Basic Power Research Articles

Toward a spirituality mode of firm sustainability strategic planning processes

PurposeThis paper aims to develop a spirituality mode of firm strategic planning processes that incorporate four basic firm spirituality elements, namely, transcendence, an inexhaustible source of will, a basic and supreme power and interconnectedness and oneness, used for promoting corporate and community sustainability.Design/methodology/approachA conceptual analysis was performed.FindingsDrawing upon prior research, this paper suggests that there are four major spiritual elements of the firm, namely, transcendence, an inexhaustible source of will, a basic and supreme power and interconnectedness and oneness. Additionally, this paper proposes that to promote long-term sustainability and survival of the firm and community, firms can place strong emphasis on firm transcendence when establishing the vision and mission statements. Moreover, firms may need to assess environmental conditions based upon an inexhaustible source of will. Furthermore, when formulating and selecting strategic alternatives, firms can utilize a basic and supreme power. Finally, firms may implement selected strategic alternatives and strategic controls with interconnectedness and oneness mentality.Originality/valueThis paper is one of the first studies that develop a spirituality mode of strategic planning processes focusing on both corporate and community sustainability.

A multiphysics fully coupled modeling tool for the design and operation analysis of planar solid oxide fuel cell stacks

A planar SOFC stack is an integral but basic power generation unit with physical conditions completely different from that of a laboratory button cell. The ability to reliably predict the operating behaviors of SOFC stacks is crucial for the technology advancement. The existing stack models either rely on simplified geometries, or handle a few selected fields that are relatively easy to couple. This paper reports the first successful development of a high geometry resolution, multiphysics fully coupled numerical model for production scale planar SOFC stacks. The computational model is developed through in-house developed multiphysics modules combined with commercial software FLUENT®. All stack components such as flow channels, manifolds, cathode-electrolyte-anode assemblies, interconnects, seals and frames are resolved in the numerical grids. The mathematical model includes the fully coupled equations of momentum, mass, species, heat and charge transports, electrochemical reaction, and methane steam reforming and shift reactions. An accurate relationship between the O2 transport and electrochemistry within the cathode-rib structure is established and used to enhance the numerical efficiency of the stack model. The stack model is validated with the experimental data. The numerical stability and modeling capability of this multiphysics stack model are illustrated by simulating a 30-cell stack of 27 million grid points. Detailed information about the distributions of flows, temperature, current and chemical species, etc, is revealed. Comparative studies show that the results obtained by simplifications of stack geometries or reductions of multiphysics couplings are unreliable, illustrating the necessity of employing a true multiphysics computational tool.

Comparison of Static Phase Shifter and Unified Power Flow Controller-Based Interphase

The basic interphase power controller (IPC) presents the interesting features of simplicity and low cost but is less flexible than most flexible ac transmission system controllers. A compromise performance can be achieved by replacing the phase shifting transformers with a reduced rating dual unified power flow controller (UPFC) resulting in a unified IPC. The comparison of the basic, phase shifter-based, with a new UPFC-based, control logic is the main goal of this paper. The control variables of the dual UPFC are computed based on an optimization procedure to minimize a given cost function. The results show the higher capability of the proposed logic not only to control the current flow through the transmission line but also to achieve this task with lower branch currents that should lead to reduced power losses.

Feasibility Study of Standalone PV-Wind-Diesel Energy Systems for Coastal Residential Application in Pekan, Pahang

Techno economic study is feasible to optimize the usage of renewable energy components that targeting low cost of electricity generation system. The selected case study area is coastal area in Pekan, Pahang, Malaysia. The autonomous system designed in this study is hybrid standalone PV-wind-diesel energy system to fulfil a basic power demand of 20.1 kWh/day. Such power system was designed and optimized further to meet the power demand at a minimum cost of energy using energy optimization software, Hybrid Optimization Model for Electric Renewables (HOMER). The analysis focused on the operational characteristics and economics. The standalone PV-wind-diesel energy system has total net present cost about $61, 911 with cost of energy $0.66/kWh. Apparently, the generation of electricity from both wind turbine and PV can be inflated with the diesel generator. In comparison, return of investment (ROI) value turned out lower for Feed in Tariff (FIT) as compared to self-sustained house. Payback period also longer for FIT program that makes the selling back of electricity generated to Tenaga National Berhad (TNB) is considered not favourable.

