No description available.

Although power system load modelling is a mature research area, there is a renewed interest in updating available load models and formulating improved load modelling methodologies. The main drivers of this interest are the introduction of new types of non-conventional (e.g. power electronic interfaced) loads, the requirement to operate power supply systems with increasing levels of renewable distributed generation and the implementation of various load control functionalities (e.g. demand side management). As the majority of existing load models do not allow for a full and precise analysis of these new operating conditions, it is essential to develop new load models and update load modelling techniques. This thesis presents a detailed study of modern loads, focussing on the requirements for their correct representation in power system analysis. The developed models of the individual loads are then combined using a new load aggregation methodology for developing aggregate load models, suitable for the analysis of both existing and future power supply systems (so called ’smart grids’). The methodology uses a circuit-based load modelling approach, as this allows reproduction of the instantaneous current waveforms of the modelled load for any given supply voltage. This approach retains all electrical characteristics of the loads and provides a more realistic representation of some important phenomena (e.g. harmonic cancellation and attenuation due to load and supply system interactions) which are often neglected in traditional load modelling procedures. Case studies of the UK residential and commercial load sectors are presented as illustrations of the load aggregation methodology. The results show significant short-term and long-term temporal variations in the load characteristics, which are not available or reported in the existing literature. This information allows for a more comprehensive assessment of demand-side management functionalities and correlation with locally connected distributed generation. Both of these effects are investigated in the thesis by quantifying the possible extent and range of changes in power system performance for some expected near future changes in load configurations and network operating conditions.

The ability of typical utility meters and advanced meters including sub-circuit metering to disaggregate residential electric loads and determine what appliances a homeowner is using at a given time in investigated. The basics of residential electricity systems, instrumentation options, and characteristics of selected residential loads are presented. This information informs a discussion on present and future disaggregation algorithms. The conclusions highlight the importance of reactive power and current harmonics in determining power consumed and identifying modern electrical devices, and raise concerns related to the ability of typical 15 minute interval utility smart meters to disaggregate loads. / text

The power utility of South Africa, Eskom, expected a supply shortfall of approximately 400MW between February and August 2006 in the Western Cape. The peak of the crisis was in mid-winter (June to August). This shortfall was firstly caused when Eskom experienced a breakdown on the one of the two nuclear supply units. Secondly the remaining of the Koeberg units was due for refuelling which necessitated the shut-down of the reactor. No electricity was therefore generated by both units. It was clear that if electricity demand was not effectively curbed, extensive power outages would be experienced; which was the case. Various demand side management (DSM) programmes were rolled-out to address lighting, switching from electricity to gas for cooking, compensating customers that could generate own electricity, energy efficiency and load curtailment in the education, commercial, and industrial sectors, as well as an extensive energy efficiency campaign. It is shown in this study that the most constrained periods were expected during the evening peak and was a consequence of electricity consumption in the residential sector. The residential evening peak is very prominent and primarily caused by water heating, cooking, space heating, lighting, and appliances. None of the mentioned programmes focused on the residential evening peak. Traditional residential DSM technologies were almost impossible to implement in the short timeframe because there are more than 625,000 residences in the Western Cape. A solution was looked for that could be implemented in a relatively short period to address the residential evening peak. This study focuses on the development, implementation, and performance evaluation of Power Alert – An innovative residential load management system. The need for such a system was identified and the expected impact was determined through a feasibility study. Power Alert was designed to be a link between Eskom and the public through the national television broadcaster. It was operational during the whole Western Cape winter. A methodology to determine the impact of Power Alert was also developed to demonstrate the actual load reductions. The methodology was applied and Power Alert demonstrated that it was a valuable residential load management tool that could be designed and implemented in a much shorter time than conventional residential DSM measures. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

