Browsing by Author "De Silva, PSN"

Now showing 1 - 14 of 14

item: Thesis-Full-text
Automated demand response for a commercial building : a model design and pilot study
Fernando, CTJ; De Silva, PSN; Rodrigo, WDAS
The inherent intermittency of non-conventional renewable resources has been the major impediment in admitting renewable resources to the traditional Electricity Grid. The flexibility of loads in the power system are disregarded in such analysis. The traditional Utility and Customer model is now subjected to change with active customer participation from demand side. With the growing renewable share in the Energy mix, power industry will require more capacity and inertia to have a better control over the power quality. Automated Demand Response is the cutting edge technology which enables the grid to use load flexibility in counteracting the NCRE intermittency. This project pilots the possibility of mitigating the rooftop solar intermittency of a building with air conditioning loads which has an inherent flexibility as DR resources. A building-wide Home Area Network is implemented together with short term solar prediction and a central controller with dynamic dispatch algorithm. esults from the pilot project are presented to demonstrate as how the solar transients are mitigated at the Point of Common Coupling (PCC) with an eye on benefits and impacts on the participants.
item: Conference-Full-text
Converting a commercial-consumer-fed, ring distribution system into a diesel-solar hybrid microgrid: technical feasibility
(IEEE, 2022-07) Herath, HDBP; Arachchige, LNW; De Silva, PSN; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Complex distribution networks like ring or meshed networks are applied for commercial and industrial cities demanding reliable power supply. Diesel generators are connected to the network to maintain system reliability under emergency states. With increasing penetration of non-dispatchable, rooftop solar-PV, proper planning is required to maintain system stability and reliability. Commercial and industrial cities do not follow the conventional diurnal load patterns, but presents load patterns similar to the diurnal generation curve of solar-PV. Thus, by introducing solar-PV, required diesel generation capacity can be reduced. Also, the system reliability and stability can be improved if the system is operated as a microgrid. The ability of forming ring-radial connected hybrid-microgrid based on an existing network for a commercial city with peak day-time loading is evaluated. Small-signal stability analysis reveals that, even with 100% solar-PV, the islanded microgrid in normal state is stable under different diesel generation integration topologies tested. The system becomes unstable due to small perturbations under the N-l emergency operation in some topologies. This study allowed identification of the proper diesel generation integration topology for the proposed microgrid.
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
Develop a series arc fault detector to minimize the risk of domestic electrical fires
Somathilaka, SP; Hewapathirana, HE; De Silva, PSN; Sumathipala, WMKS; Hemapala, KTMU; Senarathna, NT; Lucas, NT
This study is about the development of a series arc fault detector, which can be used to minimize the risk of domestic electrical fires. Electricity is a common cause of fire in residential buildings. If a parallel electrical arc fault is developed it can be detected from the residual current circuit breaker. If the arc current is higher than the rated current of the circuit, it can be detected from the miniature circuit breaker. But, if a series arc fault is developed which is lower than the rated current of the circuit, it cannot be detected by those conventional devices. In this study, an arc generator which could be connected to any electrical equipment was developed for generating a series arc fault. A set of different methods such as Fast Fourier Transform, Derivative Analysis, Discrete Wavelet Transform and Continuous Wavelet Transform were used to analyze the current and voltage waveforms in the presence and absence of series arc fault. However, only some of those methods yielded promising results. Moreover, an analysis about the parameters which will affect the risk of fire was conducted. Further research regarding the development of the series arc fault detector is in progress.
item: Thesis-Full-text
Development of a state estimation algorithm for the electrical distribution system
Mahalaksha, MMHCN; De Silva, PSN; Rodrigo, WDSN; Samarasinghe, R
Over the past decade, the complexity of the electrical distribution network has been significantly increased. Power flow of the network has been changed from unidirectional to a dynamic scenario with the introduction of distributed energy generators, and the network complexity has been increased with the introduction of numerous power electronic devices and the diversification of loads. In order to ensure the reliability of this complex network, it is essential to provide accurate information and feedback to the control center governing it. If the system operator knows exactly where the system stands in terms of its stability and operation, he would be able to get the best decision in any situation. This has created a demand for more sophisticated tools and equipment which aids in network monitoring and analysis in present time. Real time modeling of the network plays a vital role in achieving this. Further, implementation of a grid wide sensor network is one of the primary requirements of a smart grid. Extraction of the exact state of the network, to create a decision support system, is impairable from building a user friendly smart grid. This project envisages a methodology, as to how a medium scale distribution company can make use of the imperfect data from their smart meters, distribution automation devices and boundary meters to derive an accurate, real time, network status map for distribution control center operation. In this project, a statistical criterion based on the weighted least square method of power system state estimation has been used to demonstrate a successful, consistence network voltage and current estimation system, which has been developed to be the core of a practical distribution control center operation software. The network topology is directly extracted from the Geographical Information System (GIS), enabling to grab the most updated picture of this rapidly evolving system.
