J Electr Eng Technol.

2015; 10(4): 1773-1779 ISSN(Print) 1975-0102

http://dx.doi.org/10.5370/JEET.2015.10.4.1773 ISSN(Online) 2093-7423

Comparison of Insulation Coordination Between ±800kV and ±1100kV

UHVDC Systems

Dong-ju Wang* and Hao Zhou†

Abstract – Insulation coordination is a key problem in UHVDC systems in terms of safety and cost.
Although high-voltage ±1100kV UHVDC projects are being planned in China, the characteristics and
key points of high-voltage systems have not yet been analyzed. This study aims to improve the safe,
effective operation of these high-voltage power transmission systems. First, we analyzed two typical
insulation coordination schemes used in ±800kV UHVDC systems in China. Next, we used the two
typical ±800kV insulation coordination schemes as a reference to analyze the ±1100kV UHVDC
system. Finally, we compared these schemes and proposed an effective insulation coordination
solution, as well as developing principles for ±1100kV UHVDC systems. Our findings indicate that the
points enduring the highest voltage in the system should be protected separately by special arresters.
Our analysis of the insulation coordination of ±800kV and ±1100kV UHVDC systems concluded that,
in ±1100kV UHVDC systems, the main goal of insulation coordination is to lower the insulation level
of points enduring the highest voltage. However, in a ±800kV UHVDC system, the main goal is to
reduce the cost of manufacture for arresters, as well as the space occupation in the valve hall, with an
acceptable insulation level.

Keywords: Insulation coordination, UHVDC, Arrester scheme, Insulation level, Protection level,
Insulation margin

1. Introduction Since the development of HVDC transmission systems in

the 1950s, valuable contributions to insulation coordination
As China undergoes rapid development, there is a for HVDC systems have already been made, most of
growing demand for power. Therefore, there is an increasing which were summed up from operational experiences, and
need for higher power transmission capacity and longer protection devices involved valve type lightning arresters.
transmission distances. To meet this demand, five ±800kV Since the early 1980s, attention was mainly devoted to
UHVDC power transmission projects have been put into digital simulation of surges and the development and
operation. More transmission projects with higher voltage application of metallic oxide gapless surge arresters, due to
levels of ±1100kV UHVDC are also planned. For safe their excellent protection properties. After 1990s, several
and effective installation and operation, it is important to studies have focused on insulation coordination for these
study their insulation coordination design, the key technology three UHVDC projects [4, 5]. Other studies have discussed
in a ±1100kV UHVDC system. different arrester configurations for ±1100kV UHVDC
The study of insulation coordination is fundamental to projects [6, 7].
power transmission projects, as it defines the technical This study analyzes and compares the insulation
requirements to ensure the safety and economical perfor- coordination of ±800kV UHVDC and ±1100kV UHVDC
mance of these power systems. With higher system voltage systems, based on the overvoltage simulation results of 3
levels, the insulation coordination design becomes even typical UHVDC power transmission projects in China: the
more important. Particularly for UHVDC transmission ±800kV Xiangjiaba-Shanghai UHVDC project, the ±800
systems, with the highest voltage level in HVDC kV Yunnan-Guangdong UHVDC project, and the ±1100kV
transmission in the world, a sound insulation coordination Zhundong-Sichuan UHVDC project.
design not only ensures the project’s safety in operation, In this study, we first compare two typical types of
but also lowers construction costs [1-3]. A reasonable insulation coordination within the ±800kV Xiangjiaba-
insulation coordination solution can reduce the insulation Shanghai UHVDC project and the ±800kV Yunnan-
requirements of equipment, especially for high-voltage Guangdong UHVDC project. Next, we discuss key issues
conditions. in arrester configurations and the insulation coordination
† Corresponding Author: College of Electrical Engineering, Zhejiang of UHVDC systems. Finally, we propose a reasonable
University, China. (zhouhao_ee@zju.edu.cn) insulation coordination solution, as well as principles for
* College of Electrical Engineering, Zhejiang University, China. ±1100kV UHVDC systems.
(shuwei1204@163.com)
Received: April 22, 2014; Accepted: February 27, 2015 The remainder of this article is organized as follows:

1773
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 Comparison of Insulation Coordination Between ±800kV and ±1100kV UHVDC Systems

