(SANITIZED)UNCLASSIFIED SOVIET PAPER ON HIGH-VOLTAGE LONG-DISTANCE D.C. POWER TRANSMISSION(SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A004700130002-4
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 16
• Document Creation Date: December 21, 2016
• Document Release Date: December 2, 2008
• Sequence Number: 2
• Content Type: REPORT

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WORK DONE IN THE SOVIET UNION ON HIGH-VOLTAGE
LONG-DISTANCE D.C. POWER TRANSMISSION
A paper by A.M. NEKRASOV and A.V. POSSE
The work conducted in the Soviet Union on high-voltage d.c. power transmission
is based on the fact that this type of transmission may be quite effective from the
technical as well as the economical standpoint in several cases as power systems
continue to grow and become all the more interconnected.
Design estimates that have been made show that direct current is quite economical
wherever it is necessary to transmit large blocks of power over distances of 1000 km
and more. It turns out that the transmission of energy along condUCtors of a trans-
mission line may favorably compete under certain conditions with the transportation of
coal over railways or with the transportation of natural gas over pipe lines because
of the use of direct current.
Direct current opens up new technical possibilities that are important from the
operating standpoint of consolidated power pool systems and, therefore, it may be more
advantageous and expedient to use direct current not only in the case of long-distance
transmission, but also for inter-system tie lines of comparatively short length.
Direct current is indespensible whenever it is necessary to lay cable lines for
power transmission and, in particular, for crossing over long water routes (e.g. in
Sweden power is transmitted in this way to the Island of Goteland; a tie of this kind
between the power systems of England and France is being designed.)
Inroads are being made at present by scientific research and experimental design
projects so that the technical and economic benefits of d.c. transmission may be
realized in the nearest future. It is very important that the results of many of these
projects have already been put into practise, passing their check-up in operation on
the experimental-commercial d.c. transmission line from &shire to Moscow. (Ref. 1)
At present preliminary work is being carried out in the Soviet Union for the
construction of a d.c. transmission line from the Stalingrad hydro-electric station
to the Donbas. (Ref. 2 and 3). This line will be a component link in the Consolidated
Power Pool System for the European part of the Soviet Union. The parameters of this
line (transfer capacity - 750 MW, voltage - + 400 kV, length of overhead line - about
500 km) place it in one group with the most recent three-phase extra-high-voltage
high-capacity a.c. transmission systems. It may be considered that the problem of
d.c. power transmission will be essentially solved by constructing the Stalingrad-
Donbas line and putting it into commercial operation. The experience that will be
gained in constructing and operating this transmission line will enable um to employ
longer d.c. lines with larger transfer capacities more confidently. This will be re-
quired when the Consolidated Power Pool System for the entire Soviet Union will be
created.
The Ushira-Mbscow transmission line, which was put into service at the end of
1950, consists of two terminal converter sub-stations and 112 km of underground d.c.
cable line between them.
Normally power is transmitted from Kashira (where it is generated at a thermal
power plant) to Moscow (where it flows into a 110 kV network). At times, for
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experimental purposes power was transmitted in the opposite direction. The sub-station
equipment permits 200 kV d.c. and 150 A d.c. to be obtained and, therefore, 30 MW is
usually transmitted over the cable at 200 kV.
The Kashira-Moscow transmission line has already been connected up in several
schemes and subjected to various operating conditions. Moreover, experimental studies
of all kinds have been already carried out on a large scale. As a result, measures
as well as devices were developed and put into operation, thereby improving the
reliability of transmission considerably. Finally, a great deal of experience has
been gathered, which is now being used in designing and developing the equipment for
the Stalingrad-Donbas transmission line, and also in drawing up prospective plans for
further use of d.c. transmission.
During the first few years of operation of the transmission system, one bridge
was used for converting the current at each sub-station. There were three mercury-
pool tubes (rectifiers) connected in series in each arm of this bridge. Starting with
1955 other converter schemes were experimented with. At one time a single bridge was
in operation at each of the sub-stations, having one tube in each arm. The d.c. volt-
age in this case was reduced at first to 80 kV, and afterwards raised to 100 kV (in-
stead of 200 kV when three tubes were in each arm). The operation of the bridge was
checked with two tubes connected in each arm. Of recently, the scheme at the Moscow
sub-station, which is usually subjected to invertor duty, consists of two bridges
connected in series. There is only one tube connected in the arm of the first bridge,
while there are two in the arms of the second bridge which operates at a higher voltage.
