Electric arc furnaces are very often modeled using combined models which cover separately deterministic and stochastic phenomena taking place in the furnace. The deterministic…
Abstract
Purpose
Electric arc furnaces are very often modeled using combined models which cover separately deterministic and stochastic phenomena taking place in the furnace. The deterministic part is expressed by nonlinear differential equations. A closed form of the solution to one of the most popular nonlinear differential equations used for the AC electric arc modeling does not exist for some values of the parameters. The purpose of this paper is to convert electric arc furnace equation for these parameters to the quadratic polynomial form which significantly simplifies solution.
Design/methodology/approach
The solution has been obtained in the time domain by a sequence of transformations of the original nonlinear equation which lead to a system of quadratic equations, for which a periodic solution can be found easily using harmonic balance method (HBM).
Findings
Quadratic polynomial form of electric arc furnace nonlinear equation in the case for which the solution to the nonlinear differential equation describing electric arc cannot be obtained in a closed form.
Research limitations/implications
The complete model of the arc requires extension of the deterministic solution obtained for the quadratic polynomial form using stochastic or chaotic component.
Practical implications
The obtained results simplify determination of the arc voltage or radius time waveforms if a closed form solution does not exist. The arc model can be used to evaluate the impact of arc furnaces on power quality during the planning stage of new plants. The proposed approach facilitates calculation of the arc characteristic.
Originality/value
In order to avoid problems occurring when a large number of harmonics is required or the system contains strong nonlinearities, a transformation of the original equation has been proposed. Nonlinearities present in the equation have been transformed into purely quadratic polynomial terms. It facilitates application of the classical HBM and allows to follow periodic solutions of the arc equation when its parameters are varied. It also enables better understanding of the phenomenon described by the equation and makes easier the extension of the arc model in order to cover the time-varying character of the arc waveforms.
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Mahdi Rajabzadeh, Seyed Mohammad Taghi Bathaee and M. A. Golkar
This paper investigates the DC-Link voltage regulation of fuel cell electric vehicle (FCEV) with hybrid power source (HPS). The HPS consists of fuel cell (FC) as the main source…
Abstract
Purpose
This paper investigates the DC-Link voltage regulation of fuel cell electric vehicle (FCEV) with hybrid power source (HPS). The HPS consists of fuel cell (FC) as the main source and ultracapacitor (UC) as the auxiliary source in order to compensate for the slow dynamics of FC in transient conditions. The system is a multiconverter structure which is comprised of a boost DC/DC converter and a buck-boost converter connecting FC and UC to DC-link respectively.
Design/methodology/approach
The FCEV is modeled dynamically, considering the nonlinear behavior of HPS and multiconverter system. This paper presents an advanced control approach based on the control Lyapunov function (CLF) to regulate the DC-link voltage and impeccable tracking of UC current to its references. The stability analysis of closed loop system is also insured.
Findings
The performance of proposed controller is illustrated via Simulink® using numerical simulations under European Extra Urban Driving Cycle (EUDC). The simulation results show that the presented method is both satisfactory and consistent with expectation.
Originality/value
The proposed control method is state of the art in FCEV and improves the energy management system.
Dariusz Grabowski and Janusz Walczak
Electric arc furnaces are usually modelled using combined models which divide the phenomenon taking place in real objects into a deterministic and a stochastic or chaotic parts…
Abstract
Purpose
Electric arc furnaces are usually modelled using combined models which divide the phenomenon taking place in real objects into a deterministic and a stochastic or chaotic parts. The former is expressed by a nonlinear differential equation. The goal of this paper was to obtain a closed form of the solution to one of the most popular nonlinear differential equations used for the AC electric arc modelling.
Design/methodology/approach
The solution has been obtained in the time domain by a sequence of transformations of the original nonlinear equation which lead to a linear equation, for which a closed form solution is known.
Findings
The paper provides a set of parameters for which the solution to the nonlinear differential equation describing electric arc can be obtained in a closed form.
Research limitations/implications
There are still some parameter values for which the solution can be found only numerically. Moreover, due to the nature of the phenomena occurring in electric arc furnaces, in order to build a complete model of the arc the deterministic model must be extended using for example stochastic approach.
Practical implications
The obtained results enable determination of exact waveforms of the arc voltage or radius without application of numerical algorithms for ODE solving. The arc model can be used to evaluate the impact of arc furnaces on power quality during the planning stage of new plants. The proposed approach facilitates calculation of the arc characteristic.
Originality/value
The importance of having a closed form of the solution instead of the numerical ones comes from new possible ways of extension of the arc model in order to cover the time‐varying nature of the arc waveforms. So far the equation has been solved only using numerical algorithms.
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Kamel Sabahi, Amin Hajizadeh and Mehdi Tavan
In this paper, a novel Lyapunov–Krasovskii stable fuzzy proportional-integral-derivative (PID) (FPID) controller is introduced for load frequency control of a time-delayed…
Abstract
Purpose
In this paper, a novel Lyapunov–Krasovskii stable fuzzy proportional-integral-derivative (PID) (FPID) controller is introduced for load frequency control of a time-delayed micro-grid (MG) system that benefits from a fuel cell unit, wind turbine generator and plug-in electric vehicles.
