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C.B. Robledo
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3 records found
1
Energy Management
Techno-economic assessment of a power manager - towards a business case for integrating electric vehicles within a building’s electrical system
Due to the intermittent character of renewable electricity sources and increasing decentralized electricity production, grid operators are facing challenges in balancing electricity- demand and supply within grid operations. These characteristics make it challenging for operators to forecast in- and outflowing electricity in the grid. This often leads to disadvantageous frequency-, voltage-, and electricity fluctuations in the grid. The implementation of smart grid technologies allows the easier integration of sustainable electricity sources and to increase the grid’s reliability. Additionally, more components can be integrated in the grid system that can provide grid regulating services. In the context of sustainability, it’s interesting to stress the potential of grid services delivered by parked electric vehicles. The principle of a Car as Power Plant (CaPP), where vehicles can provide electricity back to the grid via Vehicle-To-Grid (V2G) technology, can potentially solve challenges that grid operators are currently facing. This can be designed in such a way that the operation becomes beneficial for all parties involved. This research implies a techno-economic assessment of a power manager device; which is a multifunctional device that includes an energy management system (EMS), allows for vehicles to charge and discharge and functions as a converter (from direct current to alternating current). The power manager enables electric vehicles to deliver ancillary services when operating in V2G mode. This research stresses the economic- and environmental benefits of a power manager; once it’s integrated in grid-connected commercial- and residential buildings. Emphasis is put on buildings in future energy systems, which are equipped with DC loads and contain features that make the building operate in a more sustainable manner than today. For this purpose, several cases have been modeled to address the cost benefits of a power manager within a buildings’ electrical system. The cost optimization is conducted by means of the HOMER optimization software. Environmental- and financial benefits could be achieved in a behind-the-meter operation, in case electricity flows are managed smartly and ancillary services are delivered to the grid. Price arbitrage and peak shaving were among the most emphasized ancillary services. By integrating electric vehicles by means of a power manager, the batteries of parked electric vehicles could get an extra function, besides being primarily used for driving purposes. Several cases have been optimized by applying a dispatch strategy, considering different components in the microgrid (solar panels, DC electrical loads, battery electric vehicles). These dispatch algorithms were embedded in the power manager’s energy management system.This research has shown that, once the vehicles’ battery capacity was aggregated for grid facilitating purposes in a behind-the-meter operation, parties could achieve financial- and environmental benefits. This could be realized by integrating permanently parked vehicles within commercial- and residential buildings’ electrical systems by means of a power manager. When a power manager was added to a building’s system without integrated solar panels, annual cost savings of € 35 and € 60 could be achieved respectively for residential- and commercial buildings by accounting for price arbitrage services. Once a power manager device was added to a building’s electrical system with integrated solar panels, the renewable energy fraction of the system increased from 53.9 to 57.4 for a residential building and from 68.0 to 70.8 in a commercial building. Altogether, price arbitrage practices primarily caused financial benefits, while peak shaving services resulted in an increase in the system’s renewability. It’s presumed that a power manager’s economic- and environmental benefits could increase once a larger battery capacity is obtained by aggregating BEVs in a ‘before-the-meter’ operation. Favorable regulations and privacy matters need to be established and discussed to make a power manager device run at its full potential. Additionally, it’s important to determine what party will be fulfilling the aggregating role, and therewith, takes the responsibility for demand response operations. For this, a potential business case is established for the implementation of a power manager in the Dutch market.
...