The sub-station at Kashira, as previously, works with three tubes in the bridge arms.
The operating experience with converter schemes having one, two, or three tubes
in the bridge arms which was gathered from the Kashira-Moscow transmission line indicated
that series connection of the tubes in itself does not give any substantial effect as
concerns reliability of the scheme in operation. The great expectations that were
earlier held with regard to this connection did not materialize in practise. (Ref. 4).
It was discovered, in addition, that the series connection of several tubes has some
drawbacks. For example, if one tube should not ignite, the full direct voltage of the
bridge arm is applied to it, while a higher back voltage appears across the other
tubes. (Ref. 5).
Changing over from the scheme with one bridge to the scheme with two series
connected bridges at the invertor station results in better transient performance when
one of the tubes breaks down, and also in better operating reliability of the trans-
mission line as a whole. The current surges and voltage fluctuations on the cable line
during transients were greatly reduced because of this change in the scheme. If indi-
vidual tubes did not ignite for a short time, the operation of the invertor sub-station
was no longer endangered. (Ref. 5).
Extra-high-capacity d.c. systems may require parallel or series-parallel connec-
tion of the tubes. Therefore, a series-parallel connection of six tubes in one arm of
the bridge was made and studied (three tubes were connected in series in the other arms
of the bridge). Experimental results and operation confirmed the merits of this
connection, namely, insensitivity of the converter scheme to lapses in the ignition
of individual tubes. At the sane time, some new phenomena were discovered which do
not take place with parallel connection of the mercury-pool tubes in law-voltage circuits.
The unpleasant consequences of these phenomena were liquidated by suppressing the high-
frequency oscillations that arose when the tubes ignited. (Ref. 6).
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While making adjustments on the Kashira-Nbscow line for normal operation, it was
discovered that certain oscillatory processes, which arise during transient conditions,
may cause dangerous overvoltages. One such process, for example, is the voltage
oscillations that arise between the poles of the sub-station after the transmission
scheme has been deenergized, and the cable is still under voltage. By installing
appropriate damping devices in the scheme, which consist of resistors and capacitors,
these oscillatory processes can be suppressed and the overvoltages associated with
them liquidated.
At first the transmission was unstable in operation,and was frequently interrupted,
primarily due to the instability of the mercury-pool tubes. Measures were taken along
two lines to improve the reliability of the transmission; a) to improve the tubes
themselves, and b) to lighten their duty in the scheme.
The tubes themselves were improved during their periodic repairs when various
changes in design were made; also, their process of manufacture and high-voltage trial
operation was brought up to date. Some of these tubes were replaced by newly manufactur-
ed ones of better design.
The duty of the tubes in the circuit was lightened by the introduction of appropri-
ate damping devices and high-frequency reactors. They reduced the rate of rise of the
back voltage and the magnitude of the current surge at the instant the tube ignited.
Alongside of lightening the duty of the tubes when they ignite, the high-frequency
reactors connected in the plate circuit of each tube enabled the radiation to be re-
duced and the radio interference to be brought down to a tolerable level.
Measures improving grid control as well as automatic control and protection played
a positive role in the establishment of normal, stable operation of the transmission
system. Among these measures, special attention should be given to the positive
experience gained from the use of automatic reclosing by means of grid control. This
enabled the pause in power transmission to be reduced to a minimum (0.1 to 0.2 seconds)
after short-time phenomena such as arc-back took place.
The experience gathered from the operation of the d.c. cable line is of great
interest. This line consists of two single-conductor cables laid alongside of each
other in one trench. They have an aluminum conductor 150 me in cross-section, a lead
sheath and paper insulation 12 um thick, which is impregnated with an oil-rosin compound.
At first the transmission worked without delay on the d.c. side. Under these conditions
both cables were at a voltage of + 100 kV. For the past 4-5 years the transmission
system has been working with one of the d.c. poles grounded and therefore, 200 kV is
applied to the ungrounded cable (the maximum potential gradient is 31 kV/mm).
In speaking of the operating experience with this cable line, it should be noted
that cable of different firms are used. The best results were obtained with cables
from the firm KWO (Germany) and from the works "Nbscable" (U.S.S.R.), which were laid
out along a section of 30 km. There was not even a single fault on this section during
the entire operating period. Tests in 1957 on pieces of cut out cable and also on
various couplings indicated that electrical strength was the same as when the cable
line had been laid in 1950.
