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Energy conservation in the transmission and distribution of electricity in the Soviet Union
Ener8y Vol. 12, No. lO/ll, pp. 1107-1110, 1987 Printed in Great Britain
0360-5442/87 $3.00 +O.OO Pergamon JwrnalsLtd
ENERGY CONSERVATION IN THE TRANSMISSION AND DISTRIBUTION OF ELECTRICITY IN THE SOVIET UNION I. G. KARAPETIAN,’
A. L. KUDOYAROV,’ U. S. ZHELEZKO’ and V. E. VOROTNITSKI~
‘Energosetprojekt
Institute,
Glavzagranenergo, Kitajsky proead ‘VNIIE. U.S.S.R.
7, Moscow,
103074, U.S.S.R.
Abstract-Strategies to reduce losses in the transmission and distribution of electricity are reviewed. A major effort is under way to improve load management by widely deploying devices which compensate for reactive load. To optimize the use of these devices, a system of rebates and surcharges is being used, and system integration is being expanded. Computerized data bases to plan the future of the electricity system of the U.S.S.R. are undergoing rapid development.
1. ELECTRICAL
NETWORKS
IN THE U.S.S.R.
Rational use of all available resources, especially energy resources, is a national task stipulated in the fundamental propositions of the Long-Term Energy Management Program of the U.S.S.R. To fulfill this task a basic technical program for reducing the losses of electricity in the power networks of the country must be developed. Consistent with the technical policy of improving the efficiency of the generation and distribution of electricity, the power industry in the U.S.S.R. managed to keep losses down to 9% of the electrical energy delivered into the network in the last lo-15 yr. Moreover, in the last few years the power industry has developed an increasingly active energy-saving policy, involving an entire complex of organizational and technical measures in combination with continuing research work. Examples of these measures are improvements in the system for registration, acquisition, and processing of incoming data; state-of-the-art operation of the electrical network; renovation and modernization of equipment while optimizing network development; and incentives to operating personnel. The technical goals include maintaining optimum load curves over the day, sectionalizing the network, controlling the voltage under variable load, making best use of compensating devices, and applying the latest achievements in science and technology. In 1984 electrical losses in our power system networks totaled 124.3 TWh, which is 9.4% of the electricity fed into these networks. Generation plants with a total capacity of 24 GW, consuming 41 million tonnes of coal equivalent (tee), or 1.2 x lo’* J, were in operation just to compensate for these losses. Research conducted by several institutes has led to the conclusion that the present level of electrical losses exceeds what is economically justified, a systems approach suggests that with extra investments, long-term losses may be reduced to an economically justified level of 8.0-8.5% of electricity delivered into the network. Table 1. Percent of total losses of electrical energy in transmission and distribution networks of various voltages (percent). The asterisk shows the partition between transmission and distribution
Voltage Current Future
500 -system system
kV
330 --
10 12.5
*
kv
220 --
7.5
16
4
15
110-150 ~-
kV *
kV
35 kV --
Total __
28.5
38
100
20
48.5
100
Table 1 shows the fractions of the total electrical losses in the nation’s networks at each voltage, both now and as planned for the future. Networks at 220 kV and above, which currently are our transmission networks, are seen to account for one-third of total losses, 1107
1108
I. G. KARAPETIAN et al.
while the remaining two-thirds of the losses are associated with our distribution networks, with voltages of 150 kV and below; the latter also account for over 80% of the total network length. In the future, all networks at 330 kV and below are to be distribution networks, and these are expected to account for more than 85% of total losses. As the U.S.S.R. National Power Grid expands, relative losses from networks at 500 kV and above, which generally carry electricity directly from the power plant, are expected to increase; relative losses from networks in the 1 lo- 150 kV category are expected to decrease as their functions are transferred to 220 and 330 kV networks.
