Current Electric Power Research Articles

Development and optimization of a PV/diesel hybrid supply system for remote controlled commercial large scale FM transmitters

This paper is devoted to a renewable hybrid PV–diesel generator developed to supply power to a designated remote controlled FM transmitters located in remote locations. The developed system can guarantee the energy demand of the station (100% reliability) with less cost of energy production. In addition, this paper presents a remote control supervisory system designed to improve the entire transmitter-facilities processes which includes applications for sensing, managing, controlling and measuring transmitter site parameters and performance from a networked computer or a dial up computer. The need for detailed monitoring of the performance of transmitter site equipment including monitoring of electrical systems as well as monitoring of communication systems is becoming critical as these sites are becoming larger and more sophisticated. The systems was set up and tested through rigorous simulations of the transmitter site failures and evaluated for three consecutive months. The proposed systems have been installed and continuously operated on live FM transmitter facilities at six locations in Malaysia. The proposed hybrid power system can be also integrated into the current electric power network of Malaysia as a backup or as a main source of power for the entire transmitter facility. The supervision and control signals of the proposed power hybrid system can be easily included and integrated with the other existed FM transmitter supervisory and control signals. The concrete study in this paper is directed to one of the FM stations located in a remote area in Kuantan, Malaysia.

Electrical injury in construction workers: A special focus on injury with electrical power

BackgroundElectrical injury in construction workers due to contact with overhead power lines accounts for an important cause of admission at the emergency department. Due to lack of specific treatment options for this type of injury, prevention remains the mainstay of management. AimsOur study aimed to demonstrate the characteristics of electrical injury in construction workers among one of the largest Iranian population at a burn care hospital. MethodsThrough a retrospective review of hospital data base, patients with electrical injuries admitted to Motahari hospital in Tehran, Iran between March 2011 and June 2012 were included for analysis. Patients were divided into construction workers and other patients. Primary characteristics and final outcomes were then compared between the 2 study groups. ResultsOf 202 patients included in this study, 105 patients (52%) were construction workers and 97 patients (48%) constituted the remainder. There was significant difference between the 2 groups in terms of mean age, gender, and average burn size. In contrast, mean duration of hospitalization and mortality rate did not differ significantly between the 2 study groups (p>0.05). Contacts with over head power-lines accounted for the most common mechanism of injury. There was significant difference between the 2 groups in terms of place of injury and electrical current power. However, total cost of treatment did not differ significantly between the 2 groups (p>0.05). Frequency of severe complications was higher in construction workers and this group underwent more invasive procedures such as limb amputation and fasciotomy. ConclusionThe most common mechanism of electrical injuries in construction workers is due to contact with over head high voltage power-lines at workplace. This type of electrical injury is associated with higher use of fasciotomy, flap and limb amputation.

An AC Pioneer: United Electric Light & Power Company [History

It often appears that everything that could be written has been written with regard to the 1890s competition between alternating current (ac) and direct current (dc) electric power systems. Much is inaccurate and, unfortunately, is repeated ad infinitum. One factor that all writers, both popular and scholarly, overlook is that the issue was not resolved in a single event nor was it immediate. The ac systems that ultimately prevailed required decades of research and development prior to universal application.

Technologies for recovery of energy from wastewaters: Applicability and potential in South Africa

This study explored technologies for recovering energy from wastewater through production of biomass, combustion and gasification, generation of biogas, production of bioethanol, heat recovery and microbial fuel cells. A first order desktop analysis of the potential for applying these solutions to wastewaters in South Africa revealed that 3 200 to 9 000 MWth of energy has potential for recovery, equating to at most 7% of South Africa’s current electrical power supply. Formal and informal animal husbandry, fruit and beverage industries and domestic blackwater were identified as wastewaters with the greatest potential for energy recovery. Of the reviewed technologies, anaerobic digestion shows applicability to the widest range of feedstocks. Net energy generated, reduction in pollution, and water reclamation are identified as the main benefits, but additional benefits such as certified emission reductions, fertiliser production and the production of secondary products may dictate the economic feasibility.

