Optimal Sizing of Stand-alone PV System using Artificial Bee Colony Algorithm

The alarming rate of depletion of fossil fuels due to the increasing energy demands has increased the reliance on renewable energy. Renewable resources, such as solar and wind, are excellent alternatives to fossil fuels due to their sustainability and they do not produce harmful gases to the environment. The most promising renewable energy resource is the solar energy since it is available almost everywhere. Renewable energy systems have considerable high initial cost. In order to reduce the cost, the size of the system should be optimized. Optimization means increasing the output energy while reducing the cost. Recently intelligent optimization techniques have been used to solve complex engineering problems. Artificial Bee Colony (ABC) is one of these techniques. In this paper we present a sizing and optimization technique for renewable energy systems using ABC algorithm. The model for the PV panel, the battery, and the loads are used to optimize the system. The method is applied to optimize a typical system and the results of the design are optimum as proved by simulation and comparison with the results of the published methods

Ferroresonance simulation studies of transmission systems

The onset of a ferroresonance phenomenon in power systems is commonly caused by the reconfiguration of a circuit into the one consisting of capacitances in series and interacting with transformers. The reconfiguration can be due to switching operations of de-energisation or the occurrence of a fault. Sustained ferroresonance without immediate mitigation measures can cause the transformers to stay in a state of saturation leading to excessive flux migrating to transformer tanks via internal accessories. The symptom of such an event can be unwanted humming noises being generated but the real threatening implication is the possible overheating which can result in premature ageing and failures.The main objective of this thesis is to determine the accurate models for transformers, transmission lines, circuit breakers and cables under transient studies, particularly for ferroresonance. The modeling accuracy is validated on a particular 400/275 kV transmission system by comparing the field test recorded voltage and current waveforms with the simulation results obtained using the models. In addition, a second case study involving another 400/275 kV transmission system with two transformers is performed to investigate the likelihood of the occurrence of sustained fundamental frequency ferroresonance mode and a possible quenching mechanism using the 13 kV tertiary connected reactor. A sensitivity study on transmission line lengths was also carriedout to determine the probability function of occurrence of various ferroresonance modes. To reproduce the sustained fundamental and the subharmonic ferroresonance modes, the simulation studies revealed that three main power system components which are involved in ferroresonance, i.e. the circuit breaker, the transmission line and the transformer, can be modeled using time-controlled switch, the PI, Bergeron or Marti line model, and the BCTRAN+ or HYBRID transformer model. Any combination of the above component models can be employed to accurately simulate the ferroresonance system circuit. Simulation studies also revealed that the key circuit parameter to initiate transformer ferroresonance in a transmission system is the circuit-to-circuit capacitance of a double-circuit overhead line. The extensive simulation studies also suggested that the ferroresonance phenomena are far more complex and sensitive to the minor changes of system parameters and circuit breaker operations. Adding with the non-linearity of transformer core characteristics, repeatability is not always guaranteed for simulation and experimental studies. All simulation studies are carried out using an electromagnetic transient program, called ATPDraw.EThOS - Electronic Theses Online ServiceBrunei GovernmentGBUnited Kingdo

An Approximate Model of Load Frequency Control Systems with Time Delay

In this paper we present an approximate model for load frequency control system with time delay. The load frequency control is one of the conventional power system control problems. In order to secure the stability of the grid the frequency must remain within its limited range which is achieved through the load frequency control. The load frequency control signals experience time delay that could destabilize the power systems. The presence of the time delay complicates the analysis of the load frequency control system. In this paper we present a stability method based on the Direct Frequency Response approximation for the time delay. This approximation transforms the transcendental time delay equation into linear equation. This results in a simple stability criterion for the load frequency control system with time delay. A one-area load frequency control system is chosen as a case study. The effectiveness of the proposed approximation has been tested through simulation and comparison with the published research work. By tracking the eigenvalues or using Routh's criterion the maximum delay margin can be estimated. The proposed stability criterion has been compared with the most recent methods and showed it is merit. The range of the PI controller parameters for a given time delay can be determined which is very important in practice

Design and Implementation of Lab Scale Automated Solar Powered Irrigation and Fertigation System

In Brunei, natural oil and gas contributes to about 99% in the generation of electricity and about 88% to the country revenue. Since Brunei is heavily dependent on a non-renewable energy, potential exhaustion of oil and gas reserves pose a challenge to the country, especially with continuous increase of energy consumption in order to meet the population demand. Additionally, Brunei has ambition to improve its agriculture sector. Implementations of PV systems in local agricultural sectors can also help improving the country revenue by increasing yield and reducing costs from electricity consumption. In this paper, we present design and practical implementation of fully automated solar powered irrigation and fertigation system. Ultrasonic sensors and moisture sensors are used to detect the state of the tank and the soil. The whole system is controlled with a microcontroller and a wireless monitoring system with mobile application is designed. The operation of the system was tested and the performance was acceptable

