Utility Load Research Articles

Privacy-preserving load profile matching for tariff decisions in smart grids

In liberalized energy markets, matching consumption patterns to energy tariffs is desirable, but practically limited due to privacy concerns, both on the side of the consumer and on the side of the utilities. We propose a protocol through which a customer can obtain a better tariff with the help of their smart meter and a third party, based on privacy-preserving load profile matching. Our security analysis shows that the protocol preserves consumer privacy, i.e., neither the load profile nor the matching result are disclosed to the utility, unless the consumer later decides to actually purchase the tariff. In addition, the utility's load profiles used for matching remain private, allowing each utility to offer special tariffs without disclosing the associated load profiles to their competitors. Our approach is shown to have a smaller ciphertext size than homomorphic encryption in practically relevant configurations. However, matching is only possible with up to about 98 % accuracy in general and 93.5 % based on real-world load profiles, respectively. Depending on the practical requirements, two protocol parameters provide a tradeoff between matching accuracy and ciphertext size.

RESIDENTIAL CUSTOMERS' OUTAGE COST ANALYSIS FOR URBAN AND SEMI-URBAN AREAS IN A DEVELOPING COUNTRY

This paper discusses cost of unreliability of electricity supply to the residential customers. Electricity supply outage cost is evaluated by customers' survey technique for urban and semi-urban residential areas of a developing country. The energy consumption pattern of urban and sub-urban areas is determined. Electricity supply outage cost is evaluated using both preparatory action approach and contingent valuation method. A detailed breakdown of customer's average outages costs for a entire day based on 8 three-hourly time durations are obtained that give easily understandable figures to the utilities. The power consumption pattern obtained are in close agreement with the utility's load curve. A MATLAB based computer program using Least Square Error Approximation is used to evaluate the outage cost.

Load Forecasting of Hybrid Electric Vehicles Under Real Time Pricing

This paper presents a generalized formulation to forecast the loads of Plug-in hybrid electric vehicles. With this method, utilities can implement customer-oriented pricing strategy to influence the load profiles and the amount of electricity demand. The pricing strategy increases customer satisfaction and produces desired changes in the utility's system load shape. The pricing strategy incorporates utilities and customer requirements into integrated planning procedures. A case study is conducted to illustrate the application of the load forecasting method.

Demand-side management for the residential sector of the San Jose, Costa Rica, metropolitan region

The residential sector is responsible for almost half of the total electricity consumption of CNFL's (Compañia Nacional de Fuerza y Luz) market, significantly affecting the utility's load curve. End-use analysis showed cooking and lighting as major contributors to peak power demand usually met by dispatching oil-fired plants. Surveys developed by CNFL revealed an unexplored potential of DSM (demand-side management) programs to promote economic and energy efficiency. This work presents, first, an assessment of the potential of efficiency programs for cooking, based on source substitution – liquefied petroleum gas (LPG) for electricity –, and for lighting, based on technology substitution – compact fluorescent lamps (CFLs) for incandescent lamps (ILs) – in the CNFL service area (metropolitan region of San Jose, Costa Rica). The expected benefits are reduction of electricity peak demand, better use of imported fuels and prevention or postponement of investments in system expansion, furthermore contributing to emission reductions. The effectiveness of these programs was assessed from consumers', utility and social perspectives. Assessment results show the feasibility of proposed measures and potential reduction in peak demand of over 60 MW (5 %) and in energy consumption of over 400 GWh/year (7 %) by the year 2015. Finally, implementation and current status of both efficiency programs are briefly described.

A Fuzzy Expert System for Evaluation of Demand-Side Management Alternatives

It is believed that the onset of true competition in the electric power industry may result in the demise of demand-side management (DSM) as it is known today, which is primarily a means of optimizing a utility's load curve. If DSM is to survive, utilities will need to evaluate the large number of possible options more efficiently and effectively than ever before. To reach this goal, the subjective portion of the evaluation process has been formulated into a fuzzy expert system, yielding faster, more efficient, and consistent results. This paper outlines the development of FEDSM, a Fuzzy Expert system designed to evaluate D emand-Side Management alternatives. FEDSM is a user-friendly, visual basic, and spreadsheet-based evaluation tool which allows the user to develop a flexible expert system. FEDSM is tested and evaluated on actual DSM data collected by a public utility in Nebraska, generating promising results.