For a long time the Kashira-Nbscow transmission line has been operating according
to the "conductor-ground" scheme. Current flows in one direction through the ground
between two special ground rods in the form of iron tubes pounded right into the soil.
Studies that were carried out and also operating experience indicate that in the case
of direct current it is quite permissible to use the ground as the return conductor.
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Protective measures may be required only on underground metal structures that are
located comparitively near the ground rods (within a radius of 5 to 10 km).
One of the existing three-phase 110 kV overhead lines running from Kashira to
Moscow was used several times in an experiment on transmission. Direct current was
transmitted over two line conductors at a voltage of + 100 kV/ and also over the
"conductor-ground" scheme at a voltage of 100 and 200 kV. The insulation of the three-
phase 110 kV line withstands quite reliably the d.c. voltage of 110 kV. At 200 kV
there were cases where the insulator string flashed over during bad weather. Tests
on the overhead line were made to single out the characteristics of transient and to
check the damping devices limiting overvoltages.
From the above survey, which is by far imcomplete, of work carried out on the
Kashira-Moscow transmission system, it is quite evident that the improvements made and
the operating experience gathered are of extreme importance.
Further developments in techniques of d.c. power transmission. Work on the
development of d.c. power transmission in the Soviet Union is carried out at the Scien-
tific Research Institute on Direct Current of the Ministry of Power Stations, the Lenin
All-Union Electrotechnical Institute, the Power Institute of the Academy of Sciences,
the Institute of the Cable Industry, and at design departments of several large electric-
al plants. Several departments of our educational institutes participate in the solu-
tion of some questions in the general problem. D.c. transmission lines are being
designed at the project institutes "Teploelectroproject" and "Hydroproject" in conjunc-
tion with the Direct Current Institute.
Scientific investigations and developments in design are coordinated by appropriately
distributing the different work, by the organization of information exchange, and by
joint conferences. All work required for creating the d.c. transmission line Stalingrad-
Donbas is coordinated by the Ministry of Power Stations and is carried out in accordance
with a general plan. Research work on some topics is carried out jointly by several
organizations in accordance with general programs. Most frequently it consists of large-
scale experimental investigations carried out on the transmission line Kashira-Moscow.
The results of work after its conclusion or at intermediate stages are generally dis-
cussed at meetings of Scientific and Technical Councils at the Institutes. Moreover,
other organizations engaged in the solution of the general problem always have their
representatives participating in the work of the Council of the given Institute.
Work on the further development of techniques for d.c. power transmission is being
carried out along the following main lines:
1 - Schemes for the d.c. transmission line are being developed as well as for its
junction with a.c. systems and large power stations. Special attention is payed at
present to questions of intermediate power take-off from d.c. lines by creating the
necessary taps and also of intermediate sub-stations. The solution to the problem of
directing power transmitted over an extra-high-capacity d.c. line to two or even more
points (instead of one) at the receiving system is part of the problem stated above.
Preliminary solutions to these problems indicate that difficulties encountered in
protecting and automatically controlling d.c. transmission systems with intermediate
sub-stations may be overcome. Moreover, in the more complicated case good use may be
made of the possibilities of grid control of the tubes.
2 - Converter schemes are being worked out, the theory of current conversion is
being developed, and steady-state and especially transient and fault conditions in the
operation of the converter sub-stations of the d.c. transmission system are being studied.
Special attention is paid to particular questions which arise in the event of cascade
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connection of several bridges on the d.c. side so as to obtain a sufficiently high volt-
age, e.g. questions of uniform voltage distribution among the bridges (after current
has ceased to flow in the circuit), internal overvoltage protection, damping oscillatory
processes, reduction of the upper harmonic content by improving the phase of the
conversion, reduction of the mutual influence of the bridges, etc. Efforts are also
being made along these lines to create the best possible schemes and means for compensat-
ing the reactive power consumed by the invertor sub-station.
3 - Studies are being conducted on joint operation of the d.c. transmission line
with an a.c. system connected to it. Here we deal with questions such as how abnormal
conditions in the transmission system influence operation of the receiving system, and
also how fault conditions in the receiving system influence operation of the invertor
sub-station. Ways are sought for using d.c. transmission lines with their high-speed
grid control to improve the transient stability of adjacent systems and of long-distance
transmission lines.
