This paper presents the scheduling risk of Independent System Operators in using the DC-based shift factor in modeling transmission constraints in its market optimization model while the incremental transmission losses are only accounted for in the power balancing constraint. Because of the inconsistency in incremental loss modeling, the effectiveness of resource adjustment in resolving transmission congestion is subject to distortion from a full lossy modeling. Under the condition that abundant effective adjustments are available, the distortion effect on the MW solution is minimal. However, when effective adjustment is exhausted, the distortion effect could give rise to false adjustments that have no real effect in resolving transmission congestion, posing a system reliability issue. The paper advocates the use of AC-based shift factor in the market optimization model to avoid the false adjustments between resources in market resolution.
These Active load and loss allocation has become a concern in power system with the introduction of deregulation. Deregulation often gives opportunity for the end user to choose their own supplier which has brought the importance of active load and loss allocation in transmission line. Thus, this paper proposed a Cuckoo Search technique as a tool to allocate both active load and losses in transmission line. The technique has been tested in normal and load increase condition. Cuckoo Search is a simple technique that did not involve complex mathematical procedures but provides a better performance in terms of accuracy and computational time. The allocation is done by treating the active load and loss as an optimization problem. This paper presented the result obtained from IEEE-30 bus system in both normal and load increase condition. In addition, comparative study has been conducted with Genetic Algorithm technique.
Renewable-based distributed generation (DG) systems present tremendous benefits when operated in an optimal manner. The benefits include among others, reduced transmission losses, increase in renewable energy penetration (REP), reduced emission levels. The purpose of this research is to determine the optimal hybrid renewable-based DG system with feed-in tariffs. We compared grid-connected wind/hydro/diesel with storage, grid-connected wind/hydro/PV with storage, grid-connected hydro/PV with storage and grid-only systems. A new transmission capacity burden index has been introduced to indicate the extent at which the transmission line is loaded in the DG environment. HOMER software has been employed as the optimization tool. An optimality ranking technique has been used as a second method to determine the best optimal hybrid DG system. Results indicate that a purely renewable based DG system is the best optimal system. Such systems are very paramount to the Kingdom of Saudi Arabia (KSA) whose energy supply is dominated by fossil fuels. If such systems are implemented, KSA can contribute to the world's call to reduce greenhouse gasses in addition to reducing dependence on nonrenewable resources.
Moisture in power transformers are undesirable but yet unavoidable; hence necessitating its continuous study. The kraft paper of the oil filled transformer absorbs much of its moisture from the insulation oil in which it is immersed. The dielectric properties of the paper can be determined as a function of the wetting, penetration and saturation of the paper by the aqueous liquid in the oil. This paper compares the absorption characteristics of aqueous substances into kraft paper in two commercial insulation oils; palm based Palm Fatty Acid Ester (PFAE) biodegradable oil and petroleum based Hyrax Hypertrans mineral oil. Kraft paper thicknesses used in this study were varies from 0.2 mm to 0.5 mm and 1.0 mm. Test oil samples are taken directly from drum given by the suppliers. The study result shows that substances absorbed by kraft paper immersed in both insulation oils is dependent on paper thickness and chemical composition of the oils. The result shows that 0.2 mm thick paper absorbs the same aqueous percentage from both insulation oils irrespective of their constituent moisture content while the substance absorbed in both the 0.5 mm and 1.0 mm thick papers immersed in PFAE is higher that immersed in Hyrax Hypertrans by about 1%. It also shows that the rate of absorption reduces as the paper thickness increases. This concludes that irrespective of the high initial moisture content of PFAE being higher than that of Hyrax Hypertans, same aqueous substance is diffused into kraft paper.
With the high penetration of distributed generations (DGs) have been connected into the local power distribution network, it will result in some deteriorative influences such as poor power quality and stability issues. And power distribution network itself with problems of power system nonlinear characteristic, power system faults and nonlinear loads makes this issue more severe. Meanwhile, in order to restraint the large output power fluctuation caused by great many DGs, enough power support, which can be implemented by energy storage technology, is needed. Thus, for solving the voltage problems in power distribution network with the high penetration of DGs, a novel Unified Power Quality Conditioner (UPQC) based on fast energy storage is introduced in this paper. Then the structure principle and the control strategy were explained at length. At last the practicality of the device was determined successfully by simulation and experiment research.
This paper presents a frugal and vibrant home SCADA energy surveillance system. The proposed SCADA system constructs a conscious mind among users on efficient utilization of electricity to operate home appliances over a daily basis. The developed system enables residential sectors to log in, display and provide real time feedback on energy consumption for each active appliance. Based on simulation results, the proposed monitoring system constantly provides end users with real-time advices on consumption level, while prompting necessary precaution steps in reducing financial losses. Therefore, it results in a tremendous saving on monetary values on energy bill. The developed SCADA system will form a more responsible society, that is, in line with energy efficiency standards as well as demand side management (DSM) strategies in power utilities.
