2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)
In order to investigate the effect of the large surface area of dispersed nanofiller on the break... more In order to investigate the effect of the large surface area of dispersed nanofiller on the breakdown strength, epoxy nanocomposites added with dispersed nanosilica, which has relative permittivity close to that of unfilled epoxy resin, needs to be prepared and their breakdown strength to be clarified. In this paper, the epoxy/ silica nanocomposites which has a primary particle size of 100 nm and a maximum agglomerate size of 500 nm in the range of filler amount from 0.4 to 5 vol% were obtained with using the particle dispersion technique combining ultrasonication and centrifugation. The impulse breakdown strength of the epoxy/silica nanocomposites was evaluated with using McKeown electrodes. We investigated the effects of ultrasonic duration and the filler amount of dispersed nanosilica on the impulse breakdown strength. These results suggested that ultrasonication and dispersed nanosilica did not significantly affect the impulse breakdown strength of epoxy resin.
2019 IEEE International Symposium on Circuits and Systems (ISCAS), 2019
Satellite imagery is useful data source for several hours-ahead forecasting of aggregated power o... more Satellite imagery is useful data source for several hours-ahead forecasting of aggregated power output of high penetration photovoltaic power generation. In order to improve the forecast accuracy of ramp event caused by a rapid transition from cloudy state to very fine state (or vice versa), this study proposes a forecast method using a sigmoid function to express a rapid weather transition. The parameters of sigmoid function is calculated based on the cloud motion vector estimated by using satellite visible imagery and the forecasted wind speed of numerical weather prediction model. This study demonstrates that the proposed method improves the forecast accuracy compared with the forecast by a conventional method based on the cloud motion vector only.
In order to realize effective asset management of a number of distribution networks, utilization ... more In order to realize effective asset management of a number of distribution networks, utilization status of individual network should be evaluated by taking into account not only the current situation but also the future situation. As a first step for this purpose, this study proposes a model to estimate the time-series of electricity demand for a year in arbitrary distribution network and examines the usefulness of the proposed model. The model is based on the publically available statistics. The aggregated electricity demand in each distribution network is calculated by determining the service territory based on map information. This study evaluates the accuracy of estimated model by comparing the estimated demand with observed demand for typical distribution networks. As an example of application of proposed model, the residual load characteristics in the case of high penetration of photovoltaic power generation and increased electrification ratio of energy demand is evaluated for...
2019 IEEE Power & Energy Society General Meeting (PESGM), 2019
Active power control of photovoltaic power generation (PV) system is one of the options to regula... more Active power control of photovoltaic power generation (PV) system is one of the options to regulate frequency fluctuation in power system with high penetration of PV. Our previous study proposes an active power control of PV system for supporting grid frequency regulation in two different forms, i.e. slow frequency control contributing to load – frequency control (LFC) and fast frequency control contributing to inertial response of synchronous generators. Two different active power – frequency droop characteristics are implemented simultaneously by using different frequency measurement methods. In this study, fast frequency response of two PV systems with $P-f$ dual droop control is tested in lab-scale experimental setup. The result shows that the fast frequency response of two PVs can perform independently without affecting each other.
2020 International Conference on Smart Grids and Energy Systems (SGES), 2020
In Japan, after establishing the control reserve market in 2021, a Merit-Order (MO) method based ... more In Japan, after establishing the control reserve market in 2021, a Merit-Order (MO) method based on cost per kWh of each generator will be applied to load frequency control (LFC). The conventional Ramp-Rate (RR) method dispatches LFC signal based on ramp-rate of LFC generators. The MO method may increase frequency fluctuation compared to RR method, because the aggregated ramp-rate of all LFC generators is not fully utilized all the time, which is the result of the change of LFC signals dispatched to some generators are different from the change of Area Requirement (AR). To solve this problem, we propose a LFC signal dispatching method considering the change of AR. The effectiveness of the proposed method is evaluated by using the IEEJ AGC30 model. This study shows that the proposed method is able to reduce frequency fluctuation compared to simplified MO method, and to reduce operating costs compared to RR method.
