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Tokyo, Japan

Miyamoto Y.,Kandenko Co. | Hayashi Y.,Waseda University
IEEE PES Innovative Smart Grid Technologies Conference Europe | Year: 2012

There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. In the previous research we demonstrated that about 20 percent of the output suppression loss was eliminated with reactive power control including PV voltage control when 225 residential PV were grid-interconnected. However, this was on a typical sunny spring day, the seasonal change of PV output and load power was not considered. So in this research we evaluated improved and smoothed generation efficiency among all residences with power factor and reactive power operating voltage through residential PV voltage control on clustered residential grid-interconnected PV for a period of one year. © 2012 IEEE. Source


Miyamoto Y.,Kandenko Co. | Hayashi Y.,Waseda University
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2013

There is a danger of output suppression of high-penetration residential PV systems due to voltage increase. It is necessary to install new technology to prevent the occurrence of such phenomenon. Therefore, we focused our attention on heat pump water heaters (HPWHs). HPWHs are usually used to heat water during night time because electricity prices are cheaper than during the daytime for the load leveling in Japan. So they can be used as a countermeasure without additional cost if they are operated during the daytime. However, HPWHs do not have sufficient capacity to absorb inverse energy at each residence. Thus HPWH operation must be optimized to minimize output suppression loss. In this research, we selected three typical sunny days in spring, autumn and winter. The optimal HPWH operation was calculated by numerical simulation. © 2013 IEEE. Source


Miyamoto Y.,Kandenko Co. | Hayashi Y.,Waseda University
IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe | Year: 2010

Installing zero-emission power sources including photovoltaic power systems (PV) is necessary to cut greenhouse gas to reduce global warming. In Japan, the target capacity for installed PV in 2020 was set to 28 GW, which was 20 times the 2005 capacity. To achieve this target, PV should be installed in 70% of new houses. The PV output (active power) must be suppressed to sustain adequate voltage (within 101±6V), due to voltage increases by inverse power from PV when clustered residential PV systems are grid-interconnected on a distribution line, even if there is sufficient irradiance. Approaches to this problem should be considered both by power systems and distribution generation. We tried to start to optimize voltage control of clustered residential grid-interconnected PV to reduce loss due to voltage increase. In this research, we evaluated improved generation efficiency through residential PV voltage control on clustered residential grid-interconnected PV. Source


Miyamoto Y.,Kandenko Co. | Hayashi Y.,Waseda University
17th Power Systems Computation Conference, PSCC 2011 | Year: 2011

In Japan, the target capacity for installed photovoltaic power systems (PV) in 2020 has been set to 28 GW. The PV output (active power) must be suppressed to sustain adequate voltage (within 101 ± 6V), which was established by the Electricity Business Act in Japan, due to voltage increases by inverse power from PV when clustered residential PV systems are grid-interconnected on a distribution line, even if sufficient irradiance exists. Simulation software was developed to analyze voltage increases when clustered PV were grid-interconnected on a large-scale demonstrative research in Ota City, Japan. From the previous fiscal year, the authors started to research improving whole generation efficiency at a site. We are developing to balance it among all the residences through voltage control, including power conditioning systems of a clustered residential grid-interconnected PV with the developed simulation software. For the subject, we have already demonstrated that 25 percent of the output suppression loss was eliminated with reactive power control when 225 residential PV are grid-interconnected to a simple single distribution line. In this research, a complex single distribution line, where 2160 residential PV are grid-interconnected, is set. We develop suitable voltage control for both simple and complex distribution lines. Source


Miyamoto Y.,Kandenko Co. | Hayashi Y.,Waseda University
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2011

Installation zero-emission power sources, including photovoltaic power systems (PV), is necessary to cut greenhouse gasses to reduce global warming. In Japan, the target capacity for installed PV in 2020 has been set at 28 GW, which is 20 times the 2005 capacity. PV should be installed in 70 percent of new houses to reach this target. The PV output (active power) must be suppressed to sustain adequate voltage (within 101±6 V), due to voltage increases by inverse power from PV when clustered residential PV systems are grid-interconnected on a distribution line, even if there is sufficient irradiance. Simulation software was developed to analyze voltage increases when clustered PV were grid-interconnected on a large-scale demonstration research in Ota City in Japan. From the previous fiscal year, the authors started to research how to improve whole generation efficiency at a site and balance it among all the residences through voltage control including power conditioning systems of a clustered residential grid-interconnected PV with the developed simulation software. For the subject, we have already demonstrated that 25 percent of the output suppression loss was eliminated with reactive power control when 225 residential PV are grid-interconnected to a single distribution line. In this research, we have evaluated the influence of increasing and decreasing active and reactive power rate in residential PV voltage control on voltage deviation. © 2011 IEEE. Source

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