Shunt connected superconducting energy management system having a single switchable connection to the grid

• US 6,215,202 B1
• Filed: 05/21/1998
• Issued: 04/10/2001
• Est. Priority Date: 05/21/1998
• Status: Expired due to Fees

• Current Assignee: Bechtel Enterprises, Inc. (Bechtel Group Incorporated), Siemens AG
• Original Assignee: Bechtel Enterprises, Inc. (Bechtel Group Incorporated), Siemens AG
• Inventors: Unterlass, Franz Josef, Luongo, Cesar A.
• Primary Examiner(s): Paladini, Albert W.
• Assistant Examiner(s): DEBERADINIS, ROBERT L
• Application Number:
  US09/083,009
• Time in Patent Office: 1,055 Days
• Field of Search: 307/43, 307/44, 307/64, 307/65, 307/66, 307/80, 307/85, 307/86, 307/87, 307/18, 307/23, 361/19, 361/141, 363/14
• US Class Current: 307/64
• CPC Class Codes: H02J 15/00 Systems for storing electric energy mechanical systems therefor F01-F04; in chemical form H01M
• CPC Class Codes: Y02E 40/60 Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
• CPC Class Codes: Y02P 90/50 Energy storage in industry with an added climate change mitigation effect

Abstract

A shunt connected superconducting energy management system (SEMS) is provided at a single switched connection between a utility grid and one or more power sensitive loads such as a semiconductor manufacturing plant having power requirements in the range on the order of 2 megawatts (MW) to 200 MW. When a voltage disturbance is sensed in the grid, power control circuitry acts to simultaneously isolate the load and the SEMS from the grid using a single switch which simultaneously provides full back up power to the load instantaneously without voltage transients or disturbances.

Claims

1. A shunt connected energy storage and back up system for supporting one or more loads receiving power from a utility grid for connecting a source of electric power to said one or more loads;

said energy storage and back up system comprising;

a control monitoring system coupled to the utility grid for providing a control signal indicative of an interruption or undervoltage condition on the utility grid and for sensing stabilization of the utility grid;

an energy storage device for providing active power in a range of 2 MW to 200 MW and stored energy in a range from 25 megajoules to 1,000 megajoules to a load for a duration commensurate with the storage capacity of said energy storage device;

a single switchable connection between the energy back up and storage system and said one or more loads, said single switchable connection responsive to the control signal for simultaneously both isolating the load and energy storage and backup system from the utility grid and for enabling the energy storage device to provide active power to the load;

a power converter unit responsive to the control signal indicative of the undervoltage or interrupt condition for coupling the energy storage device to the one or more loads such that upon activation of the single switchable connection, the disconnect from the utility grid is transient-free and the reconnect to the grid after stabilization is transient-free.

2. An energy storage system for protecting one or more power sensitive loads connected over a utility grid to a source of electric power comprising:

an energy storage system connected to said one or more loads for protecting said one or more power sensitive loads from an undervoltage condition or power interruption on the utility grid, said energy storage system further comprising;

a control circuit coupled to the utility grid for sensing an undervoltage condition or interruption on the utility grid and for providing an output signal representative of said undervoltage condition;

a switch responsive to said output signal for simultaneously isolating the load and energy storage system from the utility grid, and for simultaneously enabling the energy storage system to provide back up power to said one or more power sensitive loads upon activation by said output signal;

a power converter unit providing an energy flow in a range from 2 MWs to 200 MWs to said one or more power sensitive loads and for providing substantially transient-free, instantaneous ramp-up of power to said one or more power sensitive loads when the switch disconnects said one or more power sensitive loads from the utility grid.

3. A device as in claim 2 wherein said one or more power sensitive loads comprises a plurality of loads and further comprising:

a control system coupled with said control circuit for actively monitoring the energy need of each load of said plurality of loads and for providing a priority ordering of said plurality of loads for coupling with said energy storage system such that active power from said energy storage system is provided in accordance with the energy need of each of said plurality of loads when an undervoltage condition is detected;

a microprocessor including a system for monitoring real time information on power operating parameters for each of said plurality of loads and;

means for comparing the real time operating parameters of each of said plurality of loads to corresponding optimized operating parameters stored in a memory coupled to said microprocessor and for producing an output signal representative of a priority ranking of the power need of each of said plurality of loads over a given time interval;

a load selector circuit having an input lead connected to the converter unit, a plurality of output leads each connected to a corresponding load of said plurality of loads and a control lead for receiving said signal representative of a priority ranking of power needs, said load selector selectively switching back up power from said converter unit into selected loads from said plurality of loads as a function of power need.

4. A modular energy storage system for providing scalable back-up power to one or more loads connected to a utility grid comprising:

a plurality of superconducting magnets, each superconducting magnet being linkable to another superconducting magnet in a modular arrangement for providing a scalable source of stored energy for back-up power to at least one of said one or more loads in the event of an undervoltage condition, interruption or other power discontinuity on a utility grid;

a control circuit for monitoring the utility grid and for providing a control signal indicative of said undervoltage condition, interruption or other power discontinuity;

one or more power converter units linkable in a modular arrangement for connecting the scalable store of energy from said superconducting magnets to said at least one of said one or more loads upon activation by said control signal;

a switch providing a single switchable connection between said at least one of said one or more loads and said utility grid, said switch simultaneously isolating said at least one of said one or more loads and energy storage system from the grid and simultaneously enabling said power converter units to couple the stored energy into said at least one of said one or more loads upon activation by the control signal.