An idea towards stabilizing a grid with numerous distributed generators (DGs) and renewable energ... more An idea towards stabilizing a grid with numerous distributed generators (DGs) and renewable energy sources (RESs) is to compensate system inertia, damping characteristic, and weak dynamics, virtually. This may be established by a primary power source (e.g., DG or energy storage) together with a flexible controlled power electronics converter. This setup will then operate to emulate desirable dynamics, by flexible shaping of its output active and reactive powers. This approach provides a promising solution to improve power grid stability and performance in the presence of high penetration of DGs/RESs. In this paper, the general idea of the flexible controlled power converter (CPC) is explained and its significant role in enhancing the renewable integrated power grids is emphasized. c
2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2017
The total installed photovoltaic (PV) system capacity of Japan is currently increasing rapidly. H... more The total installed photovoltaic (PV) system capacity of Japan is currently increasing rapidly. However, the reverse power flow from PV systems causes voltage rise in distribution networks. In this paper, we analyze the cost- effectiveness of various voltage rise countermeasures, including increasing conductor sizes, applying VAR compensators, and upgrading voltage levels. We categorize these countermeasures into two types, namely: Measure 1, in which the existing 6- kilovolt line is used, and Measure 2, in which a 22-kilovolt line is partially used. We compare the cost-effectiveness of Measure 1 and Measure 2 in a distribution feeder, and then in a distribution substation area. The results show that in a concentrated PV scenario, Measure 2 is more cost-effective than Measure 1. In addition, the PV hosting capacity is larger for Measure 2 than it is for Measure 1.
2016 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2016
Integration of photovoltaics, PV, into island power systems is receiving strong attention recentl... more Integration of photovoltaics, PV, into island power systems is receiving strong attention recently. Nevertheless, high penetration of PV can yield power generation surplus. To deal with this problem, we propose a method to mitigate the surplus power of PV using waterworks pumps, which are, usually, already installed in inhabited islands. With the proposed method, we simulated and evaluated the potential of waterworks pumps to consume the surplus of PV. The simulation was done using real water consumption data and insolation data from Miyako island in Japan. The effectiveness of the proposed method was verified. Moreover, even though the water usage in winter was relatively small, the pumps were able to use the surplus of PV effectively in this simulation.
2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2017
Configuration of distribution network which has a maximum hosting capacity of large scale PV powe... more Configuration of distribution network which has a maximum hosting capacity of large scale PV power station has been investigated. The hosting capacity is expressed by the maximum capacity of PV power station interconnected to the distribution network without power quality deterioration such as violations of voltage constraint and thermal constraint of distribution feeder. Countermeasures such as replacement by a larger conductor size of distribution feeder, application of var compensator and upgrade of voltage level will improve the hosting capacity. The hosting capacity of 17-case distribution networks which are expressed by combination of the countermeasures was obtained by the power flow calculations. It was found that the upgrade of voltage level in part of the distribution network is useful for expanding the capacity of PV power station and reducing the distribution power loss.
Using Electric Vehicles (EV) as Flexible Resources (FR) to increase surplus Photovoltaic (PV) pow... more Using Electric Vehicles (EV) as Flexible Resources (FR) to increase surplus Photovoltaic (PV) power utilisation is a well-researched topic. Our previous study showed that EVs are viable as supplementary FRs in large capacity PV power systems, where EVs are likely to gather (i.e., workplaces). However, that study assumed all EVs to have identical arrival and departure times (availability), and battery capacities. As these characteristics may vary between EVs and affect their performance as FRs, this study expands the modelling of EVs to consider a variety of availabilities and battery capacities. To effectively utilise a variety of EVs as FRs, an Optimisation Electric-load Dispatching model is used to formulate priority schemes for charging and discharging the EVs based on their potential to contribute to the power system. The priority schemes are evaluated by simulating the annual operation of the power system both with and without the priority schemes, and comparing results. The po...
In a power system with very high penetration photovoltaic power (PV) generation, the curtailment ... more In a power system with very high penetration photovoltaic power (PV) generation, the curtailment of PV power will be necessary to maintain a power supply and demand balancing. PV power output can be effectively utilized by controlling the curtailment at a certain interval based on forecasting and nowcasting of aggregated power output of PV systems. By using an optimum unit commitment scheduling model, this paper assesses the effect of a scheduled curtailment control at 30 min interval on the reduction of curtailed PV power output in comparison with a fixed curtailment control throughout a day. Then, by using an electricity supply-demand simulation model, this paper discusses the effect of ramp rate control of curtailed PV power output for avoiding the steep change in grid frequency due to the stepwise change in curtailment.