Улучшение экологических показателей автомобилей воздействием магнитных полей на топливовоздушную смесь

Method for improving the environmental safety of vehicles equipped with gasoline engines is proposed. The method consists in simultaneous action of permanent magnetic fluxes with various polarities on fuel and air of basic power systems. The technique and results of experimental and theoretical studies on effect of magnetic fields on process of mixing and combustion of a fuel-air mixture in internal combustion engines are presented. Permanent magnets of different shapes and strengths were installed in various versions on the vehicle with the carburetor gasoline engine which was not equipped with exhaust gas neutralization system to create magnetic fluxes of a given configuration and intensity. The most unfavorable for toxicity modes of idling, minimum rotation speed and increased speed of crankshaft rotation were considered. Temperature and composition of exhaust gases were studied. Result of the experimental studies was reduction of such toxic components as carbon monoxide by 16–40 %, hydrocarbons by 2–20 %, nitrogen oxides by 1,25–35 % for the minimum rotating speed and reduction of CO by 0,2–20 %, CH by 12–40 % NO x by 10–14,9 % for increased rotating speed. Also dependences describing influence of magnetic fluxes on toxic components of the exhaust gases were obtained. The proposed method for improvement of ecological safety of the vehicles equipped with gasoline internal combustion engines is one of the simplest and cheapest among the previously known.

Design of Power and Load Reduction Controller for a Medium-Capacity Wind Turbine

A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

The emergy of metabolism in different ecosystems under the same environmental conditions in the agro-pastoral ecotone of northern China

The sustainability of ecosystem productivity and rules governing ecosystem development are important topics of scientific research. The emergy approach is an effective method for investigating these topics, especially when used to evaluate systems that have developed under the same environmental conditions, such as climate and soil. In this paper, emergy differences between terrestrial ecosystems were studied in Guyuan County, a region representative of the agro-pastoral ecotone in Hebei Province, China. A combination of field tests and a questionnaire survey were carried out between June and August 2015. The ecosystems studied included natural grassland, artificial grassland, field crops and commercial crops. These four ecosystems were further subdivided into a total of ten ecosystems. Natural grassland was divided into free-grazing and mowed ecosystems; artificial grassland consisted of oat, Chinese leymus and corn silage; field crops included naked oats, flax and wheat; and commercial crops consisted of cabbage and potatoes. The results showed that the rain input of 4.78×1014seJ/ha/yr constituted the highest renewable natural resource emergy and that the purchased emergy inputs of the ten ecosystems ranged from 3.53 to 147.67×1014seJ/ha/yr. Natural resource emergy input was the basic power to maintain the ecosystem, and purchased emergy input was the direct cause of the development of the ecosystems. Groundwater was the most important non-renewable purchased energy for the production of economic crops. The emergy investment ratios (EIR) for potatoes (27.81) and cabbage (19.03) were higher than those of the other ecosystems, but mowed and artificial Chinese leymus grassland had the higher emergy self-sufficiency rates (ESR). Natural grassland, artificial Chinese leymus grassland and traditional grain crops had a low environmental load and high sustainability, whereas potatoes and cabbage had a high environmental load and low sustainability. Overall, rain-fed artificial grassland has a high development potential from the perspective of environment and productivity.

Dynamics and Collapse in a Power System Model with Voltage Variation: The Damping Effect.

Complex nonlinear phenomena are investigated in a basic power system model of the single-machine-infinite-bus (SMIB) with a synchronous generator modeled by a classical third-order differential equation including both angle dynamics and voltage dynamics, the so-called flux decay equation. In contrast, for the second-order differential equation considering the angle dynamics only, it is the classical swing equation. Similarities and differences of the dynamics generated between the third-order model and the second-order one are studied. We mainly find that, for positive damping, these two models show quite similar behavior, namely, stable fixed point, stable limit cycle, and their coexistence for different parameters. However, for negative damping, the second-order system can only collapse, whereas for the third-order model, more complicated behavior may happen, such as stable fixed point, limit cycle, quasi-periodicity, and chaos. Interesting partial collapse phenomena for angle instability only and not for voltage instability are also found here, including collapse from quasi-periodicity and from chaos etc. These findings not only provide a basic physical picture for power system dynamics in the third-order model incorporating voltage dynamics, but also enable us a deeper understanding of the complex dynamical behavior and even leading to a design of oscillation damping in electric power systems.

