Electricity Load Curves Research Articles

Implementation grounding of consumer-regulator to control electric loads in the power supply systems

This article discusses the use of combined heat power generation system by the automated electric heating units (customers, regulators) and the results of research. The main aim of this study is a feasibility study for the introduction of the automated control systems of electric load in electrical and heating systems of administrative buildings. The use of electrical accumulative heating systems, which are the consumers- regulators, enables alignment of the energy load curve in the power supply system for administrative buildings. In this article, we defined the technical and economic effect of the introduction of energy-efficient combined heat supply system with the accumulation of heat and three-band metering based on the automated transformer type unit for electric heating. Presented power supply system with built-in automated electric load control units can improve the energy efficiency of modes of distribution networks of power supply systems of administrative buildings. The evaluation of the overall effect of the alignment of the electric power system load curve gives an answer about the economic feasibility of the introduction of combined heating systems. The research results can be used in the design and development of electrical and heating systems of administrative buildings to control the selected load.

Increasing the power efficiency of a 25-kV alternating current traction power supply system

One promising method of increasing the power efficiency of an electrified railway is reducing the power capacity of the transfer process and the consumption of the electric power to the train traction. A 25-kV ac traction power supply a system features the drastically variable one-phase train load, which leads to a change in voltage on substations buses and train current collectors, as well as an increase in loss powers. The rules of the composition of the traction power supply for the fulfillment of the train schedule normalize the voltage on the substation buses and train current collector of no more than 29 kV and no less than 21 kV. Analysis of operation of the traction power supply system is carried out, and steps are taken to increase the engineering and economic performance of 25-kV ac railways. A new notion of normal power supply circuits of traction loads synthesized on the basis of simulation is presented. Analyzing the structure of the imbalance of electric power and voltage in traction network allows one to define steps toward increasing power efficiency. The accuracy of the initial data is determined by comparing the expected and real train schedules, as well as electric load curves. The simulation accuracy is determined on the basis of predictable power and voltage losses with monitoring results.

Multi-Method Approach to Compare the Socio-Demographic Typology of Residents and Clusters of Electricity Load Curves in a Swiss Sustainable Neighbourhood

A sustainable neighbourhood was built Switzerland by one of the leaders in this field. Half of the 400 apartments have been equipped with smart meters delivering big data on energy consumption (electricity, water, heating…). The company would like to know if it is possible to link socio-demographic typology of residents with energy consumption patterns. To answer this question we present in this article a multimethod approach combining qualitative analysis, frequently used in marketing (multiple correspondence analyses), and quantitative analysis from applied statistics to answer this question. First, we have conducted a survey among the residents of the sustainable neighbourhood to gather socio-demographic data, and then we have proposed a marketing typology of residents. In parallel, we have analysed load curves with statistical models (clustering factors, hermano beta models, coincidence factors, som, expert practice) to see if there are patterns of energy consumption and to determine groups of similar load curves. Then we have compared the discrepancies in the composition of the groups between both methods. This study is based on a single case study generating a new research hypothesis: the typology of residents based on socio-demographic data can be linked to energy consumption pattern of a household.

Priority areas difinition for improvement of defferentied electricity tariffs

The paper deals with solving the urgent problem of leveling the daily electric load curves of power systems. Daily load curves of power systems in Ukraine and Jordan were analyzed. It was shown that uneven consumer demand for electric power is equally characteristic of power systems in both countries, and the least expensive and most feasible solution to this problem is involving electricity consumers in leveling the power system load curves. The influence of major consumer groups on the configuration of the power system daily load curves was analyzed. It was proved that the main reason for the uneven power system load is uneven demand for power of such consumer group as the population. Electricity tariffs in Ukraine and Jordan as one of the most effective tools of economic management of consumer demand for electric power were considered, the results of long-term use of time-differentiated tariffs in Ukraine were examined. It was shown that differentiated electricity tariffs in both countries need urgent improvement and further development. Priority areas for improvement and further development of time-differentiated electricity tariffs in Ukraine and Jordan were defined. The research results and findings will contribute to the development and gradual implementation of targeted, balanced management strategy of consumer demand for electric power.

