Electrical Engineering Conference

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The 2nd International Conference on Electrical Engineering 2018 (Pre Text)
(Institute of Electrical and Electronics Engineers, Inc., 2018) Samarasinghe, R; Abeygunawardana, S
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An adaptive protection scheme for small scale microgrids based on fault current level
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Peiris, WLT; Eranga, WH; Hemapala, KTMU; Prasad, WD; Samarasinghe, R; Abeygunawardana, S
With the growing of the “Microgrid” concept in the modern world, new protection systems are required. This protection system should be handled the all configurations and all conditions of the microgrids and suitable for small scale less expensive microgrids. This paper proposed a reliable, online, adaptive and accurate method for microgrid protection by using fault current level of the system considering the modes of operation, dynamic nature of the Distributed Generators (DGs) and different types of the loads. This is an adaptive protection scheme for a microgrid; where a Microgrid Central Protection Unit (CPU) monitors the microgrid continuously using a communication medium, whenever fault is detected in the network, the relay settings of the microgrid are altered adaptively based on instructions issued by CPU. This method can be operated accurately by estimation fault current level of the Microgrid at the instant and using that relay tripping current at any disturbance and can be calculated at any condition. By using this protection strategy, can create self-operated microgrid and can avoid human interference to the microgrid operation, design and calculation.
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Application of machine learning algorithms for solar power forecasting in Sri Lanka
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Amarasinghe, PAGM; Abeygunawardane, SK; Samarasinghe, R; Abeygunawardana, S
Reliability and stability of a power system get decrease with the integration of large proportion of renewable energy. Renewable sources such as solar and wind are highly intermittent, and it is difficult to maintain system stability with intolerable proportion of renewable energy injection. Solar power forecasting can be used to improve system stability by providing approximated future power generation to system control engineers and it will facilitate dispatch of hydro power plants in an optimum way. Machine Learning (ML) algorithms have shown great performance in time series forecasting and hence can be used to forecast power using weather parameters as model inputs. This paper presents the application of several ML algorithms for solar power forecasting in Buruthakanda solar park situated in Hambantota, Sri Lanka. The forecasting performance of implemented ML algorithms is compared with Smart Persistence (SP) method and the research shows that the ML models outperforms SP model.
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Application of robot autobiographical memory in long-term human-robot social interactions
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Edirisinghe, MMSN; Muthugala, MAVJ; Jayasekara, AGBP; Samarasinghe, R; Abeygunawardana, S
Robots are becoming a part of the human society. They are intended to maintain long-term social interactions with humans. A memory about each interaction partner is essential for a robot for maintaining long-term social interactions. Therefore, robot memory must possess the abilities for extracting, storing, updating and recalling information during social interactions. This work studies the application of a robot’s autobiographical memory in long-term social interactions in multi-user environments. The proposed system is capable of acquiring knowledge about users through friendly conversations and recall them during future interactions. The autobiographical memory which has been designed with a three-layered architecture is employed for storing significant information which is required for long-term social interactions. The interaction manager module has been designed as a finite state machine for managing the interaction between the robot and the user. Dialogue flows were defined for each state to communicate with the user. The system has been tested and validated by using a set of experiments.
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Design of a multi-zone dielectric fresnel lens for microwave wireless power transfer in concrete structures
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Salama, R; Liyanapathirana, R; Samarasinghe, R; Abeygunawardana, S
Wireless power transfer (WPT) can be used for a number of applications in civil engineering such as powering of embedded sensors in concrete. In this paper, a multi-zone dielectric lens is designed and used to enhance the performance of WPT in concrete structures. Analytical equations are used to calculate the design parameters of the dielectric lens andperformance pertaining to the transmission coefficient, S21, and electric field distribution of the WPT with and without the dielectric lens is investigated using computational models. It is shown that by using a dielectric lens, the performance of WPT in concrete structures can be significantly enhanced. It is also shown that by using the dielectric lens, the external power source can be placed at a distance of 1200 mm from the concrete structure and achieve an S21 that is similar to that achieved by the WPT without the dielectric lens when the external power source is placed at a distance of 200 mm.
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Design of a small electric vehicle charger with multi-ports
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Wijesekera, A; Binduhewa, P; Samarasinghe, R; Abeygunawardana, S
In developing countries, small vehicles such as three-wheelers are one of the most commonly used public transportation method and considered as an efficient way to travel in the traffic. Even though the commonly used type is based on fossil fuels, fully electric small vehicles are commercially available and developing. The biggest hurdle for the expansion of small Electric Vehicles (EVs) is the unavailability of charging stations around the country. This paper presents a charging station for small EVs. The proposed charging system has the capability of charging multiple small EVs simultaneously. Also, the charging station is capable of bi-directional power flow and thus small EVs can support grid when required. The performances of the controllers are verified by simulating the system in PSCAD/EMTDC. Finally, a cost analysis also was carried out to find out the financial feasibility.