Simulation Study of Single-Event Burnout in Power Trench ACCUFETs

This paper presents 2-D numerical simulation results of single-event burnout (SEB) in power trench accumulation mode field effect transistor (ACCUFET) for the first time. In this device, a p+ base region is used to deplete the n− base region to achieve a low leakage current density, and the blocking voltage is supported by the n− drift region. We find that the depth of the p+ base region determines both the leakage current density and SEB performance, as a result, there is a tradeoff relationship between the two characteristics. The 60 V hardened power ACCUFET shown in this paper could demonstrate much better SEB performance without sacrificing the current handling capability compared with the standard UMOSFET. The hardened structure mentioned in this paper indicates that an n buffer layer is added between the epitaxial layer and substrate layer based on a basic power device. As a result, the safe operating area (SOA) of the 60 V, 80 V and 100 V hardened ACCUFET discussed in this paper could reach the value of breakdown voltage when the buffer layer is over a certain value, that can realize safety operation throughout entire LET range.

A SiC-Based High Power Density Single-Phase Inverter With In-Series and In-Parallel Power Decoupling Method

This paper presents an in-series and in-parallel combination power decoupling method for the single-phase inverter. With basic power equation derivation, the proposed method is analyzed and compared with other methods in theory. The operating principles and the control strategy are introduced. The circuit parameters based on silicon carbide device are designed in detail, and the power losses are evaluated for the circuit. To verify the theoretical analysis, a PLECS simulation model is built. Based on the simulation results, both the proposed method and the in-series method can achieve a more than 89% reduction of the dc-link capacitance compared with the traditional inverter. Furthermore, the proposed method is superior to the in-series method, with a more than 68% reduction of the extra circuit’s capacitance. Finally, a 2-kW prototype with a size of $7.25 \,\, \times \,\, 3.6 \,\, \times \,\, 1.4$ in3 and a power density of $\sim 55$ W/in3 is developed. Compared with the in-series method, the extra capacitance can be reduced by about 64% for the proposed power decoupling method. The experimental results are almost consistent with the simulation results. The efficiency for the proposed method is higher than 95%.

Location, Industry Competition and Profitability

<p>The construction of one or more plants in optimum sites and in the best possible situation, not only improves materials circulation and customer services, but also puts the company in a desirable situation. Decisions associated with the selection and acquisition of features of a center’s site selection can have a great impact on the ability to gain and maintain competitive advantages. This study tests the impact of distance from population centers on the profitability for the first time. The sample which has been used in the food products industry, includes 21 firms listed in Tehran Stock Exchange during 2009 to 2014, and panel data regression methods were used to process and test the hypotheses. The results showed that product market competition enhances the negative impact of corporate distance from Tehran and big cities on the basic earnings power (earnings before tax). However, the relative power of the firm in a competitive environment weakens the negative impact of corporate distance from Tehran and big cities on the basic earnings power (earnings before tax).</p>

A Modular Electrical Power System Architecture for Small Spacecraft

An electrical power system for low-Earth-orbit satellites, which can be reused for a variety of mission requirements with minimal redesign, is proposed. The goals of the proposed power system are achieved by modularizing the subsystems of a small spacecraft and designing them to allow any number of each module to be connected simultaneously. The modularized subsystems include solar energy generation and energy storage. The overall objectives will be accomplished without compromising efficiency or power system stability. The purpose of this paper is to describe the proposed power system and detail the experimental results. The generalized system can be used as a one-size-fits-all solution that only requires basic power systems knowledge to configure and operate.

Iterative DC Optimal Power Flow Considering Transmission Network Loss

In today's electricity market, DC optimal power flow and AC optimal power flow have become the main models to simulate generation dispatch and calculate locational marginal price. Although DC optimal power flow has the advantage of robustness, its result is not accurate compared to AC optimal power flow due to the neglect of transmission network loss. In this article, an iterative DC optimal power flow model with explicit consideration of accurate AC network loss is proposed. A general Newton–Raphson method is applied in this method to calculate AC transmission network loss, and iteration is used to minimize the error of calculated loss. The fictitious bus load is utilized to represent the loss, which is divided equally on each line. The proposed model is compared with basic DC optimal power flow and AC optimal power flow models on the calculation of locational marginal prices using PJM 5-bus and IEEE 30-bus systems at various load levels. The results show that the proposed model obtains better approximation of AC optimal power flow model on the simulation of generation dispatch and calculation of locational marginal prices.

Study of Power Steel Corrosion During Coal Gasification1

Results are considered for a study of basic power steel corrosion rate in a producer gas atmosphere and a method is proposed for its calculation under industrial conditions.

