Initially, DSM was driven by electricity businesses as a load and investment management tool, often within a least-cost planning framework. While this aspect continues even today in some countries, DSM is increasingly being used by power utilities worldwide as a potent tool for energy management(see Fig.).
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| DSM as a Tool for Energy Management for Power Utilities |
In this section you will learn about the techniques being adopted by utilities to use DSM for meeting these aims.
Demand side management by a utility incorporates all activities that are designed to influence customer use of electricity in ways that are mutually beneficial to the customer and the utility. It assures efficient use of the electric system and provides a broader range of choices for customers.
At the core of a utility DSM programme is a series of measures intended to encourage specific groups of customers or market segments to modify their energy usage patterns. These should be implemented in a manner consistent with the utility’s DSM objectives, while maintaining or enhancing customer satisfaction. You must understand that the demand-side planning and management process is dynamic. It is flexible, comprehensive, and must accommodate changing conditions.
Utility DSM programmes usually fall into two broad categories:
• Demand/Load Management Programmes to shift and reschedule the energy consumption process; and
• Energy Conservation and Efficiency Programmes to save energy.
We now discuss the first of these categories of DSM programmes.
Load Management
In the load management approach, DSM refers to the control of customer load to improve utility operations. It comprises all those activities,products, services, tariffs, regulations, policies, or any combinations of these that will influence the time, pattern, and magnitude of participating customers’ electrical loads and affect the timing or amount of electricity used by customers.
Therefore, DSM programme of a utility has to match customer consumption patterns of electricity, i.e., load characteristics, as closely as possible to current or projected capabilities of the power supply facilities. In this connection two factors are important: peak load and load factor.Peak load is simply the highest level of electricity demand in a given time-span, usually in one day or in one year.
Load factor is the difference between the average demand and the peak demand over that given time.While a low load factor is bad, a high load factor is not necessarily good.Equipment needs routine maintenance, and failures happen. A power supplier must have enough reserve margin to cover these events.
DSM programmes are used to eliminate or reduce the need for additional peak or base load generating capacity and/or distribution facilities by controlling customer loads. The goals are to reduce the peak load and toincrease the off peak usage of energy. DSM can be used to effectively manage the system peaks and valleys.
Load management is carried out to reduce peak load, for example, through segregation of agriculture load. The peak demand can also be reduced by spreading out the consumer load more evenly over the entire daily or weekly period. Load levelling technologies are used to smooth out the peaks and dips in energy demand by reducing consumption at peak times, shifting the loadfrom peak to off-peak periods, or increasing it during off-peak times.We now describe the DSM techniques used by power utilities for managing the customer load.
DSM Techniques
Power utilities can take a host of measures for management of load in the power system at the LT level. Some of these are
• Load curve modification,
• TOD meters,
• Three shift operation and staggered off day.
We now describe these techniques, in brief.
Load Curve Modification
When a DSM programme is being planned by a power utility, it is important that the target load curve objectives be established beforehand and the electricity demand be managed accordingly.
The following are the most commonly practised load curve modification objectives:
• Peak clipping
• Valley filling
•Strategic conservation
• Strategic load growth
• Load shifting
• Flexible load shape
These terms might be new to many of you. Therefore, we shall spend some time on explaining their meaning. You may first like to look at the shape of the load curve in each case. We illustrate these load profiles in Fig.
Let us explain what these terms mean.
1. Peak Clipping means the reduction of the system peak loads at specific periods. It embodies one of the classic forms of load management. Peak clipping is generally considered to be reducing peak loads through the utility’s direct control on equipment used by the consumer or through tariff clauses whereby a consumer curtails his/her load at certain hours of the day. This procedure not only offers the possibility of reducing the need for installing additional power plants, but it also allows to reduce the operational costs of power stations and, to a certain extent, the dependence on fossil fuels (such as natural gas, heating oil) for generating electricity.