Analysis of Smart Grid with 132⁄33 KV Sub-Transmission Line In Rural Power System of Bangladesh

“Smart Grid” is a modern concept which refers to the conversion of the mainstream or typical electric power grid to a modern power grid. This new conversion is a foreseeable solution to the power system problems of the modern century. Rejuvenation of the current electric power distribution system is an important step to implement the Smart Grid technology. So, distribution system engineers should be acquainted with the knowledge of Smart Distribution System. Also the customers should acknowledge the benefits that they will be enjoying from this modernized power system. There are power crisis everywhere in the world, besides there is system loss in the existing power system. It is happening in Bangladesh also. To reduce power crisis renewable source of energy like solar energy, wind energy, raw coal energy may be used. But the quantity of electricity produced by this renewable energy source is low and several kilowatts range. This electricity is utilized by smart grid which is hard for usual power grid system. For this reason we need hybrid ac/dc smart control grid system. In this report models using Wind-mil Software is proposed for reducing system loss and also incorporate smart metering so that the power flow can reach easily to the consumers. Smart grid also helps sole proprietor and individual business man to sell their little amount of electricity to the grid which they produce by their own entrepreneurship through smart meter. Line loss and regulated voltage, regulator and capacitor are also inserted here to reduce the loss and make the effective and efficient power supply to the consumer. This metering is also centrally controlled and works over a huge area. At present developing country should develop this system.

Analytical modeling and experimental verification of vibration-based piezoelectric bimorph beam with a tip-mass for power harvesting

Power harvesting techniques that convert vibration energy into electrical energy through piezoelectric transducers show strong potential for powering smart wireless sensor devices in applications of structural health monitoring. This paper presents an analytical model of the dynamic behavior of an electromechanical piezoelectric bimorph cantilever harvester connected with an AC–DC circuit based on the Euler–Bernoulli beam theory and Hamiltonian theorem. A new cantilevered piezoelectric bimorph structure is proposed in which the plug-type connection between support layer and tip-mass ensures that the gravity center of the tip-mass is collinear with the gravity center of the beam so that the brittle fracture of piezoelectric layers can also be avoided while vibrating with large amplitude. The tip-mass is equated by the inertial force and inertial moment acting at the end of the piezoelectric bimorph beam based on D'Alembert's principle. An AC–DC converting circuit soldered with the piezoelectric elements is also taken into account. A completely new analytic expression of the global behavior of the electromechanical piezoelectric bimorph harvesting system with AC–DC circuit under input base transverse excitation is derived. Moreover, an experimental energy harvester is fabricated and the theoretical analysis and experimental results of the piezoelectric harvester under the input base transverse displacement excitation are validated by using measurements of the absolute tip displacement, electric voltage response, electric current response and electric power harvesting.

A Method of Constructing Electric Power Data Warehouse Based on Cloud Computing

Hive is a data warehouse architecture in cloud computing. In order to solve the inadequate of massive data storage, query, and computing power in current electric power data warehouse, a method of electric power data warehouse based on Hive is proposed. Combining data analysis demands of electric power entreprises, the integration architecture between Hive and column-oriented storage is designed in electric power data warehouse, and the process of which is also given. At last, electric power equipment condition data is used for experiment on Hadoop cluster, results show that this method can quickly achieve query and analysis in massive multidimensional data set.

Maximum Output Power Control Using Short-Circuit Current and Open-Circuit Voltage of a Solar Panel

A control method to optimize the output power of a solar cell is necessary because the output of a solar cell strongly depends on solar radiation. We here proposed two output power control methods using the short-circuit current and open-circuit voltage of a solar panel. One of them used a current ratio and a voltage ratio (αβ control), and the other used a current ratio and a short-circuit current–electric power characteristic coefficient (αγ control). The usefulness of the αβ and the αγ control methods was evaluated. The results showed that the output power controlled by our proposed methods was close to the maximum output power of a solar panel.

Wireless Sensor Network Applications in Smart Grid: Recent Trends and Challenges

Smart grid revolutionizes the current electric power infrastructure by integrating with communication and information technologies. With wireless sensor network, smart grid enables both utilities and customers to transfer, monitor, predict, and manage energy usage effectively and costly. However, the increased application of wireless sensor network also introduce new security challenges, especially related to privacy, connectivity, and security management, causing unpredicted expenditure and disaster to both utilities and consumers. In order to build a reliable wireless sensor network for smart grid, an application review and taxonomy of relevant cyber security and privacy issues is presented in this paper. A unified framework for identification of applications and challenge issues of wireless sensor network in smart grid is developed. Future research directions are discussed at the end of this paper.

A Clustering Approach to Wind Power Prediction based on Support Vector Regression

A sustainable production of electricity is essential for low carbon green growth in South Korea. The generation of wind power as renewable energy has been rapidly growing around the world. Undoubtedly wind energy is unlimited in potential. However, due to its own intermittency and volatility, there are difficulties in the effective harvesting of wind energy and the integration of wind power into the current electric power grid. To cope with this, many works have been done for wind speed and power forecasting. It is reported that, compared with physical persistent models, statistical techniques and computational methods are more useful for short-term forecasting of wind power. Among them, support vector regression (SVR) has much attention in the literature. This paper proposes an SVR based wind speed forecasting. To improve the forecasting accuracy, a fuzzy clustering is adopted in the process of SVR modeling. An illustrative example is also given by using real-world wind farm dataset. According to the experimental results, it is shown that the proposed method provides better forecasts of wind power.