Electric power grid interconnections in Northeast Asia: A quantitative analysis of opportunities and challenges

Power grid interconnection has gained attention in Northeast Asia (NEA) as a means to build an economically efficient power system and to effectively utilize renewable energy, such as wind and solar resources in the Gobi Desert and hydro resources in Eastern Russia.In order to quantify the potential economic and environmental benefits from connecting power grids and developing renewables in NEA, we build an NEA-wide multi-region power system model using linear programming techniques. Our analysis considers power system characteristics, such as the seasonal and daily electric load curves of the various NEA economies.Compared to a “no grid extension” scenario, increased access to renewables contributes significantly to emissions reductions and fuel cost savings. However, the results imply modest benefits in lowering total cost because of the large initial investments needed in developing the renewables and the transmission lines. These limited total cost savings are likely to pose an implementation challenge for NEA grid interconnections. Our results also suggest that grid interconnections become more economically attractive in higher fuel price or lower initial cost situations. The relevant planning organizations should carefully consider the initial cost and future fuel price trends when considering how to interconnect power girds in an economical manner.

Energy Storage System Sizing for Peak Shaving in Thailand

This paper presents a mathematical model of energy storage systems (ESSs) to minimise daily electrical peak power demand in Thailand. A daily electrical load curve on a peak day obtained from Electricity Generating Authority of Thailand (EGAT) is used to analyse the capability of energy storage system for electrical peak power demand reduction with different ESS sizes. It is found that with power rate of 50 percent of the difference between the minimum and the maximum demands of the daily load curve and with energy capacity of 50 percent of the sum of each time step absolute energy difference between the demand and the average demand of the daily load curve, ESS can decrease daily electrical peak demand approximately 7.4 percent and increase daily load factor approximately 9.9 percent.

Study of regeneration system of 300 MW power unit based on nondeaerating heat balance diagram at reduced load

More than 30 power units of thermal power stations, based on the nondeaerating heat balance diagram, successfully operate in the former Soviet Union. Most of them are power units with a power of 300 MW, equipped with HTGZ and LMZ turbines. They operate according to a variable electric load curve characterized by deep reductions when undergoing night minimums. Additional extension of the range of power unit adjustment makes it possible to maintain the dispatch load curve and obtain profit for the electric power plant. The objective of this research is to carry out estimated and experimental processing of the operating regimes of the regeneration system of steam-turbine plants within the extended adjustment range and under the conditions when the constraints on the regeneration system and its equipment are removed. Constraints concerning the heat balance diagram that reduce the power unit efficiency when extending the adjustment range have been considered. Test results are presented for the nondeaerating heat balance diagram with the HTGZ turbine. Turbine pump and feed electric pump operation was studied at a power unit load of 120–300 MW. The reliability of feed pump operation is confirmed by a stable vibratory condition and the absence of cavitation noise and vibration at a frequency that characterizes the cavitation condition, as well as by oil temperature maintenance after bearings within normal limits. Cavitation performance of pumps in the studied range of their operation has been determined. Technical solutions are proposed on providing a profitable and stable operation of regeneration systems when extending the range of adjustment of power unit load. A nondeaerating diagram of high-pressure preheater (HPP) condensate discharge to the mixer. A regeneration system has been developed and studied on the operating power unit fitted with a deaeratorless thermal circuit of the system for removing the high-pressure preheater heating steam condensate to the mixer, with extending the range of load adjustment for the 300 MW power unit load.

The shape of future electricity demand: Exploring load curves in 2050s Germany and Britain

National demand for electricity follows a regular and predictable daily pattern. This pattern is set to change due to efficiency improvements, de-industrialisation and electrification of heat and transport. These changes are independent of renewable infeed and are not well understood: contemporary studies assume that electricity load curves will retain their current shape, scaling equally in all hours. Changes to this shape will profoundly affect the electricity industry: increasing the requirements for flexible and peaking capacity, and reducing asset utilisation and profitability.This paper explores the evolution of load curves to 2050 in Germany and Britain: two countries undergoing radically different energy transformations. It reviews recent developments in Europe's electricity demand, and introduces two models for synthesising future hourly load curves: eLOAD (electricity LOad curve ADjustment) and DESSTinEE (Demand for Energy Services, Supply and Transmission in EuropE). Both models are applied to a decarbonisation scenario for 2050, and consistently show peak loads increasing by about 23% points above the change in annual demand, to 103 GW in Germany and 92 GW in Britain. Sensitivities around electrification show that a million extra heat pumps or electric vehicles add up to 1.5 GW to peak demand.The structure and shape of the future load curves are analysed, and impacts on the national electricity systems are drawn.