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Design optimization of a power generator soundproofing enclosure
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) De Zoysa, ADN; Iroshan, KA; Premaratne, UK; Ehelepola, I; Samarasinghe, R; Abeygunawardana, S
It is a vital requirement to have passive noise control enclosure in order to depress air borne noise of reciprocating engine type power generators. The design of these enclosures needs to be optimized in terms of the sound pressure level and the designing cost. We have used the existing acoustic equations to obtain the optimization based on the objective functions derived for the sound pressure level and enclosure design cost. Metaheuristic optimization algorithms such as genetic algorithms and particle swarm algorithm are capable of solving these optimization problems which have constraints for different parameters. The results obtained for a real world design problem confirms that particle swarm optimization provides better results than genetic algorithm in terms of optimality of the solutions and also the computational efficiency. Furthermore, it was observed that there is a significant linear relationship (R-Squared = 99.3%, p-value < 0.001) between the minimum enclosure design cost and the sound pressure level of the enclosure (SPLE) for the preferred range for SPLE values (65 to 70). The minimum possible enclosure design cost increases linearly with decreasing SPLE value. Therefore, the least possible SPLE value depends on the available financial resources.
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Dispatch analysis of variable renewable energy penetration in Sri Lanka with HVDC grid interconnection with India
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Rodrigo, AS; Fernando, MDV; Samarasinghe, R; Abeygunawardana, S
At present there is an increased focus on using renewable energy for power generation. In this paper a dispatch analysis is carried out to identify the effect of increasing variable renewable energy (VRE) penetration in to the Sri Lankan power system with the proposed HVDC grid interconnection with India. Future power system in 2025 was obtained based on least cost principles using WASP software considering HVDC capacity of 500 MW. The same power system was modeled in the long term dispatch simulation software, Stochastic Dual Dynamic Programing (SDDP). High wind and wet periods were considered due to higher renewable resource availability. Output of SDDP for each season was input to short term dispatch simulation software NCP to simulate the daily dispatch along with other operational constraints and seasonal renewable energy profiles. When the system cannot meet the specified constraints the renewable energy curtailments would occur. This process was carried out to obtain the RE penetration level with 500MW HVDC for three different scenarios. Scenarios considered for simulation are aggressive solar, aggressive wind and mix development of solar and wind. It was observed that with the proposed HVDC interconnection with India, the renewable energy level could be increased in the Sri Lankan power system.
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Distribution transformer based smart grids with rooftop solar : a case study for Sri Lanka
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Amarasinghe, HPP; Jayatunga, U; De Silva, N; Samarasinghe, R; Abeygunawardana, S
Trends on utilizing distributed renewable resources around the world have significantly increased the number of grid connected solar photovoltaic systems in low voltage networks. In Sri Lanka, low voltage systems are now available with the cumulative addition of the installed rooftop solar capacities is exceeding fifty percent of the rated capacity of the connected transformer. Thus, it is of vital importance to understand the technical impacts of solar photovoltaic additions in large scales on the operating performance of the networks and how to mitigate those issues. In this study, a futuristic solution is proposed with the formation of smart grid type operation, to effectively utilize the daytime solar photovoltaic generation in low voltage systems within the distribution transformer service area. Distribution transformer based smart grid, which operates with controlling mechanisms, loads, rooftop solar and battery storage systems is proposed for an urban low voltage distribution network in Sri Lanka which have more than forty percent of solar penetration level based on transformer capacity. The detailed network was modeled in MATLAB/SIMULINK simulation platform in order to develop different operating scenarios. The base model was validated with the field data available with transformer meter.
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DQ transform based current controller for single-phase grid connected inverter
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Jayathilaka, I; Lakpriya, L; De Alwis, D; Jayakody, G; Hemapala, KTMU; Karunadasa, JP; Lakshika, H; Samarasinghe, R; Abeygunawardana, S
In this paper, the design and simulation of a current controller for a grid connected inverter is implemented by using the synchronous reference frame conversion. The active power and the reactive power outputs of the inverter are controlled in the dq reference frame with the use of Proportional-Integral (PI) controllers. The measured grid current and grid voltage are used to generate an orthogonal signal pair with the use of Second Order Generalized Integrator with Phase-Locked Loop (SOGI PLL). According to the available standards for grid connected inverters, the unity power factor operation of the inverter is essential. In our design this is achieved by maintaining the reactive power reference of the controller at zero steady state value. The injected grid current is forced to be in phase with the grid voltage with the use of PLL. Also, a third order LCL output filter design is proposed in this paper to filter out the switching harmonics. The Matlab simulation results of the grid connected inverter are also included in this paper.
