Nipun Damor - Academia.edu (original) (raw)
Papers by Nipun Damor
Environmental Modelling and Software, 2008
Recent trends in the management of water supply have increased the need for modelling techniques ... more Recent trends in the management of water supply have increased the need for modelling techniques that can provide reliable, efficient, and accurate representation of the complex, non-linear dynamics of water quality within water distribution systems. Statistical models based on artificial neural networks (ANNs) have been found to be highly suited to this application, and offer distinct advantages over more conventional modelling techniques. However, many practitioners utilise somewhat heuristic or ad hoc methods for input variable selection (IVS) during ANN development. This paper describes the application of a newly proposed non-linear IVS algorithm to the development of ANN models to forecast water quality within two water distribution systems. The intention is to reduce the need for arbitrary judgement and extensive trial-and-error during model development. The algorithm utilises the concept of partial mutual information (PMI) to select inputs based on the analysis of relationship strength between inputs and outputs, and between redundant inputs. In comparison with an existing approach, the ANN models developed using the IVS algorithm are found to provide optimal prediction with significantly greater parsimony. Furthermore, the results obtained from the IVS procedure are useful for developing additional insight into the important relationships that exist between water distribution system variables.
IEEE Transactions on Software Engineering, 2008
Test adequacy criteria provide the engineer with guidance on how to populate test suites. While a... more Test adequacy criteria provide the engineer with guidance on how to populate test suites. While adequacy criteria have long been a focus of research, existing testing methods do not address many of the fundamental characteristics of distributed systems, such as distribution topology, communication failure, and timing. Furthermore, they do not provide the engineer with a means to evaluate the relative effectiveness of different criteria nor the relative effectiveness of adequate test suites satisfying a given criterion. This paper makes three contributions to the development and use of test adequacy criteria for distributed systems: 1) a testing method based on discrete-event simulations, 2) a fault-based analysis technique for evaluating test suites and adequacy criteria, and 3) a series of case studies that validate the method and technique. The testing method uses a discrete-event simulation as an operational specification of a system in which the behavioral effects of distribution are explicitly represented. Adequacy criteria and test cases are then defined in terms of this simulation-based specification. The fault-based analysis involves mutation of the simulation-based specification to provide a foil against which test suites and the criteria that formed them can be evaluated. Three distributed systems were used to validate the method and technique, including the Domain Name System (DNS).
The voltage instability phenomena may occur in distribution networks. The decline of voltage stab... more The voltage instability phenomena may occur in distribution networks. The decline of voltage stability level will restrict the increase of load served by distribution companies. Distributed generation (DG) is increasingly drawing great attention of people. The development of DGs will bring new chances to traditional power systems. DGs connected to distribution networks are potential to improve the system voltage stability. In this paper, the familiar interfaces between DGs and distribution networks are introduced. The operation modes and control characteristics of typical DGs, including asynchronous generators, synchronous generators with constant values of excitation voltage, and fuel cells, are analyzed. Based on the models of DGs proposed in power flow calculations, a new method for constructing a sensitivity matrix is presented, which is available to calculate the power flow of distribution networks with multiple types of DGs. Using this method presented here, the impacts of DGs on the system voltage stability are studied. These impacts are quantified by a voltage stability index introduced in this paper. Some important conclusions are obtained. A 90-bus system is analyzed to give an illustration of the feasibility of the proposed method
IEEE Transactions on Energy Conversion, 2011
This paper presents the analyzed results of both dynamic simulations and steady-state performance... more This paper presents the analyzed results of both dynamic simulations and steady-state performance of a tidal power generation system (TPGS) containing a permanent-magnet synchronous generator (PMSG) driven by a tidal turbine through a gearbox. The stator windings of the tidal PMSG are connected to an onshore distribution system through an ac-to-dc converter, a dc-to-ac inverter, a step-up transformer, and a transmission cable. A d-q axis equivalent-circuit model is employed to establish complete dynamic equations of the studied system under threephase balanced loading conditions. A frequency-domain approach based on eigenvalue analysis and a time-domain scheme based on nonlinear-model simulations are both carried out to systematically determine the dynamic stability of the studied system under different operating conditions. It can be concluded from the simulation results that the studied TPGS subject to different disturbance conditions can maintain stable operation.
In this paper, charging effect of dynamic Plug in Hybrid Electric Vehicle (PHEV) is presented in ... more In this paper, charging effect of dynamic Plug in Hybrid Electric Vehicle (PHEV) is presented in a renewable energy based electricity distribution system. For planning and designing a distribution system, PHEVs are one of the most important factor as it is going to be a spinning reserve of energy, and also a major load for distribution network. A dynamic load model of PHEVs is introduced here based on third order battery model. To determine the system adequacy, it is necessary to do a micro level analysis to know the PHEVs load impact on grid. Scope of such analysis will cover the performance of wind and solar generation with dynamic PHEVs load, as well as the stability analysis of the power grid to demonstrate that it is important to consider the dynamics of PHEVs load in a renewable energy based distribution network.
