Asanka Rodrigo | University of Moratuwa Sri Lanka (original) (raw)
Papers by Asanka Rodrigo
Engineer, Jul 12, 2019
Power system losses have turned out to be a major challenge for electricity utilities worldwide. ... more Power system losses have turned out to be a major challenge for electricity utilities worldwide. Bulk of the losses in power system occurs in electricity distribution. The overall energy loss and the distribution system loss in the Sri Lanka power system were about 10% in 2016. Before formulating strategies for loss reduction, it is essential to segregate and determine the losses at each level. Once losses are segregated, utilities can clearly identify their priorities and launch effective programmes to arrest losses. This paper discusses a method to segregate losses in a selected area of the electricity distribution system, Sri Lanka. The electricity distribution network in Gampaha district, Sri Lanka that belongs to the Ceylon Electricity Board(CEB), was selected for the study. Accordingly, the losses were segregated into medium voltage network loss, losses in distribution transformers and low voltage network loss. A study was also carried out to further segregate losses into technical and non-technical components in the low voltage networks of two distribution substations. Technical losses were estimated and thereby non-technical losses were derived. Test results of electricity meters were also analysed to assess contribution to Non-Technical Losses (NTL).
This p a p e r discusses a m e t h o d of i m p l e m e n t i n g t h e d e t e c t i o n of p u ... more This p a p e r discusses a m e t h o d of i m p l e m e n t i n g t h e d e t e c t i o n of p u p i l c e n t r e a n d c o r n e a l reflection f o r a l o w cost, r e m o t e eye t r a c k i n g system t h a t is d e s i g n e d f o r u s a b i l i t y a n a l y s i s researches. The m e t h o d we have used t o measure t h e eye gaze is t r a c k i n g c o r n e a l reflection a n d t h e p u p i l c e n t r e of t h e eye, w h e r e t h e p a p e r focuses o n how those f e a t u r e s a r e t r a c k e d f r o m a v i d e o i n p u t t h a t have c a p t u r e d t h e subjects ' eye movements. The m e t h o d suggested h e r e is c a p a b l e of t r a c k i n g t h e p u p i l c e n t r e even f r o m a n eye w i t h less c o l o u r c o n t r a s t between t h e p u p i l a n d t h e i r i s a n d a l s o endures h e a d movements of t h e subjects. The test r e s u l t s a r e i n c l u d e d i n terms of a c c u r a c y of t h e m e t h o d t o t h e changes i n p o i n t of gaze a n d d i s t a n c e between t h e c o m p u t e r screen a n d t h e user. The l i m i t a t i o n s of m o d e r n eye t r a c k e r s a n d p o s s i b l e s o l u t i o n s a r e a l s o addressed i n t h i s p a p e r .
2022 36th International Conference on Lightning Protection (ICLP), Oct 2, 2022
Engineer, Jul 26, 2020
Traditionally, Static Thermal Rating (STR) calculates current carrying capacity based on “Worst c... more Traditionally, Static Thermal Rating (STR) calculates current carrying capacity based on “Worst case weather conditions”, which is used by most of the utilities around the world including Sri Lanka. Assumptions made in the STR calculations may reduce the actual line capacity whenever real weather conditions are less stressful. However, the smart-grid technology based Real Time dynamic Thermal Rating (RTTR) allows to utilize the overhead line conductors by increasing the current carrying capacity of the line based on real time weather data. The identification of critical span to ensure the minimum electrical clearance is the major consideration to ensure the safety of the people and equipment when applying RTTR method. This paper presents a method to introduce real time thermal rating to overhead transmission lines in Sri Lanka. Current rating of lines is calculated using real time weather data. In here, the selected line sections have been analysed using PLSCADD software with RTTR design. This novel methodology can be used by system operators to analyse weather based current ratings for the transmission network in future.