Energy management control systems (EMCSs) can be used to switch electrical equipment on or off for load levelling purposes. Some EMCSs enable direct off-site control (by the electric supply company) of user equipment. These are direct load control switches that allow the electric company to control appliances such as air conditioners during periods of maximum demand. Typically applied to heating, cooling, ventilation, and lighting loads, EMCSs can also be used to invoke on-site generators, thereby reducing peak demand for grid electricity.
2. Valley Filling involves building the load during off-peak hours. This proves to be particularly interesting in cases where the long term marginal production costs are less than the selling price of electricity. Under these conditions, adding loads at a reasonable rate helps to reduce the overall cost price of electricity. For example, one of the ways of increasing the energy consumption during off-peak hours (valley filling) is to design buildings with thermal storage facilities (e.g., water heating and /or space heating), which can generate demand during off-peak hours or to offer special rates (tariff clauses) favouring load increases during off-peak hoursonly. For example, power utilities encourage customers to switch on their water heating appliances during off peak hours.
Demand side management by a utility incorporates all activities that are designed to influence customer use of electricity in ways that are mutually beneficial to the customer and the utility. It assures efficient use of the electric system and provides a broader range of choices for customers.
At the core of a utility DSM programme is a series of measures intended to encourage specific groups of customers or market segments to modify their energy usage patterns. These should be implemented in a manner consistent with the utility’s DSM objectives, while maintaining or enhancing customer satisfaction. You must understand that the demand-side planning and management process is dynamic. It is flexible, comprehensive, and must accommodate changing conditions.
Utility DSM programmes usually fall into two broad categories:
• Demand/Load Management Programmes to shift and reschedule the energy consumption process; and
• Energy Conservation and Efficiency Programmes to save energy.
We now discuss the first of these categories of DSM programmes.
Load Management
In the load management approach, DSM refers to the control of customer load to improve utility operations. It comprises all those activities,products, services, tariffs, regulations, policies, or any combinations of these that will influence the time, pattern, and magnitude of participating customers’ electrical loads and affect the timing or amount of electricity used by customers.
Therefore, DSM programme of a utility has to match customer consumption patterns of electricity, i.e., load characteristics, as closely as possible to current or projected capabilities of the power supply facilities. In this connection two factors are important: peak load and load factor.Peak load is simply the highest level of electricity demand in a given time-span, usually in one day or in one year.
Load factor is the difference between the average demand and the peak demand over that given time.While a low load factor is bad, a high load factor is not necessarily good.Equipment needs routine maintenance, and failures happen. A power supplier must have enough reserve margin to cover these events.
DSM programmes are used to eliminate or reduce the need for additional peak or base load generating capacity and/or distribution facilities by controlling customer loads. The goals are to reduce the peak load and toincrease the off peak usage of energy. DSM can be used to effectively manage the system peaks and valleys.
Load management is carried out to reduce peak load, for example, through segregation of agriculture load. The peak demand can also be reduced by spreading out the consumer load more evenly over the entire daily or weekly period. Load levelling technologies are used to smooth out the peaks and dips in energy demand by reducing consumption at peak times, shifting the loadfrom peak to off-peak periods, or increasing it during off-peak times.We now describe the DSM techniques used by power utilities for managing the customer load.
DSM Techniques
Power utilities can take a host of measures for management of load in the power system at the LT level. Some of these are
• Load curve modification,
• TOD meters,
• Three shift operation and staggered off day.
We now describe these techniques, in brief.
Load Curve Modification
When a DSM programme is being planned by a power utility, it is important that the target load curve objectives be established beforehand and the electricity demand be managed accordingly.
The following are the most commonly practised load curve modification objectives:
• Peak clipping
• Valley filling
•Strategic conservation
• Strategic load growth
• Load shifting
• Flexible load shape
These terms might be new to many of you. Therefore, we shall spend some time on explaining their meaning. You may first like to look at the shape of the load curve in each case. We illustrate these load profiles in Fig.