Empowering the smart grid with wireless technologies [Editor's Note

During the late 19th and early 20th centuries, electric power had replaced steam power as the driving force of the second industrial revolution. Critical inventions such as electric lighting and electric motors had significantly improved the production rate, transportation efficiency, and people's living standard. As named by the National Academy of Engineering (NAE), electrification is "the most important engineering achievement of the 20th century." As we enter the 21st century, the focus is on the green economy. Therefore, some of the basic assumptions and/or concepts of the original power grids gradually become obsolete and need to be updated. One obvious example comes from the fast growing deployment of distributed generation (DG) of electricity all over the world. According to the International Energy Agency (IEA), solar power can contribute 2.3 percent to the world's power by 2020, rising to 8.8 percent by 2030. Based on the forecast of BTM Consult, wind power market penetration is expected to reach 3.35 percent by 2013 and 8 percent by 2018. Coming along with the potential economic and environmental benefits of DG are the increased concerns about power system stability and reliability. Specifically, traditional electricity consumers are being gradually transformed into electricity "prosumers" who not only consume energy but also produce energy and send it back to the power grid. As a result, the basic assumption of unidirectional electricity delivery (from centralized generators to electricity customers) in traditional power grids is no longer suitable. Advanced power system operation mechanisms should be developed to address specific characteristics of the DG, such as the sunlight-dependent power generation of solar plants. Similar problems exist in traditional power grids as more and more electric vehicles (EVs) are integrated for transportation efficiency improvement, while more and more smart-meters are installed for household demand response purposes. All these surging demands require a transition of the current electric power grid toward a new generation of power grid, commonly referred to as the "smart grid."

A Short-Term Wind Speed Forecasting Through Support Vector Regression Regularized by Particle Swarm Optimization

A sustainability of electricity supply has emerged as a critical issue for low carbon green growth in South Korea. Wind power is the fastest growing source of renewable energy. However, due to its own intermittency and volatility, the power supply generated from wind energy has variability in nature. Hence, accurate forecasting of wind speed and power plays a key role in the effective harvesting of wind energy and the integration of wind power into the current electric power grid. This paper presents a short-term wind speed prediction method based on support vector regression. Moreover, particle swarm optimization is adopted to find an optimum setting of hyper-parameters in support vector regression. An illustration is given by real-world data and the effect of model regularization by particle swarm optimization is discussed as well.

Three-dimensional study of a polycrystalline silicon solar cell: the influence of the applied magnetic field on the electrical parameters

In this paper, we present a theoretical 3D study of a polycrystalline silicon solar cell in frequency modulation under polychromatic illumination and applied magnetic field. The influence of the applied magnetic field on the diode current density, Jd, and both electric power–photovoltage and photocurrent–photovoltage characteristics are discussed. The Nyquist diagram permitted us to determine the electrical parameters such as the series resistance Rs and parallel equivalent resistance Rp of a polycrystalline silicon solar cell. The Bode diagram is then used to calculate the cut-off frequency, capacitance C and inductance L. It has been shown that, under a magnetic field, the solar cell behavior is like that of a low-pass filter.

Climate change/variability implications on hydroelectricity generation in the Zambezi River Basin

The study has analysed the effects of various factors on hydroelectric power generation potential to include climate change/variability, water demand, and installation of proposed hydroelectric power schemes in the Zambezi River Basin. An assessment of historical (1970–2000) power potential in relation to climate change/variability at existing hydro electric power schemes(Cahora Bassa, Kariba, Kafue Gorge and Itezhi-Tezhi) in the Zambezi River Basin was conducted. The correlation of hydroelectric power potential with climate change/variability aimed at observing the link and extent of influence of the latter on the former was investigated. In order to predict the future outlook of hydro electric power potential, General Circulation Models (GCM) were used to generate projected precipitation. The monthly simulated precipitation was extracted from the GCM for every sub basin and used to compute future precipitation. Further, future water demand in the sub basins of the Zambezi River Basin were estimated based on the respective population growth rate in each sub basin. Subsequently, water balance model, with projected precipitation and water demand input was used to determine projected run-offs of sub basins of the Zambezi River Basin. .Based on the projected run-offs of sub basins, reservoir storage capacities at existing hydro electric power schemes were estimated. The baseline assessment revealed a strong relationship between hydroelectric power potential and climate change/variability. The study also revealed that the main climate and other risks associated with current and future hydro electric power generation include projected dry years, floods and increasing water demand. The results indicate that the hydroelectric power potential has a tendency towards gradual reduction in its potential in all existing and proposed hydroelectric power schemes owing to climate change and increasing water demand.