Environmental Modelling and Software, 2008
Recent trends in the management of water supply have increased the need for modelling techniques ... more Recent trends in the management of water supply have increased the need for modelling techniques that can provide reliable, efficient, and accurate representation of the complex, non-linear dynamics of water quality within water distribution systems. Statistical models based on artificial neural networks (ANNs) have been found to be highly suited to this application, and offer distinct advantages over more conventional modelling techniques. However, many practitioners utilise somewhat heuristic or ad hoc methods for input variable selection (IVS) during ANN development. This paper describes the application of a newly proposed non-linear IVS algorithm to the development of ANN models to forecast water quality within two water distribution systems. The intention is to reduce the need for arbitrary judgement and extensive trial-and-error during model development. The algorithm utilises the concept of partial mutual information (PMI) to select inputs based on the analysis of relationship strength between inputs and outputs, and between redundant inputs. In comparison with an existing approach, the ANN models developed using the IVS algorithm are found to provide optimal prediction with significantly greater parsimony. Furthermore, the results obtained from the IVS procedure are useful for developing additional insight into the important relationships that exist between water distribution system variables.
IEEE Transactions on Software Engineering, 2008
Test adequacy criteria provide the engineer with guidance on how to populate test suites. While a... more Test adequacy criteria provide the engineer with guidance on how to populate test suites. While adequacy criteria have long been a focus of research, existing testing methods do not address many of the fundamental characteristics of distributed systems, such as distribution topology, communication failure, and timing. Furthermore, they do not provide the engineer with a means to evaluate the relative effectiveness of different criteria nor the relative effectiveness of adequate test suites satisfying a given criterion. This paper makes three contributions to the development and use of test adequacy criteria for distributed systems: 1) a testing method based on discrete-event simulations, 2) a fault-based analysis technique for evaluating test suites and adequacy criteria, and 3) a series of case studies that validate the method and technique. The testing method uses a discrete-event simulation as an operational specification of a system in which the behavioral effects of distribution are explicitly represented. Adequacy criteria and test cases are then defined in terms of this simulation-based specification. The fault-based analysis involves mutation of the simulation-based specification to provide a foil against which test suites and the criteria that formed them can be evaluated. Three distributed systems were used to validate the method and technique, including the Domain Name System (DNS).
The voltage instability phenomena may occur in distribution networks. The decline of voltage stab... more The voltage instability phenomena may occur in distribution networks. The decline of voltage stability level will restrict the increase of load served by distribution companies. Distributed generation (DG) is increasingly drawing great attention of people. The development of DGs will bring new chances to traditional power systems. DGs connected to distribution networks are potential to improve the system voltage stability. In this paper, the familiar interfaces between DGs and distribution networks are introduced. The operation modes and control characteristics of typical DGs, including asynchronous generators, synchronous generators with constant values of excitation voltage, and fuel cells, are analyzed. Based on the models of DGs proposed in power flow calculations, a new method for constructing a sensitivity matrix is presented, which is available to calculate the power flow of distribution networks with multiple types of DGs. Using this method presented here, the impacts of DGs on the system voltage stability are studied. These impacts are quantified by a voltage stability index introduced in this paper. Some important conclusions are obtained. A 90-bus system is analyzed to give an illustration of the feasibility of the proposed method
IEEE Transactions on Energy Conversion, 2011
This paper presents the analyzed results of both dynamic simulations and steady-state performance... more This paper presents the analyzed results of both dynamic simulations and steady-state performance of a tidal power generation system (TPGS) containing a permanent-magnet synchronous generator (PMSG) driven by a tidal turbine through a gearbox. The stator windings of the tidal PMSG are connected to an onshore distribution system through an ac-to-dc converter, a dc-to-ac inverter, a step-up transformer, and a transmission cable. A d-q axis equivalent-circuit model is employed to establish complete dynamic equations of the studied system under threephase balanced loading conditions. A frequency-domain approach based on eigenvalue analysis and a time-domain scheme based on nonlinear-model simulations are both carried out to systematically determine the dynamic stability of the studied system under different operating conditions. It can be concluded from the simulation results that the studied TPGS subject to different disturbance conditions can maintain stable operation.
In this paper, charging effect of dynamic Plug in Hybrid Electric Vehicle (PHEV) is presented in ... more In this paper, charging effect of dynamic Plug in Hybrid Electric Vehicle (PHEV) is presented in a renewable energy based electricity distribution system. For planning and designing a distribution system, PHEVs are one of the most important factor as it is going to be a spinning reserve of energy, and also a major load for distribution network. A dynamic load model of PHEVs is introduced here based on third order battery model. To determine the system adequacy, it is necessary to do a micro level analysis to know the PHEVs load impact on grid. Scope of such analysis will cover the performance of wind and solar generation with dynamic PHEVs load, as well as the stability analysis of the power grid to demonstrate that it is important to consider the dynamics of PHEVs load in a renewable energy based distribution network.