2. REDUCING
LOSSES THROUGH
LOAD MANAGEMENT
Losses of electricity in our power systems are affected by certain basic features of the U.S.S.R. National Power Grid that are virtually impossible to influence because they have an objective character and reflect national energy policy. First, individual power plant capacity is increasing (it is now 1000-1500 MW), and power plants are being sited increasingly in large generation complexes. For example, the total generating capacity of the power plants in the Ekibastuz, Kansk-Achinsk, and Western Siberia power complexes is planned to be 13-15 GW, or even 18-20 GW. Second, in the European part of the U.S.S.R. and in the Urals 4-6GW nuclear power plants are planned, and in the eastern regions large hydropower stations with capacities up to 1OGW are planned. Third, the nominal transmission voltage continues to rise. The highest a.c. transmission voltage for over 10 yr has been 750kV, and a 750kV transmission network has been forming in the northwest, south, and central regions of the U.S.S.R. The first transmission lines at a still higher voltage have been constructed and are about to be energized at their nominal voltage in the eastern zone of the U.S.S.R. National Power Grid, which already has an extensive 500 kV network. Within this framework energy conservation objectives can be addressed through the control of electrical network parameters: degree of reactive load compensation, weightedaverage current density in aerial and cable lines, number of transformers in the network. Of these, increasing the degree of reactive load compensation is particularly effective. Identifying the optimum capacity of the compensating devices installed in the network requires both economic and systems considerations. In the U.S.S.R., it is reasonable to maintain the reactive load compensation ratio in electrical networks at a level of 0.6 kVA per kW of peak load. Reactive load compensation is done within both power system networks and consumer networks. At present about 60% of all compensating devices are installed in consumer networks. In the future this ratio should remain constant, as the basic effect is provided by compensating devices installed at the consumer. The installation of compensating devices at a steady rate ensures the highest efficiency of their utilization because there are diminishing returns, as is seen in Table 2. Two simple efficiency indices for compensating devices decrease as the rate of introduction of For example, an increase in compensating devices compensating devices increases. commissioned over 5 yr from 22 to 140 million kVA reduces one efficiency index 1.8 times and the other 3.5 times. Using these indices with optimization methods helps select the best reaction capacities and the best locations for the installation of compensating devices.
3. REBATES
AND SURCHARGES
By now most of the difficulties in selecting the best strategy for providing electrical networks with compensating devices have been solved, or are nearly solved. There are now methods and programs which determine the capacity, location, suitable sequence, and efficiency of compensating devices in a given network. There is also an organizational mechanism-rebates and surcharges on tariffs-to induce the consumer to respond to the conditions set by an electric utility for reactive power consumption. This new system of
Energy conservation in the transmission and distribution of electricity in the Soviet Union
1109
Table 2. Diminishing returns to the national system intheform of energy savings as the rate of introduction of devices compensating for reactive load is varied
A - Total capacity of compensation devices installed in a 5-year period (million kVA)
B - Reduction in system losses over the 5-year period (Twh)
Efficiency Average (B/A)
indices Marginal (dB/dA)
22
7.7
360
-_
38
12.6
330
300
50
15.6
310
250
62
18.4
290
200
115
26.0
230
140
140
28.0
200
80
rebates and surcharges stipulates that the required degree of reactive power compensation from each consumer in the network is to be determined by the power system on the basis of actual conditions. The introduction of rebates and surcharges for consumers has increased the level of deployment of compensating devices in the network, resulting in a reduction of electrical network losses by over 3.2TWh. Systematic normative-technical documents have been developed, establishing the relationship between the power system and the consumer and describing the process for settling relevant accounts. These documents are based on a determination of the minimum discounted cost, which in turn depends on the cost of the electrical losses in a given network and on the expenditures for installation and operation of compensating devices. Also, a new procedure was introduced in 1984 to allocate the annual stock of compensating devices among the consumers requesting them, wherein priority is given to those consumers situated in areas of greatest reactive power deficit. A new capacitor bank controller has been developed and manufactured commercially, having separate settings for the times of load peaks and load valleys in the power system; thereby, automatic control can be adjusted to the system task, specifying both the maximum and the minimum operating modes. And, finally, the annual volumes of production of compensating units from the present to the year 2000 have been substantiated. A distinctive feature of all of the innovations in methodology in this field is their orientation toward solutions with a guaranteed result, which is calculated from an analysis of the ranges of uncertainty in the data on the structure of the network and its loads. The strategy of guaranteed results benefits from its evident objectivity, facilitating its practical realization at this time, relative to other strategies of reactive power compensation.