Let us explain what these terms mean.
1. Peak Clipping means the reduction of the system peak loads at specific periods. It embodies one of the classic forms of load management. Peak clipping is generally considered to be reducing peak loads through the utility’s direct control on equipment used by the consumer or through tariff clauses whereby a consumer curtails his/her load at certain hours of the day. This procedure not only offers the possibility of reducing the need for installing additional power plants, but it also allows to reduce the operational costs of power stations and, to a certain extent, the dependence on fossil fuels (such as natural gas, heating oil) for generating electricity.
Energy management control systems (EMCSs) can be used to switch electrical equipment on or off for load levelling purposes. Some EMCSs enable direct off-site control (by the electric supply company) of user equipment. These are direct load control switches that allow the electric company to control appliances such as air conditioners during periods of maximum demand. Typically applied to heating, cooling, ventilation, and lighting loads, EMCSs can also be used to invoke on-site generators, thereby reducing peak demand for grid electricity.
2. Valley Filling involves building the load during off-peak hours. This proves to be particularly interesting in cases where the long term marginal production costs are less than the selling price of electricity. Under these conditions, adding loads at a reasonable rate helps to reduce the overall cost price of electricity. For example, one of the ways of increasing the energy consumption during off-peak hours (valley filling) is to design buildings with thermal storage facilities (e.g., water heating and /or space heating), which can generate demand during off-peak hours or to offer special rates (tariff clauses) favouring load increases during off-peak hoursonly. For example, power utilities encourage customers to switch on their water heating appliances during off peak hours.
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| Effects of DSM on Load Shape |
3. Load Shifting involves shifting load from on-peak to off-peak periods.The most common applications of this measure are related to heating and air conditioning. Shifting load demands associated with thermal storage involves load shifting related to conventional electricity applications (for example, building heating by electric convectors).One strategy commonly used in developed countries is to charge more per kWh during high demand periods, such as during business hours in daytime or dinnertime. Such a pricing policy encourages consumers to defer non-critical electrical loads such as operating a washing machine, dish washer or clothes drier to off-peak times. Energy storage devices located at the consumer’s end are also used to shift the timing of energy consumption and hence the loads.All these measures are undertaken in response to the crunch in electricity supply. These focus on switching off or rescheduling of non-essential and non-critical loads by the end-users in response to the utilities’ compulsions.These can save the system network from exceeding its peak rating when some equipment and applications are switched on or off at particular times thereby reducing electricity demand from the network.
4. Strategic Conservation is one of the non-traditional approaches to load management and results from utility-stimulated programmes directed at reducing end use consumption through a reduction in sales as well as a change in the pattern of use of electricity. Not normally considered load management, the change reflects a modification of the load shape.
Examples are:
•Weatherisation involving measures such as:
i) good heat insulation (use of thermocol, etc.),
ii) using sun shades,
iii) orientation of the air conditioned bed rooms to minimise solar radiation,
iv) cleaning of air filters in ACs,
v)use of solar films, reflective curtain glass, automatic door closers, etc.,
vi) controlled lighting (not all lights on at all times, sensor controlled switch off), use of natural light, etc.
•Energy efficiency improvement (improving specific energy consumption of an appliance by changing the technology deployed) like using
i) compact fluorescent lamps (CFLs),
ii) energy efficient pump sets,
iii) energy efficient motors, etc.
5. Strategic Load Growth is also one of the non-traditional approaches for load management. It results in overall increase in sales. It may mean an increased use of electricity on the energy market through the development of new applications (electric cars, industrial process heating, microwave technologies, automation).For example, power utilities in the developed countries realized that they needed to sell power for more than just electric lights. Few people used electric lamps during the day, so generators just sat idle during daylight hours. What were needed were markets that would use power during the day (and little if any at night) so as to balance demand. This is a big reason why electric street-cars (Fig.) attracted interest in these countries.
