System Load Curve Research Articles

Metering and modelling residential end-use electricity load curves

In most electricity systems the residential sector is one of the main contributors to the system peak. This makes it important to know how different residential end uses, such as space heating or cooking, contribute to the system load curve at the time of system peak and also at other times of the day. In this paper we discuss the estimation of residential end-use load curves for the state of New South Wales in Australia. Half-hourly readings were taken for 15 months on the total load and a range of end-use loads of 250 households. Information was sought on 16 different end uses, while eight metering channels were available for each household. We describe the optimal design procedure used to determine which end uses to meter in each household. The econometric model used for estimating the end-use load curves integrates a conditional demand analysis (CDA) of the total load readings for the household with the readings on all the directly metered end uses. Our integrated approach achieves impressive gains in efficiency over the conventional approach to estimating end-use loads. The paper concludes with an illustration of how end-use load curves can be used to simulate a variety of policy options.

Impacts of demand-side management on reliability cost/reliability worth analysis

Electric utilities are responding to public concern regarding the environment and the desire to conserve natural resources by placing increased attention on the customer side of the meter. Demand-side management (DSM) is now an important consideration for electric power utilities. DSM in general refers to any activity adopted by an electric utility that ultimately changes the utility's system load curve. The paper presents a model which can be used to quantify the basic load shaping goals of DSM activities. Twenty new load models were simulated that represent basic load modification goals. The proposed models can be used as the basic framework in the design and implementation of a utility DSM programme. The integration of supply-side and demand-side planning in reliability cost and reliability worth analysis is illustrated using the IEEE Reliability Test System. Studies were conducted to assess the effect of considered load-shape modifications on the planning reserve margin and on the total societal cost of electricity. This total cost includes system costs and customer interruption costs but does not include costs associated with implementing DSM.

Dynamic Tariffs: Theory of Utility-Consumer Interaction

The general theoretical models of dynamic tariffs, such as spot pricing, are extended to include the issues of optimal response of industrial consumers and the effect of large-scale penetration of these tariffs on the utility load curve. Applications-oriented, theoretical consumer and utility models are integrated for the purpose of establishing an overall systems approach to the behavior and interaction of the participants in a dynamic tariff environment. A systematic analysis of the effect of significant consumer response on the system load curve is undertaken. A methodologically sound approach to system load and price forecasting is presented. >

Dynamic tariffs: theory of utility-consumer interaction

The general theoretical models of dynamic tariffs, such as spot pricing, are extended to include the issues of optimal response of industrial consumers and the effect of large-scale penetration of these tariffs on the utility load curve. Applications-oriented, theoretical consumer and utility models are integrated for the purpose of establishing an overall systems approach to the behavior and interaction of the participants in a dynamic tariff environment. A systematic analysis of the effect of significant consumer response on the system load curve is undertaken. A methodologically sound approach to system load and price forecasting is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computerized Methods for Analysis of Impact of Demand Side Management on Distribution Systems

Demand Side Management consists of numerous techniques that seek to modify the aggregate system load curve in a manner that increases utilization of system generating capability. Changes brought about by DSM alter not only the system total load peak, but also the loads on equipment throughout the distribution system. Two techniques for analysis of DSM impact on distribution systems are presented in this paper. The first is a detailed method using computer techniques first developed for distribution plan design. The second is a very fast screening model for use in the intial evaluation of DSM impact. The two analysis methods are discussed, and guidelines for the analysis of DSM-distribution system impact are given.

Continuous Solution Simulation in the Short-Term Hydrothermal Coordination Problem

This paper presents a new approach for the solution of the short-term hydrothermal coordination problem based on the continuation method, a parametric optimization technique which solves the given problem by creating and solving a family of problems related by a single continuation parameter. In this application the continuation parameter continuously modifies the system load curve and/or the water inflows to the different reservoirs. Among some of the advantages of this approach we find: (1) It is not necessary to start with a feasible solution to the original problem. (2) The parameter continuation process yields piece-wise linear analytic optimum trajectories rather than point-wise solutions. (3) The method is very reliable. (4) Infeasible problems can be systematically detected. (5) The approach yields some unique analytic insight, as well as having applications in unit commitment, in the evaluation of load management strategies, in fast recoordination following a revision of the load forecast or reservoir inflows, and in operator training. An algorithm to implement this continuous simulation approach is presented and illustrated by various hydrothermal coordination examples.

