Multi-terminal power conversion device, multi-terminal power transfer device, and power network system

• US 9,013,902 B2
• Filed: 09/10/2010
• Issued: 04/21/2015
• Est. Priority Date: 09/10/2009
• Status: Active Grant

• Current Assignee: University of Tokyo
• Original Assignee: University of Tokyo
• Inventors: Abe, Rikiya
• Primary Examiner(s): Masinick, Michael D
• Application Number:
  US13/395,407
• Publication Number:
  US 20120173035A1
• Time in Patent Office: 1,684 Days
• Field of Search: 700/297, 307/31, 363/18, 363/35, 363/65, 363/69
• US Class Current: 363/69
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 5/4505 having a rectifier with controlled elements

Abstract

The present invention provides a multi-terminal power conversion device, a multi-terminal power transfer device, and a power network system which allows an existing power grid to be divided into a plurality of power grids that can be interconnected together and operated stably via existing or new transmission lines. An inter-power grid asynchronous interconnection network system includes a multi-terminal power conversion device characterized by connecting together a plurality of asynchronous power grids including a bulk power grid and controlling power so that the sum of inflow power and outflow power is zero. An intra-power grid synchronous network system includes a power apparatus control terminal device with means for controlling power for a power apparatus installed in an autonomous power grid. A plurality of inter-power grid asynchronous interconnection network systems are connected to an intra-power grid synchronous network system to integrate the power control with communication control.

Claims

1. A multi-terminal power conversion device characterized by comprising:

at least three self-commutated converters that convert power in a bidirectional manner;

a common bus that connects first terminals of the self-commutated converters together in parallel;

voltage and current measuring instruments that measure voltage and current of second terminals of the self-commutated converter;

a voltage measuring instrument that measures voltage of the common bus; and

a power control system that calculates voltage, current, power, frequency and phase based on measured values by the voltage and current measuring instruments and the voltage measuring instrument, and controls a plurality of the self-commutated converters so that one of the self-commutated converters maintains the voltage of the common bus and other self-commutated converters perform power control for flowing given power into or from destinations to which second terminals of the self-commutated converters are connected and a sum of power flowing from the self-commutated converters into the common bus and power fed out from the common bus to the self-commutated converters is cooperatively set to zero, thereby asynchronously interchanging power among destinations to which second terminals of the self-commutated converters are connected.

2. A multi-terminal power conversion device according to claim 1, characterized by comprising:

an energy storage device connected to the common bus.

3. The multi-terminal power conversion device according to claim 2, characterized in that the energy storage device further comprises a DC/DC converter, the energy storage device connects to the common bus via the DC/DC converter.

4. The multi-terminal power conversion device according to claim 1, characterized in that the power control system controls each self-commutated converter to synchronize the phase with each destination.

5. The multi-terminal power conversion device according to claim 1, characterized in that the power control system controls each self-commutated converter to flow the given power into or from each destination based on a power control target value with respect to each self-commutated converter entered in the power control system.

6. The multi-terminal power conversion device according to claim 1, characterized in that the power control system controls each self-commutated converter to maintain voltage or current of each destination.

7. A power conversion device characterized by comprising:

a plurality of self-commutated converters that respectively convert power in a bidirectional manner;

a voltage and current measuring instrument that measures voltage and current passing through each self-commutated converter;

a common bus that connects first terminals of the self-commutated converters together in parallel;

a communication unit for transmitting and receiving power conversion information including an identifier of each self-commutated converter, a header indicating a beginning time of transmitting and receiving power and a footer indicating an ending time of transmitting and receiving power and a power interchange profile; and

a control unit for controlling each self-commutated converter corresponding to each identifier based on the power conversion information received by the communication unit, the control unit having a memory to store the power conversion information,

wherein the control unit calculates voltage, current, power, frequency and phase based on measured values by the voltage and current measuring instruments, and controls a plurality of the self-commutated converters so that a sum of power flowing from the self-commutated converters into the common bus and power fed out from the common bus to the self-commutated converters is cooperatively set to zero, thereby asynchronously interchanging power among destinations to which second terminals of the self-commutated converters are connected.