4. IMPLEMENTATION
Standing committees have been established to coordinate and supervise the effort to reduce electrical losses in the power systems of our country. Plans are under way to set up sections for power loss optimization attached to each of our despatching services and power system monitoring services. The principal task of such groups will be to find prompt solutions to any problem connected with the fulfillment of targets for electrical loss reduction. The normative documentation that has now been developed and implemented covers practically all aspects of the activities of operating personnel related to electrical loss reduction, including computation, analysis and planning of losses, planning and
1110
I. G. KARAPETIANet al.
evaluation of cost-effectiveness of loss-reduction measures, improvements in electricity metering, flow control, and optimum reactive power compensation in electrical networks of power systems and consumers. Computer facilities of power systems and electrical networks are used to calculate losses in networks of all voltage levels. Programs for loss calculations now exist appropriate to the various levels of reference data on circuits and operating conditions. In closed, systemforming electrical networks of 220 kV and above, through which electricity is exchanged among power systems, telemetry connected directly to computers is finding ever increasing use in loss calculations, allowing the computation of losses in such networks on a realtime basis. It has proved useful to develop a list of organizational and technical measures to reduce losses and to improve practical electricity metering. The list contains all measures currently well understood and recommended for extensive application in electrical networks. Availability of such a list encourages power system personnel to make better use of available tools for loss reduction and to apply energy-saving measures more extensively. Work is under way to introduce non-traditional measures not yet widely known in the U.S.S.R.; for example, experience is being gained in repair work on live conductors of overhead lines. An All-Union center for live-line maintenance has been created in one of the Ukrainian power systems. This center not only trains service personnel, but also produces the attachments and equipment for the execution of such work. Live-line maintenance at all voltage levels makes it possible not only to reduce losses in electrical networks, but also to decrease considerably the undersupply of electricity due to power interruptions. The 12th Five Year Plan envisages pilot installations for transformer heat extraction at two or three 330 kV substations to heat the substation control buildings and the residences of service personnel. Such installations could provide considerable savings in the electricity consumed by substation auxiliaries (nationally, about 5OOGWh per year). Equipment tests and selection of the most suitable heat extraction scheme have been scheduled for a trial period, with subsequent wide-scale introduction of the acquired experience. Much attention is being paid to reduction of electrical losses in urban and rural electrical distribution networks. Here the most urgent organizational issues are the optimization of network division points and the voltage regulation rules in the main substations. An effective measure, although requiring additional investments, is the use of “deep lead-ins” in urban electrical networks, with upgrading to a higher nominal voltage (mainly upgrading from 6 to 1OkV). Certain power systems already have automated supervisory control systems for distribution networks, with associated data bases. These automated systems address problems of computation, analysis, and reduction of electrical losses in networks. In 1983 an automated system was created and commissioned, as a result of efforts by a number of agencies, for acquisition and processing of data on grid structure and losses, as well as on implementation of measures to reduce electrical losses. The system is designed for acquisition of detailed information on components of losses at each voltage level. The automated system provides statistical data for various purposes: to justify the choice of level of electrical loss projected for a planning year; to develop and adjust rules for losses from no-load transformer operation and from corona, to rationalize the consumption of electricity by substation auxiliaries, and to assess the effectiveness of specific loss-reduction measures. Such modeling allows a comparative analysis of loss-reduction measures in various systems to be made. In summary, reliable calculations of electrical losses, selection of the most effective measures for loss reduction, and planning of losses are impossible without increasingly accurate initial data on power network operating conditions. Accordingly, the calculating and metering of electricity are being perfected, Automated metering systems developed in the U.S.S.R. are being widely used at power stations, system substations, and industrial installations. Prototype automated systems are available which not only monitor power consumption but also optimize the management of load.