2022 Moratuwa Engineering Research Conference (MERCon), Jul 27, 2022
Engineer, Oct 21, 2013
Due to intense fuel dependency on energy production in the world, cost of energy is now heavily d... more Due to intense fuel dependency on energy production in the world, cost of energy is now heavily depends on the prices of fossil fuels. Most of the countries in the world are suffering due to this and Sri Lanka is no exception. It is in this context promotion of biomass, as a renewable source, is so vital to the country. Rice being the staple food of the country as well as the crop with highest land area under cultivation, rice husk (RH) generated in paddy processing was found to have a significant potential in power generation. This paper investigates the possibility of using rice husk as a viable source of power generation in Sri Lanka. It is clearly seen that there is a significant potential in the districts of Ampara, Polonnaruwa, Anuradhapura and Kurunegala for power generation using rice husk. It was found that 30% of excess RH can be exploited for power generation with an annual energy potential of 180 GWh. This potential can be exploited by (1) Commercial scale RH power plants, (2) Small scale power plants under net metering scheme and (3) Off grid RH power plants.
Energy Conversion and Management, Aug 1, 2007
Traditionally, the electricity purchase tariff of embedded generators reflected only the cost of ... more Traditionally, the electricity purchase tariff of embedded generators reflected only the cost of production and delivery of electricity to the consumers, which includes the costs of labor, capital, operation, taxes and insurance. However, the production of electricity causes adverse impacts on the environment. At present, this issue has not been widely addressed by the existing pricing methodologies. This paper proposes a pricing methodology for renewable energy based embedded electricity generation, incorporating the cost of externalities with a case study on the Sri Lanka power system. It recommends that the embedded generation tariff be based on the principle of ''avoided cost'', considering the cost of energy production, cost of externalities and the cost of network losses. While the ''impact path way'' approach is proposed for calculation of the cost of externalities of energy, the nodal-based cost calculation is proposed for the avoided cost of network losses calculation. The pricing methodology proposed in the paper provides important information for investors when choosing the most economical site for their development. It can also be used to optimize the network use. These will allow the developers of embedded generation facilities and the utilities operating the national grid to maximize the potential of embedded generation.
2022 Moratuwa Engineering Research Conference (MERCon), Jul 27, 2022
Power systems, Sep 27, 2017
Power systems, Sep 27, 2017
SLEMA Journal, Sep 30, 2017
Installation of grid-connected rooftop solar power generation modules has been allowed in Sri Lan... more Installation of grid-connected rooftop solar power generation modules has been allowed in Sri Lanka since 2008. The paper analyzes the potential use of solar power inverters at night to feed reactive power to the low voltage (LV) network. The LV network typically has undervoltage issues at the evening peak-time, and the PV inverters distributed along the line can be used to eliminate or reduce such undervoltage issues. The paper proposes an algorithm to determine the suitable operating power factor of each inverter connected to the feeder. A case study of a LV distributor with solar PV inverters is presented, to demonstrate the application of the algorithm. Financial benefits to customer by introducing a reactive power tariff is assessed. The paper concludes that such a system would yield net benefits to the utility.
ABSTRACT In IEEE80:2000-Guide for Safety in AC Substation Grounding, considers the effect of stea... more ABSTRACT In IEEE80:2000-Guide for Safety in AC Substation Grounding, considers the effect of steady state behaviour of grounding grid. However, due to lightning or any other impulses generated in power system, very high voltages could be built up for a short period of time. The impact of such transient surges on substation grounding systems is studied in this paper. An approach based on Transmission Line method is used to design an equivalent circuit to the substation grounding grid. The developed designs are then simulated for transient behaviour using PSCAD software and appropriate safety parameters are evaluated to find out whether the designs need any modifications. An energy based approach which is more appropriate for transients was used to define threshold of safety. A design software incorporating the findings of the studies was developed as a final outcome.