Design/methodology/approach
Using the Lyapunov–Krasovskii theorem, the adaptation laws for the consequent parameters and output scaling factors of the FPID controller are developed in such a way that an upper limit (the maximum permissible value) for time delay is introduced for the stability of the closed-loop MG system. In this way, there is a stable FPID controller, the adaptive parameters of which are bounded. In the obtained adaptation laws and the way of stability analyses, there is no need to approximate the nonlinear model of the controlled system, which makes the implementation process of the proposed adaptive FPID controller much simpler.
Findings
It has been shown that for a different amount of time delay and intermittent resources/loads, the proposed adaptive FPID controller is able to enforce the frequency deviations to zero with better performance and a less amount of energy. In the proposed FPID controller, the increase in the amount of time delay leads to a small increase in the amount of overshoot/undershoot and settling time values, which indicate that the proposed controller is robust to the time delay changes.
Originality/value
Although the designed FPID controllers in the literature are very efficient in being applied to the uncertain and nonlinear systems, they suffer from stability problems. In this paper, the stability of the FPID controller has been examined in applying to the frequency control of a nonlinear input-delayed MG system. Based on the Lyapunov–Krasovskii theorem and using rigorous mathematical analyses, the stability conditions and the adaptation laws for the parameters of the FPID controller have been obtained in the presence of input delay and nonlinearities of the MG system.
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Carlo Rafele, Giulio Mangano, Anna Corinna Cagliano and Antonio Carlin
This paper aims to evaluate different logistics configuration to deliver batteries from the supplier to the production lines of a European carmaker who is implementing new…
Abstract
Purpose
This paper aims to evaluate different logistics configuration to deliver batteries from the supplier to the production lines of a European carmaker who is implementing new propulsions for its models.
Design/methodology/approach
Several scenarios about the supply chain for traction batteries have been identified based on the company’s requirements and constraints. Then, the variables used for the assessment of each scenario have been selected to calculate the unit battery supply chain cost.
Findings
The results underline that a direct transport without intermediate nodes is the cheapest one. On the contrary, an additional warehouse makes the organization of the network more complex. However, with this configuration, it is possible to cover the risk of supply since that a certain level of inventory is always guaranteed.
Research limitations/implications
This study is limited to the analysis of only one model car, and just manual operations have been taken into account for computing the human resource time and cost. The present study is one of the first works exploring the organization of the supply chain for the batteries integrated in electric and hybrid vehicles together with the choice of the location of the related warehouses.
Originality/value
This paper is one of the first work on the assessment of batteries’ supply chain that are going to be integrated in low impact vehicles, focusing on location of the associated warehouse. The evaluation is carried out by taking into account all the sources of cost.
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Viswanath Gajula and Rajathy R.
Electricity utilization at electricity peak hour may differ from every single administration region, for example, mechanical region, business territory and residential zone. This…
Abstract
Purpose
Electricity utilization at electricity peak hour may differ from every single administration region, for example, mechanical region, business territory and residential zone. This paper introduces a demand-side load management (DSM) strategy, which is one of the utilization of smart grid (SG) that is fit for controlling loads inside the residential working so that the client fulfillment is augmented at least expense.
Design/methodology/approach
In this paper, a heuristic algorithms-based energy management controller is intended for a residential region in a SG. Here, Antlion Optimization technique is used for DSM techniques such as load shifting, peak clipping, and valley filling in the residential sectors for 24 h with the help of stochastic function to determine the detection of random distribution of the load.
Findings
This proposed algorithm offered the greatest fulfillment and least expense caused by the consumers when compared to the traditional cost by taking the individual consumer preferences for the loads and the ideal time scheduling for the load, which is obtained from the rebuilding trap.
Originality/value
Simulation results demonstrate that the comparison of the cost incurred by the users obtained by the DSM techniques is satisfiable.
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Farhad Khosrojerdi, Okhaide Akhigbe, Stéphane Gagnon, Alex Ramirez and Gregory Richards
The purpose of this study is to explore the latest approaches in integrating artificial intelligence and analytics (AIA) in energy smart grid projects. Empirical results are…
Abstract
Purpose
The purpose of this study is to explore the latest approaches in integrating artificial intelligence and analytics (AIA) in energy smart grid projects. Empirical results are synthesized to highlight their relevance from a technology and project management standpoint, identifying several lessons learned that can be used for planning highly integrated and automated smart grid projects.
Design/methodology/approach
A systematic literature review leads to selecting 108 research articles dealing with smart grids and AIA applications. Keywords are based on the following research questions: What is the growth trend in Smart Grid projects using intelligent systems and data analytics? What business value is offered when AI-based methods are applied? How do applications of intelligent systems combine with data analytics? What lessons can be learned for Smart Grid and AIA projects?
Findings
The 108 selected articles are classified according to the following four research issues in smart grids project management: AIA integrated applications; AI-focused technologies; analytics-focused technologies; architecture and design methods. A broad set of smart grid functionality is reviewed, seeking to find commonality among several applications, including as follows: dynamic energy management; automation of extract, transform and load for Supervisory Control And Data Acquisition (SCADA) systems data; multi-level representations of data; the relationship between the standard three-phase transforms and modern data analytics; real-time or short-time voltage stability assessment; smart city architecture; home energy management system; building energy consumption; automated fault and disturbance analysis; and power quality control.