0360-5442/87 $3.00 +O.OO Pergamon JwrnalsLtd
ENERGY CONSERVATION IN THE TRANSMISSION AND DISTRIBUTION OF ELECTRICITY IN THE SOVIET UNION I. G. KARAPETIAN,’
A. L. KUDOYAROV,’ U. S. ZHELEZKO’ and V. E. VOROTNITSKI~
‘Energosetprojekt
Institute,
Glavzagranenergo, Kitajsky proead ‘VNIIE. U.S.S.R.
7, Moscow,
103074, U.S.S.R.
Abstract-Strategies to reduce losses in the transmission and distribution of electricity are reviewed. A major effort is under way to improve load management by widely deploying devices which compensate for reactive load. To optimize the use of these devices, a system of rebates and surcharges is being used, and system integration is being expanded. Computerized data bases to plan the future of the electricity system of the U.S.S.R. are undergoing rapid development.
1. ELECTRICAL
NETWORKS
IN THE U.S.S.R.
Rational use of all available resources, especially energy resources, is a national task stipulated in the fundamental propositions of the Long-Term Energy Management Program of the U.S.S.R. To fulfill this task a basic technical program for reducing the losses of electricity in the power networks of the country must be developed. Consistent with the technical policy of improving the efficiency of the generation and distribution of electricity, the power industry in the U.S.S.R. managed to keep losses down to 9% of the electrical energy delivered into the network in the last lo-15 yr. Moreover, in the last few years the power industry has developed an increasingly active energy-saving policy, involving an entire complex of organizational and technical measures in combination with continuing research work. Examples of these measures are improvements in the system for registration, acquisition, and processing of incoming data; state-of-the-art operation of the electrical network; renovation and modernization of equipment while optimizing network development; and incentives to operating personnel. The technical goals include maintaining optimum load curves over the day, sectionalizing the network, controlling the voltage under variable load, making best use of compensating devices, and applying the latest achievements in science and technology. In 1984 electrical losses in our power system networks totaled 124.3 TWh, which is 9.4% of the electricity fed into these networks. Generation plants with a total capacity of 24 GW, consuming 41 million tonnes of coal equivalent (tee), or 1.2 x lo’* J, were in operation just to compensate for these losses. Research conducted by several institutes has led to the conclusion that the present level of electrical losses exceeds what is economically justified, a systems approach suggests that with extra investments, long-term losses may be reduced to an economically justified level of 8.0-8.5% of electricity delivered into the network. Table 1. Percent of total losses of electrical energy in transmission and distribution networks of various voltages (percent). The asterisk shows the partition between transmission and distribution
Voltage Current Future
500 -system system
kV
330 --
10 12.5
*
kv
220 --
7.5
16
4
15
110-150 ~-
kV *
kV
35 kV --
Total __
28.5
38
100
20
48.5
100
Table 1 shows the fractions of the total electrical losses in the nation’s networks at each voltage, both now and as planned for the future. Networks at 220 kV and above, which currently are our transmission networks, are seen to account for one-third of total losses, 1107
1108
I. G. KARAPETIAN et al.
while the remaining two-thirds of the losses are associated with our distribution networks, with voltages of 150 kV and below; the latter also account for over 80% of the total network length. In the future, all networks at 330 kV and below are to be distribution networks, and these are expected to account for more than 85% of total losses. As the U.S.S.R. National Power Grid expands, relative losses from networks at 500 kV and above, which generally carry electricity directly from the power plant, are expected to increase; relative losses from networks in the 1 lo- 150 kV category are expected to decrease as their functions are transferred to 220 and 330 kV networks.