5. A modular energy storage system for providing scalable back-up power to at least one of one or more loads connected to a utility grid comprising:

a plurality of superconducting magnet modules, each module comprising one or more superconducting magnets connected together such that the energy storage of the plurality of modular superconducting magnets is scalable without changing the size of the module;

a converter unit comprising a plurality of prefabricated, modular AC/DC converters, each connected for receiving the energy from one or more modular superconducting magnets, and each AC/DC converter connectable in parallel with an associated one or more AC/DC converters for current sharing to provide a scalable source of active power to said at least one of said one or more loads upon activation by a control signal;

a control monitoring system comprising a switch responsive to a control signal for simultaneously isolating said at least one of said one or more loads and energy storage system from the utility grid and for simultaneously enabling the converter unit to couple power into said at least one or more loads, said control monitoring system further comprising;

a sensor connected for monitoring the utility grid for detecting an under-voltage condition and for providing a control signal representative of that condition such that a control signal activates the switch to disconnect said at least one of said one or more loads from the utility grid and simultaneously enable the AC/DC converter to send energy to said at least one of said one or more loads such that the energy transfer from the energy storage system to said at least one of said one or more loads is transient-free and said sensor monitors the grid for reconnection when grid operation is normal.

6. An energy storage system for delivering back-up power to a load connected to a utility grid comprising:

energy storage comprising a plurality of prefabricated, containerized superconducting magnets interconnected such that the plurality of superconducting magnets provide a scalable store of energy for delivery to the load;

a converter unit for connecting the energy storage to the load, said converter unit comprising a plurality of prefabricated and containerized converters interconnected for receiving the output energy of said superconducting magnets and for coupling said energy as active power to the load upon receipt of a control signal;

a switch responsive to a control signal representative of an undervoltage condition on the grid such that activation of the switch isolates the grid from the load and simultaneously enables the converter unit to couple energy into the load such that the transfer of energy to the load is substantially transient-free.

7. A method for isolating a load from a utility grid during a voltage sag or interruption on the grid, and for simultaneously enabling energy stored in a SEMS to support the load, the method comprising the steps of:

activating a single switch for simultaneously isolating the load and SEMS from the utility grid and for simultaneously coupling power to the load from the SEMS;

sampling the line voltage on the utility grid at a sufficiently high rate to achieve a decision and activate said switch within ½

cycle;

comparing the sampled line voltage to a reference voltage (100%) and computing the resulting fraction;

defining a threshold for activating said switch in terms of the magnitude of the sag and its duration, or the duration of the interruption, in seconds such that when the product of the computed fractional voltage computed multiplied by the time elapsed from the first detection of the voltage sag, is greater than the threshold, the switch is activated to disconnect the load from the grid and simultaneously enable the energy storage system to release the stored energy into the load.

8. A method for isolating a load from a utility grid during a voltage sag/interruption and for simultaneously switching the load to a backup source of energy comprising the steps of:

sampling line voltage and load current on at least one phase of one or more phases;

comparing the sampled line voltage to a reference voltage and computing the resulting fraction;

computing one or more parameters of the sampled voltage and current, such as step-in-phase angle, power flow direction, and space vector locus;

defining a threshold time for activation of the switch in terms of the computed fraction of the reference voltage such that when an elapsed time from the beginning of the voltage sag is greater than the threshold, computed for the instantaneous magnitude of the sag the switch is activated to disconnect the load from the grid and simultaneously transfer the back up energy into the load.

9. A method as in claim 8 wherein the sampling of line voltage and load current on the grid is done at a sufficiently high sample rate to achieve a decision to isolate the load within one-half cycle.

10. A method as in claim 8 wherein the step of defining the threshold time for activation of the switch further comprises the step of monitoring and acting upon one or more characteristics of AC power on the grid such as the direction of power flow, step-in phase angle and locus of positive vector.

11. A modular energy storage system for providing scalable back-up power to one or more loads connected to a utility grid comprising:

a plurality of superconducting magnets, each superconducting magnet being linkable to another superconducting magnet in a modular arrangement for providing a scalable source of stored energy for back-up power to at least one of said one or more loads in the event of an undervoltage condition, interruption or other power discontinuity on a utility grid;

a control circuit for monitoring the utility grid and for providing a control signal indicative of said undervoltage condition, interruption or other power discontinuity;

one or more power converter units linkable in a modular arrangement for connecting the scalable store of energy from said superconducting magnets to said at least one of said one or more loads upon activation by said control signal;

a switch providing a single switchable connection between said at least one of said one or more loads and said utility grid, said switch simultaneously isolating said at least one of said one or more loads and energy storage system from the grid and simultaneously enabling said power converter units to couple the stored energy into said at least one of said one or more loads upon activation by the control signal,

a plurality of superconducting magnet modules, each module comprising one or more superconducting magnets connected together such that the energy storage of the plurality of modular superconducting magnets is scalable without changing the size of the module;

a converter unit comprising a plurality of prefabricated, modular AC/DC converters, each connected for receiving the energy from one or more modular superconducting magnets, and each AC/DC converter connectable in parallel with an associated one or more AC/DC converters for current sharing to provide a scalable source of active power to said at least one of said one or more loads upon activation by a control signal;

a control monitoring system comprising a switch responsive to a control signal for simultaneously isolating said at least one of said one or more loads and energy storage system from the utility grid and for simultaneously enabling the converter unit to couple power into said at least one or more loads, said control monitoring system further comprising;

a sensor connected for monitoring the utility grid for detecting an under-voltage condition and for providing a control signal representative of that condition such that a control signal activates the switch to disconnect said at least one of said one or more loads from the utility grid and simultaneously enable the AC/DC converter to send energy to said at least one of said one or more loads such that the energy transfer from the energy storage system to said at least one of said one or more loads is transient-free and said sensor monitors the grid for reconnection when grid operation is normal.