Browsing by Author "Hemapala, KTMU"

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item: Conference-Abstract
A Review on Multi‐Agent systems in micro grid applications
Kulasekera, AL; Gopura, RARC; Hemapala, KTMU; Perera, N
The applications of Multi-Agent Systems (MAS) in electrical power systems are becoming popular due to their inherent benefits such as increased autonomy, reactivity, pro activity and social ability. This paper reviews current research on the application of multi-agent systems in micro grid schemes. The paper is mainly focused on recent developments of multi-agent systems in different aspects of micro grids such as control, market modeling, optimization and power restoration. The future directions of multi-agent systems in micro grid applications are also discussed briefly. Furthermore, this review is concluded by discussing the development of an enhanced multi-agent based distributed control framework for micro grids.
item: Conference-Full-text
Active and passive based hybrid cell balancing approach to series connected lithium-ion battery pack
(IEEE, 2022-07) Ekanayake, EMAGNC; Hemapala, KTMU; Jayathunga, U; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Lithium-ion battery (LiB) technology is extensively used in energy storage systems (ESS), electric vehicles, and portable devices. Optimal cell balancing techniques for a battery management system are essential for the operation of the Li Battery. This paper proposes a new passive and active-based hybrid cell balancing technique integrating switched resistor balancing technique and switched capacitor balancing technique to achieve less balancing time and less power dissipation with simple control and hardware. The proposed system has been mathematically modeled and simulated, and the results show a 30% increase in the balancing time compared to the conventional capacitive balancing technique. Also, the control algorithm can adaptively operate to achieve better performance of the circuit. The simulation is done in the MATLAB Simulink environment.
item: Conference-Full-text
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.
item: Thesis-Full-text
Agent based metering system for energy networks
(2015-10-30) Ranawaka, DMD; Hemapala, KTMU
Centralized automated single server based energy meter reading systems required high-end resources, at the same time it has low efficiency benefits, low reliability and real time meter data monitoring get more complex when the connected meter base is large. Therefore objective of the research is to provide a methodological approach for energy meter reading systems to apply for the Sri Lankan context using decentralized technique. Agent based solution was implemented with Multi Agent System (MAS) to address above issues and the system is characterized de-centralized nature and self configurable nature. Low cost, high reliable, high efficient meter reading system is provided by MAS based decentralized system
item: Thesis-Full-text
Assessment of embedded energy of floor tiles manufactured in Sri Lanka
Wijerathna, WMNK; Hemapala, KTMU
Floor tile manufacturing is one of the highest energy intensive industries in the world. Basically, the thermal energy is the most prominent energy component in the value. Embedded energy is a fairly a new concept which will be used to estimate how much energy had been used to produce one unit of material. The embedded energy concept will be used to check the energy efficiency of the manufacturing. The embedded energy comprises four components as level 01,02 03 and 04. Level 01 energy is the direct energy used in the manufacturing process. Level 02 is the labour component and the ancillary services. The transport and mining energy is considered as level 03 energy. The level 04 is the energy being used for manufacturing of the capital equipment or the machineries which are being used in the manufacturing process. Accessing of level 04 energy is very difficult and that energy is not considered in this research. The fossil fuel is a limited resource to the world and in the countries like Sri Lanka, all most all the fuels are being imported. If it is strived to reduce the embedded energy or at least trying to reach the lowest values achieved by other countries will serve the world by saving energy. The embedded energy of a typical factory in Sri Lanka is 12.58 MJ/Kg for Level 01, 0.14 MJ/Kg for the level 02 and 0.84 MJ/Kg for Level 03. Which gives the embedded energy as 13.56 MJ/Kg. According to the literature revived the internationally accepted embedded energy value is 11MJ/Kg for the floor tiles as per Inventory of Carbon and Energy. To achieve the imbedded energy value 11 MJ/Kg is not an unrealistic task. For this the manufactures of the country have to rearrange their manufacturing processes in such a way that the wastages are minimized and the thermal energy is efficiently used. By rearranging the production process to have the energy efficient manner will serve two purposes. It will help to produce low embedded energy tile and lesser embedded energy means low fuel consumption in the manufacturing process. It will help to reduce the global energy demand and the unit cost of the product will be lower making it high profitable
item: Thesis-Full-text
Autonomous fault isolation and power restoration system for MV/LV distribution
Dissanayaka, DMDK; Rodrigo, WDAS; Hemapala, KTMU
The term “Distribution Automation” generally refers to a distribution network switching subsystem devices equipped with the advanced technologies dedicated for purposes such as, ease of real time monitoring and controlling, reliability improvement management, integrating of distribution network and electricity market operation. Improving the reliability of electric power delivered to the end users is one of the main targets of employing distribution automation. Therefore, developing autonomous fault isolation and power restoration system for LV/MV distribution can be attractive reliability enhancement solution for the electric utilities. Electrical utility industries are not focusing on automating Low Voltage (LV) distribution system due to complexity of the LV distribution network feeders. However, there is a room available for automation if an algorithm could be developed for autonomous fault isolation and power restoration. Development of a comprehensive algorithm opens up a new pathway for LV distribution. Electrical distribution system network consists in large numbers of Remote Switching Subsystem Devices (RSSD) and these devices communicate in different protocol. These devices can be monitored and controlled remotely by linking with Supervisory Control and Data Acquisition (SCADA) system. However, investing on a fully fledge SCADA is not so economical for a small scale distribution utility. As a solution; scalable distribution automation will enable small scale distribution utilities to enter into distribution automation with optimal capital investment. Hence, developing a scalable SCADA is the solution for smaller distribution automation. Results of this thesis are, a proto type LV distribution system has been developed to demonstrate the algorithm for autonomous fault isolation and power restoration system. Also has been implemented open platform SCADA system in view of acquiring multi-protocol remote switching subsystem devices.
