Analysis of a complex multi-path manufacturing system requires a simulation model. After model construction, it requires unique equipment inputs. Inputs consist of equipment cycle time (ECT), mean time before failure (MTBF), mean time to repair (MTTR). These inputs should be distributions that incorporate the randomness of the system. Typically simulation models are developed based on some underlying assumptions and inputs from past system performance indexes. This research proposes a new method of transforming a current simulation model to reflect actual system behaviour at various time-periods accurately. Key model system inputs were incorporated into a design of experiment (DOE) to extract levels that reflected system behaviour on particular dates. Comparing model input vs. actual manufacturing system performance confirmed simulation model validation.
This paper deals with the simplest Takagi-Sugeno fuzzy two-term controllers. The analytical structures of the simplest fuzzy controllers were developed using a modified rule base. The number of tuning parameters of the controllers is reduced by introducing a novel rule base consisting of two rules. These controllers are termed as 'the simplest' since minimal (two) number of fuzzy sets is used for fuzzification. Algebraic product (AP)/minimum (min) triangular norm, bounded sum (BS)/maximum (max) triangular co-norm, different universes of discourses (UoDs) of inputs, and centre of gravity (CoG) defuzzification method are chosen to derive the mathematical models of the fuzzy controllers. The simplest fuzzy controller with modified rule base is equivalent to a (nonlinear) variable gain/structure PI/PD controller. The BIBO stability of the closed loop control system is investigated using the small gain theorem. The gain of the controller either varies or remains constant in different regions of the input plane. The gain variations and the computational burden of the fuzzy controllers are also studied. Two examples of nonlinear dynamical systems are considered to validate the developed models of the fuzzy controllers.
In today's competitive electricity market, managing transmission congestion is a major challenging issue due to operational constraints. Flexible AC transmission system (FACTS) device can be a choice to control the power flow in the congested transmission lines. This paper explores the use of thyristor controlled series compensator (TCSC) for power flow control in congested network using firefly algorithm (FA). The optimal location of TCSC is identified based on real power performance index and reduction of total system reactive power loss methods. Further in the congestion management (CM) problem, single line outage analysis is also performed. FA is used to determine the minimum total cost which includes production cost and TCSC cost. Results of five bus, IEEE 14 and IEEE 30 bus test systems indicate that FA provides minimum cost compared to the previous literature. The efficiency of the proposed FA for obtaining the high quality solution is also established.
The population algorithms have number of advantages over classical methods for solving complex optimization problems such as tuning of controller parameters of motor drives. These algorithms for solving various problems of global optimization is often called as methods inspired by nature, methods in this class are based on the modeling of intelligent behavior of organized members of the population. Particle swarm optimization (PSO) algorithm is a population-based algorithm which has the ability to fine-tune the controller parameters. In this paper, the constriction factor, chaotic inertia weight and exponential inertia weight based PSO algorithms are proposed for tuning of proportional-integral-derivative (PID) controller parameters to control brushless direct current (BLDC) motor drive. The BLDC is modeled in MATLAB/SIMULINK. Simulation results of PSO algorithms with inertia weight strategies are compared.
The occurrence of contingencies in the power system may cause deviation from its ideal operating condition, which initiates the security assessment for efficient operation of the power system. This paper has two objectives. First, to identify and classify the power system states that provides a consistent security analysis. Second, to evaluate each curative action based on the degree of the violation of security constraint for an effective and secure power system. Therefore, a new methodology for operation state classification using the fuzzy logic technique is proposed to achieve these objectives. Moreover, two fuzzy logic controllers are developed. The first one (FLC 1) classifies the operating states of the power system in one of four categories: normal (N), alert (A), emergency (E1) and extreme (E2). The second (FLC 2) specifies the appropriate action to avoid the transition to an extreme state. The simulation program, under MATLAB environment, was applied to evaluate the classification algorithm performances developed using the fuzzy logic technique.
In recent times, focus has been on developing fast and efficient processes that are environment friendly. The spotlight has been turned on 'friction stir welding' as a joining technology, capable of providing welds that do not have defects normally associated with fusion welding processes. From the available literature, it has been observed that the effect of welding parameters on desired characteristics was determined by taking into consideration one parameter at a time or by using conventional methods. So without ignoring the limitations of earlier researches, the main focus in this study has been kept on welding of dissimilar aluminium alloys (AA6061 and AA5086) by using design of experiments which is quite rarely used multi-factor at a time technique. Tensile strength and hardness were identified as key mechanical properties and were optimised upto 0.156 KN/mm2 and 73.19 HVN respectively. The fractional factorial design has been used to achieve required optimisation by using software 'Minitab-16'.