Solving the Equity Risk Premium Puzzle and Inching Towards a Theory of Everything -- Visual Version

The equity risk premium puzzle is that the return on equities has far exceeded the average return on short-term risk-free debt and cannot be explained by conventional representative-agent consumption based equilibrium models. We review a few attempts done over the years to explain this anomaly:1. Inclusion of highly unlikely events with low probability (Ugly state along with Good and Bad), or market crashes, recently also termed as Black Swans.2. Slow moving habit, or time-varying subsistence level, added to the basic power utility function.3. Allowing for a separation of the inter-temporal elasticity of substitution and risk aversion, combined with consumption and dividend growth rates modeled as containing a small persistent expected growth rate component and a fluctuating volatility which captures time varying economic uncertainty.We explore whether a fusion of the above approaches supplemented with better methods to handle the below reservations would provide a more realistic and yet tractable framework to tackle the various conundrums in the social sciences:1. Unlimited ability of individuals to invest as compared to their ability to consume.2. Lack of an objective measuring stick of value which gives rise to heterogeneous preferences and beliefs.3. Unintended consequences due to the dynamic nature of social systems, where changes can be observed and decisions effected by participants to influence the system.4. Relaxation of the transversality condition to avoid the formation of asset price bubbles.5. How durable is durable? Since nothing lasts forever, accounting for durable goods to create a comprehensive measure of consumption volatility .The world we live in produces fascinating phenomenon despite (or perhaps, due to) being a hotchpotch of varying doses of the above elements. The rationale for a unified theory is that beauty can emerge from chaos since the best test for a stew is its taste.

Basic trigonometric power sums with applications

We present the transformation of several sums of positive integer powers of the sine and cosine into non-trigonometric combinatorial forms. The results are applied to the derivation of generating functions and to the number of the closed walks on a path and in a cycle.

Experiment on Bidirectional Single Phase Converter Applying Model Predictive Current Controller

A bidirectional converter able to manage storage is a basic power electronics device, and it is a major component of renewable energy sources, micro grid and also the smart grid concept. In this paper, single-phase bidirectional converter topology is discussed. The state space model has been derived, and a simple model based predictive current controller has been utilized to control the inverter. Control block diagrams have been designed with MATLAB and simulation results are presented and compared with experimental ones, giving credibility to the derived model and the designed control method.

Control scheme for grid‐tied distributed generation inverter under unbalanced and distorted utility conditions with power quality ancillary services

This study proposes a control scheme with a new fundamental sequence components extractor for grid interfaced distributed generation inverter under polluted grid conditions. The proposed sequence extractor is realised using third-order sinusoidal signal integrator-based frequency adaptive filters. It has an excellent ability to decompose the three-phase voltage and current signals into positive and negative sequence components under distorted grid scenario. The proposed control scheme is immune to frequency variations and is capable of providing power quality ancillary services such as reactive power compensation and harmonics rejection in addition to basic power injection. The performance of the proposed system under various grid disturbances and loading conditions is evaluated through simulation and experimental studies.

A review of cryogenic power generation cycles with liquefied natural gas cold energy utilization

Liquefied natural gas (LNG), an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG cold energy are introduced and summarized. The direction of cycle improvement can be divided into the key factors affecting basic power generation cycles and the structural enhancement of cycles utilizing LNG cold energy. The former includes the effects of LNG-side parameters, working fluids, and inlet and outlet thermodynamic parameters of equipment, while the latter is based on Rankine cycle, Brayton cycle, Kalina cycle and their compound cycles. In the present paper, the diversities of cryogenic power generation cycles utilizing LNG cold energy are discussed and analyzed. It is pointed out that further researches should focus on the selection and component matching of organic mixed working fluids and the combination of process simulation and experimental investigation, etc.

An adaptive control algorithm for grid-interfacing inverters in renewable energy based distributed generation systems

This paper proposes an adaptive control algorithm for grid-interfacing inverters in renewable energy-based distributed generation systems. The proposed control algorithm functions in two different modes: basic power generation mode, harmonics compensation mode. In basic power generation mode, the inverter pumps desired amounts of active and reactive powers into the grid at the point of common coupling. In harmonics compensation mode, the control algorithm ensures sinusoidal grid current through load current harmonics mitigation in addition to desired power generation. Moreover, the proposed control algorithm does not use any detection methods for compensation of harmonic currents. Hence, it results in low computational burden. Based on the requirements, the proposed control algorithm can be operated in either of the modes. A proportional–integral controller-based closed loop control is employed for accurate control of the power injected into the grid. A frequency adaptive notch filter is used to synchronize the grid-interfacing inverter with the fundamental component of grid voltage without using any phase locked loop. The effectiveness of the proposed control algorithm in reference active and reactive powers generation, current harmonics compensation is demonstrated successfully by simulation and experimental results.