Method for using chemical thermodynamics to buffer the voltage of electric circuits and power systems

• US 9,859,703 B2
• Filed: 11/19/2015
• Issued: 01/02/2018
• Est. Priority Date: 11/19/2015
• Status: Active Grant

• Current Assignee: Shepherd Hydricity Inc.
• Original Assignee: Shepherd Hydricity Inc.
• Inventors: Shepherd, Stephen H.
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US14/946,681
• Publication Number:
  US 20170149237A1
• Time in Patent Office: 775 Days
• Field of Search: 307152
• CPC Class Codes: H02H 9/005 avoiding undesired transient conditions
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 3/12 for adjusting voltage in ac networks by changing a characteristic of the network load
• CPC Class Codes: H02J 3/28 Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

A method for buffering the voltage of an electric system that undergoes transient voltage changes includes the step of placing a new load upon the electric system by electrically connecting at least one electrochemical device to the electric system so that electrical current flows from the electric system to the electrochemical device. Also included are the steps of causing at least one electrochemical reaction to occur within the at least one electrochemical device; varying the new load placed upon the electric system as transient voltage changes in the electric system occur; and changing the electrical current from the electric system to the electrochemical device in a manner that retards transient voltage changes in the electric system that would occur in the absence of the steps of placing, causing, and varying. The step of causing electrochemical reactions may include using water electrolysis to produce a product that is a fuel, and the method may further include producing electric power and delivering it to the electric system. The electrochemical devices used in the method may apply chemical thermodynamics to retard increasing and decreasing electric system voltage transients and cause the transient electric system voltage to remain within a pre-specified voltage range. The method may also include connecting one or more voltage support units to provide electric power.

Claims

1. A method for buffering the voltage of an alternating current (AC) electric circuit (EC) system that undergoes transient voltage changes, above or below a nominal operating voltage of the AC EC system, during use as a result of variances in loads on, or power to, the system, comprising:

placing a new load upon the AC EC system at its nominal operating voltage by electrically connecting an electrochemical device to the AC EC system by a rectified, direct current (DC) circuit via a voltage transformer;

selecting a step-up or step-down transformer rating for the voltage transformer for causing the new load to have a voltage that varies without regulation in proportion to the voltage of the AC EC system during transient voltage changes;

selecting a capacity, a chemical concentration and an electrode design for the electrochemical device, wherein the selecting steps cause the new load to be powered by the AC EC system at voltage levels that cause at least one electrochemical reaction exhibiting Nernstian behavior of the reaction rate to occur within the at least one electrochemical device;

providing, during a first transient voltage change in the AC EC system, additional voltage from the AC EC system to the electrochemical device to exponentially increase the load on the AC EC system when the AC EC system voltage increases, to retard the first transient voltage change that would occur in the absence of the placing, selecting and providing steps; and

providing, during a second transient voltage change in the AC EC system, reduced voltage from the AC EC system to the electrochemical device to exponentially decrease the load on the AC EC system when the AC EC system voltage decreases, to retard the second transient voltage change that would occur in the absence of the placing, selecting and providing steps.

2. The method of claim 1, wherein the at least one electrochemical reaction is an electrolysis reaction to produce a product that is a fuel;

and wherein the method further includes producing AC electric power from an AC-power generator powered by the fuel, and delivering the AC electric power to the AC EC system.

3. The method of claim 1, wherein the at least one electrochemical reaction is an electrolysis reaction that produces a hydrogen fuel, and wherein the method further comprises:

delivering the hydrogen fuel to a hydrogen fuel cell;

producing, in the hydrogen fuel cell, DC electric power;

inverting the DC electric power produced by the hydrogen fuel cell into AC electrical power; and

delivering the AC electrical power to the AC EC system.

4. The method of claim 1, wherein the electrochemical device is sized to allow an amount of AC EC system voltage control by reducing the magnitude of transient voltage changes, and the amount of AC EC system voltage control enables adjustment to the AC EC system that results in a zero derivative of AC EC system current with respect to AC EC system voltage before the voltage transient exceeds the limits of a desired control range.

5. The method of claim 1, wherein the AC EC system includes neutral circuitry that is connected to the electrochemical device at a nominal zero voltage, and wherein the electrochemical device is constructed with a buffer capacity to buffer the voltage of the AC EC system neutral circuitry to protect the AC EC system from overvoltage conditions caused by geomagnetically-induced voltage transient events.

6. The method of claim 1, further including the step of providing one or more ancillary services to the AC EC system that are chosen from the group consisting of supplemental reserve capacity, voltage regulation, reactive power, and black-start capability as defined by the U.S. Federal Electric Regulatory Commission.

7. A method for passively controlling the voltage of an alternating current (AC) electric power transmission and distribution (EPTD) system that includes a transmission line with transmission-line voltage, experiences varying loads during use as a result of variances in loads on, or power to, the system, and undergoes transient voltage changes above or below a nominal operating voltage of the AC EPTD system, comprising:

electrically connecting an electrochemical device to the AC EPTD system at its nominal operating voltage so that electrical current flows from the AC EPTD system, through a rectifier and a voltage transformer, to the electrochemical device;

selecting a step-up or step-down transformer rating for the voltage transformer; and

selecting a capacity, a chemical concentration and an electrode design for the electrochemical device;

wherein the selecting steps cause the electrochemical device to be powered by the AC EPTD system at voltage levels which cause at least one electrochemical reaction exhibiting Nernstian behavior of the reaction rate to occur within the at least one electrochemical device;

wherein the reaction rate of the at least one electrochemical reaction varies as transient voltage changes on the AC EPTD system occur, exponentially varying a load on the AC EPTD system from the electrochemical device as transient voltage changes on the AC EPTD system occur to retard transient voltage changes in the AC EPTD system that would occur in the absence of the electrically connecting step and selecting steps.

