Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Reexamination Certificate
2002-06-24
2004-10-26
Nguyen, Matthew V. (Department: 2838)
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
C363S132000
Reexamination Certificate
active
06809942
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system interconnection electric power generator for enabling regeneration (supply) of electric power generated therein to a commercial power supply system which is interconnected to the electric power generator, and a method of controlling the system interconnection electric power generator.
2. Description of the Related Art
Recently, there has been recently becoming widespread a solar energy generator (photovoltaic generator) as a system interconnection electric power generator in which not only electric power generated by utilizing sunlight as an energy source is supplied for personal use, but also extra electric power thus generated (which has not been used for personal use) is regenerated (supplied) to a commercial power supply system.
In such a solar energy generator, DC power generated by using a solar battery is boosted by a boosting circuit and then the DC power thus boosted is converted to AC power corresponding to the AC power of a commercial power supply system by using an inverter circuit.
In such a solar energy generator as described above, the DC power generated by the solar battery is used as a power supply source for various kinds of equipment constituting the solar energy generator, such as a boosting circuit, an inverter circuit, a controller for controlling the boosting circuit and the inverter circuit, various types of detecting sensors, etc.
Further, according to the solar energy generator thus constructed, in order to enhance the safety of the solar energy generator thus constructed, a current sensor for detecting the earth fault of DC power supplied to various kinds of equipment is equipped to DC lines at the solar battery side. A current converter or the like is generally used as the current sensor, and it contains a magnetic member around which a coil is wound. The magnetic member of the current sensor is generally formed of expensive super-saturated reactor or the like.
In such a solar energy generator as described above, since electric power is generated by using sunlight, the amount of electric power to be generated by using a solar battery is reduced under such an atmosphere that the amount of insolation is low. For example, this is liable to occur at sunset or the like. Particularly in such a case that the electric power generated by the solar battery is partially supplied as a power supply source to various kinds of equipment constituting the solar energy generator, that is, a part of the electric power generated by the solar battery is consumed at these kinds of constituent equipment, the level of electric power to be supplied (regenerated) from the solar energy generator to the commercial power supply system is lower than a specified level required for the commercial power supply system at sunset or the like. Consequently, the supply of the electric power from the solar energy generator to the commercial power supply system must be stopped, that is, the operation of the solar energy generator itself must be stopped.
Therefore, the controller of the solar energy generator judges at all times whether the amount of electric power generated by the solar energy generator is lowered to the extent that it is impossible to use the electric power thus generated for the commercial power supply system at sunset or the like, that is, whether the electric power generated in the solar energy generator is lower than the specified power level or not, and stops the operation of the solar energy generator on the basis of the above judgment. In such a case that the amount of electric power generated in the solar energy generator is lower than the specified level, the electric power to be supplied from the solar energy generator to the various kinds of equipment (containing the controller) constituting the solar energy generator is also reduced, and thus the operation of these constituent equipment is unstable. Particularly when the electric power to be supplied to the controller (control power supply source) is lower, the controller cannot surely perform the judgment as to the reduction of the electric power (i.e., sunset or the like).
Furthermore, in such a solar energy generator as described above, the operational status of the solar energy generator under operation is merely displayed on a display panel or the like at that time point. Accordingly, in such a case that for example when some abnormality occurs in the commercial power supply system, the solar energy generator carries out a protecting operation of stopping supply of electric power therefrom to the commercial power supply under abnormality in order to protect the commercial power supply from being damaged or the like by further supply of the electric power to the commercial power supply, the data on the protecting operation of the solar energy generator are merely displayed on the display panel or the like at the time point when the abnormality occurs. That is, the data of the protecting operation which has been carried out until the abnormality is fixed do not remain.
Accordingly, after such a protecting operation is finished, even the fact that the protecting operation is carried out is not left. In this case, a service man(woman), a maintenance man(woman) or the like must take a countermeasure to the lack of the electric power to be supplied from the solar energy generator to the commercial power supply system while paying his/her attention to only the integration value of the amount of electric power generated by the solar energy generator. Therefore, it is substantially impossible to take a proper countermeasure to the lack of the electric power to be supplied from the solar energy generator to the commercial power supply system. That is, it has been hitherto impossible to determine the accurate cause for the lack of the electric power to be supplied from the solar energy generator to the commercial power supply system, and take the proper countermeasure thereto.
SUMMARY OF THE INVENTION
Therefore, the present invention has been implemented in view of the foregoing situation, and has a first object to provide a system interconnection electric power generator that can always secure electric power to be supplied to various kinds of equipment of the system interconnection electric power generator, such as control electric power to be supplied to a controller, until the operation of the system interconnection electric power generator is finished, and a method of controlling the system interconnection electric power generator.
A second object of the present invention is to provide a system interconnection electric power generator that can surely judge the operational status thereof and properly perform maintenance and troubleshooting, and a method of controlling the system interconnection electric power generator.
A third object of the present invention is to provide a system interconnection electric power generator that can detect the earth fault of direct current thereof at low cost and ensure high safety, and a DC earth fault detecting device used for the system interconnection electric power generator.
In order to attain the above objects, according to a first aspect of the present invention, a system interconnection electric power generator having various kinds of equipment for generating electric power and supplying the electric power to a commercial power supply system electrically-connected thereto, is characterized by comprising: an electric power generator for generating DC power; a boosting circuit for boosting the DC power generated in said electric power generator; an inverter circuit for converting the DC power boosted in said boosting circuit to AC power; a controller for controlling at least said boosting circuit and said inverter circuit; and a power source switching device that is controlled by said controller so as to select one of said electric power generator and the commercial power supply system as a power source for the power to be supplied to the various kinds of equipment of said syste
Kobayashi Masanori
Madenokouji Masaki
Makino Yasuhiro
Onizuka Keigo
Darby & Darby
Nguyen Matthew V.
Sanyo Electric Co,. Ltd.
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