Electricity Supply Network Research Articles

Modeling and Technical-Economic Optimization of Electricity Supply Network by Three Photovoltaic Systems

To attain an ongoing electricity economy, developing novel widespread electricity supply systems based on diverse energy resources are critically important. Several photovoltaic (PV) technologies exist, which cause various pathways to produce electricity from solar energy. This paper evaluates the competition between three influential solar technologies based on photovoltaic technique to find the optimal pathways for satisfying the electricity demand: (1) multicrystalline silicon; (2) copper, indium, gallium, and selenium (CIGS); and (3) multijunction. Besides the technical factors, there are other effective parameters such as cost, operability, feasibility, and capacity that should be considered when assessing the different pathways as optimal and viable long-term alternatives. To aid this decision-making process, a generic optimization-based model was developed for the long-range energy planning and design of future electricity supply system from solar energy. By applying dynamic programming techniques, the model is capable of identifying the optimal investment strategies and integrated supply system configurations from the many alternatives. The features and capabilities of the model were shown through application to Iran as a case study.

Study of Power System Protection Devices Based on Automation Open Hardware Platform

Protection devices must recognize the errors in electricity supply network and separate the fault from the rest of the supply network, which is determined by comparing actual to adjusted intensity of voltages and currents. In order to realize the interchange of electrical protection devices, it should be developed on the basis of open hardware platforms. In this work, over currents time protection relay will be implemented on programmable logic controller and tested.

Solar Pumping for Environmental Optimization of Energy in an Electrical Network

This research lies within the scope of the environmental search for the solutions of optimizations of energy in an electrical supply network (obligation to reduce the CO2 emission Indeed, the principal aiming of this research is the decrease in the consumption of energy and the integration of the renewable resources in the wells (energy independence and the sustainable development) that it pushes us to consider from now on the energy problem not only according to the economic point of view, but also according to an ecological point of view. So our problem is the reduction of greenhouse gas emissions, from the decrease in consumption by trying to achieve equality (less production = less emission) in which based on the quality of energy, control of energy and the energy management and to satisfy demand and maintaining equal balance equation with a total cost feasible and controllable, for our case study Wells of ADE. This with us encouraged to develop our systems of energy on the basis of generation distributed on a large scale including/understanding renewable energy and the high- output solutions energetic.

Fault Location in Power Electrical Traction Line System

In this paper, methods of fault location are discussed in electrical traction single-end direct power supply network systems. Based on the distributed parameter model of the system, the position of the short-circuit fault can be located with the aid of the current and voltage value at the measurement end of the electrical traction line. Furthermore, the influence of the transient resistance, the position of the locomotive, locomotive load for fault location are also discussed. MATLAB simulation tool is used for the simulation experiments. Simulation results are proved the effectiveness of the proposed algorithms.

A Study on Transmission Replacement Plan Considering Multiple Supply Networks

Abstract – In recent years, Japanese electric power supply network equipments are almost at the end of their lifetime. It is an urgent necessity to manage their replacements[1]-[2]. In this paper, replacement planning approach for electric power supply network is studied based on the actual network model. The EENS (Expected Energy Not Supplied) is used as an index for reliability of supply network. The aging effect of equipments is also treated. It is assumed that the retransmission failure probability of single circuit fault is increased due to the aging of the equipments. In our previous papers, single supply network connected to one substation is examined[3]-[4]. On the contrary, multiple supply networks connected to different substations are examined in this paper. If the EENS of individual supply network is used for evaluation, the replacement plan may become too severe. However, evaluating the total EENS in multiple supply networks, the replacement plan becomes flexible. Keywords

Measured end-use electric load profiles for 12 Canadian houses at high temporal resolution