4 - Studies are being conducted on the performance of the insulator string as well
as on the external and internal insulation of the equipment and apparatus when subjected
to a large d.c. voltage, and also a d.c. voltage with an a.c. component of varying
frequency superimposed. The results of these studies will lead to more rational design
of the insulation for d.c. overhead lines, high-voltage d.c. cables, power transformers,
capacitors, d.c. instrument transformers and other equipment for converter sub-stations.
Research on corona discharge at a large d.c. voltage related to this line of investiga-
tion is also being carried out.
5 - High-voltage, high-capacity mercury-pool tubes, the main element in the convertor
sub-station, are being developed. The design of these tubes is based on the results of
extensive research of different physical phenomena, on the performance of sample tubes
which are tested at special set-ups and also under actual operating conditions on the
Kashira-Mbscow transmission line. The tube designed in the Soviet Union has only one
plate no matter what its capacity in contradistinction to that of the Swedish firm
A.S.E.A., in which the number of parallelly connected plates increases with the tube
capacity. (Ref. 12).
6 - The following equipment for the convertor sub-stations is being designed; power
transformers, isolating and instrument transformers, capacitors, lightning arresters,
disconnecting switches for shunting and other special apparatus. Work is being carried
out on creating high-voltage d.c. power cables, which is also associated with this line
of activity.
7 - Special automatic devices are being developed that generate pulses for the grid
control and for the automatic control and protection of the d.c. transmission line. These
devices substantially influence the performance of the transmission system during normal
as well as transient and fault conditions. Therefore, they are developed on the basis
of all-round studies of these operating conditions.
Many of the investigations listed above are carried out on laboratory installations,
which model the real d.c. transmission system of the future to a certain scale. The
parasitic parameters of real high-voltage installations, as well as the main parameters
may be modelled at these installations. This enables low-frequency as well as high-
frequency processes (up to hundreds of kc) to be investigated on these models. Models
are a powerful tool in the bands of a research worker and a designer of new devices and
apparatus.
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The Stalingrad-Donbas transmission system will be a great advance in the development
and practical application of d.c. power transmission techniques. This transmission
system (Fig. 2) contains an overhead line of about 500km long and two convertor sub-
stations, one of which is located in the building of the Stalingrad hydro-electric
station, and the other in the Donbas. The voltage between conductors is 800 kV (+ 400 kV
relative to ground) and the rated transfer capacity is 750 MW. Provision is made for
power transmission in both directions.
Eight generators are alloted at the Stalingrad hydro-electric station for the trans-
mission of direct current. They are connected through power transformers to the rectifier
bridges and 220 kV buses. The power generated by these eight units may be directed in
part over the d.c. line to the Donbas and in part to the 220 kV buses. D.c. transmission
coming from Donbas is directed to the 220 kV buses, and from there it is distributed
together with the power from all of the generators at the station.
The convertor sub-station in the Donbas links the d.c. line with the 220 kV a.c.
network there. Power is transmitted or received through several lines that run out from
the 220 kV buses.
The mid-points on the d.c. side at both convertor sub-stations are connected to
special ground rods that are designed for continuous flow of the rated current of the
transmission line. This grounding divides the transmission system into independent
halves, and enables one half to remain in operation when the other one gets out of com-
mission. In this case the current flows through the ground.
There are eight identical bridges connected in series at each converter sub-station.
With this number of bridges any possible disruptions in the operation of one of them
will little influence the operation of the other bridges and of the transmission system
as a whole. In case one of the bridges is shunted, the remaining seven ensure the latter
within limits.
In order to reduce the upper harmonic content on the d.c. side as well as on the a.c.
side, the windings of each transformer connected to the bridges are connected differently,
in wye or delta. As a result, twelve-phase conversion is obtained.
All the reactive power required at the Donbas substation is supplied by three banks
of capacitors (having a total of 400 MVARs), which are connected to the 220 kV buses,
and at the Stalingrad sub-station by the water-wheel generators.
Some auxiliary elements are installed in the scheme of the converter sub-station
so as to alleviate the duty of the main equipment, and primarily of the tubes, during
steady-state as well as transient conditions. Some of these elements are as follows:
capacitors and resistors limiting the magnitude and rate of rise of the back voltage;
plate reactors limiting the discharge current of the stray capacitances in the cir-
cuit through the tube at the instant it ignites;
capacitors and resistors for uniformly distributing the voltage between the bridges
and also for damping the voltage oscillations after the circuit is deenergized;
special arresters serving as protection against internal overvoltages.
