The new national R&D project on PV system has been started since
last year. The target of this project is to solve technical problems
such as restriction of PV system output, higher harmonics and islanding
operation where PV systems are clustered in a residential district.
In this project, about 400 to 600 gridconnected PV systems with
battery installed at residential houses and are monitored at all
times. The results obtained in this project are expected to provide
information and technologies to increase the further introduction
of PV systems.
1 Development of technology to avoid restriction of PV system output
In some cases of inverse flows, which mean a PV system supplies
its output power to the power line, the voltage in the distribution
line are beyond threshold voltage of 107 or 222 V. Those cases result
in depression of the output power of the PV systems, which reduces
merits of the systems.In this R&D, the various phenomena of the
suppression of the output of the PV systems are observed and analyzed
to develop the technology to reduce the suppression.
2 Analyses and evaluation of higher
harmonics Higher harmonics emitted from power conditioner subsystems
should be suppressed within the low levels as specified in Guideline
of Higher Harmonics. Clustered PV systems tend to increase the higher
harmonics because of interferences between those systems, which
tends to give degraded influence on power apparatuses in the power
systems and domestic electrifications. In this R&D, analyses and
evaluation of higher harmonics are made using the data of relation
between number of PV systems and the higher harmonics induced from
them. And the limitation of number gridconnected PV systems from
the tolerance limits higher harmonics in distribution lines is identified.
3 Analyses of misactuation of function
to prevent islanding operation A function to avoid islanding operation
is activated in PV systems to separate the PV systems from power
grid lines in the case of service interruptions. Misactuation of
the function tends to take place because of interferences between
the clustered PV systems. In this R&D, methods preventing the misactuation
in the clustered PV systems are considered, and the validities of
the methods are considered.
4 Development of applied simulations
Simulation techniques are developed using those data and results
obtained in three subjects. The simulations are designed to contribute
to further designs of clustered PV systems as well as to precise
evaluation of the data obtained in this R&D.


our papers
(1) T.OOZEKI, K.OTANI, H.KOIZUMI and
K. KUROKAWA:An
Evaluation method of Grid connected photovoitalic with battery systems(1.07[MByte])
(in Japanese) (in Japanese)
(2) T.OOZEKI, H.KOIZUMI, K.OTANI, and
K.KUROKAWA:"IDENTIFING
OPERATION STATUSES OF GRID CONNECTED PV SYSTEMS WITH BATTERIES UNDER
LIMITED DATA ITEMS  APPLYING THE SV METHOD TO EVALUATE GRID CONNECTED
PV SYSTEMS WITH BATTERIES , 19thEuropean Photovoltaic Solar
Energy Conference and Exhibition, Palais des Congres Paris, France
711 June 2004
(3) Y.UEDA, T.OOZEKI, K.KUROKAWA, T.ITOU,
K.KITAMURA, Y.MIYAMOTO, M.YOKOTA, H.SIGIHARA "Evaluation method
and data collection method of gridconnected clustered PV system's
performance", IEEJ Aug 2004 (in Japanese)
(4) Y.UEDA, T. OOZEKI, K.KUROKAWA,
T.ITOU, K.KITAMURA, Y.MIYAMOTO, M.YOKOTA, H.SUGIHARA, S.NISHIKAWA,"ANALYTICAL
RESULTS OF OUTPUT RESTRICTION DUE TO THE VOLTAGE INCREASING OF POWER
DISTRIBUTION LINE IN GRIDCONNECTED CLUSTERED PV SYSTEMS" , 31th
IEEE PVPS, Florida, US, January 2005
(5) N.KAWASAKI, T.OOZEKI, K.OTANI,
and K.KUROKAWA:"An Evaluation Method of the Fluctuation Characteristics
of Photovoltaic Systems by Using Frequency Analysis", PVSEC14th,
Bangkok, Thailand, 2630 January 2004 (Poster Award)
(6) N.KAWASAKI, T.OOZEKI, K.OTANI,
K.KUROKAWA, "An Evaluation method of the fluctuation characteristics
of photovoltaoc systems by using frequency analysis, IEEJ, Aug 2003
(in Japanese)
(7)Y. UEDA, T. OOZEKI, K. KUROKAWA,
T. ITOU, K. KITAMURA, Y. MIYAMOTO, M. YOKOTA, H. SIGIHARA, and S.
NISHIKAWA, "NALYTICAL RESULTS OF OUTPUT RESTRICTION DUE TO
THE VOLTAGE INCREASING OF POWER DISTRIBUTION LINE IN GRIDCONNECTED
CLUSTERED PV SYSTEMS", 31st IEEE PVSC, Orland Florida, 27
January 2005
other papers
(1) S.NISHIKAWA K.KATO, "DEMONSTRATIVE
RESEARCH ON GRIDINTERCONNECTION OF CLUSTERED PHOTOVOLTAIC POWER
GENERATION SYSTEMS", WCPEC 3rd, May 2003, Osaka, Japan
(2) Y.MIYAMOTO, M.YOKOTA, S. NISHIKAWA,
H. SUGIHARA"DEMONSTRATIVE RESEARCH ON GRIDINTERCONNECTION
OF CLUSTERED PHOTOVOLTAIC POWER GENERATION SYSTEMS",19thEuropean
Photovoltaic Solar Energy Conference and Exhibition, Palais des
Congres Paris, France 711 June 2004
(3) S. MIYASHITA, A. NAGAOKA, K. TAKIGAWA,
H. SUGIHARA, and Y. OOKUBO "A UNIFIED TEST AND EVALUATION OF
PCS ON THE MARKET FOR RESIDENTIAL PV APPLICATION IN JAPAN",
31st IEEE PVSC, Orland Florida, 27 January 2005
(4) S. Nishikawa H. Sugihara, "DEMONSTRATIVE
RESEARCH ON GRIDINTERCONNECTION OF CLUSTERED PHOTOVOLTAIC POWER
GENERATION SYSTEMS", 31st IEEE PVSC, Orland Florida, 27 January
2005