Section II presents the arrester configuration for UHVDC Siemens designed the arrester scheme for the Yunnan-
systems. Section III introduces the insulation coordination Guangdong ±800kV UHVDC project. The differences
in the ±800kV Xiangjiaba-Shanghai UHVDC project and between these two configurations are as follows: in ABB’s
the ±800kV Yunnan-Guangdong UHVDC project. Section design, the top of converters (point 5 in Fig. 1) is directly
IV discusses the insulation coordination focal points in protected by arrester CBH, and point 1 is protected by
UHVDC projects. Section V analyzes different arrester arrester MH and V2 in series. However, in Siemens’ design,
configurations for the Zhundong-Sichuan UHVDC project, point 1 is directly protected by arrester A2, and point 5 is
compared to results from former sections. Finally, section protected by arrester CB1A and C2 in a series.
VI provides conclusions. The complete arrester configurations for the two projects
are shown in the following figures. Fig. 1 presents the
arrester configuration for the ±800kV Xiangjiaba-Shanghai
2. Arrester Configuration in UHVDC UHVDC project, and Fig. 2 presents the arrester con-
Systems figuration for the ±800kV Yunnan-Guangdong UHVDC
project. The terms found within the each figure are defined
Overvoltage, especially switching overvoltage, mainly in Table 1.
determines insulation coordination. In UHVDC systems, It is evident that the main parts of the arrester
arresters are always used to restrict overvoltage, and
arrester configuration is an important part of insulation
coordination [8-10].
The basic principles of arrester configurations are as
follows:
1) The insulation at the AC side of the converter
transformer is protected by AC arresters, while the
DC side is protected by DC arresters;
2) Some important equipment at the converter station,
such as converter transformers, valves, and so on, is
directly protected by nearby arresters;
3) For other equipment that is not directly protected by a
single arrester, protection can be achieved with
several arresters connected in a series; for example,
the phase-to-earth insulation of a wall bushing at the
valve side of the converter transformer can be
protected by arresters connected in a series.
Fig. 1. Arrester scheme in the ±800kV Xiangjiaba-Shanghai
UHVDC project
3. Insulation Coordination in ±800kV UHVDC
Systems

This section introduces arrester configurations for the

two projects under review: the Xiangjiaba-Shanghai ±800
kV UHVDC project and the ±800kV Yunnan-Guangdong
UHVDC project. Based on the arrester configuration and
overvoltage simulation results from these two projects, we
then propose the calculated protection performance of
surge arresters in converter stations. Finally, we present the
protection and insulation levels for equipment at these
converter stations.

3.1 Arrester scheme

Five ±800kV UHVDC power transmission projects

have already been completed and put into operation in
China. There are two typical arrester configurations in
these projects. ABB designed the arrester scheme for the Fig. 2. Arrester scheme in the ±800kV Yunnan-Guangdong
Xiangjiaba-Shanghai ±800kV UHVDC project, and UHVDC project