8. The power conversion device according to claim 7, characterized in that the power interchange profile includes a power converting direction, and an amount of power conversion at each self-commutated converter, and

the control unit controls the plurality of self-commutated converters so that each plurality of self-commutated converters corresponding to each identifier converts power of the amount of power conversion in the power converting direction between beginning time and ending time.

9. The power conversion device according to claim 7, characterized in that the control unit transmits and receives the power conversion information via electric lines and data communication network connecting among the power conversion devices.

10. The power conversion device according to claim 7, characterized by further comprising a power storage device connected to the common bus.

11. The power conversion device according to claim 7, characterized in that each self-commutated converter is measured voltage of a second terminal of the self-commutated converter connected to a destination, the control unit controls the self-commutated converters, wherein when each of the second terminals connected to the destinations has detected AC voltage, each of the self-commutated converters synchronizes the power having a given difference with each of the destinations regarding to at least one of current, voltage, frequency and phase to transfer given active power and reactive power to and from each of the destinations,

wherein when each of the second terminals connected to the destinations has detected DC voltage, each of the self-commutated converters synchronizes the power having a given voltage difference with each of the destinations to transfer given active power to and from each of the destinations.

12. The power conversion device according to claim 7, characterized in that the control unit controls the self-commutated converters so that each of the self-commutated converters, when the destination is a load, provides a power supply with a given voltage to the destination.

13. The power conversion device according to claim 7, characterized in that the control unit, when received power conversion information includes different power conversions and implementation periods of different power conversions are at least partially overlapping, adds to the amounts of power conversion of same power converting direction and subtracts the amounts of power conversion of different power converting direction to calculate integrated amount of power conversion, the control unit controls the self-commutated converters based on the integrated amount of power conversion.

14. The power conversion device according to claim 7, characterized in that the memory stores transaction establishing condition for determining whether a power conversion is performed,

the control unit transmits information indicating for establishing a power transaction to a source of power conversion information meeting the transaction establishing condition and controls the self-commutated converters based on only power conversion information meeting the transaction establishing condition.

15. The power conversion device according to claim 7, characterized in that the power conversion information includes at least one of price of power and a power generating source.

16. A stored power control device characterized by comprising:

a plurality of self-commutated converters that respectively convert power in a bidirectional manner;

a voltage and current measuring instrument that measures voltage and current passing through each self-commutated converter;

a power storage device connected to the self-commutated converters;

a power transaction memory device for recording the power amount information of power stored in the power storage device through the self-commutated converters and a power interchange profile of the stored power in relation to an identifier for identifying the self-commutated converters;

a communication unit for transmitting and receiving signals indicative of power amount information and the power interchange profile to and from other stored power control devices; and

a control unit for controlling the self-commutated converters and the power transaction memory device so that when the identifier included in the signal received by the communication unit indicates the self-commutated converter, the self-commutated converter corresponding to the identifier included in the signal transmits and receives power based on the signal and the power interchange profile is rewritten by a power interchange profile of other stored power control device;

wherein the control unit calculates voltage, current, power, frequency and phase based on measured values by the voltage and current measuring instruments, and controls a plurality of the self-commutated converters so that a sum of power flowing from the self-commutated converters into a common bus and power fed out from the common bus to the self-commutated converters is cooperatively set to zero, thereby asynchronously interchanging power among destinations to which second terminals of the self-commutated converters are connected.

17. The stored power control device according to claim 16, characterized in that the power interchange profile includes at least one of transaction date and time, the amount of power in a transaction, a type of source of power generation, a power generation operator, a power storage operator, price, power loss, CO₂ value, RPS value and green power value.

18. The stored power control device according to claim 16, characterized in that the communication unit transmits a signal to a communication unit of other stored power control device, the signal indicates the power amount information of power stored in the power storage device and the power interchange profile of the stored power and makes other stored power control device to rewrite other power interchange profile recorded in other power transaction memory of the other stored power control device to the power interchange profile.

19. The stored power control device according to claim 16, characterized in that if an amount of second power stored in other power storage device of other stored power control device is equal to that of first power stored in the power storage device of the stored power control device, the first and second power can be exchanged between their stored power control devices by that a power interchange profile of the first power stored in the power transaction memory of the stored power control device is rewritten to other power interchange profile of the second power and a power interchange profile of the second power stored in other power transaction memory of the other stored power control device is rewritten to the power interchange profile of the first power.