2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)
In order to investigate the effect of the large surface area of dispersed nanofiller on the break... more In order to investigate the effect of the large surface area of dispersed nanofiller on the breakdown strength, epoxy nanocomposites added with dispersed nanosilica, which has relative permittivity close to that of unfilled epoxy resin, needs to be prepared and their breakdown strength to be clarified. In this paper, the epoxy/ silica nanocomposites which has a primary particle size of 100 nm and a maximum agglomerate size of 500 nm in the range of filler amount from 0.4 to 5 vol% were obtained with using the particle dispersion technique combining ultrasonication and centrifugation. The impulse breakdown strength of the epoxy/silica nanocomposites was evaluated with using McKeown electrodes. We investigated the effects of ultrasonic duration and the filler amount of dispersed nanosilica on the impulse breakdown strength. These results suggested that ultrasonication and dispersed nanosilica did not significantly affect the impulse breakdown strength of epoxy resin.
2019 IEEE International Symposium on Circuits and Systems (ISCAS), 2019
Satellite imagery is useful data source for several hours-ahead forecasting of aggregated power o... more Satellite imagery is useful data source for several hours-ahead forecasting of aggregated power output of high penetration photovoltaic power generation. In order to improve the forecast accuracy of ramp event caused by a rapid transition from cloudy state to very fine state (or vice versa), this study proposes a forecast method using a sigmoid function to express a rapid weather transition. The parameters of sigmoid function is calculated based on the cloud motion vector estimated by using satellite visible imagery and the forecasted wind speed of numerical weather prediction model. This study demonstrates that the proposed method improves the forecast accuracy compared with the forecast by a conventional method based on the cloud motion vector only.
In order to realize effective asset management of a number of distribution networks, utilization ... more In order to realize effective asset management of a number of distribution networks, utilization status of individual network should be evaluated by taking into account not only the current situation but also the future situation. As a first step for this purpose, this study proposes a model to estimate the time-series of electricity demand for a year in arbitrary distribution network and examines the usefulness of the proposed model. The model is based on the publically available statistics. The aggregated electricity demand in each distribution network is calculated by determining the service territory based on map information. This study evaluates the accuracy of estimated model by comparing the estimated demand with observed demand for typical distribution networks. As an example of application of proposed model, the residual load characteristics in the case of high penetration of photovoltaic power generation and increased electrification ratio of energy demand is evaluated for...
2019 IEEE Power & Energy Society General Meeting (PESGM), 2019
Active power control of photovoltaic power generation (PV) system is one of the options to regula... more Active power control of photovoltaic power generation (PV) system is one of the options to regulate frequency fluctuation in power system with high penetration of PV. Our previous study proposes an active power control of PV system for supporting grid frequency regulation in two different forms, i.e. slow frequency control contributing to load – frequency control (LFC) and fast frequency control contributing to inertial response of synchronous generators. Two different active power – frequency droop characteristics are implemented simultaneously by using different frequency measurement methods. In this study, fast frequency response of two PV systems with $P-f$ dual droop control is tested in lab-scale experimental setup. The result shows that the fast frequency response of two PVs can perform independently without affecting each other.
2020 International Conference on Smart Grids and Energy Systems (SGES), 2020
In Japan, after establishing the control reserve market in 2021, a Merit-Order (MO) method based ... more In Japan, after establishing the control reserve market in 2021, a Merit-Order (MO) method based on cost per kWh of each generator will be applied to load frequency control (LFC). The conventional Ramp-Rate (RR) method dispatches LFC signal based on ramp-rate of LFC generators. The MO method may increase frequency fluctuation compared to RR method, because the aggregated ramp-rate of all LFC generators is not fully utilized all the time, which is the result of the change of LFC signals dispatched to some generators are different from the change of Area Requirement (AR). To solve this problem, we propose a LFC signal dispatching method considering the change of AR. The effectiveness of the proposed method is evaluated by using the IEEJ AGC30 model. This study shows that the proposed method is able to reduce frequency fluctuation compared to simplified MO method, and to reduce operating costs compared to RR method.