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 Dong-ju Wang and Hao Zhou

Table 1. Definition of arresters for converter stations required to place these arresters.
In this case, the utilization rate of each A2 arrester is
Arresters Description
only one third, since the valves are equal in conduction in
A AC bus arrester
turns at working time. This rate is lower than that of
V11/V12/V2/V3 Valve arrester
Upper/Lower 12-pulse converter unit with 6-pulse arrester MH in the Xiangjiaba-Shanghai project. To reduce
MH/ML/M1 the protection level accordingly, the CCOV (Crest value of
bridge arrester
CBH
DC bus arrester of upper 12-pulse converter group Continuous Operating Voltage) of arrester A2 can be lower,
(to earth)
due to the low utilization rate.
DC bus arrester of the connection bus between the
A2 High Voltage (HV) Y/Y converter transformer and
the valve 3.3.2 Point 5
CBL2/CB1A DC bus arrester between the two 12-pulse groups
CBN1/CBN2/E1H Neutral bus arrester at the valve side In the Xiangjiaba-Shanghai project, the top of the upper
DB1/DB2/DB/DL DC pole bus/line arrester 12-pulse converter group (point 5 in Fig. 1) is directly
DR/SR1/SR2 Parallel arrester of smoothing reactors protected by arrester CBH. However, in the Yunnan-
E/E2/E2H Neutral bus arrester Guangdong project, it is protected by arresters CB1A and
EM Metallic return bus arrester C2 in a series. The former’s advantage is that the protection
EL Electrode line arrester level of the DC bus at point 5 could be lower than in the
C2 Arrester of upper 12-pulse converter group latter. The shortcoming is that an arrester CBH is needed,
requiring more space.
configurations for the ±800kV Xiangjiaba-Shanghai and 3.2.3 Point 6
Yunnan-Guangdong UHVDC projects are similar, except
for the arresters positioned to protect four different parts: In the Xiangjiaba-Shanghai project, the DC bus between
the top of the upper 12-pulse converter group (point 5 in the 6-pulse bridges in the upper 12-pulse converter (point 6
Fig. 1 and Fig. 2); two sides of the upper 12-pulse in Fig. 1) is directly protected by the arrester MH. However,
converter group (points 5 to 7); the 6-pulse bridge within in the Yunnan-Guangdong project, the DC bus is protected
the higher 12-pulse converter (point 6); and the connection by arresters CB1A and V2 in a series. Similar to the
bus between the High Voltage (HV) Y/Y converter description above for point 5, the former’s advantage is
transformer and the valve (point 1). The next section that the protection level of the DC bus at point 6 could be
introduces various parts of the arrester schemes. lower than the latter, and the shortcoming is that arrester
MH is needed, which requires more space.
3.2 Differences in arrester configurations for the
Xiangjiaba-Shanghai and Yunnan-Guangdong 3.2.4 Points 5 to 7
UHVDC projects
In the Xiangjiaba-Shanghai project, valve arresters in a
series protect the two sides of the upper 12-pulse converter
The arrester configurations that protect points 1, 5, 6,
group (points 5 to 7). The underlying principle is that at
and 5 to 7 in Fig. 1 and Fig. 2 differ in these two projects,
least one valve out of three is in conduction when the
as follows:
converter is working. This means that the protection level
of the upper 12-pulse converter group is equal to that of the
3.2.1 Point 1
V11 and V2 valve arresters. In the Yunnan-Guangdong
In the ±800kV Xiangjiaba-Shanghai UHVDC project, project, arrester C2 protects the converter directly, making
the connection bus between the High Voltage (HV) Y/Y the protection level lower than that of the Xiangjiaba
converter transformer and the valve (point 1 in Fig. 1) is project. The system is also in operation through a half-pole
protected by arresters MH and V2 in a series. However, in mode with the upper 12-pulse converter, which is protected
the ±800kV Yunnan-Guangdong UHVDC project, arrester by C2 in the Yunnan-Guangdong project and by CBH in
A2 protects the bus directly. the Xiangjiaba-Shanghai project. In this case, the latter is
The advantage of the former is that there is only one safer than the former. Again, however, an arrester C2 is
arrester (MH), which requires less space in the valve hall needed, which requires more space.
and is therefore more economical. However, the downside
to this configuration is that the protection level of arresters 3.3 Insulation margin between protection level and
MH and V2 in a series is higher than that of arrester A2. insulation level
Thus, the requirement for a converter transformer bus at
point 1 is higher. In contrast, the latter’s requirement for a The protection levels of arresters can be obtained from
converter transformer bushing at point 1 is lower. However, results of the overvoltage simulation. However, the
3 A2 arresters are needed for the 3 phases of the converter insulation levels of equipment protected by arresters should
transformer. Therefore, more space in the valve hall is be higher than the protection level, in consideration of the

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 Comparison of Insulation Coordination Between ±800kV and ±1100kV UHVDC Systems

