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The importance of service quality to improve customer's satisfaction is well known to company managers; however, electricity distribution companies still tend to measure customer's satisfaction by the technical performance qualified by an uninterrupted supply of energy. For this reason, the aim of this paper is to study and compile what the literature suggests regarding customer's satisfaction in electricity distribution services and other related public services, in order to propose a conceptual model to measure customer's satisfaction based on a set of performance indicators. The model is based on a content analysis of a paper set sampled from systematic literature reviews. Techniques for data gathering, organisation and representation are based on conceptual maps and data analysis provided by NVivo content analysis platform. The findings presented in this paper cover (i) a set of 20 indicators, outlining all different terminologies found in the literature to express themselves; (ii) a description of a chosen set of indicators using the record sheet proposed by Neely, Gregory, and Platts (1997); (iii) a conceptual model presenting necessary aspects to measure the customer's satisfaction of residential electrical energy distribution service. [ABSTRACT FROM AUTHOR]

This paper presents a new hybrid intelligent method for the optimal placement and sizing of active power filters (APFs) from cost point of view in the power distribution system. Different costs of APFs are presented in this paper. To achieve the more saved cost, an intelligent method based on fuzzy logic and imperialist competitive algorithm (ICA) is proposed. Four indices are used to identify the initial locations of APFs. A new discrete improved adaptive ICA is proposed to determine the optimal locations and sizing of APFs. The intelligent method is validated on the IEEE 18-bus distribution system. The results show that our hybrid intelligent method is more efficient and economical in comparison with several non-hybrid approaches in this field. Besides, this paper clearly shows the impact of the fixed cost of APFs on investment costs. [ABSTRACT FROM PUBLISHER]

Even though non-linear Optimal Power Flow model proposed in part I of this paper provide accurate results there are difficulties in solving a full non-linear Optimal Power Flow model since it is a very time consuming. Due to speed and robustness, Linear Programming model is preferred by the system operators for nodal price calculations. It is a challenge to incorporate transmission losses into the losses linear DC power model. In this paper to model line flow operating limit inequality constraint a lossless Participant Based Distributed Slack DC Power Flow model is derived from Newton- Raphson state correction scheme used in part I of this work. An equivalent lumped linear model for the Participant Based Distributed Slack Lumped Nonlinear Optimal Power Flow model called Participant Based Distributed Slack Lumped Linear Optimal Power Flow model is developed in part II of this paper. The results for market clearing and settlement of double sided electricity market by the proposed lumped linear model are compared with the nonlinear model proposed in part I of this work using case studies on PJM system, IEEE 30 bus system and IEEE 118 bus system. The results obtained indicate the speed and robustness of the proposed linear model. [ABSTRACT FROM AUTHOR]

Natural disaster blackouts lead to dissatisfaction among electricity customers. When a natural disaster or high-impact and low-probability disasters like a storm or an earthquake happens, the electricity network assets may be damaged. To increase resilience, it is essential to prioritize damaged assets so that the lost loads, especially critical ones, can be restored faster. Predicting the number of repair teams during critical times contributes to restoring the network to the initial resilience level. This paper discusses the prioritization of electricity supply lines for evaluating the number of required repair teams. So, the economic value of distribution system lines has been considered a criterion representing the network's sensitivity to hurricanes. The results show the lines located at the end of the network ranked lowest in the prioritization. Also, the relatively dispersed evaluation shows the necessity of attention to repairing teams, which must move fast to speed up the load restoration process. A list of line priorities for fault resolution is provided, in which the topology factor has a larger effect. The number of repair teams required to restore critical and essential loads is determined by this model. This modeling has been tested on an IEEE 33-bus network. [ABSTRACT FROM AUTHOR]

This paper proposes a differing methodology from the Brazilian Electricity Regulatory Agency on the efficiency estimation for the Brazilian electricity distribution sector. Our proposal combines robust state-space models and stochastic frontier analysis to measure the operational cost efficiency in a panel data set from 60 Brazilian electricity distribution utilities. The modeling joins the main literature in energy economics with advanced econometric and statistic techniques in order to estimate the efficiencies. Moreover, the suggested model is able to deal with changes in the inefficiencies across time whilst the Bayesian paradigm – through Markov chain Monte Carlo techniques – facilitates the inference on all unknowns. The method enables a significant degree of flexibility in the resultant efficiencies and a complete photography about the distribution sector. [ABSTRACT FROM AUTHOR]

With the urbanization in recent years, the power line interference noise in electromagnetic signal is increasing day by day, and has gradually become an unavoidable component of noises in magnetotelluric signal detection. Therefore, a kind of power line interference noise elimination method based on independent component analysis in wavelet domain for magnetotelluric signal is put forward in this paper. The method first uses wavelet decomposition to change single-channel signal into multi-channel signal, and then takes advantage of blind source separation principle of independent component analysis to eliminate power line interference noise. There is no need to choose the layer number of wavelet decomposition and the wavelet base of wavelet decomposition according to the observed signal. On the treatment effect, it is better than the previous power line interference removal method based on independent component analysis. Through the de-noising processing to actual magnetotelluric measuring data, it is shown that this method makes both the apparent resistivity curve near 50 Hz and the phase curve near 50 Hz become smoother and steadier than before processing, i.e., it effectively eliminates the power line interference noise. [ABSTRACT FROM AUTHOR]