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A shunting tube and a disconnecting switch are connected in parallel with every
bridge between its poles. The shunting tube serves as protection during arc backs and
break downs in the tubes as well as other short-time disruptions in the operation of the
bridge. The shunting disconnecting switch is used for cutting out the bridge for a long
time, for example, when replacing a tube.
The convertor sub-stations use single-plate tubes for 900 A, 130 kV (Fig. 2 and 3).
These tubes are six times more powerful than the tubes used in the Kithira-Moscow trans-
mission system. Air may be pumped out from the tubes. The lower part of the tube of
metal is cooled by circulating transformer oil, while the upper part of the tube con-
taining the plate has natural air cooling. The tube is 3.5 meters high and weighs about
2 tons (Ref. 13).
The power transformers are single phase and come in two insulation classes. Trans-
formers closer to the grounded mid-point in the circuit from the potential standpoint
are subjected to a test voltage of 570 kV, while the other transformers are subjected to
a test voltage of 1000 kV.
The d.c. overhead line is constructed with T-shaped steel towers (Fig. 4). Each
line pole consists of two aluminum-steel conductors having a cross-section of 712 mm?
(the aluminum part), which are diverged along the horizontal by 400 mm from each other.
The line is protected against direct lightning strokes by a single steel ground wire
having a protection angle of 30?. When designing the d.c. line, it was possible to re-
duce somewhat the requirements levied on the lightning protection because of the advan-
tages of the grid protection.
The length of the insulator string and the air insulation Clearances were selected
on the basis of limiting internal overvoltages to a value not greater than 1.7 of the
rated working voltage. In order that voltage oscillations on the line do not exceed
this value during transients special transverse damping circuits of resistors and capaci-
tors are connected at the ends of the line.
It should be noted that the length of the insulator string could not be made shorter
by even further limiting the magnitude of these internal voltages of short duration
(amounting to tenths of a second), since shorter insulator strings would flash over during
bad weather when rated voltage is applied continuously.
The overvoltages arising on the line will be applied to the sub-station equipment,
also, in the event current stops flowing in the circuit. Therefore, the maximum mag-
nitude? of the overvoltage given above (1.7) is relevent not only for the line, but also
for determining the requirements of the insulation of all of the sub-station equipment.
A system of automatic regulators is used to attain the most economical operation for
the transmission system under normal conditions and to secure its stability during various
kinds of transient conditions.
A given transfer capacity is maintained automatically regardless of the voltage
fluctuations on the 220 kV buses of both substations. For this purpose regulating trans-
formers (Fig. 1) are used and voltage regulation is employed on the water-wheel generators.
If it should:be necessary to change the direction of power flow over the transmission
line, coordinated switching in the grid control devices is carried out at both sub-stations.
When transmitting power to the Donbas, frequency control is provided at the receiving
end by appropriately varying the transmitted power.
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The grid protection worked out for the transmission system is quick acting.
Therefore, in the majority of cases it should prevent the fault from developing, pro-
tect the equipment from being damaged, and enable normal operation of the entire trans-
mission system to be restored after some fraction of a second.
The use of direct current for transmission from Stalingrad to the Donbas over a
distance of 500 km does not result in any economical benefits as concerns first costs,
losses and the cost of transmitting one kilowatt-hour. The technical and economic
characteristics of the + 400 kV d.c. scheme and of the 400 kV a.c. scheme are about
the same. All of the gain obtained by using d.c. in the line part of the transmission
system (the line is 1.6 times cheaper, and its losses are twice as less) is completely
expended in this case in the more intricate terminal sub-stations. However, the use of
direct current for such an inter-system tie has definite advantages in operation; for
example:
the frequency may be controlled independently in the two a.c. systems that are
linked;
the power transmitted may be controlled according to a pre-established program;
faults in one system are felt much weaker in the other system;
the single-circuit d.c. line is much more reliable because of the possibility of
using the ground as the return conductor, and because the automatic reclosing cycle is
limited to its minimum value.
The construction and operation of the Stalingrad-Donbas transmission system will
permit the necessary experience to be gathered so that within the next ten years we may
begin to construct d.c. transmission lines at + 600 to + 700 kV having a transfer capa-
city of 2 to 4 million kW per circuit. These lines will serve to transmit large blocks
of cheap power from the regions of central Siberia to the Urals (where fuel is expensive),
that is, over a distance of 2000 to 2500 km. The use of direct current for such trans-
mission systems will have a great effect on the national economy.