In this paper, the procedures for evaluating the High Voltage (132kV, 275kV and 500kV) overhead lines performance due to lightning in TNB transmission is discussed. The historical tripping data is analysed and compared from the international standard IEC 60071-1 and other utility practices. Approaches for evaluating the performance i.e. software simulations using TFlash and SIGMA SLP are part of the study. Lightning stroke data will also be shown, which will be compared with the tripping pattern. The condition of the transmission towers and Tower Footing Resistance are also very essential in determining the line performance. As conclusion, this paper will discuss and propose the method and actions for reducing OHL tripping due to lightning, thus improving the line performance.
Installing shunt capacitors in a radial distribution system can provide a lot of benefit to utility and users. There are many ways to install capacitors as long as the sizes do not exceed the original inductive reactive power of a system. But it is very difficult to determine the best locations and size of capacitors. In addition, the unbalance nature of distribution system make the placement becomes more complicated. Optimal placement of capacitor is a highly nonlinear optimization problem which requires discrete control variables. This paper proposed an artificial intelligence approach to obtain optimal total line loss reduction and total cost of capacitor while improving the voltage profile along the feeders. It was done by integrating the circuitry distribution model in SIMULINK with particle swarm optimization (PSO) technique constructed in MATLAB. The optimization process was done in two stage where the first stage is to determine the early optimal locations while second stage is to determine optimal sizes. A modified IEEE 13-bus three phase unbalanced radial distribution system is used to validate effectiveness of the proposed technique in solving the problem.
In this paper, the outdoor polymer insulator was studied and the related electrical and mechanical conditions were reviewed. Moreover, different outdoor insulators were technically compared together. Furthermore, voltage distribution along a real polymer 33kV insulator was studied and the results were discussed accordingly. On the other hand, the voltage and electric field profiles at longitudinal and cross sections under different voltage levels were considered and discussed.
In the paper empirical model of flicker initiated in a wind turbine sited on a hill is established. Paper offers ins and outs of impact of various shapes of hills on vertical wind shear and consequently on the flicker produced in the wind turbine which is sited on that surface. In the model vertical wind shear, length of the turbine blade, tower height, slope of the hill are reverberated. The exquisiteness of the model is that, it is expedient to sundry types of hills on which the turbine is sited. Postulations, boundary curbs and limitations of the model are also depicted.
Paper confers a newfangled empirical model to figure, flicker, instigated in the horizontal axis, upwind turbine, due to vertical wind shear, in continuous operation. Postulations, boundary curbs and limitations of the model are also depicted. In the proposed model, vertical wind shear, number of blades, blade length and tower height are echoed. The elegance of the model is that, it is expedient to range of heights of buildings on which the turbine is sited. Substantiation of model is carried out with comparative graphs revealed after fervent experimentation on a turbine in a tunnel with various heights of models of buildings.
This research have been conducted to predict the output power of grid-connected photovoltaic (GCPV) system using hybrid Bat Algorithm-Artificial Neural Network (BA-ANN) in this paper. In this project, ANN utilized data from GCPV database includes Solar Irradiance (SI), Ambient Temperature (AT) and Module Temperature (MT) as the inputs and apply output power as a single output. More importantly, bat algorithm optimization was apply to minimize Root Mean Square Error (RMSE) by optimized the number of neurons in the hidden layer, learning rate and momentum rate. After training steps, testing will take a part for affirm the ANN training. The results obtained have been compared with the results from Evolutionary Programming-Artificial Neural Network (EP-ANN) with the similar input and output configurations. It is observed that result for BA-ANN had performed more than EP-ANN in term of producing lower RMSE. Besides that, optimal learning algorithm, time taken, and population were also take part in this research.
The aim of this project is to develop a dynamic model of distribution network cell (DNC) using artificial intelligence approach. The increasing number of distributed generation (DG) technology has lead to difficulty in modeling the DNC model. The simple load modeling is no longer reliable in presenting the DNC model. In this project, the equivalent dynamic model of DNC consists of the converter-connected generator and the composite load model. The model was developed in the form of seven order state-space model. The parameter estimation of the model was developed using fuzzy system. The parameter value was updated through adaptive neuro-fuzzy inference system (ANFIS). The active and reactive power response from the fuzzy model was compared with the response from the full DNC model at various type of disturbance. The response of full DNC model was obtained from the UK 11 kV distribution network model. The model was built in DigSILENT PowerFactory software. The performance of the fuzzy model was validated by calculating the value of root means square error (RMSE) and the best fit value. Later, the performance of the fuzzy model was also compare with the system identification model. The results obtained shown that the fuzzy model was more simple as only a few parameters involved in developing the equivalent model. This simplicity was reflected in the low computational time. The efficiency was also good based on the low RMSE value and high best fit value. In conclusion, the equivalent dynamic model of DNC based on fuzzy system approach was successfully developed.