Resilience of power systems is highly impacted by factors such as increasing severity and frequency of weather events, but also smart grid advances that introduce major operational changes in power systems. Rapidly adapting to these changing circumstances and harnessing the potential of technological advances is the key to ensuring that power systems stay operational during disturbances, thereby improving resilience. This paper addresses this challenge by presenting an approach for improving resilience through local energy resource sharing across multiple distribution systems. The approach brings together the physical and the ICT layer of power systems through a self-organization approach that automatically alters the physical grid topology and forms local energy groups in order to mitigate the effects of widespread outages. Thereby, supply and demand are locally matched, and demand met is maximized during an outage. The results demonstrate that using the proposed approach, operational resilience of impacted distribution systems is improved. [ABSTRACT FROM AUTHOR]

This paper proposes a spatial Bayesian random effects stochastic frontier model that allows for unobserved heterogeneity and spillovers between firms’ efficiencies with an exogenous spatial weights matrix. Proposals for efficiency measurement in the spatial context add to the debate in the literature. The approach shows good small-sample performance, which is very relevant for applied researchers, and explores guided walk metropolis as a simple and computationally efficient alternative to classic rejection techniques. The approach is applied to a sample of 28 New Zealand electricity distribution firms between 1996 and 2010, finding spatial dependence with a second-order contiguity matrix. [ABSTRACT FROM AUTHOR]

This paper describes the design of a dynamic voltage restorer (DVR) that can simultaneously protect several sensitive loads from voltage sags in a region of an MV distribution network. A novel reference voltage calculation method based on zero-sequence voltage optimisation is proposed for this DVR to optimise cost-effectiveness in compensation of voltage sags with different characteristics in an ungrounded neutral system. Based on a detailed analysis of the characteristics of voltage sags caused by different types of faults and the effect of the wiring mode of the transformer on these characteristics, the optimisation target of the reference voltage calculation is presented with several constraints. The reference voltages under all types of voltage sags are calculated by optimising the zero-sequence component, which can reduce the degree of swell in the phase-to-ground voltage after compensation to the maximum extent and can improve the symmetry degree of the output voltages of the DVR, thereby effectively increasing the compensation ability. The validity and effectiveness of the proposed method are verified by simulation and experimental results. [ABSTRACT FROM PUBLISHER]

This paper studies the voltage stability problem in microgrid with multi-induction motor (MIM) loads. Firstly, the dynamic coupling relationship between grid voltage and each motor load slip in microgrid with MIM loads is deduced based on the power balance theory of power system. Then, a multi-source and master slave control based microgrid model is built, where Matlab/Simulink software is used to analyze microgrid voltage stability under circumstances of MIMs superimposed starting and microgrid fault. Through simulation calculation and analysis, the measures to improve the voltage stability of microgrid with MIM loads are proposed. According to the simulation results, the interaction between MIM loads has great influence on microgrid voltage stability. In addition, the critical cleaning time (CCT) of series connected master slave control based microgrid is affected by the distance between three phase short circuit fault location and the induction motor load location, as well as the distance between fault location and main control unit. The microgrid voltage stability can be effectively improved by applying methods of superimposed starting strategy and fast motor cutting strategy. The conclusion provides a reference for voltage stability research and control of the microgrid with MIM loads. [ABSTRACT FROM AUTHOR]

This paper describes a kind of mobile robot, named cable-climbing robot, and its motion planning development. That robotic system is capable of moving over electricity distribution lines, which can easily overcome the obstacles present in those installations like insulators, thanks to its kinematic motion planning of collision avoidance. The cable-climbing robot avoids the obstacles by the adoption of sequential movement planning with the objective of climbing insulators in electric posts. This approach avoids the obstacles, making the robot-articulated suspensions to retract when it is close to the obstacle and to distend after it passes over it. This kind of movement is controlled by a geometric motion planning method which is performed by the quintic polynomial interpolation law. The kinematic modelling uses the screw-based Jacobian Method combining with Virtual Kinematic chains, which permits the usage of the Kirchhoff-Davies method. Thus obtaining the cable-climbing robot inverse kinematic model. Simulation shows the potential use of this technique to cope with the cable-climbing robots control. [ABSTRACT FROM AUTHOR]

Power distribution systems must be very effective in power delivery. Utilities are continuously looking for recent technologies to enhance power delivery performance. The control of power loss is one of the most important issues directly related to system efficiency. Distribution system reconfiguration and optimal capacitor placement are the two most popular techniques adapted for the control of power loss. These techniques not only concentrate on power loss control but also control volt/volt-ampere reactive (VAR) of the distribution system, and at the same time improve the system reliability and security. This paper proposes a method to handle reconfiguration and capacitor placement simultaneously for the effective optimisation. Furthermore, it utilises opposition-based differential evolution (ODE) algorithm for efficient searching for the optimal solution. In order to consider the constraints along with the objective, heuristic fuzzy has been integrated with ODE. The effectiveness of the proposed approach is demonstrated by employing the feeder switching operation scheme to IEEE-33 bus power distribution systems. The proposed algorithm reduces the transmission loss and controls volt/VAR while satisfying power flow constraints. [ABSTRACT FROM AUTHOR]