Electric Street Cars
Power producers try to balance their customer base so that demand from different users will peak at different times, allowing more efficient use of equipment. In some cases, an increase in the use of electric energy can be motivated by national objectives in terms of reducing the use of fossil fuels in countries where hydro-electric resources are significant.
6. Flexible Load Shape is another non-traditional form of load management and it addresses problems related to the reliability of demand forecasts.Power utilities are never guaranteed to balance their production capacity with the expected demand. They must make sure that they can curtail a consumer’s load demand if need be (either for an immediate need or as a constituent for their energy reserves), in exchange for various incentives.The customer must then produce his/her own electricity or use other energy sources to meet his/her demands.Load at consumer premises can be controlled in two ways depending upon the size of load and the infrastructure: Direct Load Control and Load Control by Consumers.
Direct Load Control is done directly by the power utility for large supply consumers in consultation with them after careful planning and installing required infrastructure. We have given the example of direct load control switches that allow the electric utilities to control appliances such as conditioners during periods of maximum demand.
Load Control by Consumers can be done in cases where information is sent to them about the quantity of load to be controlled along with the other related information. Then they can take the required action within the stipulated time.We end this discussion by describing some of the latest developments in this area.
TOD meters
Installation of time of day (TOD) electronic meters and introduction of TOD tariff is an important DSM technique. This would help in flattening the load curve by way of giving incentive/disincentive to consumers during off peak/peak hours, respectively. Fig. 4.6 shows TOD charges of an Indian electric utility.
TOD meters
Installation of time of day (TOD) electronic meters and introduction of TOD tariff is an important DSM technique. This would help in flattening the load curve by way of giving incentive/disincentive to consumers during off peak/peak hours, respectively. Fig. 4.6 shows TOD charges of an Indian electric utility.
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| TOD Charges of an Indian Power Utility for Different Time Zones |
Three-shift Operation and Staggered Off Day
Demand from an industrial customer may be very steady if the company is running a three-shift operation or if the off days could be staggered. We shall discuss some DSM measures for industrial customers in the next unit.In addition, energy audit of the power system is undertaken as a part of DSM to pinpoint excessive loss prone areas. Reduction of T&D losses in LT distribution system can be done by installation of amorphous core distribution transformers (AMDTS), and installation of LT switched capacitors for improvement in voltage level and power sector. Table reveals the benefits of using high efficiency distribution transformers over conventional transformers, though the initial costs might be higher.
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| Comparison of Standard and High-Efficiency Distribution Transformers Type of Transformer − 10 |
We end this discussion by describing the latest developments in this area.
Emerging Trends
Under the current scheme of operations, customers pay the same rate throughout the year, regardless of the actual cost to the utility of generating electricity in any given hour or of distributing electricity to any particular portion of the transmission and distribution grid. As a result, consumers have little opportunity to control their electricity costs by matching their preferences, cost,timing, and reliability of service to the price and character of the services purchased. New technologies are making it practical to provide variable price signals and a range of other demand-side services to consumers.
Time-of-use pricing, real-time pricing, and other flexible load-shape programmes can take advantage of the substantial variation in generation prices by time and location that is expected in a competitive market. Utilities have started offering real-time pricing to their customers through DSM programmes that involve automated energy management, two-way communication systems, and time-of-use prices. Spot-market prices will fluctuate based on load levels, the availability of major generating units, and transmission constraints. During capacity shortages, prices could increase reflecting the cost of building new generation capacity to serve peak loads and the price signals that might be required to match demand to available supply.
We now acquaint you with some of these emerging DSM methods.Dynamic/Real Time Pricing: The de-regulated market is based on real time system of supply and demand. Prices change from time to time and hour to hour depending upon these two factors. Exposing customers to Real Time/Dynamic prices, i.e., time-varying prices, gives them a better view of the prevailing market. They get to know the information and incentive to reduce their demand at peak times. They can then shift their usage from high priced periods to low-priced periods.