2018 Moratuwa Engineering Research Conference (MERCon), 2018
Metal Oxide Surge Arresters (MOSA) are proven to be reliable protective devices for power distrib... more Metal Oxide Surge Arresters (MOSA) are proven to be reliable protective devices for power distribution and electrical transmission system. MOSA are subjected to electrical ageing or degradation due to constant AC conduction or transient voltages. Leakage current measured from surge arresters are used to observe its degradation and the resistive leakage component is extracted from the total to determine the health of the surge arresters. If resistive current increases, life of the surge arresters decreases. Generally, leakage current is measured using current shunts or current transformers where it’s necessary to measure the applied voltage which is very hard to measure in online condition. This paper develops an easy and accurate method to separate the resistive leakage current from the total leakage current without any voltage measurements by using a technique called Modified Phase Shifted Method (MPSM) and simulated in MATLAB which enables online monitoring system and easy to apply into a device.
2020 Moratuwa Engineering Research Conference (MERCon), 2020
Low efficiency can be identified as one of the main drawbacks of solar photo-voltaic systems. The... more Low efficiency can be identified as one of the main drawbacks of solar photo-voltaic systems. The main two factors that affect the efficiency of the existing solar photovoltaic cells are the operating temperature and the solar irradiance received by the solar cell. This paper presents an efficiency enhanced solar photo-voltaic system, which concentrates the solar irradiance through convex lenses and at the same time, cools the solar cells using a forced flow of mineral turpentine. The evaluation of the test results shows an enhancement of power output and efficiency by 60% & 32% respectively by both cooling and concentrating.
At present there is an increased focus on using renewable energy for power generation. In this pa... more 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 p...
Power systems, Sep 27, 2017
It is very important to have a clear idea about the power system we are concerning on to understa... more It is very important to have a clear idea about the power system we are concerning on to understand the necessity of a load shedding scheme. The parameters and their values that we use in the under frequency load shedding scheme influence in stabilizing the power system very much. The proposed load shedding scheme was designed referring to Ahsans’ scheme as a pilot model. Having identified the weaknesses with it the new load shedding schemes are proposed.
2022 36th International Conference on Lightning Protection (ICLP), Oct 2, 2022
Engineer, Jul 12, 2019
Power system losses have turned out to be a major challenge for electricity utilities worldwide. ... more Power system losses have turned out to be a major challenge for electricity utilities worldwide. Bulk of the losses in power system occurs in electricity distribution. The overall energy loss and the distribution system loss in the Sri Lanka power system were about 10% in 2016. Before formulating strategies for loss reduction, it is essential to segregate and determine the losses at each level. Once losses are segregated, utilities can clearly identify their priorities and launch effective programmes to arrest losses. This paper discusses a method to segregate losses in a selected area of the electricity distribution system, Sri Lanka. The electricity distribution network in Gampaha district, Sri Lanka that belongs to the Ceylon Electricity Board(CEB), was selected for the study. Accordingly, the losses were segregated into medium voltage network loss, losses in distribution transformers and low voltage network loss. A study was also carried out to further segregate losses into technical and non-technical components in the low voltage networks of two distribution substations. Technical losses were estimated and thereby non-technical losses were derived. Test results of electricity meters were also analysed to assess contribution to Non-Technical Losses (NTL).
This p a p e r discusses a m e t h o d of i m p l e m e n t i n g t h e d e t e c t i o n of p u ... more This p a p e r discusses a m e t h o d of i m p l e m e n t i n g t h e d e t e c t i o n of p u p i l c e n t r e a n d c o r n e a l reflection f o r a l o w cost, r e m o t e eye t r a c k i n g system t h a t is d e s i g n e d f o r u s a b i l i t y a n a l y s i s researches. The m e t h o d we have used t o measure t h e eye gaze is t r a c k i n g c o r n e a l reflection a n d t h e p u p i l c e n t r e of t h e eye, w h e r e t h e p a p e r focuses o n how those f e a t u r e s a r e t r a c k e d f r o m a v i d e o i n p u t t h a t have c a p t u r e d t h e subjects ' eye movements. The m e t h o d suggested h e r e is c a p a b l e of t r a c k i n g t h e p u p i l c e n t r e even f r o m a n eye w i t h less c o l o u r c o n t r a s t between t h e p u p i l a n d t h e i r i s a n d a l s o endures h e a d movements of t h e subjects. The test r e s u l t s a r e i n c l u d e d i n terms of a c c u r a c y of t h e m e t h o d t o t h e changes i n p o i n t of gaze a n d d i s t a n c e between t h e c o m p u t e r screen a n d t h e user. The l i m i t a t i o n s of m o d e r n eye t r a c k e r s a n d p o s s i b l e s o l u t i o n s a r e a l s o addressed i n t h i s p a p e r .