Due to the intermittent character of renewable electricity sources and increasing decentralized electricity production, grid operators are facing challenges in balancing electricity- demand and supply within grid operations. These characteristics make it challenging for operators to forecast in- and outflowing electricity in the grid. This often leads to disadvantageous frequency-, voltage-, and electricity fluctuations in the grid. The implementation of smart grid technologies allows the easier integration of sustainable electricity sources and to increase the grid’s reliability. Additionally, more components can be integrated in the grid system that can provide grid regulating services. In the context of sustainability, it’s interesting to stress the potential of grid services delivered by parked electric vehicles. The principle of a Car as Power Plant (CaPP), where vehicles can provide electricity back to the grid via Vehicle-To-Grid (V2G) technology, can potentially solve challenges that grid operators are currently facing. This can be designed in such a way that the operation becomes beneficial for all parties involved. This research implies a techno-economic assessment of a power manager device; which is a multifunctional device that includes an energy management system (EMS), allows for vehicles to charge and discharge and functions as a converter (from direct current to alternating current). The power manager enables electric vehicles to deliver ancillary services when operating in V2G mode. This research stresses the economic- and environmental benefits of a power manager; once it’s integrated in grid-connected commercial- and residential buildings. Emphasis is put on buildings in future energy systems, which are equipped with DC loads and contain features that make the building operate in a more sustainable manner than today. For this purpose, several cases have been modeled to address the cost benefits of a power manager within a buildings’ electrical system. The cost optimization is conducted by means of the HOMER optimization software. Environmental- and financial benefits could be achieved in a behind-the-meter operation, in case electricity flows are managed smartly and ancillary services are delivered to the grid. Price arbitrage and peak shaving were among the most emphasized ancillary services. By integrating electric vehicles by means of a power manager, the batteries of parked electric vehicles could get an extra function, besides being primarily used for driving purposes. Several cases have been optimized by applying a dispatch strategy, considering different components in the microgrid (solar panels, DC electrical loads, battery electric vehicles). These dispatch algorithms were embedded in the power manager’s energy management system.This research has shown that, once the vehicles’ battery capacity was aggregated for grid facilitating purposes in a behind-the-meter operation, parties could achieve financial- and environmental benefits. This could be realized by integrating permanently parked vehicles within commercial- and residential buildings’ electrical systems by means of a power manager. When a power manager was added to a building’s system without integrated solar panels, annual cost savings of € 35 and € 60 could be achieved respectively for residential- and commercial buildings by accounting for price arbitrage services. Once a power manager device was added to a building’s electrical system with integrated solar panels, the renewable energy fraction of the system increased from 53.9 to 57.4 for a residential building and from 68.0 to 70.8 in a commercial building. Altogether, price arbitrage practices primarily caused financial benefits, while peak shaving services resulted in an increase in the system’s renewability. It’s presumed that a power manager’s economic- and environmental benefits could increase once a larger battery capacity is obtained by aggregating BEVs in a ‘before-the-meter’ operation. Favorable regulations and privacy matters need to be established and discussed to make a power manager device run at its full potential. Additionally, it’s important to determine what party will be fulfilling the aggregating role, and therewith, takes the responsibility for demand response operations. For this, a potential business case is established for the implementation of a power manager in the Dutch market.
A hydrogen fuel cell scooter was tested for the first time to alternatively drive, power electric appliances (Vehicle-to-Load, V2L) and power the grid (Vehicle-to-Grid, V2G). Performance of the scooter is known to rely mainly on the fuel cell stack, and fuel cell degradation depends on the operating conditions. This study aimed to provide insights on how each mode of operation (driving, V2L and V2G) impacts the fuel cell stack performance, as well as the overall system.
Operation in each mode was mimicked by applying typical duty cycles to the hydrogen scooter via an electronic programmable load.
Analysis of the experimental data yielded clear differences between each mode of operation. Principal Component Analysis (PCA) revealed that the voltage of the fuel cell and the battery were most determining in segregating the three modes.
The highest system efficiency was found for V2G usage of the scooter (39.4\% based on higher heating value). The power demand throughout this mode was high, making the fuel cell operate at almost full capacity.
Linear regression analysis was used to determine the fuel cell degradation rate. Severe degradation was measured throughout the experiments, with an overall voltage cell drop of 402 µV/h. Distinguishing the degradation rate per mode revealed V2L operation to cause the largest fuel cell degradation (648 μV/h) and driving the least degradation (205 μV/h). This result was confirmed by comparing the IV curve of the fuel cell stack before and after the experiments: the largest voltage drop occurred at low currents.
Further research on scooter usage in combined modes should include new energy management strategies for V2G and V2L operation, which focus on minimizing fuel cell degradation. ...
Operation in each mode was mimicked by applying typical duty cycles to the hydrogen scooter via an electronic programmable load.
Analysis of the experimental data yielded clear differences between each mode of operation. Principal Component Analysis (PCA) revealed that the voltage of the fuel cell and the battery were most determining in segregating the three modes.
The highest system efficiency was found for V2G usage of the scooter (39.4\% based on higher heating value). The power demand throughout this mode was high, making the fuel cell operate at almost full capacity.
Linear regression analysis was used to determine the fuel cell degradation rate. Severe degradation was measured throughout the experiments, with an overall voltage cell drop of 402 µV/h. Distinguishing the degradation rate per mode revealed V2L operation to cause the largest fuel cell degradation (648 μV/h) and driving the least degradation (205 μV/h). This result was confirmed by comparing the IV curve of the fuel cell stack before and after the experiments: the largest voltage drop occurred at low currents.
Further research on scooter usage in combined modes should include new energy management strategies for V2G and V2L operation, which focus on minimizing fuel cell degradation. ...