This paper highlights the case study of redesigning the mixed model assembly line. Discrete event simulation approach is used to give the effective solution to the problem. The aim of this paper is to redesign the assembly line and use of simulation environment in the production line, modular fixture design, optimisation of work assignment and further computer simulation for the determination of the optimal solution like production rate of the existing and then redesigned system by reducing the takt time of the line. A welding machines manufacturing company has a mixed model assembly line. Different models of the machine are assembled on the assembly line. In this paper, the Maynard operation sequence technique (MOST) work study is carried out to analyse and minimise the NVA activities. Further, WITNESS and ARENA simulation carried out to study the bottleneck operations and optimisation of work assignment to increase the production rate with less NVA activities. The results of the combination of the line balancing by changing the work assignment, redesigning the line and further process simulation raises the production rate of the process up to 20%.
In the present experimental study, condensation of steam inside helically coiled tubes was investigated. Three helical coils of coil diameter 110, 135 and 160 mm were tested. The effect of mass flux, coil curvature ratio and temperature difference between steam and tube inner wall on the condensation heat transfer coefficient were analysed. The condensation heat transfer coefficient increases with the increase in the value of mass flux. Temperature difference has substantial effect on the heat transfer coefficient. For the first time, the effect of coil curvature ratio on condensation heat transfer is studied and discussed in the paper. It is found that helical coil having greater coil curvature ratio has high values of condensation heat transfer coefficient in comparison to a low curvature ratio. Experimental results are compared with the work of earlier investigators. A new empirical correlation is developed to predict the condensation heat transfer coefficient.
In process industries model-plant mismatch is a significant problem. Quadruple tank process (QTP) can be configured both in minimum phase and non-minimum phase (NMP). However, in NMP, the control of QTP poses a challenge. This paper addresses that and presents a novel robust wavelet based non-minimum phase control (NMPC) strategy for the challenging QTP using genetic algorithm to find the optimised value of the manipulated variables in NMPC at every sampling time. The QTP is modelled based on wavelet neural network. The simulation results indicate that significant improvements have been achieved both in modelling and control strategies for a QTP system compare to conventional approaches such as the Levenberg-Marquardt.
This paper presents a supervisory controller for DC microgrid consists of a solar photovoltaic (PV) system, fuel cell, a supercapacitor and battery bank. The DC microgrid is proposed for more efficient resilient electricity distribution in a commercial building. The operation strategy of energy storage systems (ESS) is proposed to solve the power changes from PV array and building loads fluctuations locally, instead of reflecting those disturbances into the utility grid. Furthermore, the ESS energy management scheme will help to achieve the peak reduction of the building daily electrical load demand. The DC microgrid studied in this paper is interfaced with the battery bank by using a bidirectional DC-DC converter, whilst the building electrical AC load is interfaced to grid using DC-AC inverter. The control of the studied microgrid is designed as a method to improve microgrid resilience and incorporate renewable power generation and storage into the grid.
This paper proposes a grid connected AC/DC microgrid to reduce the processes of multiple conversions in an individual AC or DC microgrid. The hybrid grid consists of both AC and DC networks connected by a bidirectional AC/DC converter. Wind generator, AC loads and utility are connected to the AC bus whereas PV, energy storage system (ESS) and DC loads are tied to the DC bus. The coordination control algorithms of supervisor controller are proposed for smooth power management between AC and DC links and for stable system operation under various generation and load conditions. In this paper, a flexible supervisor controller is developed for a grid connected AC/DC microgrid, where the power flow in the microgrid is supervised based on demanded power with maximum utilisation of renewable resources and ESS. So, the objective of this paper is to use supervisory controller to control the transferred power from AC bus to DC bus and vice versa and control the charging/discharging power of the ESS to reduce the purchased power from the grid or to increase the sold power to the grid with respect to the load demand. The microgrid has been modelled and simulated using MATLAB Simulink. The simulation results show that the system can maintain stable under load variations.
In this work, the structural, mechanical and electrical properties of YSZ-NiO anode ceramics before and after reduction in pure H2 and Ar-5 vol.%H2 mixture were studied. The NiO to Ni phase transformations that occur in the anode under reducing and reduction-oxidation (redox) cycling conditions and the impact on anode microstructure, strength and electrical conductivity have been examined. The results show that the redox treatment of the YSZ−NiO ceramic specimens influences on their properties controversially. At the treatment temperature 600° a structure providing improved physical and mechanical properties of the material is formed. However, at the treatment temperature 800° an anode structure with an array of microcracks is formed that significantly reduces the strength and electrical conductivity of the material. The results of this investigation show that reduction condition of YSZ-NiO is a powerful tool for influence on properties of the anode substrate.
Interconnection of EVs could impact adversely the power system operation including power quality and safety of the power grid since the present electric power distribution network may not be designed to support the expected proliferation of EV along with other nonlinear loads and resources that are expected to occur in the future. Numerous studies on the effects of charging EVs using the existing local distribution grid has been reported in the literature, but most works on EVs impact on the distribution network are focused on the fundamental current and voltage waveforms (i.e., 60 Hz) to derive the associated impacts to the electric grid delivery system. In this paper we present our initial work that broadens the above analysis to include current harmonic distortion (iTHD) and the associated voltage harmonic distortion (vTHD) injected into the grid from EV battery charger.