An idea towards stabilizing a grid with numerous distributed generators (DGs) and renewable energ... more An idea towards stabilizing a grid with numerous distributed generators (DGs) and renewable energy sources (RESs) is to compensate system inertia, damping characteristic, and weak dynamics, virtually. This may be established by a primary power source (e.g., DG or energy storage) together with a flexible controlled power electronics converter. This setup will then operate to emulate desirable dynamics, by flexible shaping of its output active and reactive powers. This approach provides a promising solution to improve power grid stability and performance in the presence of high penetration of DGs/RESs. In this paper, the general idea of the flexible controlled power converter (CPC) is explained and its significant role in enhancing the renewable integrated power grids is emphasized. c
2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2017
The total installed photovoltaic (PV) system capacity of Japan is currently increasing rapidly. H... more The total installed photovoltaic (PV) system capacity of Japan is currently increasing rapidly. However, the reverse power flow from PV systems causes voltage rise in distribution networks. In this paper, we analyze the cost- effectiveness of various voltage rise countermeasures, including increasing conductor sizes, applying VAR compensators, and upgrading voltage levels. We categorize these countermeasures into two types, namely: Measure 1, in which the existing 6- kilovolt line is used, and Measure 2, in which a 22-kilovolt line is partially used. We compare the cost-effectiveness of Measure 1 and Measure 2 in a distribution feeder, and then in a distribution substation area. The results show that in a concentrated PV scenario, Measure 2 is more cost-effective than Measure 1. In addition, the PV hosting capacity is larger for Measure 2 than it is for Measure 1.
2016 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2016
Integration of photovoltaics, PV, into island power systems is receiving strong attention recentl... more Integration of photovoltaics, PV, into island power systems is receiving strong attention recently. Nevertheless, high penetration of PV can yield power generation surplus. To deal with this problem, we propose a method to mitigate the surplus power of PV using waterworks pumps, which are, usually, already installed in inhabited islands. With the proposed method, we simulated and evaluated the potential of waterworks pumps to consume the surplus of PV. The simulation was done using real water consumption data and insolation data from Miyako island in Japan. The effectiveness of the proposed method was verified. Moreover, even though the water usage in winter was relatively small, the pumps were able to use the surplus of PV effectively in this simulation.
2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia), 2017
Configuration of distribution network which has a maximum hosting capacity of large scale PV powe... more Configuration of distribution network which has a maximum hosting capacity of large scale PV power station has been investigated. The hosting capacity is expressed by the maximum capacity of PV power station interconnected to the distribution network without power quality deterioration such as violations of voltage constraint and thermal constraint of distribution feeder. Countermeasures such as replacement by a larger conductor size of distribution feeder, application of var compensator and upgrade of voltage level will improve the hosting capacity. The hosting capacity of 17-case distribution networks which are expressed by combination of the countermeasures was obtained by the power flow calculations. It was found that the upgrade of voltage level in part of the distribution network is useful for expanding the capacity of PV power station and reducing the distribution power loss.
Using Electric Vehicles (EV) as Flexible Resources (FR) to increase surplus Photovoltaic (PV) pow... more Using Electric Vehicles (EV) as Flexible Resources (FR) to increase surplus Photovoltaic (PV) power utilisation is a well-researched topic. Our previous study showed that EVs are viable as supplementary FRs in large capacity PV power systems, where EVs are likely to gather (i.e., workplaces). However, that study assumed all EVs to have identical arrival and departure times (availability), and battery capacities. As these characteristics may vary between EVs and affect their performance as FRs, this study expands the modelling of EVs to consider a variety of availabilities and battery capacities. To effectively utilise a variety of EVs as FRs, an Optimisation Electric-load Dispatching model is used to formulate priority schemes for charging and discharging the EVs based on their potential to contribute to the power system. The priority schemes are evaluated by simulating the annual operation of the power system both with and without the priority schemes, and comparing results. The po...
In a power system with very high penetration photovoltaic power (PV) generation, the curtailment ... more In a power system with very high penetration photovoltaic power (PV) generation, the curtailment of PV power will be necessary to maintain a power supply and demand balancing. PV power output can be effectively utilized by controlling the curtailment at a certain interval based on forecasting and nowcasting of aggregated power output of PV systems. By using an optimum unit commitment scheduling model, this paper assesses the effect of a scheduled curtailment control at 30 min interval on the reduction of curtailed PV power output in comparison with a fixed curtailment control throughout a day. Then, by using an electricity supply-demand simulation model, this paper discusses the effect of ramp rate control of curtailed PV power output for avoiding the steep change in grid frequency due to the stepwise change in curtailment.
Uploads
Papers by Masaki Imanaka