A hydrogen fuel cell scooter was tested for the first time to alternatively drive, power electric appliances (Vehicle-to-Load, V2L) and power the grid (Vehicle-to-Grid, V2G). Performance of the scooter is known to rely mainly on the fuel cell stack, and fuel cell degradation depends on the operating conditions. This study aimed to provide insights on how each mode of operation (driving, V2L and V2G) impacts the fuel cell stack performance, as well as the overall system.
Operation in each mode was mimicked by applying typical duty cycles to the hydrogen scooter via an electronic programmable load.
Analysis of the experimental data yielded clear differences between each mode of operation. Principal Component Analysis (PCA) revealed that the voltage of the fuel cell and the battery were most determining in segregating the three modes.
The highest system efficiency was found for V2G usage of the scooter (39.4\% based on higher heating value). The power demand throughout this mode was high, making the fuel cell operate at almost full capacity.
Linear regression analysis was used to determine the fuel cell degradation rate. Severe degradation was measured throughout the experiments, with an overall voltage cell drop of 402 µV/h. Distinguishing the degradation rate per mode revealed V2L operation to cause the largest fuel cell degradation (648 μV/h) and driving the least degradation (205 μV/h). This result was confirmed by comparing the IV curve of the fuel cell stack before and after the experiments: the largest voltage drop occurred at low currents.
Further research on scooter usage in combined modes should include new energy management strategies for V2G and V2L operation, which focus on minimizing fuel cell degradation.
Operation in each mode was mimicked by applying typical duty cycles to the hydrogen scooter via an electronic programmable load.
Analysis of the experimental data yielded clear differences between each mode of operation. Principal Component Analysis (PCA) revealed that the voltage of the fuel cell and the battery were most determining in segregating the three modes.
The highest system efficiency was found for V2G usage of the scooter (39.4\% based on higher heating value). The power demand throughout this mode was high, making the fuel cell operate at almost full capacity.
Linear regression analysis was used to determine the fuel cell degradation rate. Severe degradation was measured throughout the experiments, with an overall voltage cell drop of 402 µV/h. Distinguishing the degradation rate per mode revealed V2L operation to cause the largest fuel cell degradation (648 μV/h) and driving the least degradation (205 μV/h). This result was confirmed by comparing the IV curve of the fuel cell stack before and after the experiments: the largest voltage drop occurred at low currents.
Further research on scooter usage in combined modes should include new energy management strategies for V2G and V2L operation, which focus on minimizing fuel cell degradation.
Master thesis
(2017)
-
Michelle Poorte, Ad van Wijk, Carla Robledo, Reinier van der Veen, Henrie Mathijssen, Mart van der Meijden
In the Netherlands the main sources of electricity are currently coal and gas fired power plants. Due to the increasing share of electricity that is produced from renewable energy sources, the operational hours of these conventional power plants are decreasing. However, these power plants are also the main source of frequency reserves, which are required to guarantee the stability of the electricity grid. Stability is maintained if there is a real time balance between the electricity production and consumption. Due to the decreasing availability of conventional power plants, the possibility to offer frequency reserves with other power sources must be explored. A possible provider is the Car Park as Power Plant (CPPP). This is an aggregation of Fuel Cell Electric Vehicles (FCEV) parked in a car park and operating in Vehicle to Grid (V2G) mode. This thesis contains a technical and economic feasibility assessment of a Car Park as Power Plant offering frequency reserves in a future power system with a low share of conventional power plants.
The dynamics of the frequency was analysed considering the reduction of the operational hours of the conventional power plants. This causes the inertia in the system to decrease. As a consequence, this increases the rate of change of frequency (RoCoF). A high RoCoF makes the frequency react faster which will make it more feasible that the maximum instantaneous frequency deviation will be reached. When this maximum deviation is reached, the system enters the alert state, which could endanger the global security of the system. To prevent the frequency from reaching the maximum instantaneous frequency deviation under conditions of a high RoCoF, the full activation time (FAT) of the frequency reserves could be reduced. The FAT is the maximum time between the moment that the signal for a change in power output is given and the actual moment that the required power output is reached. Reserves with a reduced FAT are referred to as fast frequency reserves. By measuring the FAT of the FCEV in V2G mode with an experimental setup, it was tested if the FCEV could offer the fast frequency reserves. The FCEV appeared to be a suitable power source to offer fast frequency reserves. When the power output of the battery and the fuel cell are combined, an even higher power gradient and thus a shorter full activation time, can be obtained. However, improvements must be implemented in the V2G discharge unit and the energy management system of the FCEV to optimise the operation in V2G mode. The economic feasibility of the CPPP as provider of frequency reserves was then analysed. The factor that has the highest impact, is the position of the CPPP on the bid ladder. Only when the price for frequency reserves is relatively high, the reserves of the CPPP will be activated. This is caused by the high price for hydrogen, which is the dominant factor in the marginal costs of the CPPP. Most of the time the prices for frequency reserves and for electricity sold on the spot market are lower than the marginal costs of the CPPP.