An efficient load model for analyzing demand side management impacts

The authors present an efficient technique to model the system load such that the impact of demand-side management (DSM) on the power system can be easily and accurately evaluated. The main objective of implementing DSM in power systems is to change the utility's load shape, i.e., changes in the time pattern and magnitude of the utility's load. Changing the load shape as a result of demand side activities could change the peak load, base load and/or energy demand. Those three variables have to be explicitly modeled into the load curve for properly representing the effects of DSM. The impact of DSM will be manifested as higher or lower reliability levels. The proposed technique to model the load duration curve will facilitate the representation of DSM effects on loss-of-load probability, energy not served, and energy consumption. This will provide an analytical method to study the impact of DSM on capacity requirements. So far iterative methods have been applied to study these effects. The proposed analytical method results in a faster solution with higher accuracy. It takes only 18 s on an 80486 PC to solve each case study involving different peak and base loads, and energy use. >

Software design and evaluation of a microcomputer-based automated load forecasting system

Several electric utilities (viz., Virginia Power) in the United States apply demand charge on the basis of coincidental peak hour load (PHL). This is in addition to the usual kWhr charge. The hour during which the utility experiences the highest demand (MW) for the month is called the peak hour and this MW value is referred to here as the PHL. The hourly demand meter readings for the appropriate consumer (e.g., industrial or large commercial customer, wholesale purchaser, etc.) are examined to determine their demand during the peak hour of the month. The monthly demand charge is computed on the basis of the consumer's contribution to this PHL. This monthly capacity charge can run into millions of dollars for industrial and large commercial customers. Thus it is very valuable for the concerned consumer to receive advance information about the time and size of the utility's peak load. This information would enable them to take load control actions such that their demand can be reduced during the hour of peak load. The motivation behind the research reported in this paper is precisely this-to be able to predict the time and size of this PHL. The load forecast software is part of a load forecasting-load management decision support system based on microcomputers. An IBM-RT/PC is used as the central computer around which the load forecasting and load management simulator has been built in our laboratory.

Flexible strategies for load/demand management using dynamic pricing

The need for and potential role of flexible pricing options which offer an efficient means for achieving a utility's load demand management objectives are discussed. The focus is on dynamic tariffs. By incorporating real-time features within one or more key parameters of the tariff, such pricing options can be tailored to offer the degree of flexibility that is necessary and cost effective for achieving the given demand management objective(s). >

Software Design and Evaluation of a Microcomputer-Based Automated Load Forecasting System

Several electric utilities (viz., Virginia Power) in the United States apply demand charge on the basis of coincidental peak hour load (PHL). This is in addition to the usual kWhr charge. The hour during which the utility experiences the highest demand (MW) for the month is called the peak hour and this MW value is referred to here as the PHL. The hourly demand meter readings for the appropriate consumer (e.g., industrial or large commercial customer, wholesale purchaser, etc.) are examined to determine their demand during the peak hour of the month. The monthly demand charge is computed on the basis of the consumer's contribution to this PHL. This monthly capacity charge can run into millions of dollars for industrial and large commercial customers. Thus it is very valuable for the concerned consumer to receive advance information about the time and size of the utility's peak load. This information would enable them to take load control actions such that their demand can be reduced during the hour of peak load. The motivation behind the research reported in this paper is precisely this-to be able to predict the time and size of this PHL. The load forecast software is part of a load forecasting-load management decision support system based on microcomputers. An IBM-RT/PC is used as the central computer around which the load forecasting and load management simulator has been built in our laboratory.