8. The method of claim 7, wherein the at least one electrochemical reaction is an electrolysis reaction to produce a product that is a fuel;

and wherein the method further includes producing AC electric power from an AC-power generator powered by the fuel, and delivering the AC electric power to the AC EPTD system.

9. The method of claim 8, wherein the fuel produced from the electrolysis produces direct current (DC) electric power from a hydrogen fuel cell powered by the fuel, and further including the step of inverting the DC electric power produced by the hydrogen fuel cell into AC electrical power, and delivering the AC electrical power to the AC EPTD system.

10. The method of claim 7, wherein the electrochemical device is sized to allow an amount of AC EPTD system voltage control by reducing the magnitude of transient voltage changes, and the amount of AC EPTD system voltage control enables adjustment to the AC EPTD system that results in a zero derivative of AC EPTD system current with respect to AC EPTD system voltage before the voltage transient exceeds the limits of a desired control range.

11. The method of claim 7, wherein the electrochemical device has a voltage buffer capacity that is higher than a buffer capacity required to buffer voltage rises from loss of all loads in the AC EPTD system.

12. The method of claim 7, wherein the AC EPTD system includes neutral circuitry that is connected to the electrochemical device at a nominal zero voltage, and wherein the electrochemical device is constructed with a buffer capacity to buffer the voltage of the AC EPTD system neutral circuitry to protect the AC EPTD system from overvoltage conditions caused by geomagnetically-induced voltage transient events.

13. The method of claim 7, further including the step of providing one or more ancillary services to the AC EPTD system that are chosen from the group consisting of supplemental reserve capacity, voltage regulation, reactive power, and black-start capability as defined by the U.S. Federal Electric Regulatory Commission.

14. A system for retarding transient voltage changes occurring on an alternating current (AC) electric circuit (EC) system, above or below a nominal operating voltage of the AC EC system, the system comprising:

an AC EC system, wherein the AC EC system comprises a high voltage AC transmission line;

a DC circuit;

a step down transformer connected to the AC EC system to step down a high voltage AC on the high voltage AC transmission line of the AC EC system to provide a low voltage AC whose voltage varies without regulation in proportion to the high voltage AC of the AC EC system during transient voltage changes;

a rectifier connected to the step down transformer to convert the low voltage AC to low voltage DC;

an electrochemical device electrically connected to the rectifier and electrically connected through the rectifier and the step down transformer to the AC EC system so that electrical current can flow from the AC EC system to the electrochemical device, wherein the step down transformer comprises a voltage transformer rating and the electrochemical device comprises a capacity, a chemical concentration and an electrode design that are selected to cause the electrochemical device to be powered by the AC EC system at voltage levels that cause at least one electrochemical reaction exhibiting Nernstian behavior of the reaction rate to occur within the electrochemical device so that the low voltage AC flowing to the electrochemical device varies with changes in the voltage level on the high voltage AC transmission line causing the load provided by the electrochemical device to exponentially vary to retard transient voltage changes occurring on the AC EC system that occur as a result of variances in loads on or power to the AC EC system;

wherein the system provides, during a first transient voltage change in the AC EC system, additional power from the AC EC system to the electrochemical device to exponentially increase the load on the system when the AC EC system voltage increases, to retard the first transient voltage change; and

wherein the system provides, during a second transient voltage change in the AC EC system, reduced power from the AC EC system to exponentially decrease the load on the system when the AC EC system voltage decreases, to retard the second transient voltage change.

15. The system of claim 14, wherein the AC EC system is an AC electric power transmission and distribution system.

16. The system of claim 14, wherein the electrochemical device is an electrolysis device, and the at least one reaction is an electrolysis reaction to produce a product that is a fuel;

and wherein the system further comprises an AC-power generator that is powered by the fuel to produce AC electric power;

wherein the AC-power generator is electrically connected to the AC EC system to deliver the AC electric power from the AC-power generator to the AC EC system.

17. The system of claim 14, wherein the electrochemical device is an electrolysis device, and the at least one reaction is an electrolysis reaction to produce a hydrogen fuel;

and wherein the system further comprises;

a hydrogen fuel cell configured to receive the hydrogen fuel and to produce DC electric power from the hydrogen fuel; and

an inverter, connected between the hydrogen fuel cell and the AC EC system to receive the DC electric power, to invert the DC electric power into AC electric power, and to deliver the AC electric power to the AC EC system.

18. The system of claim 14, wherein the electrochemical device is sized to allow an amount of AC EC system voltage control by reducing the magnitude of transient voltage changes, and the amount of AC EC system voltage control enables adjustment to the AC EC system that results in a zero derivative of AC EC system current with respect to AC EC system voltage before the voltage transient exceeds the limits of a desired control range.

19. The system of claim 14, wherein the AC EC system includes neutral circuitry that is connected to the electrochemical device at a nominal zero voltage, and wherein the electrochemical device is constructed with a buffer capacity to buffer the voltage of the AC EC system neutral circuitry to protect the AC EC system from overvoltage conditions caused by geomagnetically-induced voltage transient events.

20. The system of claim 14, further including the step of providing one or more ancillary services to the AC EC system that are chosen from the group consisting of supplemental reserve capacity, voltage regulation, reactive power, and black-start capability as defined by the U.S. Federal Electric Regulatory Commission.