A new fault location algorithm for two-end series-compensated double-circuit transmission lines utilizing unsynchronized two-terminal current phasors and local voltage phasors is presented in this paper. The distributed parameter line model is adopted to take into account the shunt capacitance of the lines. The mutual coupling between the parallel lines in the zero-sequence network is also considered. The boundary conditions under different fault types are used to derive the fault location formulation. The developed algorithm directly uses the local voltage phasors on the line side of series compensation (SC) and metal oxide varistor (MOV). However, when potential transformers are not installed on the line side of SC and MOVs for the local terminal, these measurements can be calculated from the local terminal bus voltage and currents by estimating the voltages across the SC and MOVs. MATLAB SimPowerSystems is used to generate cases under diverse fault conditions to evaluating accuracy. The simulation results show that the proposed algorithm is qualified for practical implementation. [ABSTRACT FROM PUBLISHER]

This paper presents and discusses the methodology used in a numerical investigation of the aggregated effect of model predictive control (MPC) strategies implemented in hundreds of residential buildings on demand reduction in the electricity distribution feeder. This approach includes reduced order models for the homes and heating, ventilating and air conditioning systems, a model for typical group of buildings served by a distribution feeder, and a simple model for the description of real and reactive power flows. The methodology is demonstrated with a simple MPC example. This paper is intended to serve as the basis of a study, presented in the companion paper, on the effect of using residential predictive control strategies to complement the integration of renewable energy technologies in the grid. [ABSTRACT FROM AUTHOR]

Urban infrastructures have traditionally been mono-functional: water, sewage, and electricity are notable examples. Embedded with digital technologies, urban infrastructures have the potential to communicate with one another and become multi-functional platforms that integrate data gathering and actuation cycles. In this paper, we focus on public lighting infrastructures. Despite the technological development of lights, including LED technology, streetlights have been primarily treated as a mono-functional infrastructure. Based on case studies, we discuss the potential of reimagining streetlight infrastructure, and advance some initial proposals that focus on sensing and actuation cycles, which could transform this pervasive infrastructure into a digital urban platform. [ABSTRACT FROM AUTHOR]

In power distribution networks, voltage instability can lead to voltage collapse and thus power blackout. A considerable amount of research has been carried out on voltage stability analysis of transmission and radial distribution networks. However, voltage stability analysis considering loop nature of distribution network is largely unaddressed. In this paper, a simplistic analytical approach is proposed, based on circuit analysis and famous biquadratic method to evaluate voltage stability of loop distribution networks in terms of voltage stability index (VSI). This work derives mathematical expressions for VSI of loop configuration for two realistic cases. The performance of proposed VSI is initially evaluated for Korean Electric Power Corporation distribution network. Benchmark analysis has been conducted on IEEE 69 bus test distribution networks to demonstrate the validity of the proposed approach in comparison with relevant works. The proposed approach is also applied for distributed generation placement and faults identification analysis. The results demonstrate the performance improvement in VSI of loop-based distribution networks which are expected to be useful for practical applications of future smart grids. [ABSTRACT FROM AUTHOR]

Japan suffered from the Great East Japan Earthquake followed by the nuclear disaster. As a result, we experienced rolling outages for a few months in the Tokyo and Tohoku area. Japan’s power transmission system consists of 50 Hz AC and 60 Hz AC in eastern and western Japan respectively. When the nuclear disaster occurred in Fukushima, enough electricity hasn’t been supplied in eastern area. Power interchange capacity between east and west was small because of small redundant T&D system design. Based on this rolling outage and some present electricity supplying issues in Japan, METI (Ministry of Economy, Trade and Industry) has set the electricity system reform committee to improve this situation and make a good T&D system for the future. This committee reported the discussed issue to the Japanese METI and METI proposed policy on Electricity System Reform to the Japanese Cabinet. As a result, the Japanese Electricity System Reform policy was adopted. This future T&D system deals with redundant T&D systems between east and west, how to handle large amounts of renewable electrical energy, and how to fully de-regulate the distribution market. HVDC (VSC system) will be introduced between Hokkaido and Honshu as a subsea cable transmission system and HVDC transmission system between eastern area and western area. This paper describes recent and future Japan’s T&D systems. This will be helpful to understand how to solve the issues of Japan’s T&D system. [ABSTRACT FROM AUTHOR]

The cost of loss of production in oil and gas plants is on average 6.5 times higher than that of plants in any other industry. Thus the reliability performance and analysis of oil and gas plants are unique. There have been many studies that have produced reliability indices for equipment that is used in industrial distribution networks, but these are all industry generic and none are specific to the oil and gas industry. This paper presents a set of equipment reliability indices that has been established from data collected from oil and gas plants and is suitable for use in reliability evaluations of the distribution networks of oil and gas plants. In the design of distribution networks for new oil and gas plants, engineers either do not have enough operational data, enough time or do not know how to perform the analysis required for establishing what type of network topology to use. This paper recommends the optimal network topology to use in such cases and provides evidence to support this proposal. [ABSTRACT FROM AUTHOR]