The effect expected from using direct current for power transmission over long
distances. By,making use of design material that has already been compiled, it is
possible at present to compare from the economic standpoint transmission by means of
direct current with that by means of three-phase alternating current, and also with the
transportation of coal over the railways and of natural gas over pipe lines (all per-
taining to the conditions of the Soviet Union).
When comparing the a.c. and d.c. schemes for a definite case of power transmission,
the optimal solution to the problem using each of these schemes should be taken. By
that we mean the optimal values of the line voltage, the conductor cross-section, etc.
Calculations made for many different transmission systems with overhead lines
indicate that the relationship between the optimal voltages is usually the following:
+ U = Und', where U is the voltage of one line pole to ground in the d.c. scheme,
and UN is the r.m.s. value of the line-to-line voltage in the a.c. scheme. The total
conductor cross-section Selected in each scheme on the basis of the economical current
density is 1.5 to 2.5 times smaller for d.c. than for a.c. When these relationships
are observed, the d.c. line is always less expensive and has smaller losses.
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The characteristics of two concrete transmission lines (a d.c. line and an a.c.
line) are given below in the table. (Ref. 14).
TABLE
Economic Comparison of D.C. and A.C. Transmission Systems
No.
Basic Parameters
Transmission
System 1
Transmission
System 2
1
2
3
Length of line, km
Capacity, NW
Annual energy transfer,
billion kWh
d.c. a.c.
1000
1000
7
d.c. a.c.
2200
6000
42
4
Voltage, kV
?500
500
4.600
600
5
Number of circuits
1
1
2
3
6
Conductor cross-section per
phase or pole, ma. mm.
3x712
3x712
4x712
43E712
7
Losses (%)
in lines
2.74
5.33
8.84
12.15
at substations
2.70
1.44
3.20
2.19
in compensating devices
0.58
1.40
total
5.44
7.35
12.04
15.74
8
Cost of transmitting one
0.80
1.05
0.72
1.22
kWh, kopeks
From a comparison of both schemes it follows that the use of alternating current
for transmission system 1 is more expensive by 25%, while for transmission system 2
this figure rises to 98.5%. There is some descrepancy here as regards the percentage
distribution of the cost of the elements for both transmission systems. This cost
distribution among the various elements is given below.
Transmission System Transmission System
1
2
d.c.
a.c.
d.c.
a.c.
Lines
58.5
66.6
56.o
59.2
Sub-stations
41.5
23.0
44.0
16.6
Compensating devices
-.
10.4
--
24.2
Total 100 100 100 100
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It is seen that the use of direct current is expedient economically not only when
constructing extra-long-distance extra-high-capacity transmission systems (transmission
system 2), which is usually not questioned, but also in the case of transmitting 1000 MW
over a distance of about 1000 km (transmission system 1).
The benefits of using direct current become greater not only for an increase in the
transmission distance, but also for an increase in the power transmitted. When large
blocks of power are to be transmitted, the d.c. scheme has additional advantages con-
nected with the greater, transfer capacity of its line. This follows clearly from the
example of transmission system 2. In the a.c. scheme three circuits have to be used
instead of two as in the d.c. scheme. The a.c. line is more than twice as expensive
and the losses in it are 1.4 times greater than in the d.c. case.
Calculations have been made in the U.S.S.R .comparing power transmission over
conductors with the transportation of coal over the railways for various concrete cases.
In certain cases when the distances involved were sufficiently large, it turned out that
power transmission using direct current is economically justified rather than transporting
the coal. For example, d.c. transmission from power stations working on cheap untrans-
portable coals to the industrial districts of the Urals over a distance of 2200 km was
compared with the transportation of more expensive high-calory-content coals from the
Kuznets basin to the power stations in the Urals. It turned out that the first costs for
erecting the d.c. transmission line are somewhat greater; however, the operating costs
and the energy cost at the consumer are lower. These additional first costs will be
reimbursed in the course of four to five years.