The electricity drawn by appliances and lighting represents a significant fraction of the total energy used in residential buildings. As construction techniques improve and as building regulations become more stringent, it is expected that the relative significance of these non-HVAC electrical loads will grow. Not only is the annual energy consumption of non-HVAC electrical loads of growing importance, their temporal distribution influences the operation of energy conversion equipment within the building and in the electrical supply network. This work provides new measured data on the electrical consumption of a sample of 12 Canadian houses. Measurements at 1-min intervals were taken of whole-house electricity draws, as well as the draws of individual devices, including the furnace, air-conditioner, range/cooker, clothes dryer, dishwasher, and domestic hot water heater. The annual consumption patterns of the 12 houses were found to range widely. Furthermore, daily variations in the temporal distribution of electrical loads of each house were found to be significant. The probability distribution of some of the measured data was compared with previously developed synthetically derived non-HVAC electric load profiles, and it was found that the latter do not adequately capture either the temporal variability nor the variation between households observed in the measurements.

A Fuzzy Based Solution for Improving Power Quality in Electric Railway Networks

There are many fundamental differences between electric traction networks and other industrial supply networks in terms of dynamic behavior and static characteristics. For example, the time variation of a load causes voltage variations in a supply network, which results in variations of power flow in the supply network. Today, reactive power compensators are the most practical solutions for keeping voltage levels in normal boundaries. In this paper, with the aim of fuzzy logic, a method for compensating reactive power losses in electrical traction networks is proposed. The proposed method has many advantages such as decreasing the reactive power compensation costs, determining the optimum switching step of capacitor banks and deducing the losses in electric traction networks.

Capacity Expansion in the Integrated Supply Network for an Electricity Market

Constraints in fuel supply, electricity generation, and transmission interact to affect the welfare of strategic generators and price-sensitive consumers. We consider a mixed integer bilevel programming model in which the leader makes capacity expansion decisions in the fuel transportation, generation, and transmission infrastructure of the electricity supply network to maximize social welfare less investment cost. Based on the leader's expansion decisions, the multiple followers including the fuel suppliers, ISO, and generation companies simultaneously optimize their respective objectives of cost, social welfare, and profit. The bilevel program is formulated as a mathematical program with complementarity constraints. The computational challenge posed by the discrete character of transmission expansions has been managed by multiple model reformulations. A lower bound provided by a nonlinear programming reformulation increases the efficiency of solving a binary variable reformulation to global optimality. A single-level optimization relaxation serves as a competitive benchmark to assess the effect of generator strategic operational behavior on the optimal capacity configuration.

Toward five-dimensional scaling: How density improves efficiency in future computers

We address integration density in future computers based on packaging and architectural concepts of the human brain: a dense 3-D architecture for interconnects, fluid cooling, and power delivery of energetic chemical compounds transported in the same fluid with little power needed for pumping. Several efforts have demonstrated that by vertical integration, memory proximity and bandwidth are improved using efficient communication with low-complexity 2-D arrays. However, power delivery and cooling do not allow integration of multiple layers with dense logic elements. Interlayer cooled 3-D chip stacks solve the cooling bottlenecks, thereby allowing stacking of several such stacks, but are still limited by power delivery and communication. Electrochemical power delivery eliminates the electrical power supply network, freeing valuable space for communication, and allows scaling of chip stacks to larger systems beyond exascale device count and performance. We find that historical efficiency trends are related to density and that current transistors are small enough for zetascale systems once communication and supply networks are simultaneously optimized. We infer that biological efficiencies for information processing can be reached by 2060 with ultracompact space-filled systems that make use of brain-inspired packaging and allometric scaling laws.

Life Cycle Environmental Implications of Residential Swimming Pools

Ownership of private swimming pools in the U.S. grew 2 to 4% per annum from 1997 to 2007. The environmental implications of pool ownership are analyzed by hybrid life cycle assessment (LCA) for nine U.S. cities. An operational model is constructed estimating consumption of chemicals, water, and energy for a typical residential pool. The model incorporates geographical climatic variations and upstream water and energy use from electricity and water supply networks. Results vary considerably by city: a factor of 5-6 for both water and energy use. Water use is driven by aridness and length of the swimming season, while energy use is mainly driven by length of the swimming season. Water and energy impacts of pools are significant, particularly in arid climates. In Phoenix for example pools account for 22% and 13% of a household's electricity and water use, respectively. Measures to reduce water and energy use in pools such as optimizing the pump schedule and covering the pool in winter can realize greater savings than many common household efficiency improvements. Private versus community pools are also compared. Community pools in Phoenix use 60% less swimming pool water and energy per household than subdivisions without community pools.