The neutral current can significantly harm the operation of a system, increase the losses of distribution transformers, and reduce the energy efficiency of a system. These negative effects of the neutral current highlight the importance and necessity of investigating neutral current control strategies. In this paper, we propose a novel scheme for controlling the neutral current caused by a linear unbalanced load in three-phase four-wire distribution transformers. The scheme, which is based on the static var compensator (SVC) technology, aims to: (i) control the neutral current, and (ii) reduce distribution transformer losses. It takes into account the effects of unbalanced fundamental currents and the SVC's compensating capability. Combining optimisation theory with a sequential quadratic programming method, we derive the optimal solution for the current control scenario we studied in this work. Simulation results show that our neutral current control scheme can significantly reduce the neutral current and distribution transformer losses. We also present some interesting observations on the SVC's capability and its significant impact on the neutral current and energy efficiency of a system. We hope that our work will encourage future research on SVC-based neutral current control approaches. [ABSTRACT FROM AUTHOR]

Regulators of electricity distribution networks have typically applied Data Envelopment Analysis (DEA) to cross-section data for benchmarking purposes. However, the use of panel data to analyse the impact of regulatory policies on productivity change over time is less frequent. The main purpose of this paper is to construct a Malmquist productivity index to examine the recent productivity change experienced by Norwegian distribution companies between 2004 and 2007. The Malmquist index is decomposed in order to explore the sources of productivity change, and to identify the innovator companies that pushed the frontier forward each year. The input and output variables considered are those used by the Norwegian regulator. In order to reflect appropriately the exogenous conditions where the companies operate, the efficiency model used in this paper incorporates geography variables as outputs of the DEA model. Unlike the model used by the regulator, we included virtual weight restrictions in the DEA formulation to correct the biases in the DEA results that may be associated to a judicious choice of weights by some of the companies. [ABSTRACT FROM AUTHOR]

This paper presents a fast, low cost and accurate instrumentation scheme for powerrelated measurements and power-factor correction. These measurements include the root-meansquare values of current and voltage, the active and reactive powers, the total harmonic distortion and the true power factor. It is a microcontroller-based digital sampling system which runs a fast algorithm for displacement power factor measurement. The controlling system monitors and senses any variations in power factor, and accordingly switches the appropriate capacitor combination across the load. The scheme presents an economical and efficient solution to the power distribution companies for its customers. [ABSTRACT FROM AUTHOR]

This paper proposes and investigates a control strategy for the distribution networks when isolated from a main utility in order to improve continuity of electricity to important loads. Specifically, the paper presents the operation and control of proton exchange membrane fuel cell based generation unit feeding to the islanded industrial network. The central controller defines all distributed generation units reference power and voltage with consideration of system and unit normal rating in order to maintain reliable and high quality power to the important loads. Simulation results verify that the proposed control scheme is effective for stable operation of the industrial islanded network with dynamic and variable loads. [ABSTRACT FROM AUTHOR]

An optimum maintenance plan for the protection systems of substations leads to improve the reliability while reducing the related costs. Reliability-centered maintenance (RCM) is one of the widely used strategies to obtain an optimal maintenance plan. An important issue in the protection systems is lack of a direct way between normal operation states of the pieces of equipment and their failure states, which is named "hidden function". This hidden function of the equipment in the protection systems is the main issue challenging the implementation of RCM on such systems. Over-current protection systems are one of the main protection systems which are installed in the outgoing distribution feeders of substations. This paper presents a novel approach for the implementation of RCM on the over-current protection systems. The main advantage of the proposed approach is its global consideration of a protection system instead of only focusing on relays. The proposed approach has been applied on two different substations using real data of their over-current protection systems obtained from The Organization of Generation, Transmission, and Distribution Management of Electric Power in Iran (Tavanir). The results reveal a higher reliability and lower costs of the proposed maintenance plan in comparison with current maintenance plans. [ABSTRACT FROM AUTHOR]

With the increasing deployment of battery storage devices in residential electricity networks, it is essential that the charging and discharging of these devices be scheduled so as to avoid adverse impacts on the electricity distribution network. In this paper, we propose a non-cooperative, price-based hierarchical distributed optimisation approach that provably recovers the centralised, or cooperative, optimal performance from the point of view of the network operator. The distributed optimisation algorithm provides important insights into the appropriate design of contracts between an energy provider and their associated residential customers, who can themselves act as energy providers as well as consumers (e.g. due to rooftop solar photovoltaics and batteries) depending on the time of the day and on real-time prices. To make the presentation self-contained, and to highlight key properties of the price-based optimisation algorithm, the dual ascent method and its convergence properties are reviewed. The performance of the proposed price-based optimisation algorithm is validated on recent measurement taken from an Australian electricity distribution company, Ausgrid. In addition to analysing the results of the open loop solution, we investigate the effect of real-time prices in the closed loop using a model predictive control framework. [ABSTRACT FROM AUTHOR]