Combination of load curves and tangent curve for customer’s load curve clustering

The load curve clustering for electrical customers traditionally is based on the 24- dimension input space. It means that every load curve is considered as an element with 24 attributes corresponding to 24 load values per 0day. But in some cases, the load curve itself can not lead to the right cluster when the two curves have different forms but have the same distance to the third one. To overcome this limitation, the present paper pays attention to the selection of the input space. From each load curve, the tangent curve will be received. Now the clustering will be based not only on the load curve but on the tangent curve. The clustering techniques used the Pulsar algorithm with some modifications to fit the input space. Examining for the electrical load curve of Ho Chi Minh city constumers, the propose approach has achieved the best results.

Electric Power Grid Interconnections in Northeast Asia: A Quantitative Analysis of Opportunities and Challenges

Power grid interconnection has gained attention in Northeast Asia (NEA) as a means to build an economically efficient power system and to effectively utilize renewable energy, such as wind and solar resources in the Gobi Desert and hydro resources in Eastern Russia.In order to quantify the potential economic and environmental benefits from connecting power grids and developing renewables in NEA, we build an NEA-wide multi-region power system model using linear programming techniques. Our analysis considers power systems particulars, such as the seasonal and daily electric load curves of the various NEA economies.Compared to a “no grid extension” scenario, increased access to renewables contributes significantly to emissions reductions and fuel cost savings. However, the results imply modest benefits in lowering total cost because of the large initial investments needed in developing the renewables and the transmission lines. These limited total cost savings are likely to pose an implementation challenge for NEA grid interconnections. Our results also suggest that grid interconnections become more economically attractive in higher fuel price or lower initial cost situations. The relevant planning organizations should carefully consider the initial cost and future fuel price trends when considering how to interconnect power girds in an economical manner.

The effectiveness of power-generating complexes constructed on the basis of nuclear power plants combined with additional sources of energy determined taking risk factors into account

The effectiveness of combining nuclear power plants equipped with water-cooled water-moderated power-generating reactors (VVER) with other sources of energy within unified power-generating complexes is analyzed. The use of such power-generating complexes makes it possible to achieve the necessary load pickup capability and flexibility in performing the mandatory selective primary and emergency control of load, as well as participation in passing the night minimums of electric load curves while retaining high values of the capacity utilization factor of the entire power-generating complex at higher levels of the steam-turbine part efficiency. Versions involving combined use of nuclear power plants with hydrogen toppings and gas turbine units for generating electricity are considered. In view of the fact that hydrogen is an unsafe energy carrier, the use of which introduces additional elements of risk, a procedure for evaluating these risks under different conditions of implementing the fuel-and-hydrogen cycle at nuclear power plants is proposed. Risk accounting technique with the use of statistical data is considered, including the characteristics of hydrogen and gas pipelines, and the process pipelines equipment tightness loss occurrence rate. The expected intensities of fires and explosions at nuclear power plants fitted with hydrogen toppings and gas turbine units are calculated. In estimating the damage inflicted by events (fires and explosions) occurred in nuclear power plant turbine buildings, the US statistical data were used. Conservative scenarios of fires and explosions of hydrogen-air mixtures in nuclear power plant turbine buildings are presented. Results from calculations of the introduced annual risk to the attained net annual profit ratio in commensurable versions are given. This ratio can be used in selecting projects characterized by the most technically attainable and socially acceptable safety.

エネルギーエンドユースモデルの研究開発動向

Recently, with the progress in energy management system (EMS), better understanding of the detailed mechanism of energy demand occurrence becomes an important subject in energy efficiency research. One of the effective measures is the development of energy end-use simulation model. Firstly in this paper, component of energy demand formative mechanism in building sector is explained. Secondly, researches on energy end-use modeling are reviewed. In the final part, example of electricity load curve simulation in city block is introduced.

