ALTERNATING CURRENT AUTONOMOUS DISTRIBUTED AC POWER SYSTEM

• US 20110175443A1
• Filed: 03/12/2009
• Published: 07/21/2011
• Est. Priority Date: 03/12/2009
• Status: Active Grant

• Current Assignee: VPEC, Inc.
• Original Assignee: VPEC, Inc.
• Inventors: Nagata, Satoshi, Koyanagi, Kaoru
• Granted Patent: US 9,018,795 B2
• Time in Patent Office: Days
• US Class Current: 307/21
• CPC Class Codes: H02J 2300/10 The dispersed energy generation being of fossil origin, e.g. diesel generators
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 2300/40 wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin
• CPC Class Codes: Y02P 80/14 District level solutions, i.e. local energy networks
• CPC Class Codes: Y02P 80/15 On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply

Abstract

The objective of this invention is to provide an autonomous distributed electric power system without depending on a known electric power system. In order to achieve such objective, this invention proposes a following feature: Output frequencies of autonomous grid-connection inverters (104, 164) are to be variably controlled by the control system depending on a change of a stored electric power amount [kWh] of the direct current electric power storage device (102) within an alternating-current autonomous-distributed electric power system; and, such electric power system is built of plural electric power supplier and demander (11, 12, 13, 14, 15) who have electric power storage devices with a system which can control such inverters (104, 164); those inverters are voltage self-exciting as well.

Claims

1. An alternating current autonomous distributed electric power system of electric power suppliers and demanders including an electric power generation device, a direct current electric power storage device to which electric power is stored by the electric power generation device, autonomous grid-connection inverters for connecting the direct current electric power storage device to an alternating current system of an alternating current electric power consumption device, and an electric power storage system composed of a control system for controlling the inverters, characterized in that output frequencies of the inverters are variably controlled by the control system according to a change of a stored electric power amount (kWh) of the direct current electric power storage device.

2. An alternating current autonomous distributed electric power system, characterized in that in neighboring electric power suppliers and demanders of the autonomous distributed electric power system according to claim 1, portions between direct current electric power storage devices of one electric power suppliers and demanders and the autonomous grid-connection inverters and alternating current systems of the other the electric power supplier and demanders are mutually connected through neighboring grid-connection inverters, whether stored electric power amounts of the respective direct current electric power storage device are excessive or deficient are determined by comparing output frequencies of the connected systems, and a grid-connection tide flow is controlled by control systems of the neighboring grid-connection inverters so that the grid-connection tide flow flows from a system having a high output frequency to a system having a low output frequency.

3. An autonomous distributed electric power system, characterized in that in the autonomous distributed electric power system according to claim 2, grid-connection tide flows of the neighboring grid-connection inverters are controlled based on whether output frequencies of the autonomous grid-connection inverters are larger or smaller than frequencies of neighboring systems detected by the neighboring grid-connection inverters.

4. The alternating current autonomous distributed electric power system according to claim 2, wherein an electric power supplier and demander includes a group of a plurality of electric power suppliers and demanders which are gathered and mutually connected through the neighboring grid-connection inverters.

5. The alternating current autonomous distributed electric power system according to claim 2, wherein non-operating or non-communicating dead zones are formed to controllers of the autonomous grid-connection inverters or to controllers of the neighboring grid-connection inverters provided as electric power supply and demand control devices and the controllers of the inverters are operated based on reference levels that can arbitrarily set or change output frequencies or output voltages.

6. The alternating current autonomous distributed electric power system according to claim 5, wherein, in the autonomous grid-connection inverters, a stored electric power amount of the direct current electric power storage device is related to a change of the output frequencies of the inverters in the inverter, and when a reduction of the stored electric power amount is within a predetermined range, the output frequencies of the inverters are controlled so that they do not change.

7. The alternating current autonomous distributed electric power system according to claim 5, wherein the neighboring grid-connection inverters compare an output frequency of one system with an output frequency of the other system, and when a difference of the frequencies is within a predetermined range, the predetermined range is set as a dead zone and a grid-connection tide flow is controlled so that it does not flow therethrough.

8. The alternating current autonomous distributed electric power system according to claim 3, wherein an electric power supplier and demander includes a group of a plurality of electric power suppliers and demanders which are gathered and mutually connected through the neighboring grid-connection inverters.

9. The alternating current autonomous distributed electric power system according to claim 3, wherein non-operating or non-communicating dead zones are formed to controllers of the autonomous grid-connection inverters or to controllers of the neighboring grid-connection inverters provided as electric power supply and demand control devices and the controllers of the inverters are operated based on reference levels that can arbitrarily set or change output frequencies or output voltages.

10. The alternating current autonomous distributed electric power system according to claim 9, wherein, in the autonomous grid-connection inverters, a stored electric power amount of the direct current electric power storage device is related to a change of the output frequencies of the inverters in the inverter, and when a reduction of the stored electric power amount is within a predetermined range, the output frequencies of the inverters are controlled so that they do not change.

11. The alternating current autonomous distributed electric power system according to claim 9, wherein the neighboring grid-connection inverters compare an output frequency of one system with an output frequency of the other system, and when a difference of the frequencies is within a predetermined range, the predetermined range is set as a dead zone and a grid-connection tide flow is controlled so that it does not flow therethrough.