This paper presents a new nonlinear optimization neural network approach to study the problem of security-constrained interconnected multiarea economic dispatch. It is a penalty-minimizing neural network approach with weights based on optimization theory and neural optimization method. In the paper the model of security-constrained multiarea economic dispatch is set up, in which tie-line security and transfer constraints in each area are considered. In addition, a simple analysis of buying and selling contract in a multiarea environment is made. The proposed method is tested on a system of three interconnected areas. The detailed results and analysis are given in the paper. [ABSTRACT FROM AUTHOR]

This paper presents the Load Increase Index, which is a new computationally efficient loadability limit index derived from the continuation power flow method. The continuation power flow is a well-known procedure for identifying the maximum loading point of a static power system network. The proposed index is a byproduct of the continuation power flow, and may be obtained with little extra computational effort while yielding considerable information about the distance to the critical loading point. This paper also presents the mathematical relationship of the proposed index to two other commonly used voltage stability indices: the smallest singular value of the loadflow Jacobian and the determinant of the loadflow Jacobian. The proposed index has been verified on numerous test systems of various sizes. [ABSTRACT FROM AUTHOR]

Various schemes of distribution systems, such as radial, ring, flower, etc., exist in practice, and one can establish the degree of reliability at which a particular configuration serves its customers only by performing a quantitative reliability performance assessment of the different configurations. The study results expressed in terms of reliability indices can serve as a basis of comparison of the reliabilities of two or more configurations. More importantly, the reliability indices of new or proposed systems can be predicted using realistic data, which in turn can be used to make judicious decisions between alternative schemes. This paper describes the application of Windows-based user-friendly software to evaluate the reliability of different types of distribution system configurations, in particular, three types of connections, viz., radial, meshed or ring, and flower networks. A comparison is made between the reliability indices of these three types of configurations, and conclusions are drawn. [ABSTRACT FROM AUTHOR]

Using a six-year case study of Glasgow's Sustainable City business model, this paper examines interactions between financialised governance of cities and clean energy strategies. Research on the role of cities in developing clean energy has paid limited attention to the interaction with financialised governance of infrastructure, which makes the implementation of plans largely dependent on private investment. A conceptual approach combining economic sociology of actor networks and urban political economy is used to analyse the career of the business model designed to transform old infrastructures into new clean energy assets. The analysis focuses on interactions between city council, public bodies and electricity distribution network business. Climate policies are creating uncertainties for energy businesses over revenues from ageing networks, suggesting scope for alliance with local governments. Making new liquid assets for clean energy from old infrastructure is however shown to be a process marked by instability and reversals. In conclusion, it is argued that concepts from actor-network theory and urban political economy used together reveal the hidden contingencies of financialisation in particular socio-technical interactions, and their materiality in the context of climate change. [ABSTRACT FROM AUTHOR]

Improving fuel economy and lowering emissions are key societal goals. Standard driving cycles, pre-designed by the US Environmental Protection Agency (EPA), have long been used to estimate vehicle fuel economy in laboratory-controlled conditions. They have also been used to test and tune different energy management strategies for hybrid electric vehicles (HEVs). This paper aims to estimate fuel consumption for a conventional vehicle and a HEV using personalized driving cycles extracted from real-world data to study the effects of different driving styles and vehicle types on fuel consumption when compared to the estimates based on standard driving cycles. To do this, we extracted driving cycles for conventional vehicles and HEVs from a large-scale U.S. survey that contains real-world GPS-based driving records. Next, the driving cycles were assigned to one of three categories: volatile, normal, or calm. Then, the driving cycles were used along with a driver-vehicle simulation that captures driver decisions (vehicle speed during a trip), powertrain, and vehicle dynamics to estimate fuel consumption for conventional vehicles and HEVs with power-split powertrain. To further optimize fuel consumption for HEVs, the Equivalent Consumption Minimization Strategy (ECMS) is applied. The results show that depending on the driving style and the driving scenario, conventional vehicle fuel consumption can vary widely compared with standard EPA driving cycles. Specifically, conventional vehicle fuel consumption was 13% lower in calm urban driving, but almost 34% higher for volatile highway driving compared with standard EPA driving cycles. Interestingly, when a driving cycle is predicted based on the application of case-based reasoning and used to tune the power distribution in a hybrid electric vehicle, its fuel consumption can be reduced by up to 12% in urban driving. Implications and limitations of the findings are discussed. [ABSTRACT FROM AUTHOR]

This paper proposes a robust optimal reactive power flow (RORPF) model to cope with uncertainties of load perturbations. It incorporates information of load-increase directions to reduce the uncertain effect of system loads, searching for solutions that are immune to parameter drifts and load changes. According to the numerical study on IEEE-118 systems, optimal solutions of RORPD are superior in the presence of uncertain load perturbations. The robust solutions are proved to be comparatively less sensitive to load perturbations and can maintain their objective values against uncertain load changes. RORPD can provide optimal solutions with a higher degree of stability in the face of perturbations and can be more practical in the reactive power optimization of real-time operation systems. [ABSTRACT FROM AUTHOR]