A high-resolution determination of the technical potential for residential-roof-mounted photovoltaic systems in Germany

In Germany the introduction of a feed-in tariff for renewable energies in the year 2000 led to a massive increase in newly constructed photovoltaic (PV) plants reaching a total installed capacity of 35GWp as of November 30th, 2013. The distribution of these plants shows a large disparity between regions, which motivates investigations of regional potentials which earlier studies of Germany have not addressed in detail. This study presents a high-resolution calculation for the technical potential of residential-roof-mounted photovoltaic systems for each municipality in Germany. Electricity load curves for municipalities were generated based on the socio-economic structure and used to draw generalized conclusions about the relationship between the (potential) supply from PV and the local demand. The total German residential-roof-mounted technical PV potential was determined as 148TWh/a with an installable capacity of 208GWp. About 30% of municipalities could become autonomous based on a yearly balance of PV electricity generation. If the daily and seasonal variations in demand and PV electricity generation were considered, only 53 of the 11,593 German municipalities could become autonomous, provided they installed a short-term storage system which would have to be sized around 57% of their daily electricity demand. Imposing the restriction that no feedback of electricity into the distribution network outside the municipality should occur, and assuming that no local storage exists, around 49% of the total technical potential, i.e. 103GWp could be installed (i.e. 90GWp additional potential since some municipalities already experience feedbacks into the distribution network). A validation of the results with municipal solar cadastres has shown that the discrepancy between them and the technical potential calculated in this study is quite consistently about 30%, which is assumed to be due to non-residential buildings not being considered here. The calculated technical potential is most sensitive to the assumptions on the module efficiency and the usable area of (slanted) roofs. A validation of building data assumptions as well as a comparison with other studies both show a good agreement.

Pattern recognition algorithms for electricity load curve analysis of buildings

Buildings consume 40% of the total primary energy and 30% of the annual electricity, contributing significantly to greenhouse gas emissions. Naturally, therefore, building energy efficiency and notions like the nearly zero energy buildings are continuously gaining importance and popularity as means to reduce carbon emissions and the strong dependence on fossil fuels. A step towards this direction is the incorporation of smart grid technologies, mainly through the widespread of automatic meter reading and smart meters. This enables automatic collection of in depth information of the customer's behavior along with the building's performance and, thus, introduces new opportunities for energy saving and efficient management. However, the recorded amassing ream of data requires efficient processing and interpretation, so as to provide for meaningful information. In order to tackle this problem, this paper proposes a comprehensive methodology for the investigation of the electricity behavior of buildings, using clustering techniques. Utilizing a university campus as a case study, the proposed methodology is applied to the load curves of different buildings leading to the determination of an optimum clustering procedure. The methodology may be generalized for any type of building.

Application of Combined-Cycle Plants to Control the Electrical Load Curve

Conducted research based on the well-known information containing in publications that are listed in referees. Comparative calculation was made with using the method of incremental rate based on equal operation conditions. By virtue of conducted research was made a conclusion about prospective place of combined-cycle gas turbine in power- transmission system. At the present stage of power industry development the main tendency is the fuel consumption reduction for turbines with the simultaneous increase of their capacity as well as the decrease of harmful influence on the environment. Electric installations must have high maneuverable and flexible characteristics and high quality of released energy. Moreover, they must operate using the main types of fuel and have the ability to produce thermal energy. The above mentioned characteristics and advantages are typical for combined-cycle steam-gas plants (CCSGP) with different construction. The high significance of CCSGP in the international and domestic power industry requires high attention to its role and place in the covering of electric load curves and demands. The factors that have influence on the control range of CCSGP are analyzed and studied in this article. Moreover, maneuverability, flexibility and the economic efficiency of CCSGP were compared with the efficiency of traditional steam power units (SPU).

A comparative study of electric load curve changes in an urban low-voltage substation in Spain during the economic crisis (2008-2013).

