due to disconnector closing a 500kV busbars. The transient duration is about 15μs. The peak value is 15A. The frequency range is 0.1~2MHz, the dominant frequencies are 0.3~0.4MHz and 1.1~2.2MHz respectively.
0 10 20 30 40 50 60-15
-10
-5
0
5
10
15
20
t (µ s)
I (A
)
105 106 107 10810-8
10-7
10-6
10-5
10-4
f (Hz)
I (A
/Hz)
(a) Waveform (b) Spectrum
Fig. 16 Differential mode current in respect todisconnector closing operation.
4. Conclusions and suggestions
The transient disturbances were measured during the switching operations in nine 500kV substations in China. Some typical waveforms are given and the data are analyzed. The typical characteristic parameters are summarized as follows:
(1) Electric fields: The maximum peak-peak value is up to 18kV/m, the 10% peak-peak values are between 8kV/m~14kV/m. The 40% rise times of the measured electric fields are from 1µs to 3µs. The dominant frequencies are from 0.1MHz to 5MHz. The analysis results indicate that the worst case takes place in disconnector operations. Although the transient electric field strength is high, it is relatively easy to be shielded.
(2) Magnetic fields: For the disconnector operations, the maximum peak-peak value is 149A/m, the rise time is about 0.1µs~2µs, the dominant frequencies are from 0.5MHz to 1MHz and the highest dominant frequency is up to 10MHz. There are higher frequencies for the circuit breaker operations, but the strength is lower than the disconnector operations. The highest dominant frequency take place in the circuit breaker operating 35kV reactors, but the transient duration is shorter and the strength is lower. So the worst case takes place in also the disconnector operations. In the standard IEC61000-4-10 [10], the peak value of the highest level for damped oscillatory magnetic field immunity test is 100A/m with oscillatory frequencies 0.1MHz and 1MHz. Comparing these parameters with the measured results, we suggest adding test items with higher oscillatory frequencies, e.g. 5MHz and 10MHz.
(3) Voltages: For the transient voltages measured in 500kV switchyard, the maximum peak-peak value of differential mode voltages is 180V and the dominant frequency is 0.25MHz. The maximum peak-peak value of common mode voltages is 15.9kV and the highest dominant frequency is 6.4MHz. For the transient voltage measured in the relay cell installed in 500kV switchyard, the maximum peak-peak value of differential mode voltages is 348V and some dominant frequencies are from 0.3MHz to
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4.3MHz. The maximum peak-peak value of common mode voltages is 6.4kV. The dominant frequency is 1MHz and the highest frequency is near 10MHz. In the standard IEC61000-4-12, the peak value of the highest level for damped oscillatory waves immunity test is common mode voltage 2.5kV with oscillatory frequencies 0.1MHz and 1MHz. Comparing these parameters with the measured results, we suggest adding test items with higher common mode voltage 4kV and higher oscillatory frequencies, e.g. 6MHz and 10MHz.
(4) Currents: There were large discrepancies in the recorded data. Typically, the transient durations are 10~15μs. The peak values are 15~40A. The frequency range is 0.1~5MHz, the dominant frequencies are 0.3~0.4MHz, 1~2MHz and some up to 10MHz.
Acknowledgments
This work is supported by the Scientific Funds for Outstanding Young Scientists of China (No. 50325723). The authors are also grateful for the technical and financial support provided by the State Grid Corporation of China and the electric utilities who hosted the tests. BIBLIOGRAPHY [1] F.M.Tesche. “Coupling models for transient electromagnetic field disturbances on electric power
systems” (CIGRE Symposium, Lausanne, Paper 200-01, 1993) [2] K.Feser, W.Köhler. “Measurement of fast transients in HV substations” (CIGRE Symposium,
Lausanne, Paper 500-07, 1993) [3] C.M.Wiggins, D.E.Thomas, F.S.Nickel, T.M.Salas, S.E.Wright. “Transient electromagnetic
interference in substations” (IEEE Transactions on Power Delivery, Vol.9, No.4, pp1869-1884, October 1994)
[4] M.Ianoz, L.Dellera, C.A.Nucci, L.Quinchon. “Modeling of fast transient effects in power networks and substations” (CIGRE Session, Lausanne, Paper 36-204, 1996)
[5] CIGRE WG 36.04. “Guide on EMC in power plants and substations” (CIGRE Guide No.124, December 1997)
[6] M.G. Stewart, W.H.Siew, K.F.Walker, B.L.Shen, C.S.Barrack, L.C.Campbell, F.C.Muir. “Conducted immunity requirements for equipment operational during high voltage network switching operations” (IEE Proceedings on Generation, Transmission and Distribution, Vol.148, No.5, pp391-396, September 2001)
[7] M.G. Stewart, W.H.Siew, K.F.Walker, B.L.Shen, C.S.Barrack, L.C.Campbell, F.C.Muir. “Radiated immunity requirements for equipment operational during high voltage network switching operations” (IEE Proceedings on Generation, Transmission and Distribution, Vol.148, No.6, pp610-614, November 2001)
[8] C.Imposimato, J.Hoeffelman, A.Eriksson, W.H.Siew, P.H.Pretorius, P.S.Wong. “EMI characterization of HVAC substations-updated data and influence on immunity assessment” (CIGRE Session, Paper 36-108, 2002)
[9] Weidong Zhang, Xiang Cui, Shuang Wang, Xuesong Gu. “Measurement and analysis of switching transients in 500kV substations” (Asia-Pacific Conference on Environmental Electromagnetics, Hangzhou, 2003.11, pp391~393)
[10] IEC61000-4 international standard --- testing and measurement techniques.
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