Page 47 - Analysis Report of Global Market in the Submarine Cable Field (2017)

. these crosslinking by-products are resolved in the electric field, and strength of the sample 5 is basically close to that of the sample.
come into being heteropolar space charges, which weaken the electric Tab 4 Flexible high voltage produced by different technological conditions
field in the sample; sample 2 degassing under atmospheric pressure 12 h The dielectric strength test of DC submarine cable
has a higher resistivity; The conductivity of sample 3~ sample 5 is higher
slightly, but the conductivity did not change significantly with field
strength. B. The degree of nonlinearity of the insulation conductivity
of sample 3~ sample 5 is lower, but the nonlinearity of the insulation
conductivity of the sample 1 is larger, which is unfavorable to the electric
field distribution inside the DC cable.
Figure 6 Flexibility in production under different process conditions
The conductivity of HVDC submarine cable sample

4.3 Process optimization results
Tab 5 compares the effects of different process conditions of electrical
insulation properties and shape parameters of the flexible HVDC
submarine cable. Therefore, compared with the 24 h vacuum degassing
sample 3, sample 1 did not degassing, and the conductivity of sample 1
is decreased ,increase the amount of space charge, breakdown strength,
shape parameter is relatively low, the change of electrical performance
greatly, in order to improve the electrical insulation properties and shape
parameters of flexible HVDC submarine cable, In theory, the production
mode of sample 3 is recommended. but in the actual production due
to equipment and manufacturing conditions, 2 of the sample model is
4.2.2 Analysis of test results of insulation space charge distribution more suitable for the actual production.
In order to understand the different process conditions (degassing Tab 5 Flexible HVDC submarine cable in different conditions of trial
process, crosslinking temperature and pressure) effect of insulation Comparison of electrical properties and shape parameters of specimens
of space charge distribution of the flexible HVDC submarine cable,
submarine cable insulation of the 5 specimens by space charge density
test, the test results are shown in figure 7. By the sample degassing of
the space charge distribution of 7a 1) ~c) visible, sample in 20 kV/mm
field of anode negative charge obviously, and with the time accumulated,
40 kV/mm in the field of space charge increases further, in case of a
short circuit anode accumulated space charge density of about 6 C /
m3 there are also internal, and the sample space charge distribution of.
This may be due to the inclusion of more crosslinked byproducts in
the degassed sample 1, which dissociate and migrate along the electric
field in the presence of an electric field and eventually accumulate near
the electrode to form an ISO polarity charge. By 12 h samples under
atmospheric pressure degassing of space charge distribution of 7D 2)
~f) shows that the presence of specimen under short-circuit conditions
like charge injection, mainly concentrated in the vicinity of the cathode, 5. Conclusion
the injection volume is not. By vacuum degassing of 24 h samples 3 of With the continuous expansion of the power grid, the cable tends to
the space charge distribution of 7G) ~i) visible at 20 kV/mm and 40 kV/ high voltage level, long-distance transmission, AC cable loss and other
mm electric field inside the sample space charge in the sample is very shortcomings become increasingly obvious, the voltage source converter
few, short circuit conditions there are only small amount of negative input represents the future direction of DC transmission. Process
charge, which indicates that the vacuum degassing of specimen after optimization on mechanical properties and electrical performance
internal heteropolar charge was significantly reduced. By the pressure of optimization design of this paper, the flexible DC submarine cable
5 MPa crosslinking sample space charge distribution of 7J 4) ~l) visible, has mechanical and electrical performance and excellent safety
anode and cathode were not different charges, and the pressure of 14.5 and reliability. At present, Nan'ao demonstration project ±160 kV
MPa crosslinking sample 3 of the space charge distribution is more flexible DC submarine cable and the national network of Zhoushan
similar to that in the case of a short circuit inside the sample residue is demonstration project ±200 kV flexible DC submarine cable has
the main hole, and cross pressure sample 14.5 MPa 3 internal residues been put into use, on behalf of the domestic flexible DC submarine
is mainly electronic. This may be because the cross-linked sample press cable technology matures, you can expect this kind of products will
crosslinking pressure is 5 MPa when there are more pores, it is conducive be more and more applied in deep-sea power transmission, offshore
to the transfer of electron, and hole migration plays a key role, finally wind power, oil platform in the field of dynamic transmission. If in the
resulting in the sample residue is mainly internal hole. The space charge optimization design of mechanical properties, first through the reign
characteristics of the sample from the space charge distribution (7m) of hydrodynamic analysis to determine the load, then according to the
of the sample 5 whose cross temperature is 200 DEG C) show that the sea wave spectrum analysis in the environment of fatigue, rationality is
space charge characteristic of the sample is not different from that of the more conducive to the design of cable mechanical properties. However,
sample 3 at a temperature of 175 DEG
the domestic research in these fields is still in its infancy, and there are a
lot of technical difficulties need to be overcome.
4.2.3 Analysis of dielectric performance test results of insulation
In order to understand the different process conditions (degassing
process, crosslinking temperature and pressure) influence on the flexible REFERENCES
[1] Li Yan, Luo Yu, Xu ShukaiG. Flexible HVDC technology: application, progress and expectation [J].
HVDC cable insulation dielectric properties, the 5 specimens of cable China Southern Power Grid technology, 2015,9 (1): 1-12.
insulation dielectric performance test, the test results are shown in table [2] TICW Rated voltage 500 kV and below DC power transmission power cables with extruded insulation
4. It can be seen that the DC dielectric strength of the sample 1 without specification system 3rd parts of DC submarine cable: TICW 7.3 - 2012[S]. Shanghai: National Quality
degassing is larger than that of the sample of 12 h at atmospheric Supervision and test center of wire and cable, 2012.
pressure. The direct dielectric strength of the sample 2 is smaller than [3] Xia Feng, Chen Kai, Zhang Yongming. Mechanical strength analysis and design of submarine cable
that of the vacuum degassing sample 3~, and the direct dielectric armored structure [J]. wire and cable, 1672-6091 (2011) 03-0008-04, 2010-09-16
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