This paper deals with the strategies of households living in a peripheral high-mountain region in order to cope with the post-Soviet energy crisis. The Soviet modernization project failed at connecting the region to the grid, and imported coal for heating and fuel for producing electric energy at high costs over long distances. After the collapse of this alimentation system, people have substituted energy demands with wood and shrubs, and used increasingly available low-cost Chinese solar equipment to produce electrical energy. International development actors have failed to increase acceptance for energy efficiency technologies. Despite the Pamirs' high potential for solar and wind energy and decreasing installation costs, Soviet-style state planning of energy infrastructure still favours big hydropower stations, despite their high (social) costs and the limited potential on the Pamir plateau. The paper will discuss bottom-up effects of household decisions and top-down strategies as potentials and obstacles for a sustainable energy supply in the Pamirs. [ABSTRACT FROM PUBLISHER]

This paper proposes an approach to the cross-efficiency evaluation that considers all the optimal data envelopment analysis (DEA) weights of all the decision-making units (DMUs), thus avoiding the need to make a choice among them according to some alternative secondary goal. To be specific, we develop a couple of models that allow for all the possible weights of all the DMUs simultaneously and yield individual lower and upper bounds for the cross-efficiency scores of the different units. As a result, we have a cross-efficiency interval for the evaluation of each unit. Existing order relations for interval numbers are used to identify dominance relations among DMUs and derive a ranking of units based on the cross-efficiency intervals provided. The approach proposed may also be useful for assessing the stability of the cross-efficiency scores with respect to DEA weights that can be used for their calculation. [ABSTRACT FROM AUTHOR]

Large-scale penetration of photovoltaic (PV) energy in a distribution network requires careful planning of its location on the distribution network since it evidently demands large space, flexible maintenance access and exposure to driving energy sources such as sunlight for PV plants. Besides that, the technical aspects of the design should consider possible constraints that may introduce inefficiency in the generation or simply unexpected loss in the distribution. This paper addresses the decentralisation requirement for large-scale deployment of PV power sources as it resists the intermittency of the PV output naturally. In this study, a Monte Carlo method was used to justify the validity of this implication. A modified Gaussian distribution function was used to model the random fluctuations of the PV source and was used in the Monte Carlo simulation. The result shows considerable boost in the average power level and suppression of the fluctuation rate while the interconnected sources are uncorrelated. [ABSTRACT FROM AUTHOR]

The sum-rate performance of multi-cell wireless networks with feedback bits allocation strategy are analysed in this paper. The Doppler power spectrum and autocorrelation function are not appropriate to describe the real wireless channels for which the random environment are time varying. Accordingly the channel is non-constant to describe the Doppler power spectrum and autocorrelation functions. The channel temporal correlation is modelled as a function of delay using the Gauss-Markov model. This paper incorporates the fluctuations in component phases in traditional Clarke's model and studies the effect of number of bits required to quantise the signal plus interference noise ratio. The analysis provides insights on the feedback designs and also shows significant improvement in sum-rate and outage probability [ABSTRACT FROM AUTHOR]

Management of harmonic voltage levels can impose significant economic impacts for both electricity suppliers and customers. For the case where harmonic voltage levels are high, economic costs include damage to equipment and associated loss of production due to high voltage harmonic levels as well as the costs associated with mitigation of harmonic currents, for example, harmonic filters. In the alternate scenario, ie. the case where harmonic voltage levels are acceptable, considerable expense may be incurred mitigating harmonic currents unnecessarily due to lack of knowledge of harmonic levels and/or network capabilities. As such, there is considerable potential for industry to make large economic gains if harmonic voltage levels can be better understood. Using data collected as part of an ongoing long-term power quality monitoring project, this paper details the characteristics of voltage harmonic behaviour on Australia electricity distribution networks [ABSTRACT FROM AUTHOR]

One of the most difficult problems in compensated distribution networks is the grounded fault location. This paper proposes a new method for locating single-line-to-ground (SLG) faults in compensated distribution networks. The grounded fault location system is made up of the host, the controller, the signal generator and the grounded fault indicator (GFI). When a SLG fault occurs, the fault phase is identified firstly, and then a signal generator paralleled with the arc suppression coil injects a special current into the system. Subsequently, GFIs along the fault phase are activated to sample the fault phase current and send it back. The fault phase current is computed by the host with a fast Fourier transform algorithm. By comparing these frequency components of the fault phase current, the fault section is identified based on the significant difference of the second harmonic of two adjacent GFIs. Due to the short length of feeders, the distance between two adjacent GFIs is short enough for line patrol personnel to find and repair the fault easily. Finally, a modified IEEE 13-node feeder test is constructed in PSCAD/EMTDC to evaluate this method. The simulations results confirm the validity of the proposed approach [ABSTRACT FROM AUTHOR]