2. REDUCING
LOSSES THROUGH
LOAD MANAGEMENT
Losses of electricity in our power systems are affected by certain basic features of the U.S.S.R. National Power Grid that are virtually impossible to influence because they have an objective character and reflect national energy policy. First, individual power plant capacity is increasing (it is now 1000-1500 MW), and power plants are being sited increasingly in large generation complexes. For example, the total generating capacity of the power plants in the Ekibastuz, Kansk-Achinsk, and Western Siberia power complexes is planned to be 13-15 GW, or even 18-20 GW. Second, in the European part of the U.S.S.R. and in the Urals 4-6GW nuclear power plants are planned, and in the eastern regions large hydropower stations with capacities up to 1OGW are planned. Third, the nominal transmission voltage continues to rise. The highest a.c. transmission voltage for over 10 yr has been 750kV, and a 750kV transmission network has been forming in the northwest, south, and central regions of the U.S.S.R. The first transmission lines at a still higher voltage have been constructed and are about to be energized at their nominal voltage in the eastern zone of the U.S.S.R. National Power Grid, which already has an extensive 500 kV network. Within this framework energy conservation objectives can be addressed through the control of electrical network parameters: degree of reactive load compensation, weightedaverage current density in aerial and cable lines, number of transformers in the network. Of these, increasing the degree of reactive load compensation is particularly effective. Identifying the optimum capacity of the compensating devices installed in the network requires both economic and systems considerations. In the U.S.S.R., it is reasonable to maintain the reactive load compensation ratio in electrical networks at a level of 0.6 kVA per kW of peak load. Reactive load compensation is done within both power system networks and consumer networks. At present about 60% of all compensating devices are installed in consumer networks. In the future this ratio should remain constant, as the basic effect is provided by compensating devices installed at the consumer. The installation of compensating devices at a steady rate ensures the highest efficiency of their utilization because there are diminishing returns, as is seen in Table 2. Two simple efficiency indices for compensating devices decrease as the rate of introduction of For example, an increase in compensating devices compensating devices increases. commissioned over 5 yr from 22 to 140 million kVA reduces one efficiency index 1.8 times and the other 3.5 times. Using these indices with optimization methods helps select the best reaction capacities and the best locations for the installation of compensating devices.
3. REBATES
AND SURCHARGES
By now most of the difficulties in selecting the best strategy for providing electrical networks with compensating devices have been solved, or are nearly solved. There are now methods and programs which determine the capacity, location, suitable sequence, and efficiency of compensating devices in a given network. There is also an organizational mechanism-rebates and surcharges on tariffs-to induce the consumer to respond to the conditions set by an electric utility for reactive power consumption. This new system of
Energy conservation in the transmission and distribution of electricity in the Soviet Union
1109
Table 2. Diminishing returns to the national system intheform of energy savings as the rate of introduction of devices compensating for reactive load is varied
A - Total capacity of compensation devices installed in a 5-year period (million kVA)
B - Reduction in system losses over the 5-year period (Twh)
Efficiency Average (B/A)
indices Marginal (dB/dA)
22
7.7
360
-_
38
12.6
330
300
50
15.6
310
250
62
18.4
290
200
115
26.0
230
140
140
28.0
200
80
rebates and surcharges stipulates that the required degree of reactive power compensation from each consumer in the network is to be determined by the power system on the basis of actual conditions. The introduction of rebates and surcharges for consumers has increased the level of deployment of compensating devices in the network, resulting in a reduction of electrical network losses by over 3.2TWh. Systematic normative-technical documents have been developed, establishing the relationship between the power system and the consumer and describing the process for settling relevant accounts. These documents are based on a determination of the minimum discounted cost, which in turn depends on the cost of the electrical losses in a given network and on the expenditures for installation and operation of compensating devices. Also, a new procedure was introduced in 1984 to allocate the annual stock of compensating devices among the consumers requesting them, wherein priority is given to those consumers situated in areas of greatest reactive power deficit. A new capacitor bank controller has been developed and manufactured commercially, having separate settings for the times of load peaks and load valleys in the power system; thereby, automatic control can be adjusted to the system task, specifying both the maximum and the minimum operating modes. And, finally, the annual volumes of production of compensating units from the present to the year 2000 have been substantiated. A distinctive feature of all of the innovations in methodology in this field is their orientation toward solutions with a guaranteed result, which is calculated from an analysis of the ranges of uncertainty in the data on the structure of the network and its loads. The strategy of guaranteed results benefits from its evident objectivity, facilitating its practical realization at this time, relative to other strategies of reactive power compensation.