2022 36th International Conference on Lightning Protection (ICLP), Oct 2, 2022
Engineer, Jul 26, 2020
Traditionally, Static Thermal Rating (STR) calculates current carrying capacity based on “Worst c... more Traditionally, Static Thermal Rating (STR) calculates current carrying capacity based on “Worst case weather conditions”, which is used by most of the utilities around the world including Sri Lanka. Assumptions made in the STR calculations may reduce the actual line capacity whenever real weather conditions are less stressful. However, the smart-grid technology based Real Time dynamic Thermal Rating (RTTR) allows to utilize the overhead line conductors by increasing the current carrying capacity of the line based on real time weather data. The identification of critical span to ensure the minimum electrical clearance is the major consideration to ensure the safety of the people and equipment when applying RTTR method. This paper presents a method to introduce real time thermal rating to overhead transmission lines in Sri Lanka. Current rating of lines is calculated using real time weather data. In here, the selected line sections have been analysed using PLSCADD software with RTTR design. This novel methodology can be used by system operators to analyse weather based current ratings for the transmission network in future.
2022 Moratuwa Engineering Research Conference (MERCon), Jul 27, 2022
Engineer, Oct 21, 2013
Due to intense fuel dependency on energy production in the world, cost of energy is now heavily d... more Due to intense fuel dependency on energy production in the world, cost of energy is now heavily depends on the prices of fossil fuels. Most of the countries in the world are suffering due to this and Sri Lanka is no exception. It is in this context promotion of biomass, as a renewable source, is so vital to the country. Rice being the staple food of the country as well as the crop with highest land area under cultivation, rice husk (RH) generated in paddy processing was found to have a significant potential in power generation. This paper investigates the possibility of using rice husk as a viable source of power generation in Sri Lanka. It is clearly seen that there is a significant potential in the districts of Ampara, Polonnaruwa, Anuradhapura and Kurunegala for power generation using rice husk. It was found that 30% of excess RH can be exploited for power generation with an annual energy potential of 180 GWh. This potential can be exploited by (1) Commercial scale RH power plants, (2) Small scale power plants under net metering scheme and (3) Off grid RH power plants.
Energy Conversion and Management, Aug 1, 2007
Traditionally, the electricity purchase tariff of embedded generators reflected only the cost of ... more Traditionally, the electricity purchase tariff of embedded generators reflected only the cost of production and delivery of electricity to the consumers, which includes the costs of labor, capital, operation, taxes and insurance. However, the production of electricity causes adverse impacts on the environment. At present, this issue has not been widely addressed by the existing pricing methodologies. This paper proposes a pricing methodology for renewable energy based embedded electricity generation, incorporating the cost of externalities with a case study on the Sri Lanka power system. It recommends that the embedded generation tariff be based on the principle of ''avoided cost'', considering the cost of energy production, cost of externalities and the cost of network losses. While the ''impact path way'' approach is proposed for calculation of the cost of externalities of energy, the nodal-based cost calculation is proposed for the avoided cost of network losses calculation. The pricing methodology proposed in the paper provides important information for investors when choosing the most economical site for their development. It can also be used to optimize the network use. These will allow the developers of embedded generation facilities and the utilities operating the national grid to maximize the potential of embedded generation.