insulation performance loss from insulation material burn- Table 4. Protection and Insulation Levels in ±800kV
in, arrester burn-in, weather factors such as rain, fog and Xiangjiaba-Shanghai UHVDC projects
moisture, and environmental factors such as pollution LIPL/SIPL LIWL/SIWL Marg
and high altitude. Therefore, the required insulation levels Pos Protected By
(kV) (kV) (%)
of equipment may be obtained by multiplying extra 1 MH+V2 1454/1386 1800/1600 24/16
coefficients according to the different equipment and surge 2 CBL2+V2 1087/1079 1400/1300 29/20
3 ML+V2 813/871 1050/1050 29/21
types based on these protection levels. Such coefficients
4 CBN1+V2 826/823 1050/1050 27/28
are called insulation margin coefficients, and the margin 5 CBH 1426/1385 1800/1600 26/16
is always expressed in a percentage, called the insulation 6 MH 1078/1027 1350/1200 25/17
margin. An evaluation of the insulation margin in each 7 CBL2 752/717 950/850 26/19
UHVDC system is provided below. 8 ML 495/485 650/600 31/24
An appropriate insulation margin is important to 9 CBN1/CBN2 458/437 550/550 20/26
UHVDC systems. Small insulation margins make the 10 DB 1625/1391 1950/1600 20/15
12 Min(E,EM,EL) 386/341 500/450 30/32
system unsafe, but large margins waste manufacturing cost.
Therefore, the characteristics of the equipment, as well as
the environment in which it is installed, should be taken Table 5. Protection and Insulation Levels in ±800kV
into consideration. Yunnan-Guangdong UHVDC projects
As a reference, the insulation margins in HVDC systems Pos Protected By
LIPL/SIPL LIWL/SIWL Marg
are listed in Table 2 [11]. (kV) (kV) (%)
1 A2 1344/1344 1800/1600 34/19
2 CB1A+V3 -/1101 1550/1300 -/18
Table 2. Insulation margin in HVDC systems 3 M1+V3 -/830 1300/1050 -/27
Insulation Margin 4 E1+V3 -/631 950/750 -/19
Equipment 5 CB1A+C2 -/1412 1800/1600 -/19
Switching Lightning Fast Transient
Valve 15% 15% 20% 6 CB1A+V3 -/1101 1550/1300 -/18
Converter transformer 15% 20% 25% 7 CB1A 791/706 1175/950 49/35
Smooth reactor 15% 20% 25% 8 M1 435/435 750/550 72/26
Equipment in valve hall 15% 15% 20% 9 E1 320/263 450/325 41/24
Equipment in DC yard 15% 20% 25% 10 D 1579/1328 1950/1600 23/20
12 E2 320/263 450/325 41/24

In UHVDC systems, thyristor valves are better designed

and manufactured, the valve control system is more
advanced, and the environment within the valve hall is 4. Key Points of Insulation Coordination
maintained with more stability than those in HVDC in UHVDC Projects
systems. Furthermore, a lower valve insulation level
reduces costs for valve hall construction, lowering the From the two typical arrester schemes introduced in
valve insulation margin compared to that of HVDC section 3, it can be concluded that all valves and every
systems. Table 3 lists the insulation margins in UHVDC point of junction within converter stations should be
systems. protected by arresters, either directly or indirectly. In
addition, this protection should consist of no more than 2
Table 3. Insulation margin in UHVDC systems arresters.
The higher the insulation level of the equipment, the
Insulation Margin
Equipment
Switching Lightning Fast Transient
greater the manufacturing costs, especially for UHVDC
Valve 10% 10% 15% systems. Points 1, 5, 10, and 12 are the highest insulation
Converter transformer 15% 20% 25% level points in UHVDC systems. The rated voltage at these
Smooth reactor 15% 20% 25% points is much higher than that of ±500kV HVDC systems.
Equipment in valve hall 15% 15% 20% Therefore, insulation levels at these points are the focal
Equipment in DC yard 15% 20% 25% points for insulation coordination of UHVDC systems.
Overvoltage on these points should be as low as possible
3.4 Protection and insulation levels in Xiangjiaba- so that the insulation level of these points can be much
Shanghai and Yunnan-Guangdong UHVDC lower.
projects Moreover, attention should also be paid to points 2 and 6,
whose operating voltage is lower than that of those points
Tables 4 and 5 display protection levels and insulation above, but higher than other points, except for points 1 and
levels in the Xiangjiaba-Shanghai and Yunnan-Guangdong 5. Lowering the insulation level of these points also helps
UHVDC projects, according to arrester scheme and reduce equipment manufacturing cost and improves the
overvoltage simulation results [12]. stability of the UHVDC system.