Research and development centres, as an initial chain of industrial sectors, are amongst large energy consumers worldwide. Thus, implementing energy management system(s) in such centres would be beneficiary to both economy and livelihood of environment. Additionally, harbouring renewable energy sources play a key and strategic role in policies circumventing both energy production/consumption and environment. Accordingly, design of a unique and comprehensive management system, with the focus on research institutes and organisations, for both energy efficiency improvement and renewable energy production seems to be inevitable. Here and for the first time, designing of an energy management system for such Iranian organisations has been proposed. The evaluation method of our proposed management system was classified in three phases with two approaches: internal and external evaluation. This method allows compare different organisations with each other.
The Reforming the Energy Vision (REV) program of the New York State (NYS) outlines a strategy to reach the goal of having 50% of the electric power by renewable energy resources by the year 2030. Now realising that this date is not that far away, it seemed appropriate that an interim evaluation of the progress that has been made should be done based on the available information. The review provides a clear picture of the advancement of inverter-based PV generation in the state of New York, how the state might use inverter-based solar to power residences, and the interconnection of microgrids. In this paper we present a summary of the findings that include lists of possible challenges in areas of the program. Our review indicates that a number of distributed generation resources is growing. But a lot more work needs to be done to include new technologies to reach the goal of non-carbon-based electric power system that would be able to meet the future electrical energy needs of the New York State safely and efficiently.
This paper examines the energy consumption of the electric drives and permanent magnet machines considering the actual system performance of machine and variable speed drive. Most common solution in the current trend of elevator technology is permanent magnet synchronous motor with variable frequency drive with direct current voltage bus intermediate. Energy consumption has been understand with actual measurements and examine the behavior to understand the load on the system that would be higher efficient.
The smart grid allows its consumers to participate in producing cost effective, sustainable, and environmentally friendly electricity. The consumers in a smart grid, for example, can plug their Electric Vehicles (EVs) into the grid to charge and discharge their vehicles' batteries. However, charging of the electric vehicles, especially during the peak periods, can adversely impact the grid performance. Thus, in this paper, the coordinated charging of the electric vehicles problem is tackled. A fuzzy logic-based approach is developed to coordinate the electric vehicle charging such that the system minimum voltage is within the allowable limits. The inputs to the Fuzzy Charging Controller (FCC) include the States of Charge (SOC) of the electric vehicles, the grid parameters represented in the system minimum voltage, and the hourly energy price. The output of the FCC is the charging levels of the electric vehicles' batteries. The developed fuzzy logic-based charging strategy was validated on the 69-bus test system. The Fuzzy Charging (FC) was compared with three modes of uncoordinated charging, namely Slow Charging (SC), Medium Charging (MC), and Fast Charging (FC). The results of the comparative study prove the superiority of the developed fuzzy charging approach over uncoordinated charging schemes.
Thermoplastics are converted to hydrocarbon fuels in a chemical reaction called pyrolysis. The work highlights the energy consumption using Aspen HYSYSV8.8 simulations in each process stage starting with granulation, preheating, pyrolysis reactor and condensation as major process steps concluding that the highest required heat duty which is around 61% in the pyrolysis reactor thus having the highest operating cost. Aspen HYSYS is used to calculate energy consumption in each stage. The design is 10 tonne/hour of thermoplastic mixture. Pyrolys is reactor operating temperatures are 550°C at atmospheric pressure. The condensation system shows recovery duty of 3.4 MW of which can be used to heat cold streams. Pinch analysis was also carried out to design a heat exchanger network (HEN) between hot and cold streams in order to reduce energy consumption. Heat recovery from pyrolysis reactor effluent gases shows possible 3.439 MW recovery in a 10 tonne per hour pyrolysis plant.
Biofuels, for reasons such as the high demand of fossil fuels, the need for energy security and concerns over greenhouse gas emissions, have attracted the attention of researchers.Production of biofuels can be costly.On the other hand, the environmental benefits of biofuels depend on the technique they are produced, transported and used.This article studies a mathematical programming model for optimal planning of a biofuel supply chain based on existing facilities.The developed model is based on multi-objective linear programming (MOLP) and considers the economic, environmental and social concerns related to the proposed biofuel supply chain.The model takes into account feedstock availability, biofuel demand, existing biofuel plants and processing technologies.The proposed model is used to evaluate biodiesel production from palm oil and jatropha oil based on existing biodiesel plants in Malaysia.From developed model, the ε-constraint method is applied to solve the optimisation problem.Solving of the proposed model determines the optimal quantity of biomass to be harvested, transportation schedules and the quantity of biodiesel produced at biorefineries as well.
