2019 9th International Conference on Power and Energy Systems (ICPES), 2019
Photovoltaic module soiling is recognized as a significant issue in reducing the performance of p... more Photovoltaic module soiling is recognized as a significant issue in reducing the performance of photovoltaic installations around the world. Areas that receive regular rainfall are less affected as the panels are regularly rinsed to reduce the amount of built up soiling. A 4.5 MWac installation in San Luis Obispo, California is studied to determine the power loss experienced due to soiling. San Luis Obispo has an average rainfall of 19.02 inches per year with almost all precipitation occurring between Oct 1 – Feb 28. The months of May, June, July August and September rarely receive any precipitation which means that soiling builds up during these months without any natural periodic rinsing from rain. This results in power loss due to soiling that is far more significant in the summer months than in many other areas. The study of power losses from the particular installation allow for decisions to be made on whether and when the modules in the installation should be cost effectively cleaned.
Measurement of soiling losses is a critical tool to determine when it is economically appropriate... more Measurement of soiling losses is a critical tool to determine when it is economically appropriate to clean a solar array. There are a number of techniques to determine the soling losses. A particularly useful technique is to measure the short circuit current of a clean versus soiled cell to determine a measurement of the soiling on the reference cell. However this assumes that the removal of soiling will increase the energy generated by the solar array in the same proportion. However the losses involved in the solar array involve a combination of factors. One in particular is the clipping loss that may be seen due to various DC to AC ratios. Particularly in single-axis tracking arrays, there are many situations a reduction in soiling loss will not be realized as additional generated energy as it will only serve to increase the clipping loss. This paper addresses the adjustments that must be made to the base soiling rate to include the interactions with different DC to AC ratios. With this adjusted soiling rate, more accurate determinations can be made as to the true benefits of cleaning and the economic value.
2019 9th International Conference on Power and Energy Systems (ICPES), 2019
Backtracking is typically used in PV systems which employ single axis tracking to reduce the perf... more Backtracking is typically used in PV systems which employ single axis tracking to reduce the performance losses that would result from row to row shading if optimal tilt angles were used at all times. Although a backtracking algorithm to eliminate shading is straightforward in theory, it becomes more complex in real world installations. This paper will demonstrate the advantages in energy generation that can be achieved by using half cut cell modules as opposed to standard full cell modules when a more complex terrain causes shading on adjacent rows in the morning or evening. It is shown that arrays that use half cut cell modules produce significantly more energy than full cell modules when exposed to a backtracking error that causes minimal shading in a large proportion of the strings connected to a particular inverter.
An investigation into performance improvements to the modulator stage of a class-D amplifier is c... more An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved selfoscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.
The cost benefit analysis of when to wash a solar system and how often is an important considerat... more The cost benefit analysis of when to wash a solar system and how often is an important consideration for solar PV system operators. This paper discusses two site specific methods for owners to cost effectively determine suitable timings of module washings. One method uses IV curve tracing on test panels while the other uses direct measurement of energy production on control and system panels. Through a specific California based case study it is shown that both methods can provide details that will give the operator greater confidence that the choice to clean is a cost effective decision.
ABSTRACT This paper presents a boost-resonant hybrid power supply topology designed to provide a ... more ABSTRACT This paper presents a boost-resonant hybrid power supply topology designed to provide a PWM inverter with a constant but inherently current-limited DC voltage from a low-voltage source at significant power levels. The resonant topology inherently has indefinite short-circuit protection. To verify its functionality, the topology was designed for a DC-DC converter application with a 12Vdc input and 180 Vdc output. Computer simulation of the topology was conducted to verify the design and evaluate the converter's performance. A hardware prototype was then built and assessed to examine actual operating parameters.