This paper presents a comparative study of the electricity consumption (EC) in an urban low-voltage substation before and during the economic crisis (2008–2013). This low-voltage substation supplies electric power to near 400 users. The EC was measured for an 11-year period (2002–2012) with a sampling time of 1 minute. The study described in the paper consists of detecting the changes produced in the load curves of this substation along the time due to changes in the behaviour of consumers. The EC was compared using representative curves per time period (precrisis and crisis). These representative curves were obtained after a computational process, which was based on a search for days with similar curves to the curve of a determined (base) date. This similitude was assessed by the proximity on the calendar, day of the week, daylight time, and outdoor temperature. The last selection parameter was the error between the nearest neighbour curves and the base date curve. The obtained representative curves were linearized to determine changes in their structure (maximum and minimum consumption values, duration of the daily time slot, etc.). The results primarily indicate an increase in the EC in the night slot during the summer months in the crisis period.

A Study of a Next Day Electric Load Curve Forecasting Method and its Accuracy Improvement

A Study of a Next Day Electric Load Curve Forecasting Method and its Accuracy Improvement

Analysis of Energy Saving and Environmental Characteristics of Electric Vehicles in Regionally Disaggregated World Energy Model

SUMMARYThis paper investigates the impact of an extensive introduction of electric vehicles (EV) and plug‐in hybrid vehicles (PHEV) into the global energy system by 2050. The significant growth of automobile ownership in emerging countries is likely to increase world oil demand and the associated carbon dioxide emissions. In order to address these energy, security, and environmental concerns, the deployment of clean energy vehicles, such as EV and PHEV, is expected to play a crucial role due to their high fuel efficiency. Consequently, we develop both a global energy system model and a world vehicle penetration model, which can explicitly analyze the impact of EV introduction into the seasonal daily electric load curve, with consideration of the specific electricity charging profile through 2050. The simulation results confirm that EV deployment contributes to energy conservation, because oil demand reduction outstrips the growth in electricity demand and the associated fuel input into the power generation mix. Concerning carbon dioxide abatement, the magnitude of the impact relies on the carbon intensity of the power generation mix. If the intensity is low enough to guarantee a carbon mitigation effect due to EV fuel saving, emissions reduction is well assured. It should be noted, however, that in regions with high carbon intensity in the power generation mix, carbon emissions per mileage of EVs is almost equivalent to that of efficient gasoline vehicles such as hybrid vehicles, and the figure for PHEV is slightly higher than for hybrid vehicles. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 20–36, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22373

An assessment of household electricity load curves and corresponding CO2 marginal abatement cost curves for Gujarat state, India

Gujarat, a large industrialized state in India, consumed 67TWh of electricity in 2009–10, besides experiencing a 4.5% demand–supply short-fall. Residential sector accounted for 15% of the total electricity consumption. We conducted load research survey across 21 cities and towns of the state to estimate residential electricity load curves, share of appliances by type and usage patterns for all types of household appliances at utility, geographic, appliance, income and end-use levels. The results indicate that a large scope exists for penetration of energy efficient devices in residential sector. Marginal Abatement Cost (MAC) curves for electricity and CO2 were generated to analyze relative attractiveness of energy efficient appliance options. Results indicate that up to 7.9TWh of electricity can be saved per year with 6.7Mt-CO2 emissions mitigation at negative or very low CO2 prices of US$ 10/t-CO2. Despite such options existing, their penetration is not realized due to myriad barriers such as financial, institutional or awareness and therefore cannot be taken as baseline options for CO2 emission mitigation regimes.

The Influence on Clustering Results of Electricity Load Curves Using Different Distances

Distance choice is an important issue in power load pattern extraction using clustering techniques, so it is necessary to find the influence on clustering result of load curves using different distances in clustering algorithms. In this paper several distances are used in the k-means algorithm for clustering load curves and their influences on the clustering results are analyzed, therefore, the suitable distance for the k-means algorithms is obtained. An example with 147 electricity customers load curves shows distances have different influences on clustering results using the same clustering algorithm. The comparison results indicate that the choice of distances is an important issue in power load pattern extraction using clustering techniques and a suitable distance may improve the accuracy of mining algorithms.