Technical and economic feasibility of solar powered air conditioners in Brunei Darussalam

On daily basis, a huge amount of fossil fuel is being burnt which results in a substantial amount of greenhouse gasses being released into the atmosphere. Air conditioners are becoming more common and are a major strain on energy demands especially in tropical climate countries like Brunei Darussalam. The photovoltaic electricity is a clean and sustainable. In this paper, we present a techno-economic feasibility study for solar powered air conditioning system in Brunei Darussalam. Four alternatives are investigated, 1) the PV system supplies 50% of the loads, 2) the PV system supplies 75% of the loads, 3) the PV system supplies 100% of the loads, and finally 4) the PV system supplies 125% of the loads. Where in the last two case the excess electricity is sold to the grid. With 0.3$ feed-in tariff. The best alternative is the grid-connected PV system with 125% capacity factor which was chosen due to its short payback time period as well as high profit rate over the lifetime of the project

Efficient charging pad for unmanned aerial vehicle based on direct contact

Recently there has been significant interest in the development of autonomously Unmanned Aerial Vehicles (UAVs), especially the rotor-based robots, which are highly maneuverable and can vertically take-off and land. However, the discharge characteristics and charge storage capacity limitations of their lithium-ion battery can restrict their flight time endurance. The utilization of an automatic drone charging station is therefore desirable for these robots. This paper proposes a fully automatic contact-based charging station for UAVs to recharge UAV's and thereby solve the UAV's flight endurance limitations. The ground station comprises square-shaped copper plates of consecutively polarized positively and negatively in the form of a chess board with specific dimensions to ensure electrical contact when landing. The design methodology employed with the charging station accounts for the variations of the orientation of the UAV after landing on the platform. Furthermore, this innovation employs an autonomous recharging process after touchdown. Subsequently, this technology relaxes usual flight time constraints and improves overall mission times. The UAV equipped with a suitable hardware circuit the onboard circuit consists of six bridge diode rectifiers to modulate the polarity of the four UAV's contact terminals that allows autonomous recharge regardless of the yaw angle between UAVs and the charging pad platform, this, in turn, simplifies landing protocols. The result shows that the charging circuit successfully charged the UAV battery until 12.5v

Modelling and simulation of 1.2 MWpTenaga suria brunei photovoltaic power plant

The energy demand in Brunei Darussalam will increase in near future. The renewable energy is one of the alternative energy sources that could satisfy the increasing energy demands. Brunei Darussalam depends heavily on fossil fuel to generate its electricity needs. Fossil fuels are depleted and the main source of pollution. Photovoltaic (PV) systems generate electricity directly from the sunlight without any emission of global warming gases, and the fuel is free. In order to optimize the performance of PV systems their operation should be well understood. In this paper, we present the modelling of a real 1.2 MWp photovoltaic system. The PV power plant is tied to the grid. The PV array, the DC/DC converter and the DC/AC inverter are modelled and implemented in Matlab/Simulink. The controller of the grid-connected inverter is modelled to achieve constant voltage, constant frequency and to be synchronized with the grid. The system is simulated under Brunei weather conditions and the results are acceptable. © 2019 Mattingley Publishing. All rights reserved

Development of an in-sole plantar pressure measurement device

This paper describes the design and development of an In-sole Plantar Pressure Device (IPPD) to measure underfoot pressure. Knowledge on underfoot pressure is important for different purposes. It is essential for doctors and clinicians to have information about underfoot pressure to enable them to diagnose foot problems. Currently, underfoot pressure ranges have not been effectively established, and there is insufficient information about the minimum and maximum values of underfoot pressure. Likewise, constraints with regard to the implementation of insole systems still persist and are represented by the need to put a spacer on the sensor during measurements, and the problem of sensor parameters changing after the calibration. These challenges are addressed in this work and preliminary results or performance of the proposed device are then presented

Foot plantar pressure distribution modeling based on image processing

Several factors have been associated with the distribution of plantar foot pressure, including: (i) the body weight, (ii) age, (iii) foot structure and (iv) standing / walking strategy. It is predicted that the biomechanics of the foot is influenced by the structure of the foot. The objective of this study was to obtain the plantar pressure distribution model of the foot using custom image processing algorithms upon the images captured by a commercial plantar pressure measurement machine, the EMED-X. The study involved the participation and data collection from 79 human subjects, ranging from age 20–60 years old. This model can be analysed further to be used as a predictor for the formation of foot ulceration in certain subjects