1776 │ J Electr Eng Technol.2015; 10(4): 1773-1779

 Dong-ju Wang and Hao Zhou

The operating voltages of other points are lower, while Table 6. Protection and Insulation Levels in the ±1100kV
the equipment at these points is easier to manufacture than Zhundong-Sichuan UHVDC project with arrester
for the aforementioned points in section 4. The rated configuration of the Xiangjiaba-Shanghai UHVDC
operating voltage of the neutral bus is the lowest in the project.
UHVDC system. It is always less than 50kV. However, the LIPL/SIPL LIWL/SIWL Marg
Pos Protected By
protection levels of the arresters E, EM EL, E1 and E2 (kV) (kV) (%)
installed on the neutral bus are much higher than the rated 1 MH+V2 2037/1945 2500/2250 25/16
operation voltage. This reduces the difficulty of the neutral 2 CBL2+V2 1577/1563 1950/1800 24/15
3 ML+V2 1227/1230 1550/1550 26/26
bus arrester design and raises reliability. When the neutral 4 CBN1+V2 1004/1011 1300/1200 29/19
bus insulation level is lower, it is more easily threatened by 5 CBH 2038/1946 2500/2250 23/16
overvoltage, reducing its reliability. In contrast, a higher 6 MH 1504/1436 1850/1700 23/18
neutral bus insulation level can naturally prevent lower 7 CBL2 1031/984 1300/1200 26/22
overvoltage, as is the case with a majority of overvoltage 8 ML 681/651 850/850 25/31
cases in operation. 9 CBN1/CBN2 458/432 550/550 20/27
10 DB 2162/1859 2600/2150 20/16
The insulation level of the neutral bus should be
12 Min(E,EM,EL) 478/380 650/450 36/18
appropriately high. This can improve reliability of the
UHVDC system, while at the same time limiting the cost
Table 7. Protection and Insulation Levels in the ±1100kV
of equipment manufacture for the neutral bus.
Zhundong-Sichuan UHVDC project with arrester
Once a proper protection level of neutral bus arresters
configuration of the Yunnan-Guangdong UHVDC
is selected, the most important factor is selection of an
project.
arrester’s energy capacity to absorb overvoltage energy.
In conclusion, the focal point of UHVDC system LIPL/SIPL LIWL/SIWL Marg
Pos Protected By
(kV) (kV) (%)
insulation coordination is protection for points where 1 A2 1837/1819 2250/2100 22/15
operating voltage is higher, such as points 1, 2, 5, 6, 10, 2 CB1A+V3 1575/1548 1950/1850 24/20
and so on. The insulation levels of equipment at these 3 M1+V3 1181/1187 1550/1400 31/18
points should be carefully considered and properly designed. 4 E1+V3 958/996 1200/1200 25/20
Energy capacity design is the most important factor to 5 CB1A+C2 2162/1859 2600/2150 20/16
consider for neutral bus arresters. 6 CB1A+V3 1575/1548 1950/1850 24/20
7 CB1A 1031/984 1300/1200 26/22
Based on this conclusion, the next section details
8 M1 637/623 850/750 33/20
insulation coordination in ±1100kV UHVDC systems. 9 E1 414/432 550/550 33/27
10 D 2162/1859 2600/2150 20/16
12 E2 489/389 650/550 33/41
5. Insulation Coordination in ±1100kV UHVDC
Systems It is evident that the protection and insulation levels of
±1100kV UHVDC systems are very high. Furthermore,
According to the plan, the Zhundong-Sichuan ±1100kV protection levels are in proportion to the system’s rated
UHVDC bipolar power transmission project has a rated voltage. Compared to ±800kV UHVDC systems, there are
capacity of 10450 MW, a rated DC voltage of 1100kV, and 2 differences in ±1100kV UHVDC systems:
a rated DC current of 4750A. 1. The insulation margins in ±1100kV UHVDC systems
Compared with ±800kV UHVDC systems, the rated are lower than those in the ±800kV systems, especially
voltage of ±1100kV systems is much higher, highlighting at points 1, 5, and 10.
the problem of insulation level design. This problem then 2. Under different arrester configurations, points 1 and 5
affects the details of insulation coordination design. do not share the same insulation levels as the ±800kV
UHVDC systems.
5.1 Analysis of the Arrester Scheme in ±1100kV
UHVDC Systems As discussed in section 4, the insulation of points 1, 2, 5,
6, and 10 is the key component of the ±1100kV UHVDC
To design the arrester scheme, we can first refer to systems. It is important to limit the insulation level of
±800kV UHVDC systems. Based on conclusions in Section these points to as low a level as possible. Table 6 and 7
4, Section 5 focuses on the insulation levels of points 1, demonstrate this, as follows:
2, 5, 6, and 10. Based on arrester configurations of the
±800kV Xiangjiaba-Shanghai and Yunnan-Guangdong 1. Under the arrester configuration of the Xiangjiaba-
UHVDC projects, protection and insulation levels calculation Shanghai project, the insulation level of point 1 is
results are listed in Tables 6 and 7, respectively. higher than that under the arrester configuration of the
Yunnan-Guangdong project. This is because there is