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Effect of barrier and its shape over the breakdown voltage of oil gaps
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Ediriweera, WEPS; Jayarathna, KLIMPB; Samarasinghe, R; Lucas, JR; Samarasinghe, R; Abeygunawardana, S
This paper studies the use of insulating barriers on the breakdown voltage of oil gaps upon two type of coconut oils under AC voltage. A point plane electrode arrangement connected to a AC transformer is used to find out the breakdown voltage of a short oil gap. A square shaped solid sample and a circular shaped solid sample are used to analyze the effect of using different shaped barrier inside actual high voltage apparatus. Field values given by three dimensional simulated model are used to analyze the field distribution inside the oil gap and its effect over the breakdown voltage.
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Extended Kalman filter based autonomous flying system for quadcopters
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Somasiri, JAAS; Chandima, DP; Jayasekara, AGBP; Samarasinghe, R; Abeygunawardana, S
This paper presents mathematical modeling, implementation and experimentation results of Extended Kalman filter (EKF) implemented on existing flight control algorithm which is used to control multi-rotor unmanned aerial vehicles such as quadcopters, hexacopters, and octocopters. Purpose of implementing the EKF is to improve flight performance and reliability of the vehicles during its autonomous navigation which may include automatic take-off landing, waypoint navigation, and to improve the robustness for wind disturbances at the same time. Initially vision positioning data were used as a ground truth to validate the EKF outputs. Then the filter is tested in real-time using a quadcopter and experimental results were presented and compared with raw sensor data to evaluate system performance.
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Graphical user interface for the supervisory motion control of BlueROV1.1
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Jayasinghe, MC; Samarasinghe, R; Abeygunawardana, S
Graphical User Interface (GUI) is a platform which can be used to vary out communication with machines in an interactive method. A GUI designed for a Remotely Operated Vehicle (ROV) bridges the communication gap and the limitations between the operator of the vehicle and the vehicle in operation. The interface enables the operator of the ROV to enhance the visual perception of the operations of the ROV with the data provided on the interface and command/control the vehicle according to the need of the task at hand. To perform remote monitoring and control of any parameter on the vehicle, it is required to assess the real-time controller data and user commands by processing and analysing the available data. This paper discusses the development of a graphical using interface for a remotely operated underwater vehicle using Microsoft Visual Studio as the interface development platform. Data such as orientation, depth, video feed, thruster speeds are collected from the sensors on board the ROV and processed by Arduino and Raspberry Pi microcontrollers before being displayed on the interface for user reference. The main objective of developing an interface was the ease of use, efficient, and accuracy of data representation for any user.
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High performance AC-AC regenerative 5-level NPC converter with capacitor voltage balancing
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Karunadasa, JP; Bandara, IBH; Dayananda, WDD; Kumara, KGSU; Tennakoon, GMR; Samarasinghe, R; Abeygunawardana, S
Regenerative AC-AC converters are required for serving AC loads that draw and return power during operation, when input is also taken from an AC source. AC motor drives, static VAR compensators, harmonic compensators and inverter testbeds are some of the examples using regenerative AC-AC converters. Generally, these are implemented as 2-level converters and operated with Pulse Width Modulated (PWM) control, incorporating higher switching frequencies. The use of higher switching frequencies leads to correspondingly higher switching losses and EMI issues. This paper describes the development of a 5-level regenerative AC-AC converter that can deliver equally good performance but operating at very low switching frequencies. It was developed as part of a testbed for performance testing of grid-tie solar PV inverters. The output specifications were accordingly drawn to comply with the requirements of IEEE1547. Input specifications were chosen to produce sinusoidal current and inphase with input voltage all the times. The converter employed back-to-back connected 5-level neutral point clamped (NPC) structure with middle DC-link. The input stage is operated with current control and the output stage with voltage control. DC-link capacitors were equipped with separate voltagebalancing circuits so that the voltage across each capacitor could be regulated at the nominal value all the times. The details of design, operation, control and simulation with operating waveforms are presented in the paper.
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Identification of cognitive navigational commands for mobile robots based on hand gestures and vocal commands
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Bandara, HMRT; Basnayake, BMSS; Jayasekara, AGBP; Chandima, DP; Samarasinghe, R; Abeygunawardana, S
Assistive robots are developed to uplift living standards of human beings. An assistive robot needs to be friendly, reliable, and understandable in order to be a human like companion. A robot should be able to navigate in an environment according to users’ commands. Users’ commands can be vocal or gestures. Combining users’ command types to identify the navigation information will enhance the user-robot interaction and makes navigation more effective and purposeful. Moreover, understanding the relationship between the navigation commands makes the robot a more human friendly companion. A robot should be capable of interpreting spatial information in uncertain terms. Moreover it should be able to improve the knowledge through communicating with the user, itself. The Cognitive Map Creator (CMC) has been introduced to create a cognitive map of direct navigational commands to enhance the interaction between the human and the robot which will help to make a robot more human-friendly. The Conversation Management Module (CMM), Spatial Data Interpreter (SDI) and Navigational Command Identifier (NCI) have been introduced in order to create a cognitive map of navigational commands. The capabilities of the robot have been demonstrated and evaluated from experimental results.