Electrical Technologies for Grid Integration of Ocean Wave Power into the UK National Grid

In this paper, multiple offshore wave energy converters with different output characteristics are connected to one power distribution substation. The connection between the power take-off of the different wave energy converters and the electrical power transmission system is presented in order to investigate whether multiple wave energy converters can augment energy yield and improve network integration capabilities. Moreover, the model of an array of wave energy converters is developed with the goal of analyzing the effects of the offshore wave farm on the electrical network to which it is connected. It is also developed to ensure that the electricity generated by the array is sufficiently controllable, and of a quality that can be integrate into the electricity supply network without unduly increasing the cost of connection, production or delivery.

Visible technologies, invisible organisations: An empirical study of public beliefs about electricity supply networks

Reducing carbon emissions in the energy system poses significant challenges to electricity transmission and distribution networks. Whilst these challenges are as much social as economic or technical, to date few research studies have investigated public beliefs about electricity supply networks. This research aimed to address this gap by means of a nationally representative study of UK adults ( n=1041), probing beliefs about how electricity reaches the home, responsibility for electricity supply, associations with the words ‘National Grid’, as well as beliefs about the planning of new infrastructure. Findings suggest that electricity networks are represented predominantly in terms of technologies rather than organisations, specifically in terms of familiar, visible components such as cables or wires, rather than more systemic concepts such as networks. Transmission and distribution network operators were largely invisible to members of the public. In terms of planning new lines, most respondents assumed that government ministers were involved in decision-making, while local residents were widely perceived to have little influence; moreover, there was strong public support for placing new power lines underground, regardless of the cost. In conclusion, organisational invisibility, coupled with low expectations of participatory involvement, could provoke public opposition and delay siting new network infrastructure.

Construction and Testing of the 3.3 kV, 300 kVA UNIFLEX-PM Prototype

SummaryThis paper presents details of the experimental implementation of a prototype multi-cellular converter for application in future electricity supply networks. Such a converter is capable of independently controlling power flow between various parts of an electricity grid, interfacing renewable energy systems directly into the grid and connecting grids of different voltages and frequency. An outline of the challenges for converter construction are presented as well as experimental results for the converter operating at 300kVA whilst connected between two 3.3 kV grids.

Urban exposure to ELF magnetic field due to high-, medium- and low-voltage electricity supply networks

The regional environment protection agency (ARPA) of the Aosta Valley region in north Italy performed a survey of magnetic field triggered by the power supply network in high, medium and low voltages on the entire area of Aosta town. The electrical distribution system for houses was not however taken into account. The aim of the survey was to evaluate the global population exposure and not simply the assessment of the legal exposure limit compliance.

Robustness of square networks

The topic of security often enters in many real world situations. Inthis paper we focus on security of networks on which it is based thedelivery of services and goods (e.g. water and electric supplynetworks) the transfer of data (e.g. web and telecommunicationnetworks), the movement of transport means (e.g. road networks),etc... We use a fluid dynamic framework, networks are described bynodes and lines and our analysis starts from an equilibrium status:the flows are constant in time and along the lines. When a failureoccurs in the network a shunt changes the topology of the network andthe flows adapt to it reaching a new equilibrium status. The question weconsider is the following: is the new equilibrium satisfactory interms of achieved quality standards? We essentiallyindividuate, for regular square networks, the nodes whose breakagecompromises the quality of the flows. It comes out that networks whichallow circular flows are the most robust with respect to damages.