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 Comparison of Insulation Coordination Between ±800kV and ±1100kV UHVDC Systems

no arrester installed at point 1 in the former, but there the advantages of these two arrester configurations, the
is an arrester (A2) installed at point 1 in the latter. suggested arrester scheme for ±1100kV UHVDC systems
Arrester A2 only endures the highest voltage for can be designed based on the Xiangjiaba-Shanghai project,
about half of the time in a power frequency cycle, but with arrester A2 added at point 1. This configuration is
CBH endures the voltage for the full cycle. This shown in Fig. 3.
means that the protection level of arrester A2 is lower
than that of arrester CBH, despite the same CCOV for 5.2 Comparison of Insulation Coordination in ±1100
points 1 and 5. Thus, the insulation level of point 1 kV and ±800kV UHVDC Systems
with arrester A2 is lower. Point 1 is on the valve side
of the converter transformer, so that there are 6 wall According to the suggested arrester scheme, the
bushings. A higher insulation level requirement protection and insulation level calculation results of key
makes the cost of bushing manufacture higher, points 1, 2, 5, 6, and 10 in the ±1100 Zhundong-Sichuan
especially for such a high voltage level. Furthermore, UHVDC project are listed in Table 8.
the stability of this point in the former is lower than
the latter because it endures a higher overvoltage. Table 8. Protection and Insulation Levels in the ±1100kV
2. Similar to point 1, under the arrester configuration of Zhundong-Sichuan UHVDC project with different
the Yunnan-Guangdong project, the insulation level arrester schemes
of point 5 is higher than that under the arrester
LIPL/SIPL LIWL/SIWL
configuration of the Xiangjiaba-Shanghai project. Pos Scheme Protected By
(kV) (kV)
Arrester CBH should protect point 5 directly in order 1 A2 1837/1819 2250/2100
to decrease the cost of wall bushings and increase the 2
Arrester A2
CBL2+V2 1577/1563 1950/1800
stability of the system. 5 Max(A2, DB) 2038/1859 2500/2150
added
3. Similarly, the insulation level of point 6 under the 6 MH 1504/1436 1850/1700
10 DB 2162/1859 2600/2150
arrester configuration of the Yunnan-Guangdong project 1 MH+V2 2037/1945 2500/2250
is higher than that under the arrester configuration of 2 CBL2+V2 1577/1563 1950/1800
the Xiangjiaba-Shanghai project. Arrester MH is also No Arrester
5 CBH 2038/1946 2500/2250
A2
needed in the ±1100kV UHVDC system. 6 MH 1504/1436 1850/1700
4. Arrester C2 in the arrester configuration of the 10 DB 2162/1859 2600/2150
Yunnan-Guangdong project is useful to protect the
upper 12-pulse converter in half-pole operation mode. Table 8 shows that the suggested arrester scheme
However, it is not necessary when arresters MH and reduces the protection and insulation levels of point 1 and
CBH are installed. point 5. Therefore, it makes the system more economical
5. The insulation level of point 10 under these two and stable.
arrester confutations is similar. Compared with the insulation coordination of ±800kV
UHVDC systems, ±1100kV UHVDC systems require a
In conclusion, in ±1100kV UHVDC systems, points 1, 5, more complex arrester scheme and a more thorough
and 10 should be directly protected by arresters. Considering coordination principle. The key recommendations for this
insulation coordination are that the points enduring the
highest voltage in the system should be separately protected
by special arresters. However, in ±800kV UHVDC systems,
the points that endure the highest voltage can be protected
by other arresters indirectly to lower the cost of arresters
and reduce the space needed for arresters in the valve hall.
In other words, in ±1100kV UHVDC systems, the key
recommendation for insulation coordination is to lower
the insulation level of points that endure the highest
voltage. However, in ±800kV UHVDC systems, this scheme
with arrester A2 added reduces the cost of arresters’
manufacture and space occupation in the valve hall with an
acceptable insulation level.