The efficiency of the energy sector in India, the world’s third-largest energy consumer, is becoming an important issue amid growing concerns about global warming. This paper examines the efficiency of electricity distribution utilities in India using panel data from 2005 to 2012. We perform a two-stage data envelopment analysis with a bootstrap estimation, in which bias-corrected efficiency estimates are calculated in the first stage and then regressed on external environmental variables in the second stage. First, we find positive effects of customer structure and population density on the efficiency of utilities. Second, we find efficiency advantages of public utilities in the Indian power distribution sector. However, the interaction between ownership and population density is negative, implying that public utilities are less efficient than private enterprises in high population density areas. Finally, we find that government subsidies are negatively related to the efficiency of utilities. [ABSTRACT FROM AUTHOR]

The AC-DC distribution systems have recently gained huge popularity due to advancements in power converters, high penetration of renewable energy resources and widespread use of DC loads. However, load flow in such systems is a challenging task, due to non-linear characteristics of power converters. This paper presents a new and computationally efficient load flow algorithm for AC distribution systems using graphical search technique along with matrix algebra and has been further extended for solving AC-DC distribution systems load flow problem by making use of proposed per-unit equivalent model of various power converter devices. In contrast with traditional methods, the proposed technique does not require any LU decomposition, matrix inversion and forward backward substitution of admittance matrix or Jacobian matrix. The significant feature of the proposed algorithm lies in formulation of path impedance matrix and loads beyond branch matrix, which will remain unaltered for the entire operation. Reconfiguration of these matrices takes place automatically in accordance with the change in input data. Because of the aforementioned reasons, the developed technique is computationally potent when applied on large sized distribution systems. The proposed method has been validated on various standard test systems. Results show feasibility and authenticity of the proposed method. [ABSTRACT FROM AUTHOR]

With more than one billion people lacking access to electricity in the world, ensuring universal access to electricity by 2030 remains a major challenge which cannot be left to the government initiatives alone. Access to local information and identification of potential areas for investment can be a challenge for investors. This paper provides a tool for preliminary assessment of potential markets for off-grid electrification in developing countries and applies this to Ghana to demonstrate its applicability. A multi-criteria approach is used to rank the districts according to the overall potential and the best markets and least favourable areas for investment are identified. The tool offers flexibility to include new inputs to the analysis and the factor weights can be adjusted as appropriate. The case study shows that the tool can effectively identify potential areas from a list of candidates and offers support to analysts. [ABSTRACT FROM AUTHOR]

The customers of distribution system are generally encouraged to maintain better power factor through suitable tariff structures. The feeder power loss allocation is a part of tariff. The feeder power losses also depend upon power factor of loads. Therefore, loss allocation method should incorporate suitable rewarding and penalizing strategy for better and poor factors loads. This paper proposes a new distribution loss allocation method that considers load power factor to allocate losses in a more practical way. The proposed method employs bifurcation of cross terms of branch power loss among contributing nodes. The method provides loss allocation to system nodes in such a way that it provides rebates/penalties against variation in load power factor only to the concerned nodes. The proposed method is applied to 30-bus and 33-bus test distribution system and compared with other established methods. The analysis of the application results highlights the importance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents the improved control strategy with optimal switching scheme to improve the bidirectional converter's power flow control capability and to allow for different modes of operation in hybrid AC/DC microgrid. Also, this improved control strategy eliminates the need of PI controller for independent reactive power control. With the improvements in digital controllers, it is possible to implement complex control circuitry easily. The performance of bidirectional converter with improved control strategy is verified first in simulation environment and then on lab scale experimental set-up with the control circuit is implemented using hardware in loop in the real-time digital simulation platform. The simulation and experimental results for all the cases show that the controller is highly capable for power transfer between AC and DC grid with very fast response and also control reactive power without additional PI controller. Also, it maintains the current total harmonic distortion (THD) within standard limits. [ABSTRACT FROM AUTHOR]

A reliability enhancement scheme for an electric distribution system is impossible to be cost-effective without the guidance of accurate reliability index estimations. As one of the widely used basic reliability indices, average interruption duration is of foremost concern, due to being a straightforward indicator of the electric power supply quality in the aspect of customer satisfaction to the incident response capability of electric utilities to outage events. This paper proposed an analytical distribution system reliability evaluation method that allows for considering stochastic load point interruption durations together with stipulated network reconfiguration constraints. Through case studies on the Roy Billinton Reliability Test System, advantages of the proposed method over a traditional section technique-based reliability evaluation method are discussed. The proposed method is validated to yield more realistic estimations in the case of considering stochastic interruption durations and postfault network reconfigurations, thus is expected to be capable of supporting economical system reliability-enhancing decision-making. [ABSTRACT FROM AUTHOR]

This paper focuses on implementation of differential equation of the single-phase source-load system based control algorithm for three-phase distribution static compensator (DSTATCOM) in a power distribution system with a stiff source. The DSTATCOM has been adopted to alleviate the power quality issues such as load unbalancing, reactive power, and current harmonics, which are caused by solid-state equipment and devices. The proposed control algorithm is employed for extraction of fundamental active and reactive current components of polluted load currents, which are used for estimation of reference source currents. The control algorithm carries out computations by using a sliding sampling window that has a width of half of the fundamental cycle. The primary advantages of this control algorithm are immune to noise, not influenced from DC component that may exist in load current, and being less affected from frequency deviations. A prototype of voltage source converter (VSC)-based DSTATCOM is developed using a field programmable gate array (FPGA) processor to validate the proposed control algorithm and its performance is analyzed under steady-state and dynamic conditions. Experimental results demonstrate satisfactory performance of the DSTATCOM with the proposed control algorithm under linear and non-linear loads. [ABSTRACT FROM AUTHOR]