A survey of communication/networking in Smart Grids

Smart Grid is designed to integrate advanced communication/networking technologies into electrical power grids to make them “smarter”. Current situation is that most of the blackouts and voltage sags could be prevented if we have better and faster communication devices and technologies for the electrical grid. In order to make the current electrical power grid a Smart Grid, the design and implementation of a new communication infrastructure for the grid are two important fields of research. However, Smart Grid projects have only been proposed in recent years and only a few proposals for forward-looking requirements and initial research work have been offered in this field. No any systematic reviews of communication/networking in Smart Grids have been conducted yet. Therefore, we conduct a systematic review of communication/networking technologies in Smart Grid in this paper, including communication/networking architecture, different communication technologies that would be employed into this architecture, quality of service (QoS), optimizing utilization of assets, control and management, etc.

How to transform mechanical work into electrical energy using a capacitor

In this paper the method of converting mechanical work into electrical energy with the participation of a preliminarily charged condenser while the electrodes are sliding in it is presented. Using this method, we can obtain a considerable increase of converted electrical power, depending on the initial energy of the charged condenser, distance between the electrodes and frequency of conversion. Exemplary time–voltage, time–current and instantaneous electrical power (for determined system work conditions) dependences are described in the paper. A recommended resistor resistance value is given to obtain the maximal system efficiency at the determined condenser capacity and assumed conversion frequency. The method can be used to convert renewable wind energy into electric energy in an ecologically pure manner.

Fundamental of an AC MHD Generation with Single-side Exciting Winding

This paper presents the possibility to generate the alternating current (AC) electrical power by using a linear MHD generator. The single-sided exciting winding of the generator is considered. Its structure consists of a channel, an insulator and stators. The channel type is a flat rectangular and the liquid flows along the channel as a conductor. The channel wall acted as an insulator separates the metal fluid and stator coil. The top stator winding of the generator is connected to polyphase systems. Under this condition, it can produce a magnetic field by means of time harmonics function in the same direction of the metal fluid. Energy in the channel is extracted by inductive coils at the bottom stator. An interaction between traveling wave and metal fluid is explained by finite element technique. The distributions of magnetic vector potential and magnetic field throughout channel are evidently shown in xy-plane. Power flow in an AC MHD generator is reported with magnetic Reynolds number and slip value. The optimized value of active power is suggested by small slip value as s < 0 and small magnetic Reynolds number.

Probabilistic life cycle analysis model for evaluating electric power infrastructure risk mitigation investments

One effect of climate change may be increased hurricane frequency or intensity due to changes in atmospheric and geoclimatic factors. It has been hypothesized that wetland restoration and infrastructure hardening measures may improve infrastructure resilience to increased hurricane frequency and intensity. This paper describes a parametric decision model used to assess the tradeoffs between wetland restoration and infrastructure hardening for electric power networks. We employ a hybrid economic input–output life-cycle analysis (EIO-LCA) model to capture: construction costs and life-cycle emissions for transitioning from the current electric power network configuration to a hardened network configuration; construction costs and life-cycle emissions associated with wetland restoration; and the intrinsic value of wetland restoration. Uncertainty is accounted for probabilistically through a Monte Carlo hurricane simulation model and parametric sensitivity analysis for the number of hurricanes expected to impact the project area during the project cycle and the rate of wetland storm surge attenuation. Our analysis robustly indicates that wetland restoration and undergrounding of electric power network infrastructure is not preferred to the “do-nothing” option of keeping all power lines overhead without wetland protection. However, we suggest a few items for future investigation. For example, our results suggest that, for the small case study developed, synergistic benefits of simultaneously hardening infrastructure and restoring wetlands may be limited, although research using a larger test bed while integrating additional costs may find an enhanced value of wetland restoration for disaster loss mitigation.

Permanent Magnet Type Eddy Current Heater Based on Cylindrical Halbach Array for Reducing Oil's Viscosity

The eddy current, Joule heat and input electrical power of a permanent magnet type eddy current heater based on cylindrical Halbach arrays to reduce the viscosity of crude oil in oil wells were analysed and studied by means of a three-dimensional finite-element method. The results show that when Halbach arrays generate a 0.9 T sinusoidal static field and the annulus conductor is copper, the Joule heat is about 575 W/m for a relative translational motion of 0.5 m/s in direction. The thermal efficiency of the heater is about 77.6%.

Basic Electronics: AC Transformers

Basic Electronics: AC Transformers