6. Conclusion

Fig. 3. Suggested arrester scheme in the ±1100 kV In this work, we compared two types of typical
Zhundong-Sichuan UHVDC project insulation coordination used in ±800kV UHVDC systems

1778 │ J Electr Eng Technol.2015; 10(4): 1773-1779

 Dong-ju Wang and Hao Zhou

and proposed that the key recommendation for UHVDC Converter Station,” Power System Technology, vol.
system insulation coordination is to protect the points 36, pp. 1-8, 2012.
where the operating voltage is higher, such as points 1, 2, 5, [7] H. Zhou, X. Deng, D. Wang, Y. Shen, X. Chen and
6, and 10, and so on. Finally, we proposed a reasonable K. SUN, “Overvoltage and Insulation Coordination
insulation coordination solution as well as principles for for ±1100kV UHVDC Converter Station,” High
±1100kV UHVDC systems. The points that endure the Voltage Engineering, vol.39, pp. 2477-2484, 2013.
highest voltage in the system should be separately protected [8] Y. Han, H. Chen, Y. Lu, and L. Li, “Research on DC
by special arresters. Transient Overvoltage and Insulation Coordination
In terms of the insulation coordination of ±800kV and of ± 800kV Converter Station,” in Power and
±1100kV UHVDC systems, it can be concluded that in Energy Engineering Conference (APPEEC), 2011
±1100kV UHVDC systems, the key goal of insulation Asia-Pacific, Wuhan, 2011, pp. 1-4.
coordination is to lower the insulation level of points that [9] F. Su, S. Yuan, D. Zhang, and H. Zhou, “Insulation
endure the highest voltage. However, in ±800kV UHVDC co-ordination of UHVDC transmission lines,” in
systems, the key goal is to reduce the cost of arrester Electric Utility Deregulation and Restructuring and
manufacture and space occupation in the valve hall with an Power Technologies (DRPT), 2011 4th International
acceptable insulation level. Although the arrester scheme Conference on, Weihai, Shandong, 2011, pp. 259-265.
for ±1100kV systems is more complex and requires more [10] F. Su and H. Zhou, “Simulation on lightning over-
thorough coordination, it is no less attainable. voltage of ± 800kV converter station,” in
Lightning (APL), 2011 7th Asia-Pacific International
Conference on, Chengdu, 2011, pp. 491-495.
Acknowledgements [11] IEC, T. (2002). 60071-5 - 2002 Insulation co-ordi-
nation, part 5: procedures for high-voltage direct
This paper is supported by National Basic Research current (HVDC) converter stations.
Program of China (973 Program)(2011CB209405). [12] M. Haeusler, H. Huang and K. Papp, “DESIGN AND
TESTING OF 800 kV HVDC EQUIPMENT,” in
Cigre Conference Paris, 2008.

References

[1] Z. Yi-ying, J. Wei-ping and W. Ya-ni, “Influence of Dong-ju Wang He received M.S.
UHVDC Control and Protection Characteristics on degree in Zhejiang University, Hang-
Inner Overvoltage,” in The International Conference zhou, China in 2008. He is curently
on Electrical Engineering 2008 OKINAWA, JAPAN, working toward a PH.D. degree at the
2008. College of Electrical Engineering, Zhe-
[2] D. Manling, X. Shijun, Z. Dandan, H. Hengxing, B. jiang University. His major research
Minghui, H. Junjia, H. Ying, L. Xiaolin, and C. interests is overvoltage and insulation
Zongyuan, “Influence of smoothing reacteor arrange- coordination of UHVDC system.
ment on transients of converter station for ±
500kV double-circuit HVDC system,” in Power and
Energy Society General Meeting, 2010 IEEE, Minne- Hao Zhou He received Ph.D. degree in
apolis, MN, 2010, pp. 1-8. electrical engineering all from Zhejiang
[3] L. Hua, L. Fuchang, H. Junjia, L. Yuxin, Y. Huisheng, University, Hangzhou, China, in 2004.
and Z. Zhigang, “Analysis and Simulation of He is currently a professor at the
Monopolar Grounding Fault in Bipolar HVDC College of Electrical Engineering, Zhe-
Transmission System,” in Power Engineering Society jiang University. His major research
General Meeting, 2007. IEEE, Tampa, FL, 2007, pp. interests includs overvoltage, insulation
1-5. coordination, lightning protection, power
[4] J. LV and J. ZHAO, “Study on the Overvoltage and market and its application.
Insulation Coordination of Yunnan-Guangdong ±800
kV UHVDC Transmission System,” Southern Power
System Technology, pp. 18-22, 2009.
[5] D. NIE, W. MA and J. ZHENG, “Insulation Coor-
dination for ±800 kV UHVDC Converter Stations,”
High Voltage Engineering, pp. 75-79, 2006.
[6] H. ZHOU and D. WANG, “Overvoltage Protection
and Insulation Coordination for ±1100 kV UHVDC

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