item: Thesis-Abstract
Distribution system reliability modeling and analysis
(2015-02-22) Gamage, MD; Kumarawadu, S; De Silva, PSN
With the background of imposing new electricity act and the regulatory regime for electricity industry, utilities have to be concerned not only the cost of the electricity but also the quality of the supply. As the cost of electricity is embedded to the electricity tariff, cost of reliability will also be added to the tariff in near future. Hence, utilities need to have a reliability study model to enhance the reliability of power supply at optimum level. Aim of this research is to formulate methodology to calculate supply reliability to end user by component reliability. Past three years outage data of Lanka Electricity Company (LECO) had been analysed to calculate reliability of critical path components of the distribution network. Two reliability models named direct restoration method and step restoration method had been applied to calculate sustained end user reliability indices such as SAIDI and SAIFI. End user reliability indices had been calculated using the derived component reliability for the selected distribution network portion of LECO for this purpose. Finally, the results had been compared with the absolute data for the same network as a measure of model validation. The result from the direct restoration model is deviated from the recorded results. It is noted that the results calculated by step restoration model comply with the recorded data. There were instances of deviation caused due to the non conformity of step restoration Markovian model of the network portion. Considering the validation of results, it was identified that LECO distribution network reliability shall be modeled using step restoration model. It is also noted that due to the statistical nature of component reliability, the results are also statistically distributed. The requirement of utilities to incorporate reliability criteria into their planning objectives is a requirement today in view of the regulatory governance of the electricity sector. The tariff when comes cost reflective essentially needs to incorporate cost of reliability as well.
item: Thesis-Full-text
Feasibility study on distribution transformer based urban grid connected energy islands with distributed generation
Amarasinghe, HPP; De Silva, PSN; Jayatunga, JVUP
Sri Lanka’s distribution network has been facing drastic changes during recent past due to the continuous addition of distributed renewable generation into the network. Addition of rooftop solar PV into the low voltage distribution feeders has significantly increased during 2016-2017, due to the government initiative “Surya Bala Sangramaya” on promoting rooftop solar generation. As a result, in highly populated urban areas, some distribution transformer service areas now have more than 50% of installed solar rooftop capacity, compared to the connected transformer capacity. These transformers export power to the medium voltage network from low voltage side during daytime due to high solar generation and low energy usage inside these service areas. An increasing number of transformers will experience such reverse power flow in near future with the acceleration of promoting rooftop solar programs. Operating with higher density of rooftop solar in distribution transformer service areas will result in numerous power quality issues and higher distribution losses in spite of the advantages of utilizing household rooftops for solar PV generation. In this study, a futuristic solution is proposed to effectively utilize the daytime solar PV generation in a single distribution transformer service area itself with the formation of smart grid type operation. Distribution transformer based smart grid, which operates with controlling mechanisms, loads, rooftop solar and battery storage systems is discussed in this report. This system can be developed and operated as a community-based smart grid that is formed inside the distribution transformer service area with the contribution of the electricity customers. Other than operating as individual energy customers and energy producers, public can become procumers who operate and control their loads and PV generation together to optimize load flow, power quality and economics in this proposed smart grid. This research is a preliminary study to identify the possibility of such distribution transformer based smart grid for Lanka Electricity Company Private Limited operation area. Extensive simulations were carried out using Matlab Simulink by modeling the three phase four wire LV network for a single transformer area to identify the present behavior of the LV Network. Then the model was upgraded to proposed future smart grid arrangement. Results on the customer behaviors, load flows and power quality on both normal and smart grid type scenarios are presented for several case studies including the present situation, future expected situation and for the proposed smart grid. As the outcome of this research, simulated results were obtained for smart grid arrangement inside an actual transformer service area and technical compatibility of the concept is presented to the Sri Lankan urban distribution transformers.