item: Thesis-Full-text
Benchmarking medium voltage feeders using data envelopment analysis : case study WPSI-CEB
Herath, HMJN; Hemapala, KTMU
Presently there is no any proper method of finding performance of Medium voltage feeders except the number of feeder failures. Therefore available limited resources are not utilized for the most required feeders and also various issues and contradictions are occurred among Engineers when giving targets to be achieved for feeders. By identifying actual performance of feeders, system improvements can be done to the most needed feeders using limited resources. Performance benchmarking can be used to identify actual performance of feeders. Results of such benchmarking studies allow the organization to compare feeders with themselves and identify poorly performing feeders. Then the limited resources can be used to develop poorly performing feeders therefore both Utility and Consumers can get maximum benefit from available limited resources. In order to produce a suitable benchmarking methodology this dissertation focuses on prominent benchmarking techniques used in international regulatory regime and analyses the applicability to Medium Voltage Feeders. Through the analysis Data Envelopment Analysis (DEA) method was selected. Correlation analysis and DEA analysis with different models were carried out. Then the base model was selected for the analysis and relative performance of 32 Medium voltage feeders of Western Province South-I of CEB were evaluated using the Data Envelopment Analysis (DEA). Relative efficiency scores can be identified for each feeder. This paper also discusses the classification of Feeders according to the sensitivity analysis. Generally, the study concludes that DEA analysis can be carried out to evaluate the performance of Medium Voltage Feeders. The evaluation can be carried out once a year or once in two years with the medium voltage Distribution Development Plan in order to identify the performance of feeders and utilized the available limited resources efficiently.
item: Thesis-Abstract
Benchmarking of electricity distribution licensees operating in sri lanka
(2016-05-23) Neelawala, L; Hemapala, KTMU
Electricity sector regulators are practicing benchmarking of electricity distribution companies to regulate allowed revenue to each company. Mainly this is done by using the relative efficiency scores produced by frontier benchmarking techniques. Some of these techniques, for example Corrected Ordinary Least Squares method and Stochastic Frontier Analysis have econometric approach to estimate efficiency scores, while method like Data Envelopment Analysis uses Linear Programming to compute efficiency scores. Using the relative efficiency scores, the efficiency factor (X-factor) which is a component of the revenue control formula is calculated. The approach used by the regulators to derive X-factor by the relative efficiency scores is varying among regulators. In electricity distribution industry in Sri Lanka the allowed revenue for a particular distribution licensee is calculated according to the allowed revenue control formula as specified in the tariff methodology of Public Utilities Commission of Sri Lanka. This control formula contains the X-factor as well, but it has been kept zero, since there were no relative benchmarking studies carried out by the utility regulator to decide on X-factor. In order to produce a suitable benchmarking methodology this dissertation focuses on prominent benchmarking techniques used in international regulatory regime and analyses the applicability to Sri Lankan context, where only five Distribution Licensees are operating at present. The main challenge was to produce robust efficiency scores using frontier techniques for lower sample size (i.e. five) where in contrast many countries have large number of distribution companies or licensees (i.e. large sample size). Importantly this discussion gives directing signals to the utility regulator on possibility to control allowed revenue of Distribution Licensees according to their efficiencies.