This paper presents the implementation of Modified Swarm Firefly Algorithm (MSFA) technique which considers the effect of population size in solving directional overcurrent relay coordination problem. The coordination of directional overcurrent relays is formulated as linear programming problem and the proposed technique is compared with those obtained using Particle Swarm Optimization (PSO). Implementation of the MSFA technique in minimizing the operating time of the relay which depends on the time setting multiplier has shown better results and avoiding miscoordination between each relay pairs. The simulation results on 8 bus test system demonstrated that the MSFA technique is capable in solving directional overcurrent relay coordination problem much better than PSO in terms of computation time.
Power transformers illustrate the majority of capital investment in transmission and distribution centers. Additionally, interruptions of power transformer have a significant economic Effects on the Performance of an electrical network. For this reason, the safe and reliable Performance relate directly to the Security and stability of power system. This paper studies the growth of power losses and Derating of Distribution transformer, working under unbalance voltage and unbalanced load conditions. In this paper, computer-based simulation utilizing the two and three dimensional finite element methods (3-D and 2_D FEM) are exploited as a tool for visualizing magnetic fields of distribution transformers. Finite Element Method (FEM) is one among popular numerical methods that is able to handle problem complexity in various forms. The performance of the transformer when the load and supply are balanced compared to the case in which voltage or load is unbalanced indicates that the unbalanced load only causes the copper loss to increase, while the unbalanced voltage not only increases copper loss but also adds to the core loss. The indices of voltage unbalance factor (VUF) are used in this paper to evaluate the unbalance propagation. This process enables the software to simulate and analyze different electromagnetic parameters such as magnetic flux lines, flux density, losses, and etc, under different input sources with high accuracy.
Maintaining dynamic security of the power system subject to large disturbances is one of serious concerns of power utilities nowadays. Besides detection of the instability event, fast determination of emergency control is also very important. This paper presents an application of artificial neural network (ANN) to find the automatic generator tripping at the eastern corridor of the peninsular Malaysian power system. The database processed by the ANN is simulated based on real measured data. The input features are selected by engineering judgments on the set of readily available data and no dimensionality reduction was used. The results obtained are encouraging. Thereby the potential integration of ANN to the real-time application platform (RTAP) is being considered.
A wireless power transfer (WPT) using inductive coupling for mobile phone charger is studied. The project is offer to study and fabricate solar WPT using inductive coupling for mobile phone charger that will give more information about distance is effect for WPT performance and WPT is not much influenced by the presence of hands, books and types of plastics. The components used to build wireless power transfer can be divided into 3 parts components, the transceiver for power transmission, the inductive coils in this case as the antenna, receiver and the rectifier which act convert AC to DC. Experiments have been conducted and the wireless power transfer using inductive coupling is suitable to be implemented for mobile phone charger.
The objective of this research is to improve the ranking of the power transformer condition based on their severity which will then facilitate the maintenance engineer to prioritize maintenance work on more critical transformer. It describes a hybrid methodology to fuse power transformer condition's evidence by using Weibull function and Yager Combination Rule. Field transformer data were collected and mathematical algorithms were developed to model degree of belief assigned to power transformer condition's propositions. The ranking of the power transformers based on this methodology is compared with the ranking of power transformer by single evidence. Different sets of failed transformers data were collected to evaluate this approach. Finally, we demonstrate the interpretation of power transformer condition based on Yager's combination rule.
The authors have developed a successful method for improving the thermal cyclic resistance of the thermal barrier coating system that is deposited on gas turbine components. Conventional thermal barrier coating consists of duplex systems, top coating and bond coating. The developed system introduces a protective intermediate layer of MoSi2 for preventing oxidation of the bond coating. Conventional duplex plasma sprayed coating was delaminated after 20 thermal cycles. On the other hand the developed triple layered coating system was not delaminated up to 60 cycles. The reason for the enhanced resistance to thermal cycle of the developed triple layered coating system is that the MoSi2 layer existing between the top coating and the bond coating has the self-repairing property. Here, MoSi2 oxidizes to form SiO2 which seals the cracks and pores formed between the top coating and the bond coating. Thus, the formation of TGO which leads to coating delamination is prevented and the thermal cyclic resistance is improved.
This paper presents the performance analysis of 12Slot-14Pole hybrid excitation flux switching machine (HEFSM) with outer-rotor configuration. Nowadays, research on flux switching machines (FSMs) become an attractive research topic due to several excessive advantages of robust rotor structure, high torque and power capability, and low manufacturing cost that suitable for heavy applications. The FSMs that constructed with two flux sources namely permanent magnet (PM) and flux excitation coil (FEC) which also known as hybrid excitation flux has additional advantage of flux controllable. Furthermore, the outer-rotor configuration of the machines can provides higher torque density and appropriate for in-wheel direct drive application. Based on 2-D finite element analysis (FEA), the design improvement has been made on the initial design machine shows that there is great enhancement on torque and power.
