Methods and apparatus for design and control of multi-port power electronic interface for renewable energy sources

• US 8,442,698 B2
• Filed: 01/29/2010
• Issued: 05/14/2013
• Est. Priority Date: 01/30/2009
• Status: Expired due to Fees

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Fahimi, Babak, Jiang, Wei
• Primary Examiner(s): JARRETT, RYAN A
• Application Number:
  US12/696,896
• Publication Number:
  US 20100198421A1
• Time in Patent Office: 1,201 Days
• Field of Search: 700/287, 700/297
• US Class Current: 700/297
• 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 2300/40 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 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02J 3/466 Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: Y02B 10/70 Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• 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

Abstract

Methods and systems for energy management are disclosed. An example system includes a first port connected to an energy storage device for bidirectional flow of energy, a second port connected to an energy source device for unidirectional flow of energy, a third port connected to a utility grid for bidirectional flow of energy, and a unified control system with control logic configured to simultaneously control energy flow between the first, second, and third ports based on at least two factors from the group consisting of: a state of charge of the energy storage device, a state of the energy source device, and a state of the utility grid. Other embodiments are described and claimed.

Claims

1. An energy management system, comprising:

a first port configured for bidirectional flow of energy and connected to an energy storage device;

a second port configured for unidirectional flow of energy and connected to an energy source device;

a third port configured for bidirectional flow of energy and connected to a utility grid; and

a unified control system wherein the unified control system comprises control logic configured to operate in a generation mode, a recovery mode, and an emergency/UPS mode and operable to simultaneously control energy flow between the first, second, and third ports based on at least two factors from a group consisting of;

a state of charge of the energy storage device,

a state of the energy source device, and

a state of the utility grid, and

wherein the emergency/UPS mode comprises energy transfer from the energy source device and the energy storage device to a power load or the utility grid when the state of charge of the energy storage device is less than 90% and a load power demand is greater than a maximum state of charge of the energy storage device plus the state of the energy source device.

2. The energy management system of claim 1, further comprising:

an intelligent energy management system wherein the intelligent energy management system comprises control logic operable to purchase, sell, store, or schedule energy between the first, second, and third ports based on at least one factor from the group consisting of;

a renewable energy generation forecast,

an energy consumption forecast, and

a substantially real-time price of energy.

3. The energy management system of claim 2, wherein the renewable energy generation forecast is based on a weather forecast.

4. The energy management system of claim 2, wherein the energy consumption forecast is based on a weather forecast and past energy consumption data.

5. The energy management system of claim 1, wherein the energy source device comprises at least one device from the group consisting of:

a photovoltaic device, a fuel cell, a wind turbine, a vibration energy harvester, and a nuclear device.

6. The energy management system of claim 1, wherein the energy storage device comprises at least one device from the group consisting of:

a battery, a hydraulic device, and an ultra capacitor.

7. The energy management system of claim 1, further comprising:

a DC source interface converter configured to process unidirectional energy flow from the energy source device and bidirectional energy flow from the energy storage device to support a stable DC-link; and

an AC load interface converter supplied by the stable DC-link; and

wherein the AC load interface is configured to process bidirectional energy flow from the utility grid.

8. The energy management system of claim 1, wherein the generation mode comprises energy transfer from the energy storage device and the energy source device to the utility grid when the state of charge of the energy storage device is greater than 95% and the state of the energy source device is greater than zero.

9. The energy management system of claim 1, wherein the recovery mode comprises energy transfer from the energy source device and the utility grid to the energy storage device when the state of charge of the energy storage device is less than 50%.

10. The energy management system of claim 1, wherein the emergency/UPS mode comprises energy transfer from the energy source device and the energy storage device to the utility grid when the state of charge of the energy storage device is greater than 95%.

11. The energy management system of claim 1, wherein the emergency/UPS mode comprises energy transfer only from the at least one energy source device to a power load or the utility grid when the state of charge of the energy storage device is less than 50% and the load power demand is less than the state of the energy source device.