item: Thesis-Full-text
High impedance fault identification and localization in MV distribution feeders
De Silva, PT; Lucas, JR; De Silva, PSN
High Impedance Faults (HIF) in distribution feeders are kind of an abnormal condition that most of the electric distribution utilities face if they are maintaining a bare overhead distribution network. These faults cause not only poor quality of supply to the consumers but an immense threat to their lives, if not well managed. By nature, identification and localization of these faults are very hard due to the limited current it draws from the source. But the severe potential threat remains same as it takes distribution medium voltage in to human reach unnoticed. This study focuses on developing a methodology that can be simply implemented by the utilities to identify and localize the HIF. As a summary, starting from data acquisition, this study identifies a methodology to detect and localize the HIF and finally provides an insight on how to implement the proposed methodology. Data acquisition is one of the main difficulties faced by the distribution utilities to monitor and identify the network conditions and take necessary precautions over the anomalies before or after the particular incidents. This is mainly due to the high cost incurred for each measuring device installed in the field with the required insulation levels up to the operating voltage classes. This study has proposed a unique time stamp based data acquisition device (based on the concept of Phasor Measurement Units) mounted on top of the conductors to collect the required data and wirelessly transmit over to a terminal unit mounted on the pole. The transmitted data is then processed in this pole mounted concentrator and notifies a central server about the identified network anomaly. Extensive simulation analysis carried out by this study using MATALAB SIMULINK shows that the proposed methodology provides an accurate way to identify and localize the HIF under various network operational conditions.
item: Thesis-Abstract
Modeling and control of a surface vessel for "ITS for the Sea" applications
Kumara, KJC; Kumarawadu, S; De Silva, PSN
In the emerging field of intelligent transportation systems (ITS), ''TS for the sea'' refers to the area of maritime traffic. Automated vehicle control systems are a key technology for ITS. An autonomous surface vessel (ASV) can be defined as a vehicle controlling its own steering and speed for Navigation, dynamic positioning, motion stabilization and obstacle detection and avoidance. The scope of the research is defined by two main objectives viz. developing complete mathematical model of a surface vessel by analyzing hydrodynamic forces and main other effects arising when manoeuvring in the ocean, and design online-learning adaptive controller for path tracking and speed control using real control inputs; propeller thrust and steering angle. The vessel moves in a hydrodynamic environment where many uncertainties, non-linear and non-predictive behaviours always appear. The ocean vehicle is modelled mathematically using first principles and derivations wherever possible. In this work, the problem of control with guaranteed sway and yaw stability for automated surface vessel operation is addressed with special emphasis on speed control. A control scheme to solve this problem without simplifying the dynamics is proposed and extensively studied using formative mathematical analyses and simulations. The main academic motivation of this research was to study and synthesis the power of artificial intelligence techniques in controlling of non-linear dynamical systems with online-learning and adaptive capabilities. A model-based neural network adaptive controller is developed blending a self adaptive neural network module and a classical Proportional plus Derivative (PD)-like control to obtain optimum control performance by complementing each other. The adaptive neural module counteracts for inherent model discrepancies, strong nonlinearities and coupling effects.
item: Thesis-Full-text
Network optimization based load balancing technique for LV electricity distribution network
Hewage, GHC; De Silva, PSN; Hemapala, KTMU
Network optimization is vital requirement for all the electricity distribution companies. Energy loss reduction, fulfill the statutory requirements, lifetime improvements of the network accessories and healthy operation of network are some of benefits of network optimization. Load arrangement within the network is one of key factor influence for network condition. Proper load balancing mechanism among phases is based on the appropriate positioning of consumers within the electricity distribution network which empowers network optimization. So load balancing can be referred as way of consumer arrangement within the context of electricity distribution. Ceylon Electricity Board (CEB) and Lanka Electricity Company (LECO) are the utilities responsible for electricity distribution within Sri Lanka. Presently there is not proper methodology used for load balancing by Sri Lankan electricity utilities. According to the electricity demand growth and increasing sensitivity to network by consumers, better network planning methodology will be required to cater their requirements. In order to address this issue, this dissertation focuses on development of network optimization based load balancing technique for LV electricity distribution network. Actual features enriched distribution network model and appropriate power flow analysis method are essential infrastructure for accurate determination network condition. Such kind of platform can be used to evaluate different consumer arrangement patterns along low voltage feeders using their load profiles to find network optimized arrangement. Consumer load profiles can be represented by characteristic curves which illustrate their electrical behavior. Evaluation of network status generated due to combined effect throughout each and every point of consumer load profiles for all consumer arrangement patterns provide better result rather than just consideration of particular set of values. Three phase four wire neutral grounded systems are using for electricity distribution in Sri Lanka. Incorporation of ground return path in to network model is considered within this research work. Applicability of forward backward load flow techniques is validated for proposed distribution network model. Proposed an algorithm for network optimization based load balancing which provide consumer arrangement plan at nodes for a certain low voltage feeder of distribution network. Generally, this study provides the platform for network planners to find best arrangement of consumers at the network to achieve optimum network condition. This can be used for existing network evaluation as well as future planning of the distribution networks.