Time-of-Use Rates: This is the tool or rate structure by which customers are offered different rates for electricity usage at different times of the day. If customers are offered lower rates for consumption at off-peak time, they can use some of the power at that low-priced time. For example, customers can be offered lower rates for using washing machines, geysers, dish washers, etc. during off-peak hours.
Automated/Smart Metering: Implementing Dynamic/ Real Time Pricing or Time-of-use rate structure and billing is not so complicated any more.Communication linkages can be used to send out variable price signals or schedule time periods when low, moderate, or high price levels will be in effect. The technology used to receive and respond to such price signals will be automated energy management systems that implement predetermined consumer preferences regarding tradeoffs between cost and comfort or convenience. Automatic/Smart Metering successfully used by various utilities provides the best effective solution to this problem.
Web-based/Communication System: This tool is used along with the above measures to convey information to the customer about the prevailing demand,supply, prices on real time basis and the incentives and options, which can be used by the customer to manage the demand. In addition, there are other methods like e-mail, cell phone, pagers and fax, etc., which can be used as a communication tool to convey the required information and data. Two-way communication permits utilities to determine the effects of load management at the premise and end-use levels. Utilities could offer load control services that include a customer override option, with billing dependent upon whether the option was exercised.
Communication and information management systems can be used to provide customers with an array of energy information services, including:
• continuously updated break-ups of monthly energy use by major appliances or end uses and variable pricing category;
• comparisons of energy use by appliances or end uses in the current and prior periods;
• projections of the monthly electricity bill based on partial month data;
• comparisons of energy use to typical neighbourhood profiles; and
• DSM recommendations, including estimates of energy cost impacts of potential efficiency improvements.
Benefits from automated meter reading, remote connect/disconnect services, electronic billing, automated bill payment, theft or tampering detection,distribution automation, and non-energy services may also contribute to the cost-effectiveness of energy-related two-way communication systems.In some cases, energy information services may be provided as part of a broad band communication network that also makes available cable TV,telephone, internet, security system, video-on-demand, medical alert, and other telecommunications services. But, a choice of communication technologies, including use of existing telephone lines, wireless, and hybrid fibre optic/coaxial cable systems, will permit energy information services to develop at a pace that is independent of the construction of broad band telecommunication networks.
Power utilities have not been able to undertake load management activities on a large scale due to several reasons, which we discuss briefly.Factors affecting the Load Management Programme Implementing these techniques/ technologies has substantial financial implications and utilities need to consider the following factors before applying them at large scale for the whole market:
Emerging Trends
Under the current scheme of operations, customers pay the same rate throughout the year, regardless of the actual cost to the utility of generating electricity in any given hour or of distributing electricity to any particular portion of the transmission and distribution grid. As a result, consumers have little opportunity to control their electricity costs by matching their preferences, cost,timing, and reliability of service to the price and character of the services purchased. New technologies are making it practical to provide variable price signals and a range of other demand-side services to consumers.
Time-of-use pricing, real-time pricing, and other flexible load-shape programmes can take advantage of the substantial variation in generation prices by time and location that is expected in a competitive market. Utilities have started offering real-time pricing to their customers through DSM programmes that involve automated energy management, two-way communication systems, and time-of-use prices. Spot-market prices will fluctuate based on load levels, the availability of major generating units, and transmission constraints. During capacity shortages, prices could increase reflecting the cost of building new generation capacity to serve peak loads and the price signals that might be required to match demand to available supply.
We now acquaint you with some of these emerging DSM methods.Dynamic/Real Time Pricing: The de-regulated market is based on real time system of supply and demand. Prices change from time to time and hour to hour depending upon these two factors. Exposing customers to Real Time/Dynamic prices, i.e., time-varying prices, gives them a better view of the prevailing market. They get to know the information and incentive to reduce their demand at peak times. They can then shift their usage from high priced periods to low-priced periods.