Originality/value
Given the diversity of issues reviewed, a more capability-focused research agenda is needed to further synthesize empirical findings for AI-based smart grids. Research may converge toward more focus on business rules systems, that may best support smart grid design, proof development, governance and effectiveness. These AIA technologies must be further integrated with smart grid project management methodologies and enable a greater diversity of renewable and non-renewable production sources.
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The purpose of this study is to examine the changing political orientation of Air Tiris, Kampar, Riau community towards Islamic political parties in general elections; to analyze…
Abstract
Purpose
The purpose of this study is to examine the changing political orientation of Air Tiris, Kampar, Riau community towards Islamic political parties in general elections; to analyze the factors that influenced the political orientation of Air Tiris community in general elections; and to realize the political rights of the society including Air Tiris community.
Design/methodology/approach
The subject in this study is the political orientation of the Air Tiris community in the 1999, 2004, 2009 and 2014 general elections with a period of research from 2009 to 2016. This qualitative research method consists of sources, data collection, informants, data collection techniques, data analysis and processing and writing systematics.
Findings
The results of the research indicate that there are three dominant factors affecting the change in the political orientation of the Air Tiris community towards Islamic political parties characterized by the deterioration of vote acquisition for Islamic political parties in Air Tiris village in 1999, 2004, 2009 and 2014 general elections. The weakening of the link between religious identity and voting behaviour, as well as the weakening of political movement. The identification or loyalty of the santri community towards Islamic parties has faded.
Originality/value
The originality of this research lies in the analysis of the political orientation of Air Tiris, Kampar, Riau community, in general, elections towards Islamic political parties. Traditionally, this community has more political orientation on religious/Islamic political parties but such orientation experiences developments and changes that lead to non-Islamic parties. This research contains new information about the analysis of the political orientation of Air Tiris, Kampar, Riau community in the general election of Islamic political parties.
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Comprehensive basis to measure civil servants’ neutrality in the effectuation of concurrent regional head elections, valid basis to determine the most appropriate strategy to…
Abstract
Purpose
Comprehensive basis to measure civil servants’ neutrality in the effectuation of concurrent regional head elections, valid basis to determine the most appropriate strategy to enhance civil servants’ neutrality in the governance.
Design/methodology/approach
This research is a normative or doctrinal research. Secondary data are retrieved from the literature in the forms of legal documents and regulations concerning civil servants’ role in general elections. In this research, two products of law were analyzed as follows: first, the one related to the urgency of civil servants’ neutrality in regional head election and second, the one related to the synchronization of legal norms about civil servants’ neutrality during regional head elections. Data analysis was done using a juridical qualitative analysis model.
Findings
The urgency of neutrality is real in the implementation of concurrent regional head elections due to 3 reasons as follows: Historically, state civil apparatus neutrality and regulations. There is a synchronization of the neutrality of the civil state apparatus in the legislation concerning civil state apparatus with the laws and regulations concerning the implementation of concurrent regional head elections including the following: Act Number 5 of 2014, Act Number 10 of 2016 and Act Number 8 of 2012.
Originality/value
The study investigated the neutrality of civil servants during the concurrent regional head election in Indonesia. The objectives of this research were investigating, comprehending and analyzing the urgency of civil servants’ neutrality in regional head election, and describing and analyzing the synchronization of civil servants’ neutrality based on the laws related to civil servants and laws related to the effectuation of concurrent regional head election.
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Bahareh Golkar, Siew Hoon Lim and Fecri Karanki
A major source of external funding for US airports comes from issuing municipal bonds. Credit rating agencies evaluate the bonds using multiple factors, but the judgments behind…
Abstract
Purpose
A major source of external funding for US airports comes from issuing municipal bonds. Credit rating agencies evaluate the bonds using multiple factors, but the judgments behind the ratings are not well understood. This paper examines if airport rate-setting methods affect the bond ratings of US airports.
Design/methodology/approach
Using a set of unbalanced panel data for 58 hub airports from 2010 to 2019, we examine the effect of the rate-setting methods and other airport characteristics on Fitch’s airport bond rating.
Findings
We find that compensatory airports consistently receive a very high bond rating from Fitch. The probability of getting a very high Fitch rating increases by ∼28 percentage points for a compensatory airport. Additionally, the probability of getting a very high rating is about 33 percentage points higher for a legacy hub.
Research limitations/implications
The study uses Fitch bond ratings. Future studies could examine if S&P’s and Moody’s ratings are also influenced by airport rate-setting methods and legacy hub status.
Practical implications
The results uncover the linkage between bond ratings and their determinants for US airports. This information is important for investors when assessing airport creditworthiness and for airport operators as they manage capital project financing.
Originality/value
This is the first study to evaluate the effects of rate-setting methods on airport bond rating and also the first to document a statistically significant relationship between airports’ legacy hub status and bond ratings.