2012 Ninth International Conference on Information Technology - New Generations, 2012
ABSTRACT As more sustainable energy generation is integrated into power grid, the control of powe... more ABSTRACT As more sustainable energy generation is integrated into power grid, the control of power flow in an efficient and effective manner becomes more and more essential. A new innovative device is presented that allows the control of line power flow without the high harmonics and efficiency losses of traditional methods. This paper presents the dynamic response and the harmonics of a laboratory prototype Virtual Air Gap Variable Reactor (VAG-VR) and compares them with those of a thyristor controlled reactor (TCR). Variable Reactors have many applications in the power industry. Their use allows control of line power flow, voltage regulation, as well as damping of power oscillations and sub synchronous resonances. A variable reactor is most commonly implemented as a TCR by switching in and out a constant reactance to achieve an averaged variable reactance. By using a virtual air gap, implementation of a continuously variable reactance is possible with a better dynamic response and without introducing the harmonics created by the thyristor switching of a TCR.
He is past chair of Windy Hills Caledon Renewable Energy, past chair of the OSEA (Ontario Sustain... more He is past chair of Windy Hills Caledon Renewable Energy, past chair of the OSEA (Ontario Sustainable Energy Association) Board and was an executive chair of the 7th World Wind Energy Conference 2008 (WWEC 2008). He is currently a member of the management com mittee for the Ontario Green Energy Act Alliance in the midst of implementation of the most progressive renewable energy policy in North America. His research interests involve sustainable/renewable energy generation, wind power generation, smart grid technology, power systems, electromagnetics, power elec tronic applications for distributed generation, grid connection impacts of renewable generation, energy policy promoting widespread implementation of sustainable power generation, sustainable energy project economics and sustainability of technologies.
A method for selecting a set of coupling and bypass capacitors is presented. The approach uses sh... more A method for selecting a set of coupling and bypass capacitors is presented. The approach uses short-circuit time-constant analysis and for a given −3 dB cutoff frequency minimises the total capacitance used. This study offers a derivation of design formulas and shows their use via examples.
2006 Canadian Conference on Electrical and Computer Engineering, 2006
This paper applies the electrogeometric model of lightning exposure to a wind turbine to compute ... more This paper applies the electrogeometric model of lightning exposure to a wind turbine to compute its risk of damage due to a direct lightning strike in an area of known lightning flash density. For a typical 45 m wind turbine, the probability of being struck by a downward negative flash, as predicted by the model, agrees with the observed lightning strike data for wind turbines of comparable size in Denmark. Moreover, statistical distribution of the stroke current, which is useful in turbine design, can be derived from the model.
With increasing interest in renewable energies, large amounts of money and effort have been put i... more With increasing interest in renewable energies, large amounts of money and effort have been put into research and development for photovoltaic systems. The larger interest in PV systems has increased demand for appropriate equipment to test PV systems and for teaching and training the next generation of workers for the sector. A photovoltaic emulator is a device that satisfies a portion of these needs. A photovoltaic (PV) emulator was created using a programmable DC power supply and a developed GUI using Labview. The photovoltaic emulator provides the same current and voltage characteristics as any desired PV panel under various sets of environmental conditions. A PV emulator allows the remaining system to be analyzed in a controlled environment with control over the inherent variability of outside temperature and weather conditions and allows repeatable conditions to test PV equipment such as inverters and MPPT algorithms. The emulator provides an ideal tool and environment for both teaching and research at the University level without the costly investment of a set of commercial PV emulators. An existing power supply that can be used for a variety of other purposes is controlled via Labview to emulate a photovoltaic panel. The power supply can provide an open circuit voltage of 60V and short circuit current of 9A, such that any panel with parameters within this range may be emulated. Thus an extensive variety of panels may be emulated and the majority of panels from the Sandia database are within the capabilities of the available power supply.