The microgrid is an environment constructed with the aim of controlling local distributed resources. The most common power flow control technique utilised in a power electronics dominated or standalone microgrid is a technique known as power frequency droop. This paper develops a novel droop controller based on an arctan power profile that can provide natural limiting of frequency deviations and accurate frequency output. The new control system has been simulated in SABER and results are presented that show the advantages of the control. A low voltage microgrid consisting of two inverters and a passive load has been constructed. Experimental results from the hardware system are presented to confirm the operation of the new droop controller. [ABSTRACT FROM AUTHOR]

This paper analyzes determinants of costs and real prices for retail electricity supply in Slovenia. We estimate cost and price functions in a retail electricity distribution enterprise in Slovenia by ordinary least square regressions on time series data. We confirm the hypotheses that real costs for electricity supply are positively and significantly associated with the costs for purchases of electric energy from electricity producers/wholesalers and with remuneration costs in electricity distribution enterprises. We did not confirm a negative association between the real costs for retail electricity supply and the proxy variable for electricity market liberalization. Market deregulation and price liberalization with increased competition have caused an initial decline in real consumer prices of electric energy. We found that the real consumer price of electric energy is positively associated with producer/wholesaler prices of electric energy, real wages in electricity distribution enterprises, and real tax expenses in the distribution enterprise, but negatively associated with the variable for electricity market liberalization. The results confirm the crucial role of the transmission of producer/wholesaler prices of electric energy and costs within the distribution enterprises, including labor costs, on the consumer prices of electric energy. [ABSTRACT FROM AUTHOR]

A novel iterative method for identifi cation of grid integration points and size of distributed generators (DGs) with simultaneous capacity evaluation of a distribution system for DG integration is proposed in this paper. In order to achieve this, various performance indices governing the optimal operation of a distribution system with DG units are strategically combined to form a multi-objective index. Identifi cation of suitable nodes and size of each DG unit for integration in the distribution system is performed by minimising the multi-objective index such that on placement of every additional DG unit, reduction in the values of performance indices is resulted without any violation in the system operating constraints. The effects of different types of DGs and load models in this DG placement problem are also analysed. The proposed technique is tested on 33- and 25-bus systems, and is found to be very effective in identifying the suitable number of locations, size of DG units and evaluating the capacity of distribution system for DG integration. [ABSTRACT FROM AUTHOR]

In 2005 Joint Research Centre of the European Commission (EC-JRC) started an in-depth survey of the electricity end-use consumption and energy efficiency trends in order to assess the energy efficiency potential in the building sector in the European Union Member States (EU-27).1 The survey is updated every two years, the last one being carried out in 2009. Data for end-use electricity consumption for the tertiary sector are very scarce and are not routinely collected by any national or European statistical office. The data are assembled from a variety of sources: published reports and papers, interviews with experts and researchers, including electricity distribution companies' data. At the same time, data on efficiency trends of the most common end-use equipment are collected from multiple sources, including equipment manufacturers. The survey aims to link the efficiency improvements to the trends in consumption, and to have an estimate of the impact of efficiency policies on energy consumption. In particular, accounting for electricity consumption is a very important step for the development of energy policies, but so far electricity consumption analysis has been neglected or underestimated in policy development and related research. The paper presents the main results and conclusion of the 2009 survey. [ABSTRACT FROM AUTHOR]

In this paper, a new CMOS variable gain low noise amplifier (VG LNA) with continuous gain variation for 2-11 GHz employing a resistance feedback current reuse stage and a cascode stage is presented. By controlling the transimpedance feedback resistor of the first stage and the bias current of the second stage, a continuous gain tuning range of 26 dB is achieved without influencing the input match and output match. The VG LNA is simulated based on the TSMC 0.18 μm CMOS process and shows the following performance at the highest gain mode: S11 is less than -10 dB from 3 to 10.2 GHz, and S22 is less than -18 dB from 2 to 11 GHz. In the total 2-11 GHz frequency range, the gain is more than 17 dB, and the noise figure is less than 3.8 dB, while drawing 7.57 mA from 1.4 V supply voltage. [ABSTRACT FROM AUTHOR]

The complex permittivity measurement of ferroelectric thin film is discussed in this paper. Considering the small thickness of ferroelectric thin film, the CPW (coplanar waveguide) with material under test (MUT) deposited on the Al2O3 is used as measurement configuration. The propagation constant is calculated and the complex permittivity of the MUT is extracted from effective permittivity by using SVR (support vector regression) method. The results show that the errors of both real part and imaginary part of the permittivity (ε′r and ε′′r) are less than 1%. [ABSTRACT FROM AUTHOR]