Simple Models for Model-based Portfolio Load Balancing Controller Synthesis

Abstract This paper presents a collection of models of so-called ‘effectuators', i.e., subsystems in a power plant portfolio that represent control actions with associated dynamics and actuation costs. These models are derived in order to facilitate higher-level model-based control synthesis of a portfolio of generation units existing in an electrical power supply network, for instance in model-based predictive control or declarative control schemes. We focus on the effectuators found in the Danish power system. In particular, the paper presents models for boiler load, district heating, condensate throttling and wind turbine effectuators. Each model is validated against actual measurement data. Considering their simplicity, the models fit the observed data very well and are thus suitable for control purposes.

Mitsui to pilot methanol synthesis

The twin requirements of reducing CO2 emission levels and increasing the level of penetration of renewable energy will involve innovative technical and operational solutions. This paper describes a novel but proven process (CO2+3H2→CH3OH+H2O) which could be adapted to use, as input reagents, CO2 emitted from fossil-fuelled power stations and hydrogen from electrolysis of water by a zero-emissions electricity source, e.g. renewable and/or nuclear energy. This approach, in addition to addressing the above two issues, would produce methanol for which there is a ready and expanding market.A preliminary analysis is presented of the process economics and operational regimes necessary in the UK Electrical Supply Industry to accommodate the methanol plant. Four different designs are assessed, all based on a supply of renewable energy limited to 16h/day when demand is off-peak. Option ‘A’ relies on a variable 100–500MW supply, whereas Option ‘B’ makes use of a steady 100MW during the availability period. Option ‘C’ is identical to ‘B’, except for the use of pressurised electrolysers at 30bar instead of conventional ones. Option ‘D’ departs from ‘B’ with the use of hydrogen-powered fuel cells for power generation during the period of no availability. In the absence of a market for the electrolytic oxygen, Option ‘B’ is found to be the most economical, and it should be profitable if a favourable taxation regime applies on zero-emission automotive fuels. However, if the oxygen can be sold to a local industry via pipeline, Option ‘C’ could be potentially viable, even in the absence of tax breaks.It is claimed that significant benefits might accrue from successful development of a methanol process and that it may ease the absorption of increasing levels of embedded generation into the electricity supply network.

Power Alert: An Innovative System to Control Residential Loads Under Peak Conditions Using National TV