Plans exist in the Soviet Union for increasing the use of natural gas as the fuel
at power stations. The following question may be asked: is it more expedient to trans-
port gas over a long distance through pipe lines or to build power stations at the place
where the gas deposits are and to transmit power over conductors? Calculations indicate
that when sending 2000 to 4000 MW over a distance of 1000 km or more, the use of direct
current for transmission is entailed with additional first costs as compared with the
gas pipe line; however, these additional costs are reimbursed not over a long period
since the operating costs in the d.c, scheme are lower. For example, when transmitting
2400 MW over 1500 km the period for reimbursement of the additional first costs in the
d.c. scheme amounts to about six years.
Work done on d.c. transmission schemes and on the design of the terminal elements
allow us to expect cost reductions there.
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REFERENCES
1 - A.M. Nekrasov, M.R. Sonin - Experience in high-voltage d.c. power transmission,
Elektricheskie Stantsii, #7, 1955.
2 - V.P. Pimenov, A.V. Posse, A.M. Raider, S.S. Rokotjan, V.E. Turetski - The d.c.
Stalingrad-Donbas transmission system, Elektricheskie Stantsii, #11, 1956 and
Direct Current, vol. 3, #4, 1957.
3 - A.M. Nekrasov, E.SJGrois, M.L. Zelikin, V.E. Turetski, B.A. Nankin - The d.c.
Stalingrad-Donbas transmission system, Elektrichestvo, #9, 1957.
4 - K. Baudisch - Energieubertragung mit gleichstram hoher spannung, 1950.
5 - A.V. Posse, A.M. Raider - On the use of series connected bridges and tubes in the
d.c. transmission scheme, Izvestija Postojanovo Toka, #3, 1958.
6 - L.R. Neyman, S.R. Glinternick, A.V. Eteljanov, N.A. Shipulina - Group connection of
tubes as a method of improving the operating reliability of powerful converters,
Elektrichestvo, #6, 1956.
7 - A.M. Raider - A compounding device for the invertor in the Kashira-Nbscow transmis-
sion system, Izvestija Postojanovo Toka, #21 1957.
8 - E.M. Berlin - Control system stability in a d.c. transmission when using a new no-
tube current regulator, Izvestija Postojanovo Toka, #1, 1957, and Direct Current,
vol. 3, #8, 1958.
9 - V.S. Nelik-Sarkisov - Protecting a d.c. transmission system, Izvestija Postojanovo
Toka, 0, 1957.
10 - A.V. Posse, V.P. Pimenov - Arcing back of an invertor, Elektrichestvo, #6, 1956.
11 - A.V. Posse - A method of connecting d.c. transmission lines, U.S.S.R. Patent #99716.
12 - I. Liden - The design of the d.c. connection across the English Channel, ASEA Journal,
vol. 31, #6, 1958.
13 - F.I. Butaev, N.S. Klimov, A.A. Sakovitch, N.P. Stepanov - High-voltage
for d.c. power transmission, Vestnik Elektropromishlennosti, #9, 1957.
14 - A.V. Posse, M.M. Akselrod, A.K. Hertsik, E.S. Grois, V.M. Kvatkovski -
Elektrichestvo, #2, 1958
CAPTIONS TO THE FIGURES
converters
Discussion,
Fig. 1 - Circuit diagram of the d.c. Stalingrad-Donbas transmission system.
1 - 105 NW 13.8 kV water-wheel generators; 2,3,4 - power transformer windings;
5 - regulating transformers; 6 - bridges; 7 - shunting tubes; 8 - shunting dis-
connecting switches; 9 - output devices; 10 - working ground rods; 11 - + 400 kV
d.c. overhead line; 12 - 132 MAR, 220 kV, three-phase bank of capacitors.
Fig. 2 - Drawing of a 130 kV, 900 A tube.
Fig. 3 - General view of a 130 kV, 900 A tube.
Fig. 4 - Suspension tower for the ?00 kV, 750 NW d.c. transmission line.
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2.7. OKI
C madruirtpayeKali /7 o CM 011L(14A
?r
+400
-400gs
,11
JI 0116CICCKCIA 'Wpm OiNUR
FIGURE 1
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Approved For Release 2008/12/02 : CIA-RDP80T00246A004700130002-4
Lc,
lII 'I II
IL I
Nrt.Aets. rt,!'
XXX%
1)1,7431
FIGURE 2
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Approved For Release 2008/12/02 : CIA-RDP80T00246A004700130002-4
FIGURE 3
ryoi
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50
iI
50
to
1147,4i`VPI 4T
II 0
II 0
11 it
1 II
II
0 0
38
FIGURE 14-
(Distances given in meters)
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