The power utility of South Africa, Eskom, expected a supply shortfall of approximately 400MW between February and August 2006 in the Western Cape. The peak of the crisis was in mid-winter (June to August). This shortfall was firstly caused when Eskom experienced a breakdown on the one of the two nuclear supply units. Secondly the remaining of the Koeberg units was due for refuelling which necessitated the shut-down of the reactor. No electricity was therefore generated by both units. It was clear that if electricity demand was not effectively curbed, extensive power outages would be experienced; which was the case. Various demand side management (DSM) programmes were rolled-out to address lighting, switching from electricity to gas for cooking, compensating customers that could generate own electricity, energy efficiency and load curtailment in the education, commercial, and industrial sectors, as well as an extensive energy efficiency campaign. It is shown in this study that the most constrained periods were expected during the evening peak and was a consequence of electricity consumption in the residential sector. The residential evening peak is very prominent and primarily caused by water heating, cooking, space heating, lighting, and appliances. None of the mentioned programmes focused on the residential evening peak. Traditional residential DSM technologies were almost impossible to implement in the short timeframe because there are more than 625,000 residences in the Western Cape. A solution was looked for that could be implemented in a relatively short period to address the residential evening peak. This study focuses on the development, implementation, and performance evaluation of Power Alert – An innovative residential load management system. The need for such a system was identified and the expected impact was determined through a feasibility study. Power Alert was designed to be a link between Eskom and the public through the national television broadcaster. It was operational during the whole Western Cape winter. A methodology to determine the impact of Power Alert was also developed to demonstrate the actual load reductions. The methodology was applied and Power Alert demonstrated that it was a valuable residential load management tool that could be designed and implemented in a much shorter time than conventional residential DSM measures. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

No description available.

Orientador: Prof. Dr. Carlos Eduardo Capovilla / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2014. / Este trabalho academico apresenta a modelagem eletrica de um ambiente residencial e a disponibiliza como infraestrutura necess'aria para pesquisas futuras na 'area de redes inteligentes dom'esticas (Home Smart Grids). Tais modelos são disponbilizados em um formato de arquivo de biblioteca do ambiente de simulação MatLab/Simulink. Para atingir este objetivo, é realizada a modelagem te'orica e experimental de diversos aparelhos domésticos e cabos elétricos. Dois modelos de medidores de energia inteligentes são desenvolvidos, que podem ser conectados a qualquer ponto da instalação el'etrica residencial. Um modelo de resid¿encia com seu respectivo diagrama unifilar da simulação el'etrica 'e apresentado, permitindo execução de simulações de seu funcionamento completo. / This academic work presents the electric modeling of a residential wiring and makes it available as a necessary infrastructure for future researches about Home Smart Grids. The models are available in a MatLab/Simulink simulation environment library format. In order to achieve this objective, both theoretical and experimental modeling is performed for many electric loads (home appliances) and cables. Two kinds of electric smart meters are also developed, which can be connected at any point of the residential wiring. A residence model with its wiring diagram is presented, allowing the simulation execution of a full residence operation.

The energy system is being transitioned to increase sustainability. This transition has been accelerated by the increased awareness about the adverse effects of the greenhouse gas (GHG) emissions into the atmosphere. The transition includes switching to electricity as the energy carrier in some sectors, e.g., transportation, increasing the contribution of renewable energy sources (RES) to the grid, and digitalizing the grid services. Electric vehicles (EVs) are promoted and subsidized in many countries among the sustainability initiatives. Consequently, the global sales of EVs rapidly increased in the recent years. Many EV owners might charge their EVs only at home, thereby increasing the residential load. The residential load might further increase due to the initiatives to electrify the heating/cooling sector. This thesis contributes to the knowledge about the operation of the future energy system by modeling the spatial charging load of private EVs in cities, and by proposing a forecasting model to predict the residential load. Both models can be used to evaluate the impacts of both technologies on the local electricity grid. In addition, demand response (DR) schemes can be proposed to reduce the adverse effects of both the charging load of EVs and the residential load. A case study of the EV model on the Herrljunga city grid showed that 100% EV penetration with 3.7 kW (charging rate of 14.8 km/h) chargers will not cause voltage violations in the grid. Winter load is responsible for 5% voltage drop at the weakest bus, and EVs add only 1% to this drop. In a Swedish city, charging EVs will require adding extra 1.43 kW/car to the grid capacity—assuming 22 kW (charging rate of 88 km/h) residential chargers. If the EV charging is not restricted to residential locations, an increase of 1.23 kW/car is expected. The proposed forecasting model is comparable in accuracy to previously developed models. As an advantage, the model produces a probability density function (PDF) describing the model’s certainty in the forecast. In contrast, many previous contributions provided only point forecasts.