2022 Moratuwa Engineering Research Conference (MERCon), Jul 27, 2022
Power systems, Sep 27, 2017
Power systems, Sep 27, 2017
SLEMA Journal, Sep 30, 2017
Installation of grid-connected rooftop solar power generation modules has been allowed in Sri Lan... more Installation of grid-connected rooftop solar power generation modules has been allowed in Sri Lanka since 2008. The paper analyzes the potential use of solar power inverters at night to feed reactive power to the low voltage (LV) network. The LV network typically has undervoltage issues at the evening peak-time, and the PV inverters distributed along the line can be used to eliminate or reduce such undervoltage issues. The paper proposes an algorithm to determine the suitable operating power factor of each inverter connected to the feeder. A case study of a LV distributor with solar PV inverters is presented, to demonstrate the application of the algorithm. Financial benefits to customer by introducing a reactive power tariff is assessed. The paper concludes that such a system would yield net benefits to the utility.
ABSTRACT In IEEE80:2000-Guide for Safety in AC Substation Grounding, considers the effect of stea... more ABSTRACT In IEEE80:2000-Guide for Safety in AC Substation Grounding, considers the effect of steady state behaviour of grounding grid. However, due to lightning or any other impulses generated in power system, very high voltages could be built up for a short period of time. The impact of such transient surges on substation grounding systems is studied in this paper. An approach based on Transmission Line method is used to design an equivalent circuit to the substation grounding grid. The developed designs are then simulated for transient behaviour using PSCAD software and appropriate safety parameters are evaluated to find out whether the designs need any modifications. An energy based approach which is more appropriate for transients was used to define threshold of safety. A design software incorporating the findings of the studies was developed as a final outcome.
2018 Moratuwa Engineering Research Conference (MERCon), 2018
Metal Oxide Surge Arresters (MOSA) are proven to be reliable protective devices for power distrib... more Metal Oxide Surge Arresters (MOSA) are proven to be reliable protective devices for power distribution and electrical transmission system. MOSA are subjected to electrical ageing or degradation due to constant AC conduction or transient voltages. Leakage current measured from surge arresters are used to observe its degradation and the resistive leakage component is extracted from the total to determine the health of the surge arresters. If resistive current increases, life of the surge arresters decreases. Generally, leakage current is measured using current shunts or current transformers where it’s necessary to measure the applied voltage which is very hard to measure in online condition. This paper develops an easy and accurate method to separate the resistive leakage current from the total leakage current without any voltage measurements by using a technique called Modified Phase Shifted Method (MPSM) and simulated in MATLAB which enables online monitoring system and easy to apply into a device.
2020 Moratuwa Engineering Research Conference (MERCon), 2020
Low efficiency can be identified as one of the main drawbacks of solar photo-voltaic systems. The... more Low efficiency can be identified as one of the main drawbacks of solar photo-voltaic systems. The main two factors that affect the efficiency of the existing solar photovoltaic cells are the operating temperature and the solar irradiance received by the solar cell. This paper presents an efficiency enhanced solar photo-voltaic system, which concentrates the solar irradiance through convex lenses and at the same time, cools the solar cells using a forced flow of mineral turpentine. The evaluation of the test results shows an enhancement of power output and efficiency by 60% & 32% respectively by both cooling and concentrating.
At present there is an increased focus on using renewable energy for power generation. In this pa... more 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 p...
Power systems, Sep 27, 2017
It is very important to have a clear idea about the power system we are concerning on to understa... more It is very important to have a clear idea about the power system we are concerning on to understand the necessity of a load shedding scheme. The parameters and their values that we use in the under frequency load shedding scheme influence in stabilizing the power system very much. The proposed load shedding scheme was designed referring to Ahsans’ scheme as a pilot model. Having identified the weaknesses with it the new load shedding schemes are proposed.
2022 36th International Conference on Lightning Protection (ICLP), Oct 2, 2022