12. An energy management system, comprising:

a first port configured for bidirectional flow of energy and connected to an energy storage device;

a second port configured for unidirectional flow of energy and connected to an energy source device;

a third port configured for bidirectional flow of energy and connected to a utility grid; and

a unified control system wherein the unified control system comprises control logic configured to operate in a generation mode, a recovery mode, and an emergency/UPS mode and operable to simultaneously control energy flow between the first, second, and third ports based on at least two factors from the group consisting of;

a state of charge of the energy storage device,

a state of the energy source device, and

a state of the utility grid, and

wherein the emergency/UPS mode comprises energy transfer from the energy source device to the energy storage device and a power load or the utility grid when the state of charge of the energy storage device is less than 50% and a load power demand plus a minimum state of charge of the energy storage device is less than the state of the energy source device.

13. A method for managing energy movement, the method comprising:

receiving, at a unified control system for a multi-port power interface operable to provide for energy flow between first, second, and third ports of the multi-port power interface, information pertaining to a state of charge of an energy storage device connected to the first port;

receiving, at the unified control system, information pertaining to a state of at least one energy source device connected to the second port;

receiving, at the unified control system, information pertaining to a state of a utility grid connected to the third port; and

automatically determining whether operational characteristics of the multi-port power interface should be modified, based on at least two factors from the group consisting of;

the information pertaining to the state of charge of the energy storage device;

the information pertaining to the state of the energy source device; and

the information pertaining to the state of the utility grid; and

in response to determining that operational characteristics of the multi-port power interface should be modified, automatically modifying the operational characteristics of the multi-port power interface accordingly, wherein the operation of automatically determining whether operational characteristics of the multi-port power interface should be modified comprises automatically selecting between at least three modes, comprising;

a recovery mode for purchasing energy from the utility grid;

a generation mode for selling energy to the utility grid; and

an emergency mode, wherein the emergency mode is selected in response to determining that the state of charge of the energy storage device is less than 90% and a load power demand is greater than a maximum state of charge of the energy storage device plus the state of the energy source device;

wherein the unified control system comprises control logic configured to operate in the generation mode, the recovery mode, and the emergency mode.

14. The method of claim 13, wherein:

the operation of selecting between at least three modes comprises selecting the generation mode in response to determining that the state of charge of the energy storage device is greater than 95% and the state of the energy source device is greater than zero; and

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy from the energy storage device and the energy source device to the utility grid.

15. The method of claim 13, wherein:

the operation of selecting between at least three modes comprises selecting the recovery mode in response to determining that the state of charge of the energy storage device is less than 50%; and

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy from the energy source device and the utility grid to the energy storage device.

16. The method of claim 13, wherein the emergency mode is selected in response to determining that the state of charge of the energy storage device is greater than 95%;

and

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy from the energy source device and the energy storage device to a power load or the utility grid.

17. The method of claim 13, wherein:

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy from the energy source device and the energy storage device to a power load.

18. The method of claim 13, wherein the emergency mode is selected in response to determining that the state of charge of the energy storage device is less than 50% and a load power demand is less than the state of the energy source device;

and

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy only from the at least one energy source device to a power load or the utility grid.

19. The method of claim 13, wherein the emergency mode is selected in response to determining that the state of charge of the energy storage device is less than 50% and a load power demand plus a minimum state of charge of the energy storage device is less than the state of the energy source device;

and

the operation of automatically modifying the operational characteristics of the multi-port power interface accordingly comprises configuring the multi-port power interface to transfer energy from the energy source device to the energy storage device and a power load or the utility grid.

20. The method of claim 13, wherein the determination of whether operational characteristics of the multi-port power interface should be modified is further based on at least one factor from the group consisting of:

a renewable energy generation forecast,

an energy consumption forecast, and

a substantially real-time price of energy.

21. The method of claim 20, wherein the renewable energy generation forecast is based on a weather forecast.

22. The method of claim 20, wherein the energy consumption forecast is based on a weather forecast and past energy consumption data.

23. The method of claim 13, wherein the energy source device comprises at least one device from the group consisting of:

a photovoltaic device, a fuel cell, a wind turbine, a vibration energy harvester, and a nuclear device.

24. The method of claim 13, wherein the energy storage device comprises at least one device from the group consisting of:

a battery, a hydraulic device, and an ultra capacitor.

25. The method of claim 13, further comprising:

configuring a DC source interface converter to process unidirectional energy flow from the energy source device and bidirectional energy flow from the energy storage device to support a stable DC-link; and

configuring an AC load interface converter supplied by the stable DC-link to process bidirectional energy flow from the utility grid.