The Western Cape region of South Africa experienced severe power supply problems between February and August 2006. The reason for this was that Eskom, the electricity supply utility, lost one of its nuclear supply units. Forecasts predicted a winter shortfall of 300 MW for the region out of an average supply of about 4000 MW. It was clear that if something could not be done to reduce demand, power outages would be experienced. The main concern was the evening peak between 18:00 and 21:00, due to the high evening load. Eskom sent out a request for proposals to energy solution providers and ESCOs to come up with solutions to the crisis. The problem was that there was not enough time to implement solutions like residential hot water control systems in the 625,000 households of the Western Cape. The total residential load was around 1,200 MW. Energy Cybernetics, an energy solution provider, came up with the solution to use the national TV broadcaster to inform the public on the status of the electricity supply network between 18:00 and 21:00 on weekdays. Energy Cybernetics and Yardstick implemented the project for Eskom. It was called power alert. Power alert made use of real-time total electrical load data obtained from Eskom’s national control centre to identify when the electrical supply was under strain. Predictive modeling was also used to determine the total electrical demand for the Western Cape based on real-time data, historical data, and predicted weather conditions. The real-time predictive modeling was then used to predict the demand of the Western Cape 30 minutes, 60 minutes, and 24 hours in advance. An online computer system and application was also developed that connected the power alert control centre to the broadcasters control centre. This provided the power alert control centre with the capability to change any message to be broadcast within fi ve minutes. The real-time predictive modeling was used to predict the total electrical demand and consequently the expected level of strain. The level of strain was then prioritized according to four status levels. The status levels were: • Green—Indication that there was no strain on the electrical supply of the Western Cape.• Orange—Indication that there was strain on the electrical supply.• Red—Indication that there was increasing strain on the electrical supply and that load shedding was imminent.• Brown—Indication that there was signifi cant strain on the electrical supply and that load shedding was in progress. Based on the strain level experienced at that time, the public was asked to switch off certain appliances, thereby relaxing the strain on the network and preventing power outages. Power alert was deployed within three weeks and was in operation from April 2006 until the nuclear power station came again online during August. No further power outages were experienced during this period except for two short occasions: one when there was a transmission line failure, and two when Eskom lost a second unit on the nuclear power station. The power station tripped on a Thursday evening and it was too late to inform the public. Power outages were experienced for the whole next day until the fi rst power alert message was fl ighted on Friday afternoon at 18:00. The demand then started to drop and continued to drop further as more messages were broadcast. No additional power outages were experienced from 18:30 onwards until the unit came back on line on Sunday. Independent measurement and verifi cation results showed that power alert achieved impacts of up to 180 MW when red and brown messages were broadcast. Power alert achieved a total savings of more than 19,000 MWh over this period. The total cost to implement and operate power alert was about US$3 million, resulting in an average peak reduction cost of US$156 per MWh or 15.6 c/kWh. With all the initiatives, Eskom reduced the demand in the Western Cape by more than 400 MWs over a period of three months. The project has been a huge success, and Eskom decided to roll power alert out nationally as well as to other regions. Because the project will reach a bigger audience, the expected cost for the national power alert will come down to US$56 per MWh or 5.6 c/kWh. Eskom is also looking at expanding power alert to the commercial and industrial sectors. This will be done by “hard wiring” the power alert control center to non-essential loads in these sectors and controlling them when the networks come under pressure.

ANN for multi-objective optimal reactive compensation of a power system with wind generators

In this paper, we develop a method aimed to impose an acceptable voltages profile and to reduce active losses of an electrical supply network including wind generators in real time. These tasks are ensured by acting on capacitor and reactor banks implemented in the load nodes. To solve this problem, we minimize multi-objective functions associated to the active losses and the compensation devices cost under constraints imposed on the voltages and the reactive productions of the various banks. The minimization procedure was realised by the use of evolutionary algorithms. After a training phase, a neural model has the capacity to provide a good estimation of the voltages, the reactive productions and the losses for actual curves of the load and the wind speed, in real time.

Registering the form and spectrum of a signal with a digital kilovoltmeter

222 Developments in domestic market economics result in continual and considerable charge growth in the quality of production and service. This is absolutely relevant to electric energy, which is used in practically all aspects of vital human activity. In keeping with the Russian law “On Ensuring Uniformity in Measurement,” all electric energy payments are the subject of State metrological control and service. At the same time, more precise electric energy evaluations are important for the energy sale organizations themselves. Therefore, there is a need among modern high-precision measurement apparatuses to determine the quality of electric energy performance. The available high-voltage measurement sets, such as C100 and C196 type kilovoltmeters, IPN measurement systems (OOO Diatrans, Russia), KVM 100 kilovoltmeters (Phenix Technologies, USA), etc. can, as a rule, only measure the effective amplitude values of harmonic signals or dc voltages and do not provide automatic registration of the measurement process, spectral analysis, or statistical processing of the measurement data. Moreover, they are characterized by insufficient interference immunity, most of them do not have line-off power supply units, and their measurement accuracy depends on the signal amplitude and spectrum. These devices are not assigned to electric energy quality control. Devices for electric energy quality control made by well known producers like GOOD WILL, APPA, MOTECH, etc. purchasable on the Russian market and Russian-produced devices (Marsenergo, Energotekhnika, ABB VEI Metronika), in many cases, do not meet the standard requirements and can only be used as control devices for an industrial electricity supply network. Specialized measurement facilities for the electric energy quality control from the high-voltage side are absent, and, as a rule, the control of the electrical parameters on high-voltage substations is made with use of tedious measuring transformers.