4. IMPLEMENTATION
Standing committees have been established to coordinate and supervise the effort to reduce electrical losses in the power systems of our country. Plans are under way to set up sections for power loss optimization attached to each of our despatching services and power system monitoring services. The principal task of such groups will be to find prompt solutions to any problem connected with the fulfillment of targets for electrical loss reduction. The normative documentation that has now been developed and implemented covers practically all aspects of the activities of operating personnel related to electrical loss reduction, including computation, analysis and planning of losses, planning and
1110
I. G. KARAPETIANet al.
evaluation of cost-effectiveness of loss-reduction measures, improvements in electricity metering, flow control, and optimum reactive power compensation in electrical networks of power systems and consumers. Computer facilities of power systems and electrical networks are used to calculate losses in networks of all voltage levels. Programs for loss calculations now exist appropriate to the various levels of reference data on circuits and operating conditions. In closed, systemforming electrical networks of 220 kV and above, through which electricity is exchanged among power systems, telemetry connected directly to computers is finding ever increasing use in loss calculations, allowing the computation of losses in such networks on a realtime basis. It has proved useful to develop a list of organizational and technical measures to reduce losses and to improve practical electricity metering. The list contains all measures currently well understood and recommended for extensive application in electrical networks. Availability of such a list encourages power system personnel to make better use of available tools for loss reduction and to apply energy-saving measures more extensively. Work is under way to introduce non-traditional measures not yet widely known in the U.S.S.R.; for example, experience is being gained in repair work on live conductors of overhead lines. An All-Union center for live-line maintenance has been created in one of the Ukrainian power systems. This center not only trains service personnel, but also produces the attachments and equipment for the execution of such work. Live-line maintenance at all voltage levels makes it possible not only to reduce losses in electrical networks, but also to decrease considerably the undersupply of electricity due to power interruptions. The 12th Five Year Plan envisages pilot installations for transformer heat extraction at two or three 330 kV substations to heat the substation control buildings and the residences of service personnel. Such installations could provide considerable savings in the electricity consumed by substation auxiliaries (nationally, about 5OOGWh per year). Equipment tests and selection of the most suitable heat extraction scheme have been scheduled for a trial period, with subsequent wide-scale introduction of the acquired experience. Much attention is being paid to reduction of electrical losses in urban and rural electrical distribution networks. Here the most urgent organizational issues are the optimization of network division points and the voltage regulation rules in the main substations. An effective measure, although requiring additional investments, is the use of “deep lead-ins” in urban electrical networks, with upgrading to a higher nominal voltage (mainly upgrading from 6 to 1OkV). Certain power systems already have automated supervisory control systems for distribution networks, with associated data bases. These automated systems address problems of computation, analysis, and reduction of electrical losses in networks. In 1983 an automated system was created and commissioned, as a result of efforts by a number of agencies, for acquisition and processing of data on grid structure and losses, as well as on implementation of measures to reduce electrical losses. The system is designed for acquisition of detailed information on components of losses at each voltage level. The automated system provides statistical data for various purposes: to justify the choice of level of electrical loss projected for a planning year; to develop and adjust rules for losses from no-load transformer operation and from corona, to rationalize the consumption of electricity by substation auxiliaries, and to assess the effectiveness of specific loss-reduction measures. Such modeling allows a comparative analysis of loss-reduction measures in various systems to be made. In summary, reliable calculations of electrical losses, selection of the most effective measures for loss reduction, and planning of losses are impossible without increasingly accurate initial data on power network operating conditions. Accordingly, the calculating and metering of electricity are being perfected, Automated metering systems developed in the U.S.S.R. are being widely used at power stations, system substations, and industrial installations. Prototype automated systems are available which not only monitor power consumption but also optimize the management of load.