item: Conference-Abstract
Capacitor switching transient analysis on a transmission grid substation
Hemapala, KTMU; Munasinghe, DLP
The quality of electric power system has a great concern and also it has been a constant topic of study. A transient originated from capacitor bank switching are main reason which affects the power quality. The analysis, simulation and optimal use of capacitor banks under harmonic conditions are required in a power network to optimally locate and sizing of a capacitor bank. The breaker switched capacitor (BSC) banks are commonly used for power factor correction, reactive power requirement and voltage support by many utilities in the world. Ceylon electricity board (CEB) has also installed total of 370 Mvar capacitor banks island-wide in transmission grid substations (GSS) in 33 kV level. The motivation for the study is the switched off capacitor banks at Thulhiriya GSS due to the failure of 100 Mvar BSC banks installed at the Pannipitiya GSS. Thulhiriya GSS was modelled as the case study to analyze the switching transients of the 33 kV BSC banks to the system. Data for the selected substation were recorded and analyzed and the selected substation was modelled using PSCAD simulation program to analyze the transients and harmonics. The results obtained for the Thulhiriya GSS are extrapolated to a general concept to suit any substation in the CEB network.
item: Thesis-Full-text
Capacitor switching transient analysis on a transmission grid substation (case study : Thulhiriya GSS)
(2015-10-26) Munasinghe, DLP; Hemapala, KTMU; Gnanarathna,U.N
The quality of electric power system has a great concern and also it has been a constant topic of study. A transient originated from capacitor bank switching are main reason which affects the power quality. The analysis, simulation and optimal use of capacitor banks under harmonic conditions are required in a power network to optimally locate and sizing of a capacitor bank. If the capacitor banks are not properly selected and placed in the power system they could amplify and propagate harmonics, deteriorate the power quality to unacceptable levels and the transients produce under different conditions will be negatively affected to the switchgears in the substation. The breaker switched capacitor (BSC) banks are commonly used for power factor correction, reactive power requirement and voltage support by many utilities in the world. Ceylon electricity board (CEB) has also installed total of 370 Mvar capacitor banks island-wide in transmission grid substations (GSS) in 33 kV level. The motivation for the study is the failure of 100 Mvar BSC banks installed at the Pannipitiya GSS after putting in to operations. After this incident the Thulhiriya GSS and Athurugitriya GSS BSC banks were switched off since they also came under same project with same equipment. In this study the Thulhiriya GSS was selected as the case study to analyze the switching transients of the 33 kV BSC banks to the system. Data for the selected substation were recorded and analyzed and the selected substation was modeled using PSCAD simulation program to analyze the transients and harmonics. The objective of the study is to investigate the particular BSC bank is safe for operations without under utilizing by comparing the obtained simulated results with the standards and specifications, observe the switching transients and harmonics, introduce a safe region for closing of the BSC banks, introduce a proper sequence for closing of the BSC banks and introduce time delays for back to back switching of the BSC banks with minimum effect to the quality of the waveform. The results obtained for the particular substation are expected to be extrapolated to a general concept to suit the whole substations in the CEB network.
item: Conference-Full-text
Coordination of pv smart inverters for grid voltage regulation
(IEEE, 2023-12-09) Latani, T; Parameswaran, G; Priyanthan, G; Hemapala, KTMU; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
In the contemporary energy market, the utilization of photovoltaic (PV) is increasing considerably. This change brings new challenges to the power grid because of its variable and intermittent nature. One of the main issues is voltage violations and PV curtailment. A smart inverter (SI) provides a fast response method to regulate the voltage by varying real or reactive power at the point of common coupling (PCC). When multiple SIs operate under an autonomous control scheme, the reactive power level exceeds the threshold level. This creates an undesirable situation in the system. This paper mainly considers the coordination of the SI using a deep reinforcement learning algorithm (DRL). The DRL agent learns the policy through interaction with the IEEE-37 test feeder in the OpenDSS simulation to find out the optimal action. By defining the rewards scheme of the action carefully, the reactive power of SI can be utilized optimally, and the PV voltage will be maintained within the normal operating zone. Validation of the DRL agent’s performance is done with the local autonomous control scheme. The results assure that a well-trained DRL agent can coordinate multiple SIs for voltage regulation and PV curtailment reduction.