Analysis of interrelationships between photovoltaic power and battery storage for electric utility load management

The impact of photovoltaic power generation on an electric utility's load shape under supply-side peak load management conditions is explored. Results show that some utilities utilizing battery storage for peak load shaving might benefit from use of photovoltaic (PV) power, the extent of its usefulness being dependent on the specific load shapes as well as the photovoltaic array orientations. Typical utility load shapes both in the eastern (at Rayleigh, NC) and in the western (at Hesperia, CA) parts of the USA are examined for this purpose. It is concluded that while photovoltaic power generation seems to present a bigger impact on the load of the western utility, both utilities will experience considerable savings on the size of the battery system required to shave the peak loads as well as in the night-time base capacity required to charge the battery.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The concept of demand-side management for electric utilities

Demand-side management (DSM) is the planning and implementation of those electric utility activities designed to influence customer uses of electricity in ways that will produce desired changes in the utility's load shape. While the objective of any DSM activity is to produce a load-shape change, the art of successful implementation and the ultimate success of the program rests within the balancing of utility and customer needs. This paper describes demand-side management for electric utilities and discusses the evolution of this concept for load management, strategic conservation, and marketing.

Solar energy/utility interface: Technical issues

Typical solar heating, hot water, and air-conditioning systems cannot provide all of the thermal energy required by a structure. Auxiliary or “backup” energy is supplied by public utilities. Energy storage capability usually provided as an element in such systems may be employed for utility load management purposes. Technical issues relating to this are explored, including the need for development of standards to optimize the interaction between the solar system and the utility, the effect of variability in the utility's load profile upon the interface, and the impact of the use of solar storage for load management on solar systems. Passive solar heating systems are technically diverse. Technical requirements for interfacing passive systems with utilities in an optimum manner are discussed. Suggested approaches to improvement of this interface are reviewed. One solution to successfully interfacing passive systems with utilities is the development of hybrid systems. This potential is explored.

A new approach to peak load pricing

AbstractThis paper explores an alternative method of ‘solving’ the problem of recurring time variable demands in a public utility context. It views the utility's load curve as a series of horizontal layers or ‘slices’ of varying lengths, rather than as a series of vertical slices as in the traditional approach. Several cases are examined, and traditional time‐of‐day pricing is shown to be inefficient or inapplicable in some of them, while ‘demand‐layer’ pricing, based on horizontal slicing, is efficient. In still other cases, neither method of pricing is efficient.

Practical Benefits of Load Modification for the Detroit Edison Company

The benefits of modification of a utility's load shape by using either load management or supply management techniques has been a topic of great interest for the last several years. Most of the previous studies regarding this topic have only looked at a "snapshot year". Thus, the effect on system expansion could never be properly determined. This paper presents the results of a study that was performed by Energy Management Associates, Inc. under the direction of the Planning Department of Detroit Edison. The study investigated a wide range of potential load shapes for the Detroit Edison system. The objective was to identify those load patterns which minimize the revenue requirement per kilowatthour at a constant level of reliability over a 15-year period. Load shapes depicting seasonal, weekly and daily load modification techniques were analyzed. The study was structured to determine gross maximum benefits without taking into account the implementation costs required to attain the various load shapes. The results of the study show that while there are benefits derived from load modification, these benefits are minimal.

Practical Benefits of Load Modification for the Detroit Edison Company

The benefits of modification of a utility's load shape by using either load management or supply management techniques has been a topic of great interest for the last several years. Most of the previous studies regarding this topic have only looked at a "snapshot year". Thus, the effect on system expansion could never be properly determined. This paper presents the results of a study that was performed by Energy Management Associates, Inc. under the direction of the Planning Department of Detroit Edison. The study investigated a wide range of potential load shapes for the Detroit Edison system. The objective was to identify those load patterns which minimize the revenue requirement per kilowatthour at a constant level of reliability over a 15-year period. Load shapes depicting seasonal, weekly and daily load modification techniques were analyzed. The study was structured to determine gross maximum benefits without taking into account the implementation costs required to attain the various load shapes. The results of the study show that while there are benefits derived from load modification, these benefits are minimal.

Electrical Features of Fairfield Pimped Storage Project, South Carolina Electric and Gas Company

South Carolina Electric & Gas Company is currently constructing the 900 MW Virgil C. Summer nuclear plant and has completed the 512 MW Fairfield pumped storage plant on the Broad River north of Columbia, S. C. Construction began on the nuclear station in mid-1973 and on Fairfield in September 1974. The plants will supplement each other in meeting the utility's load demand.