UTILITY INTERACTIVE INVERTER WITH VAR DISPATCH CAPABILITIES

• US 20090024255A1
• Filed: 07/17/2008
• Published: 01/22/2009
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Gridpoint (Twenty First Century Utilities LLC)
• Original Assignee: Gridpoint (Twenty First Century Utilities LLC)
• Inventors: Yan, Guohui, Penzenstadler, Ernest, Sauve, John, Golden, Brian
• Granted Patent: US 9,031,708 B2
• Time in Patent Office: Days
• US Class Current: 700/297
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 2219/25318 Power supply module in common for all modules
• CPC Class Codes: H02J 3/18 Arrangements for adjusting, eliminating or compensating reactive power in networks for adjustment of voltage H02J3/16
• CPC Class Codes: H02J 3/1842 wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
• CPC Class Codes: H02M 7/539 with automatic control of output wave form or frequency H02M7/5375 - H02M7/5387 take precedence
• CPC Class Codes: Y02E 40/20 Active power filtering [APF]

Abstract

A VAR dispatch system. A central control system connected to a network is configured to receive data reflecting local variations in conditions on a power grid and to transmit system control commands over the network. A plurality of VAR dispatch devices are connected to the network and to the power grid. Each VAR dispatch device is configured to detect local variations in conditions on the power grid and to transmit the data reflecting such local variations to the central control system and to receive control commands from the central control system. Each VAR dispatch device is configured to store power and to output stored power to the power grid based on local variations in conditions on the power grid. Each VAR dispatch device is further configured to output stored power to the power grid when the VAR dispatch device receives system control commands from the central control system.

Claims

1. A VAR dispatch device comprising:

a control system connected to a network, wherein the control system is configured to receive system control commands over the network from an external system;

a monitoring device operatively connected to the control system and to a power grid, wherein the monitoring device is configured to detect local variations in conditions on the power grid and wherein the monitoring device is further configured to communicate the local variations in conditions on the power grid to the control system;

at least one power storage device operatively connected to the control system;

an energy conversion device operatively connected to the control system, the power storage device, and the power grid, wherein the energy conversion device is configured to input power from the at least one power storage device and output the power to the grid varying at least one property of the power,

wherein the control system is further configured to command the at least one power storage device and the energy conversion device to output the power to the power grid varying the at least one property of the power when the control system receives notification of a local variation in conditions on the power grid that indicate a state of the power grid, and

wherein the control system is further configured to command the at least one power storage device and the energy conversion device to output the power to the power grid varying the at least one property of the power when the control system receives a system control command from the external system commanding the control system to output power to the power grid.

2. The VAR dispatch device of claim 1 wherein the network is a wide area network and the external system is a central control system of an entity which manages the power grid.

3. The VAR dispatch device of claim 1 wherein the control system is further configured to transmit, over the network, the local the variations in conditions on the power grid received from the monitoring device to the external system.

4. The VAR dispatch device of claim 1 wherein the at least one property of the power is selected from the list:

frequency, voltage, power factor.

5. The VAR dispatch device of claim 1 wherein the at least one power storage device is selected from the list:

battery, capacitor, fuel cell, flywheel.

6. The VAR dispatch device of claim 1 wherein the state of the power grid is selected from the list:

grid instability, insufficient power on power grid, loss of power on the power grid.

7. The VAR dispatch device of claim 1 wherein the control system is further configured to command the energy conversion device to recharge at least one power storage device with power from the power grid.

8. The VAR dispatch device of claim 1 wherein the control system is programmable and is further configured to command the at least one power storage device and the energy conversion device to output power to the power grid with a specific at least one property when a specific state occurs on the power grid based on rules downloaded to the control system over the network from the external system.

9. The VAR dispatch device of claim 1 wherein the energy conversion device is an inverter.

10. The VAR dispatch device of claim 9 wherein the energy conversion device is an inverter comprising an H bridge, a series inductor, and a transformer.