Time-of-Use Rates: This is the tool or rate structure by which customers are offered different rates for electricity usage at different times of the day. If customers are offered lower rates for consumption at off-peak time, they can use some of the power at that low-priced time. For example, customers can be offered lower rates for using washing machines, geysers, dish washers, etc. during off-peak hours.
Automated/Smart Metering: Implementing Dynamic/ Real Time Pricing or Time-of-use rate structure and billing is not so complicated any more.Communication linkages can be used to send out variable price signals or schedule time periods when low, moderate, or high price levels will be in effect. The technology used to receive and respond to such price signals will be automated energy management systems that implement predetermined consumer preferences regarding tradeoffs between cost and comfort or convenience. Automatic/Smart Metering successfully used by various utilities provides the best effective solution to this problem.
Web-based/Communication System: This tool is used along with the above measures to convey information to the customer about the prevailing demand,supply, prices on real time basis and the incentives and options, which can be used by the customer to manage the demand. In addition, there are other methods like e-mail, cell phone, pagers and fax, etc., which can be used as a communication tool to convey the required information and data. Two-way communication permits utilities to determine the effects of load management at the premise and end-use levels. Utilities could offer load control services that include a customer override option, with billing dependent upon whether the option was exercised.
Communication and information management systems can be used to provide customers with an array of energy information services, including:
• continuously updated break-ups of monthly energy use by major appliances or end uses and variable pricing category;
• comparisons of energy use by appliances or end uses in the current and prior periods;
• projections of the monthly electricity bill based on partial month data;
• comparisons of energy use to typical neighbourhood profiles; and
• DSM recommendations, including estimates of energy cost impacts of potential efficiency improvements.
Benefits from automated meter reading, remote connect/disconnect services, electronic billing, automated bill payment, theft or tampering detection,distribution automation, and non-energy services may also contribute to the cost-effectiveness of energy-related two-way communication systems.In some cases, energy information services may be provided as part of a broad band communication network that also makes available cable TV,telephone, internet, security system, video-on-demand, medical alert, and other telecommunications services. But, a choice of communication technologies, including use of existing telephone lines, wireless, and hybrid fibre optic/coaxial cable systems, will permit energy information services to develop at a pace that is independent of the construction of broad band telecommunication networks.
Power utilities have not been able to undertake load management activities on a large scale due to several reasons, which we discuss briefly.Factors affecting the Load Management Programme Implementing these techniques/ technologies has substantial financial implications and utilities need to consider the following factors before applying them at large scale for the whole market:
•cost to the customer to shed and reschedule the load;
•tariff variations;
•time taken to activate the load response;
•losses, if any, in case of reliability problems; and
•any losses in production by implementing these programmes.
However, there are many opportunities where utilities can apply these measures without any additional cost or investment. There is significant interest within the electricity industry in packaging flexible pricing, load management, energy information, and other services. The extent to which such approaches become cost-effective for small consumers will depend upon the degree of variation in spot prices, the number of hours per year in which spot prices are high, the willingness of customers to pay for energy information and other services, and the ability of manufacturers to continue to lower the cost of communication and energy management systems.
Finally, in this unit, we discuss the provisions of the Energy Conservation Act, 2001 and the role of ERCs in helping the utilities take up this activity.
•tariff variations;
•time taken to activate the load response;
•losses, if any, in case of reliability problems; and
•any losses in production by implementing these programmes.
However, there are many opportunities where utilities can apply these measures without any additional cost or investment. There is significant interest within the electricity industry in packaging flexible pricing, load management, energy information, and other services. The extent to which such approaches become cost-effective for small consumers will depend upon the degree of variation in spot prices, the number of hours per year in which spot prices are high, the willingness of customers to pay for energy information and other services, and the ability of manufacturers to continue to lower the cost of communication and energy management systems.
Finally, in this unit, we discuss the provisions of the Energy Conservation Act, 2001 and the role of ERCs in helping the utilities take up this activity.
Nice articles and your information valuable and good articles thank for the sharing information electrical distribution control
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