From a technical point of view the CPPP is a suitable power source to offer fast frequency reserve. The profitability of the CPPP is, however, strongly related to the occupation pattern of the car park and the price for frequency reserves. The occupation pattern can be influenced by the aggregator by giving incentives to the car owners, combining different car parks with deviating occupation patterns or by operating company car parks with, for example, autonomous driving cars. The price for frequency reserves is dependent on the quickly evolving market and can not be influenced by the aggregator of the CPPP. The aggregator can influence the marginal costs of the CPPP. By adding relevant components to the system, like hydrogen production units or storage facilities, the aggregator can offer reserves with different power sources, which will have different marginal costs. From the point of view of the transmission system operator, it could be possible to add an extra product for fast frequency reserves instead of changing the requirements of the existing reserves. This could have a positive effect on the profitability of the CPPP. The specific requirements such as the minimum bid size, validity period and payment mechanism for this product should be evaluated in further studies. ...
In the Netherlands the main sources of electricity are currently coal and gas fired power plants. Due to the increasing share of electricity that is produced from renewable energy sources, the operational hours of these conventional power plants are decreasing. However, these power plants are also the main source of frequency reserves, which are required to guarantee the stability of the electricity grid. Stability is maintained if there is a real time balance between the electricity production and consumption. Due to the decreasing availability of conventional power plants, the possibility to offer frequency reserves with other power sources must be explored. A possible provider is the Car Park as Power Plant (CPPP). This is an aggregation of Fuel Cell Electric Vehicles (FCEV) parked in a car park and operating in Vehicle to Grid (V2G) mode. This thesis contains a technical and economic feasibility assessment of a Car Park as Power Plant offering frequency reserves in a future power system with a low share of conventional power plants.
The dynamics of the frequency was analysed considering the reduction of the operational hours of the conventional power plants. This causes the inertia in the system to decrease. As a consequence, this increases the rate of change of frequency (RoCoF). A high RoCoF makes the frequency react faster which will make it more feasible that the maximum instantaneous frequency deviation will be reached. When this maximum deviation is reached, the system enters the alert state, which could endanger the global security of the system. To prevent the frequency from reaching the maximum instantaneous frequency deviation under conditions of a high RoCoF, the full activation time (FAT) of the frequency reserves could be reduced. The FAT is the maximum time between the moment that the signal for a change in power output is given and the actual moment that the required power output is reached. Reserves with a reduced FAT are referred to as fast frequency reserves. By measuring the FAT of the FCEV in V2G mode with an experimental setup, it was tested if the FCEV could offer the fast frequency reserves. The FCEV appeared to be a suitable power source to offer fast frequency reserves. When the power output of the battery and the fuel cell are combined, an even higher power gradient and thus a shorter full activation time, can be obtained. However, improvements must be implemented in the V2G discharge unit and the energy management system of the FCEV to optimise the operation in V2G mode. The economic feasibility of the CPPP as provider of frequency reserves was then analysed. The factor that has the highest impact, is the position of the CPPP on the bid ladder. Only when the price for frequency reserves is relatively high, the reserves of the CPPP will be activated. This is caused by the high price for hydrogen, which is the dominant factor in the marginal costs of the CPPP. Most of the time the prices for frequency reserves and for electricity sold on the spot market are lower than the marginal costs of the CPPP.
From a technical point of view the CPPP is a suitable power source to offer fast frequency reserve. The profitability of the CPPP is, however, strongly related to the occupation pattern of the car park and the price for frequency reserves. The occupation pattern can be influenced by the aggregator by giving incentives to the car owners, combining different car parks with deviating occupation patterns or by operating company car parks with, for example, autonomous driving cars. The price for frequency reserves is dependent on the quickly evolving market and can not be influenced by the aggregator of the CPPP. The aggregator can influence the marginal costs of the CPPP. By adding relevant components to the system, like hydrogen production units or storage facilities, the aggregator can offer reserves with different power sources, which will have different marginal costs. From the point of view of the transmission system operator, it could be possible to add an extra product for fast frequency reserves instead of changing the requirements of the existing reserves. This could have a positive effect on the profitability of the CPPP. The specific requirements such as the minimum bid size, validity period and payment mechanism for this product should be evaluated in further studies.