This study presents a determination of the optimum operating parameters of a unipolar PWM inverte... more This study presents a determination of the optimum operating parameters of a unipolar PWM inverter through theoretical and experimental analysis. The inverter is investigated in its simplest form without input DC-DC conversion or output filtering. The intent of this study is to understand the core of the inverter thoroughly before adding peripheral elements such as output filtering. Variations on the input voltage level and switching frequency were investigated to determine their impacts on the operation of the inverter and harmonics produced. Theoretical modeling and calculations confirmed by experimental measurements and analysis allow determination of the inverter operating conditions which allow highest converter efficiency with lowest distortion. Results suggest highest efficiency and lowest harmonic distortion is achieved at the lowest input voltage (just above the peak of the desired fundamental component) and lowest switching frequency independent of output power. v
2019 9th International Conference on Power and Energy Systems (ICPES), 2019
Photovoltaic module soiling is recognized as a significant issue in reducing the performance of p... more Photovoltaic module soiling is recognized as a significant issue in reducing the performance of photovoltaic installations around the world. Areas that receive regular rainfall are less affected as the panels are regularly rinsed to reduce the amount of built up soiling. A 4.5 MWac installation in San Luis Obispo, California is studied to determine the power loss experienced due to soiling. San Luis Obispo has an average rainfall of 19.02 inches per year with almost all precipitation occurring between Oct 1 – Feb 28. The months of May, June, July August and September rarely receive any precipitation which means that soiling builds up during these months without any natural periodic rinsing from rain. This results in power loss due to soiling that is far more significant in the summer months than in many other areas. The study of power losses from the particular installation allow for decisions to be made on whether and when the modules in the installation should be cost effectively cleaned.
Measurement of soiling losses is a critical tool to determine when it is economically appropriate... more Measurement of soiling losses is a critical tool to determine when it is economically appropriate to clean a solar array. There are a number of techniques to determine the soling losses. A particularly useful technique is to measure the short circuit current of a clean versus soiled cell to determine a measurement of the soiling on the reference cell. However this assumes that the removal of soiling will increase the energy generated by the solar array in the same proportion. However the losses involved in the solar array involve a combination of factors. One in particular is the clipping loss that may be seen due to various DC to AC ratios. Particularly in single-axis tracking arrays, there are many situations a reduction in soiling loss will not be realized as additional generated energy as it will only serve to increase the clipping loss. This paper addresses the adjustments that must be made to the base soiling rate to include the interactions with different DC to AC ratios. With this adjusted soiling rate, more accurate determinations can be made as to the true benefits of cleaning and the economic value.
2019 9th International Conference on Power and Energy Systems (ICPES), 2019
Backtracking is typically used in PV systems which employ single axis tracking to reduce the perf... more Backtracking is typically used in PV systems which employ single axis tracking to reduce the performance losses that would result from row to row shading if optimal tilt angles were used at all times. Although a backtracking algorithm to eliminate shading is straightforward in theory, it becomes more complex in real world installations. This paper will demonstrate the advantages in energy generation that can be achieved by using half cut cell modules as opposed to standard full cell modules when a more complex terrain causes shading on adjacent rows in the morning or evening. It is shown that arrays that use half cut cell modules produce significantly more energy than full cell modules when exposed to a backtracking error that causes minimal shading in a large proportion of the strings connected to a particular inverter.
An investigation into performance improvements to the modulator stage of a class-D amplifier is c... more An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved selfoscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.
The cost benefit analysis of when to wash a solar system and how often is an important considerat... more The cost benefit analysis of when to wash a solar system and how often is an important consideration for solar PV system operators. This paper discusses two site specific methods for owners to cost effectively determine suitable timings of module washings. One method uses IV curve tracing on test panels while the other uses direct measurement of energy production on control and system panels. Through a specific California based case study it is shown that both methods can provide details that will give the operator greater confidence that the choice to clean is a cost effective decision.
ABSTRACT This paper presents a boost-resonant hybrid power supply topology designed to provide a ... more ABSTRACT This paper presents a boost-resonant hybrid power supply topology designed to provide a PWM inverter with a constant but inherently current-limited DC voltage from a low-voltage source at significant power levels. The resonant topology inherently has indefinite short-circuit protection. To verify its functionality, the topology was designed for a DC-DC converter application with a 12Vdc input and 180 Vdc output. Computer simulation of the topology was conducted to verify the design and evaluate the converter's performance. A hardware prototype was then built and assessed to examine actual operating parameters.