item: Conference-Full-text
Defining Multi Agent System for a Reliable Micro-Grid
(2015-08-03) Dinushi, HMN; Kariapper, MHMS; Porawagamage, GD; Rathnayaka, PKH; Srimal, UP; Hemapala, KTMU
Electrical power supply to serve critical facilities are of high importance in today’s world. Instead of building a large electric power system, an intelligent Micro Grid (MG) can be considered as a promising power supply alternative for those critical facilities. This study presents the development and controlling of a laboratory scale MG which consists of several Distributed Energy Resources (DERs) such as Solar PV, Diesel Generator, Micro Hydro model, Battery Bank with a bidirectional inverter and critical and non-critical loads. Controlling of the MG is done by using distributed autonomous control strategies and Multi Agent System Architectures. It can operate in a grid connected mode as well as autonomous mode when it is isolated. The whole system was simulated using MATLAB and the simulation results and practical results were compared when MG is operated in different scenarios. The effectiveness of this controlling method is discussed in this paper.
item: Conference-Abstract
Defining multiagent system for a reliable Micro-Grid
Dinushi, HMN; Kariapper, MHMS; Porawagamage, GD; Rathnayaka, PKH; Srimal, UP; Hemapala, KTMU
Electrical power supply to serve critical facilities are of high importance in today’s world. Instead of building a large electric power system, an intelligent Micro Grid (MG) can be considered as a promising power supply alternative for those critical facilities. This study presents the development and controlling of a laboratory scale MG which consists of several Distributed Energy Resources (DERs) such as Solar PV, Diesel Generator, Micro Hydro model, Battery Bank with a bidirectional inverter and critical and non-critical loads. Controlling of the MG is done by using distributed autonomous control strategies and Multi Agent System Architectures. It can operate in a grid connected mode as well as autonomous mode when it is isolated. The whole system was simulated using MATLAB and the simulation results and practical results were compared when MG is operated in different scenarios. The effectiveness of this controlling method is discussed in this paper.
item: Thesis-Full-text
Defining of normalized load profile curves for domestic customer groups to estimate feeder power loss
Jayawardhana, HACH; Hemapala, KTMU; De SIlva, PSN
‘Estimation of load profiles for domestic customers’ is a multi-purpose activity and ‘Estimation of daily feeder power loss' is only a one use of customer load profiles. In a country, domestic electricity customer percentage is higher in number wise, but energy usage of one customer is lower compared to other categories. Therefore installation of load profile recording meters for each domestic customer to obtain customer load profile is impractical and not economical. In this research, set of domestic customers are grouped by clustering their daily load profiles with respect to differences of patterns. Representative normalized load profile is obtained for each group. Same customers were interviewed for collecting family member composition and electric equipment usage information. Relationships between load profile pattern and customer information were investigated. Then a methodology was developed to estimate load profile of a new customer by only using customer information and monthly total energy consumption. These load profiles were used to calculate low voltage feeder power loss. As outcome of this research, MATLAB GUI software interface was developed to input customer information and selection of best-matched representative load profile of a new customer. An algorithm is proposed to estimate time dependant LV feeder power loss by using estimated customer load profiles.
item: Conference-Full-text
Defining of normalized load profile curves for domestic customer groups to estimate feeder power loss
(Information Technology Research Unit, Faculty of Information Technology, University of Moratuwa, Sri Lanka, 2018) Jayawardhana, HACH; Hemapala, KTMU; Bandara, AWAL; De Silva, PSN; Wijesiriwardana, CP
In a country, domestic electricity customer percentage is higher in number wise, but energy usage of one customer is lower compared to other categories. Therefore, installing a load profile recording meter for each domestic customer is not worthwhile and impractical. In this research, a methodology is proposed to estimate domestic customer load profile by using customer information to avoid the use of advanced costly energy meter. In methodology, the domestic customers were divided into several groups by clustering their daily load profiles according to differences of patterns. Representative normalized load profile is defined for each group. Same customers were interviewed for collecting family member information and electric equipment usage information. Relationships between load profile and customer information were investigated. Then a methodology was developed to estimate load profile of another new customer. These load profiles were used for calculation of low voltage feeder power loss estimation. As outcome of this research, MATLAB GUI software interface was developed to input customer information and selection of relevant load profile of a new customer depending on customer information. An algorithm is proposed to estimate hourly LV feeder power loss variation by using preestimated customer load profiles.