The variation of electricity prices in response to supply-demand conditions and devices for consumer interaction

A new approach to electricity tariff structuring is being developed internationally, in which the tariff varies continuously according to the actual production cost of electricity. Mainsborne communication is considered as a way of notifying consumers of these spot prices, and also for metering consumption. This paper discusses the applicability of such a tariff to domestic and industrial sectors in Hong Kong, and possible effects on the system load curve. A consumer survey has been carried out to gauge reaction to such a scheme; the results are reported, and show a wide degree of support for the idea in the domestic sector.

Load Research and Its Application to Electricity Demand Forecasting

This paper describes the actual systems for half-hourly demand metering of consumers, together with the scope of the research programme in covering different types of consumer and electricity usage, and the statistical methodology involved. Demand patterns obtained from the research may be linked with sales (TWh), actual or estimated, to build total system load curves. This approach, which automatically compensates for differing mixes of consumers or sales, is demonstrated by preparing a mediumterm (seven year) of system maximum demand. As an aid to evaluation the forecast method is applied to historic data and is seen to provide an excellent explanation of changes in the relationship between sales and demand (expressed in terms of unrestricted load factor) which have occurred over the last 15 years. The method may be applied from any base year and is readily able to absorb new or improved data whilst also providing an indication of where future research could most usefully be directed.

Saturation Estimation In Interactive Computer Systems

AbstractThis paper presents a systematic method for estimating the saturation point of interactive computer systems in an environment of incomplete information (in particular, where per interaction information is unavailable). This method is an improvement over the ad hoc, highly subjective, and time-consuming iterative approach commonly used. Following an operational analysis approach and using only commonly available data, a simple model was constructed to estimate the mean response time of a task characterized by its ci’u and I/O requests running in a given level of system load. The system work load is characterized by the CPU, disk, drum, and channel load factors. The system is periodically measured (or the system log examined) to obtain the parameter values needed to estimate the mean response time ofthe task as well as the corresponding work load level. With sufficient samples, a mean response time vs. system load curve can be plotted. The system saturation load is taken to be that corresponding to ...

Reshaping residential electricity load curves through time-of-use pricing

This paper examines residential response to time-of-use (TOU) electricity pricing in two experiments funded by the Department of Energy. A flexible functional form is employed to estimate systems of non-homothetic demand functions, derived from a general model of utility maximization, for each experiment. The principal areas of agreement between the two experiments are that: (1) TOU prices are generally the most significant variables explaining consumption, and (2) TOU elasticities imply a substantial reduction in the level of peak demand and an overall leveling of the residential and total system load curves under TOU pricing strategies employed relative to the standard declining block structure.

A Computer Model for the Generation of System and Component Load Curves

ABSTRACT This paper presents a procedure for calculating system and component utilization patterns or load curves which describe the use of a single service facility by several independent agencies. Such load curves are frequently used to allocate cost of the facility among the agencies it serves. The procedure is a computer model that establishes a link between data that are readily obtain ed and data that are required by allocation formulas. The model derives detailed load curves for each agency and for the-total system. A Monte Carlo procedure is suggested in which the model may be used to estimate the sensitivity of allocation formulas to error in the underlying data.

Allocation of the Peak Load Part of System Load Curve to Pawer Plants Located on a Stream

Allocation of the Peak Load Part of System Load Curve to Pawer Plants Located on a Stream

Power-System Planning in the City of Los Angeles

development of a basic power-system plan adequate for the future load requirements and capable of accomplishment through step-by-step construction processes. The segregation of the load requirements as to load classes enables the drawing of probable system load curves, the determination of kilowatt-hour requirements, and estimates of possible revenues. Furthermore, the unit area survey provides data for detailed study of the requirements of the receiving station, distributing station, and local feeder load areas.

Economic proportion of hydroelectric and steam power

This paper describes a new method of determining for any power system, what proportion of generation should be hydroelectric, and what steam, from the standpoint of economics. A method is outlined for obtaining a curve showing “Total cost per kilowatt-year for hydroelectric and steam power”, for any percentage combination of generation. With system load curve, fixed charges on steam and hydroelectric plants, cost of fuel and other steam energy charges all known quantities, this curve can readily be calculated, and one can see at a glance the limiting economical percentage of steam power for the given conditions.

Economic Proportion of Hydroelectric and Steam Power

This paper describes a new method of determining for any power system, what proportion of generation should be hydroelectric, and what steam, from the standpoint of economics. A method is outlined for obtaining a curve showing ``Total cost per kilowatt-year for hydroelectric and steam power'', for any percentage combination of generation. With system load curve, fixed charges on steam and hydroelectric plants, cost of fuel and other steam energy charges all known quantities, this curve can readily be calculated, and one can see at a glance the limiting economical percentage of steam power for the given conditions.