item: Thesis-Full-text
Spatial electric load forecasting model for Sri Lanka
Madawala, MK; Lucas, JR; De Silva, PSN
With the high level of city expansion observed during the last few decades, distribution utilities currently face new challenges when planning network expansion with profitable operations. Thus distribution utilities should consider spatial electric load forecasting as the basis for the planning of the electricity distribution networks. Spatial electric load forecasting helps in determining how the increase in demand of electrical energy will be distributed geographically in the service area. In Sri Lanka, the load forecasting in distribution planning is mainly based on trending methods which lacks the accuracy needed for present dynamic consumer market. The objective of this research is to prepare a simple yet accurate and effective spatial electric load forecasting model which can be used in the local context. This research deals with a new method for spatial electric load forecasting using artificial neural networks. The electric load growth inside the service area of an electric utility can be expected for two reasons, natural load growth of existing consumers and addition of new loads because of new consumers. In the study, the addition of new consumers in future is regarded as the new load additions in the vacant areas. This is forecasted using the spatial electric load forecasting model implemented using artificial neural network. The growth of existing consumers is addressed with a constant growth. The implemented model is presented and tested with data from two real midsized cities. The outcome is compared with the ones obtained from the utility planning department existing software. The results illustrate that the proposed model provides an accurate and user-friendly technique to predict yearly residential electrical load in Sri Lanka
item: Conference-Abstract
Spatial load forecasting model for Sri Lanka
(2008) De Silva, PSN; Rasara, HL; Wijesinghe,WNU; Bartholomeuz, SA; Kalyanarathne, NDPSR
This paper presents a Spatial Load Forecasting Model that yields to an accurate prediction of both magnitude and locations of future electric loads in the Sri Lankan context. This paper also discusses about fuzzy logic technique which is primarily used to decide the consumer classes based on membership functions which are derived using actual data instead of the more traditional approaches. Finally it will conclude with a discussion of the suitability of the proposed model to Sri Lanka.
item: Thesis-Full-text
Techno economic analysis, design and implement a suitable communication method for utility systems
Dunuweera, MS; De Silva, PSN; Hemapala, KTMU; Wavegedara, C
This thesis presents a research work which is carried out to optimize the Zigbee based remote meter reading network. There are various technologies available to automate the meter reading such as PLC, GSM, Optical fibre and RF technologies. As far as utilities providers are concerned, their focus is on a reliable RMR system to read the meter at minimum possible cost. The development of a reliable RMR system is highly dependent on telecommunication infrastructure which is costly if GPRS is used as a way of communication. Therefore, research were done in depth to analyse the cost and function of RMR system as large number of sensors are used in the electrical utility. This particular research is on data concentrator based RMR system focusing on the analysing of communication delay and resource optimization. In this research Matlab Simulink software was used for simulations and Visual Studio C# is used for creating the software. Several simulations were carried out in this research, for simulating communication speed, communication path and study the behaviour with the presence of noises. As the final outcome of the research, software was developed for selecting Zigbee power rating based on GPS locations and generated algorithms for calculating communication delay and path which can be incorporated to the coordinator.
item: Thesis-Full-text
Unified power flow controllers as power system stabilizer
Warusapperuma, WKMP; Lucas, JR; De Silva, PSN
The FACTS device - Unified Power Flow Controller (UPFC) and its performance is studied under transient condition in the usage as a power system stabilizer. This device creates an impact on power system stability with its unique capability to control real and reactive power flows simultaneously on a transmission line and regulate voltage at the bus connected. These features become significant as the UPFC can allow loading of the transmission lines up to their thermal limits by regulating the power flow through desired paths. This gives the power system operators the desired flexibility in satisfying the deregulated power system imposed requirements. The new technology associated with the UPFC and its structure is studied. The theoretical analysis is done in verifying its capability for stability enhancement. A practical system IS modelled to verify the theoretical analysis in MATLAB/SIMULINK platform. Theoretical and practical verification reveals the function of UPFC in power system stabilisation. The parameters associated with the UPFC are studied for optimum stability criterion.