The grid connected solar PV system with battery storage is one of the promising alternativeenergy solutions for electricity consumers. The Local System Operator (LSO) will be a newactor to operate its own energy system by integrating PV and battery system with other technicalsolutions. This thesis investigates the technical and economic viability of a grid connected PVsystem with battery storage in behind-the-meter approach for aggregated residential load toassess the LSO model for the present conditions in Sweden.The system model is developed using the System Advisory Model (SAM) – a simulationsoftware for renewable energy system analysis. The PV system model is designed using solarirradiation profile and fifty multi-dwelling aggregated residential load data from Sweden. Theappropriate design inputs of solar PV module, inverter and system loss are taken from previousstudies. The electricity price is analysed from the comparative study of Nord-pool wholesaleprice, market retail price and distribution grid tariffs. The financial metrics such as discountrate, inflation rate, system cost and currently available PV incentives are considered to make anaccurate model. To help with the assessment, three cases are formed; the first case representsonly the PV system and the other cases include storage - using a lithium-ion or lead-acid battery.This comparative study helps to determine the optimum PV and battery size at two differentlocations in Sweden.The optimum net present value (NPV) and profitability index (PI) is found at the 40 kW PVand 3 kWh battery system at Karlstad, Sweden. The optimum case is considered for furtherinvestigation to evaluate the system life time energy profile, electricity bill saving capabilityand battery performance. The system peak shaving potential is investigated by making twoother scenarios with higher battery capacity. Sensitivity analysis is also performed to assess thesystem’s technical and financial input parameters. The system capacity factor at the site locationis found as an influential parameter to the annual production and profitability. The optimumsize of PV system with a lithium-ion battery investment is found feasible for the LSO realimplementation only considering the current PV incentives and electricity price in Sweden. Thereport concludes with the assessment, the technical and economic feasibility of the studied PVand battery storage system profitability depends on the system site location, residential loadsize, consumer electricity cost and available PV incentives. / solcellsystem (PV) med batterilagring är en lovande alternativenergilösning förslutkonsumenten. Den 'local system operator', LSO, blir en ny aktör som driver egetenergisystem genom att integrera PV- och batterisystem med andra tekniska lösningar. Dennaavhandling undersöker det tekniska och ekonomiska genomförbarhetet i ett nätanslutet PVsystem med batterilagring i 'bakom mätaren' scenario för aggregerade bostäder i ettflerbostadshus, för att urvärdera LSO modellen.Systemmodellen är utvecklat med 'system advisory model' (rådgivande modell), SAM, ettsimuleringsprogram för förnybara energisystem. PV systemparametrarna beräknas med hänsyntill väderprofiler och lastdata från Sverige. Lämpliga parametrar för solcellsmoduler, omriktareoch systemförluster tas från tidigare studier. Slutkonsumenternas elpriser analyseras frånjämförande studie av NordPool grosshandelspris, konsumentpris och distributionnätstariffer.Finansiella mått såsom system kostnad, rabatt och inflationstakten och tillgängliga incitamentför PV investeringar används för att göra modellen noggrannare. Tre fall undersöks; det förstarepresenterar systemet med bara PV, och de övriga fallen lägger till lagring, genom antingenlitiumjon eller bly-syre batterier. Denna jämförande studie är ett underlag för att bestämma denoptimala PV och batteristorleken för anläggninar på två olika område i Sverige.Den optimala netto nuvarande värde (NPV) och lönsamhet index (PI) är på 40 kW PV systemetoch 3 kWh batteri på Karlstad, Sverige. Ytterligare undersökning av detta fall används för attutvärdera energiprofilen under systemets livstid, möjlighet till minskad elräkning, och batterietsprestanda. Potential för utjämning av systemets topplast utreds genom att skapa två andrascenarier med högre batterikapacitet. Känslighetsanalys utförs också för att bedöma de tekniskaoch ekonomiska parametrarna. Den optimuma storleken på PV system med ett litium-jonbatterifinns rimligt för LSO riktiga genomförande med tanke på incitamenten. Simuleringsresultatenoch systemkonsekvenserna av LSO modellen diskuteras. Rapporten visar att den tekniska ochekonomiska genomförbarheten av det studerade PV systemet med litium-jon batteri beror påslutkonsumentelpriset, PV incitament och globala trender i kostnaderna försystemkomponenter, samt på valet av lämplig plats med en effektiv analys av väder profil ochsystemetförluster.