item: Conference-Abstract
Demand side management for micro grids through smart meters
Hemapala, KTMU; Kulasekera, AL
Microgrid is a small scale power system consisting of distributed small power facilities such as solar power, wind power and micro-turbines. The microgrid has been researched and encouraged actively in many countries, because of some merits such as an eco-friendly system, good quality power supply and energy security. Microgrid power generation satisfies the power requirement of considerable number of consumers during the islanded operation. During this off grid time of operation a Demand Side Management (DSM) system can be used for better power distribution among the consumers. DSM promotes the efficient usage of power, while focusing on the network stability and reliability. Because it monitors the real time power consumption of users and automatically distribute the excess power of the system while controlling the power usage of the users to keep the network stability. The authors have developed few smart meter units, robust communication system and a main server to help to transmit the real time information to the consumer as well as to the main control unit which runs the DSM program.
item: Conference-Extended-Abstract
Demand side management for micro grids through smart meters
(2011) Wettasinghe, WADSL; Widisinghe, HR; Wijayasekara, PDDS; Wijesekara, SRMDTS; Hemapala, KTMU
A microgrid is a small scale power system consisting of distributed small power facilities such as solar power, wind power and micro-turbines. Because of some merits such as an eco-friendly system, good quality power supply and energy security, the microgrid has been researched and encouraged actively in many countries.For commercialization, the effective operation for the micro grid is very important. Microgrid power generation satisfies the power requirement of considerable number of off-grid consumers. Therefore consumers are limited to a low power usage. A Demand Side Management (DSM) system can be used for better power distribution among the consumers which is not in use nowadays. In this project the authors have made a network among consumers through Smart meters which are providing the ability to measure the real time power consumption and send those usage stats to the central server.
item: Conference-Full-text
Demand side management for micro grids throughs Smart meters
(2011) Widisinghe, HR; Wijayasekara, SRMDTS; Wettasinghe, WADSL; Hemapala, KTMU; Wijayasekara, PDDS
A microgrid is a small scale power system consisting of distributed small power facilities such as solar power, wind power and micro-turbines. Because of some merits such as an eco-friendly system, good quality power supply and energy security, the microgrid has been researched and encouraged actively in many countries. For commercialization, the effective operation for the microgrid is very important. Microgrid power generation satisfies the power requirement of considerable number of off-grid consumers. Therefore consumers are limited to a low power usage. A Demand Side Management (DSM) system can be used for better power distribution among the consumers which is not in use nowadays. In this project the authors have made a network among consumers through Smart meters which are providing the ability to measure the real time power consumption and send those usage stats to the central server.
item: Article-Abstract
Design and development of a landmines removal robot
Hemapala, KTMU; Razzoli, RP
Humanitarian demining is a calamity of war affecting many third world countries. Mines are cheap weapons, built to sustain horrible injuries that target active people with a knock‐on effect upon economic growth. The clearing is time consuming and expensive. Clearing is an engineering duty and the humanitarian goal is a technical challenge. Advanced robotics fulfils this task cleanly and reliably on the condition that upgrades and cost are met, meaning that they lose third‐world appropriateness. The challenge is to turn local machines and awareness into effective robotic aids, willingly used by the local people, and to enhance the on‐going outcomes. The solution to the demining problem shall be a low cost robotic outfit with resort to nearby available resources and competences (e.g., drawn from the local agricultural machinery and know‐how). This paper discusses an ongoing project that aims to develop a low‐cost robot with intelligent remote‐command abilities, as a cheap productivity upgrading, assembled from standard farming devices, through the shared know‐how and commitment of locally involved operators. During the study, the authors have developed a low‐cost robot capable of removing mines. The robot consists of modified agricultural components including its mobile carrier and the mine effectors.
item: Article-Abstract
Design and development of a landmines removal robot
(2016-09-06) Hemapala, KTMU; Razzoli, RP
Humanitarian demining is a calamity of war affecting many third world countries. Mines are cheap weapons, built to sustain horrible injuries that target active people with a knock‐on effect upon economic growth. The clearing is time consuming and expensive. Clearing is an engineering duty and the humanitarian goal is a technical challenge. Advanced robotics fulfils this task cleanly and reliably on the condition that upgrades and cost are met, meaning that they lose third‐world appropriateness. The challenge is to turn local machines and awareness into effective robotic aids, willingly used by the local people, and to enhance the on‐going outcomes. The solution to the demining problem shall be a low cost robotic outfit with resort to nearby available resources and competences (e.g., drawn from the local agricultural machinery and know‐how). This paper discusses an ongoing project that aims to develop a low‐cost robot with intelligent remote‐command abilities, as a cheap productivity upgrading, assembled from standard farming devices, through the shared know‐how and commitment of locally involved operators. During the study, the authors have developed a low‐cost robot capable of removing mines. The robot consists of modified agricultural components including its mobile carrier and the mine effector.