11. The VAR dispatch device of claim 9 wherein the inverter further comprises a closed loop control configured to compare at least one measured value to at least one commanded value to generate an error signal, wherein the error signal causes a modulator within the inverter to generate at least one PWM gate signal controlling the power input to the inverter and the power output by the inverter.

12. The VAR dispatch device of claim 1 wherein the control system is a conventional field oriented controller configured to convert sinusoidal signals to direct and quadrature components.

13. The VAR dispatch device of claim 1 wherein the control system is further configured for island detection, voltage range detection and frequency range detection.

14. The VAR dispatch device of claim 13 wherein the control system is further configured to disconnect the energy conversion device from the power grid if the grid fails.

15. The VAR dispatch system comprising:

a central control system connected to a network, wherein the control system is configured to receive data reflecting local variations in conditions on a power grid, and wherein the central control system is further configured to transmit system control commands over the network;

a plurality of VAR dispatch devices, each VAR dispatch device being connected to the network and to the power grid,

wherein each VAR dispatch device is configured to detect local variations in conditions on the power grid and to transmit the data reflecting local variations in conditions on the power grid to the central control system,

wherein each VAR dispatch device is further configured to receive control commands from the central control system,

wherein each VAR dispatch device is further configured to store power from at least one source,

wherein each VAR dispatch device is further configured to output stored power to the power grid when local variations in conditions on the power grid indicate a local state on the power grid,

wherein each VAR dispatch device is further configured to output stored power to the power grid when the VAR dispatch device receives system control commands from the central control system commanding the device to output stored power to the power grid.

16. The VAR dispatch system of claim 15 wherein the central control system is further configured to use the data reflecting local variations in conditions received from the plurality of VAR dispatch devices to detect at least one condition on the power grid.

17. The VAR dispatch system of claim 15 is further configured to issue commands to at least one of the plurality of VAR dispatch devices commanding the devices to set the rate of response under which the at least one of the plurality of VAR dispatch devices should operate.

18. The VAR dispatch system of claim 16 wherein the central control system is further configured, upon detecting the at least one condition on the power grid, to issue commands to at least one of the plurality of VAR dispatch devices commanding the devices to output stored power to the power grid to mitigate the at least one condition.

19. The VAR dispatch system of claim 15 wherein the local state is selected from the list:

grid instability, high demand for power on the grid, insufficient power on power grid, loss of power on the power grid.

20. The VAR dispatch system of claim 16 wherein the at least one condition is selected from the list:

grid instability, high demand for power on the grid, insufficient power on power grid, loss of power on the power grid.

21. The VAR dispatch system of claim 15 wherein at least some of the plurality of VAR dispatch devices are each located near a load and supply backup power to the load during an power grid outage.

22. The VAR dispatch system of claim 15 wherein at least one of the plurality of VAR dispatch devices is a second central control system of a second VAR dispatch system.

23. A method of managing a power grid comprising the steps:

receiving, over a network, data reflecting local variations in conditions on a power grid from a plurality of VAR dispatch devices;

determining, using a computer, based on the data reflecting local variations in conditions on the power grid, that at least one condition exists on the power grid;

transmitting, over the network, at least one control command to at least one of the plurality of VAR dispatch devices to output power to the power grid to mitigate the at least one condition exists on the power grid.

24. The VAR central control system of claim 23 wherein the at least one condition is selected from the list:

grid instability, high demand for power on the grid, insufficient power on power grid, loss of power on the power grid.

25. A VAR dispatch device comprising:

a control system connected to a network, wherein the control system is configured to receive system control commands over the network from an external system;

a monitoring device operatively connected to the control system and to a power grid, wherein the monitoring device is configured to detect local variations in conditions on the power grid and wherein the monitoring device is further configured to communicate the local variations in conditions on the power grid to the control system;

at least one power storage device operatively connected to the control system;

an energy conversion device operatively connected to the control system, the power storage device, and the power grid, wherein the energy conversion device is configured to input power from the at least one power storage device and output the power to the grid varying at least one property of the power,

wherein the control system is further configured to command the power storage device and the energy conversion device to output the power to the power grid varying the at least one property of the power when the control system receives a system control command from the external system commanding the control system to output power to the power grid.