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An improved wide frequency model for VFTO of power transformers using transfer functions
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Jayarathna, KLIMPB; Ediriweera, WEPS; Samarasinghe, R.; Lucas, JR; Samarasinghe, R; Abeygunawardana, S
An accurate understanding of power transformer high frequency behavior is very important to assess the impacts on power system due to transient over-voltage conditions. An improved method of modeling power transformer under very fast transient over-voltage conditions (VFTO) is presented in this paper that provides a convenient way of obtaining winding and core responses of power transformers using existing circuit synthesis method. End-to-end short circuit and open circuit sweep frequency response analysis data are converted into transfer functions using a novel algorithm based on Levy and Sanathanan- Koerner methods, that are used in the development of lumped circuit model later. These transformer models can be implemented in a transient analysis software and can be used in power system analyzing under VFTO with greater accuracy.
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Integrated control strategy for grid connected photovoltaic array, battery storage and supercapacitors
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Silva, CMMRS; Premadasa, PND; Dassanayake, DMCT; Pradeep, RAH; Sirithunge, C; Chandima, DP; Prasad, WD; Samarasinghe, R; Abeygunawardana, S
Upon various renewable based power generation, Solar Photovoltaic (PV) technology is continually developing nowadays. However, the major drawback of this technology is the intermittent issue due to the rapid fluctuations in solar insolation level. Energy storage systems such as batteries and super capacitor banks are used to reduce the above problem. There is a requirement of an integrated controller strategy in order to achieve a power generation unit which includes power share among those energy storage units in between with solar PV array. Using a hybrid system of a battery bank and a super-capacitor bank over using a battery bank alone, helps to increase the lifetime of the batteries. Integrated control strategy is the common method used to control the solar PV array with energy storage units in order to supply the required islanded demand and supply excess energy to the grid while maintaining the DC-link stability through the synchronized control of DC-DC power electronic converters. This paper presents an integrated control strategy for grid connected PV array together with a battery bank and a super-capacitor bank. This further state mathematical proof for the sizing of storage devices. Performance of the integrated control strategy was evaluated using a practical experiment by developing customized DC-DC power electronic converters.
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Intelligent robot companion capable of controlling environment ambiance of smart houses by observing user's behavior
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Senarathna, SMSS; Muthugala, MAVJ; Jayasekara, AGBP; Samarasinghe, R; Abeygunawardana, S
Robot companions are being developed to assist humans in domestic environments. This paper proposes an intelligent robot companion which is capable of adapting the ambient conditions of a smart home environment in accordance to the user behavior. The user behavior identification is facilitated by an artificial neural network that has been trained to detect the different postures of humans such as sitting and standing. Based on the identified user behavior, the robot controls smart devices available in the home to realize the adaptation of ambient conditions. The smart devices and the companion robot connect over a wireless network. Furthermore, voice interaction capabilities have also been incorporated to the robot companion to facilitate voice interaction based controlling of ambient conditions. A prototype of the system has been developed and the capabilities of the system have been validated experimentally.
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Modeling and simulation of an electromechanical system for a hybrid rubber tire gantry crane
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Bolonne, SRA; Chandima, DP; Samarasinghe, R; Abeygunawardana, S
This paper presents study on the modeling of a Rubber Tire Gantry Crane (RTGC) used in container terminals for container handling. The electrical systems and mechanical systems are modelled by specific blocks from the Power System and Driveline block-sets while the control systems are modeled using Simulink. An “average modeling” approach is selected to simplify the operation of the motor drives and to speed up the simulation for tuning control parameters during long simulations. The model has the potential to be used for simulating a hybrid power pack, incorporating an energy management system for RTGC.
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Potential of ambient radio frequency energy harvesting from an industrial dielectric heater
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Dasanayake, DMHT; Anuruddha, G; Premaratne, U; Samarasinghe, R; Abeygunawardana, S
Dielectric heaters are mainly used in industry for various applications. Due to generation of near field energy from stray electromagnetic fields, these machines were selected for analysis as a source for RF energy harvesting. In this research, the energy harvester was designed using a ferrite core loop antenna, rectifying and smoothing circuit and an ultra-low power management system in order to provide energy to a temperature and humidity sensor node. This application was tested within the footwear manufacturing industry due to availability of dielectric heaters (RF Welding Machine) and temperature and humidity are continuously measured during the production process.