2012 Ninth International Conference on Information Technology - New Generations, 2012
ABSTRACT As more sustainable energy generation is integrated into power grid, the control of powe... more ABSTRACT As more sustainable energy generation is integrated into power grid, the control of power flow in an efficient and effective manner becomes more and more essential. A new innovative device is presented that allows the control of line power flow without the high harmonics and efficiency losses of traditional methods. This paper presents the dynamic response and the harmonics of a laboratory prototype Virtual Air Gap Variable Reactor (VAG-VR) and compares them with those of a thyristor controlled reactor (TCR). Variable Reactors have many applications in the power industry. Their use allows control of line power flow, voltage regulation, as well as damping of power oscillations and sub synchronous resonances. A variable reactor is most commonly implemented as a TCR by switching in and out a constant reactance to achieve an averaged variable reactance. By using a virtual air gap, implementation of a continuously variable reactance is possible with a better dynamic response and without introducing the harmonics created by the thyristor switching of a TCR.
He is past chair of Windy Hills Caledon Renewable Energy, past chair of the OSEA (Ontario Sustain... more He is past chair of Windy Hills Caledon Renewable Energy, past chair of the OSEA (Ontario Sustainable Energy Association) Board and was an executive chair of the 7th World Wind Energy Conference 2008 (WWEC 2008). He is currently a member of the management com mittee for the Ontario Green Energy Act Alliance in the midst of implementation of the most progressive renewable energy policy in North America. His research interests involve sustainable/renewable energy generation, wind power generation, smart grid technology, power systems, electromagnetics, power elec tronic applications for distributed generation, grid connection impacts of renewable generation, energy policy promoting widespread implementation of sustainable power generation, sustainable energy project economics and sustainability of technologies.
A method for selecting a set of coupling and bypass capacitors is presented. The approach uses sh... more A method for selecting a set of coupling and bypass capacitors is presented. The approach uses short-circuit time-constant analysis and for a given −3 dB cutoff frequency minimises the total capacitance used. This study offers a derivation of design formulas and shows their use via examples.
2006 Canadian Conference on Electrical and Computer Engineering, 2006
This paper applies the electrogeometric model of lightning exposure to a wind turbine to compute ... more This paper applies the electrogeometric model of lightning exposure to a wind turbine to compute its risk of damage due to a direct lightning strike in an area of known lightning flash density. For a typical 45 m wind turbine, the probability of being struck by a downward negative flash, as predicted by the model, agrees with the observed lightning strike data for wind turbines of comparable size in Denmark. Moreover, statistical distribution of the stroke current, which is useful in turbine design, can be derived from the model.
With increasing interest in renewable energies, large amounts of money and effort have been put i... more With increasing interest in renewable energies, large amounts of money and effort have been put into research and development for photovoltaic systems. The larger interest in PV systems has increased demand for appropriate equipment to test PV systems and for teaching and training the next generation of workers for the sector. A photovoltaic emulator is a device that satisfies a portion of these needs. A photovoltaic (PV) emulator was created using a programmable DC power supply and a developed GUI using Labview. The photovoltaic emulator provides the same current and voltage characteristics as any desired PV panel under various sets of environmental conditions. A PV emulator allows the remaining system to be analyzed in a controlled environment with control over the inherent variability of outside temperature and weather conditions and allows repeatable conditions to test PV equipment such as inverters and MPPT algorithms. The emulator provides an ideal tool and environment for both teaching and research at the University level without the costly investment of a set of commercial PV emulators. An existing power supply that can be used for a variety of other purposes is controlled via Labview to emulate a photovoltaic panel. The power supply can provide an open circuit voltage of 60V and short circuit current of 9A, such that any panel with parameters within this range may be emulated. Thus an extensive variety of panels may be emulated and the majority of panels from the Sandia database are within the capabilities of the available power supply.
This study presents a determination of the optimum operating parameters of a unipolar PWM inverte... more This study presents a determination of the optimum operating parameters of a unipolar PWM inverter through theoretical and experimental analysis. The inverter is investigated in its simplest form without input DC-DC conversion or output filtering. The intent of this study is to understand the core of the inverter thoroughly before adding peripheral elements such as output filtering. Variations on the input voltage level and switching frequency were investigated to determine their impacts on the operation of the inverter and harmonics produced. Theoretical modeling and calculations confirmed by experimental measurements and analysis allow determination of the inverter operating conditions which allow highest converter efficiency with lowest distortion. Results suggest highest efficiency and lowest harmonic distortion is achieved at the lowest input voltage (just above the peak of the desired fundamental component) and lowest switching frequency independent of output power. v
Uploads
Papers by Dale Dolan