Systems and method for obtaining a load model and related parameters based on load dynamics

• US 8,706,309 B2
• Filed: 04/10/2010
• Issued: 04/22/2014
• Est. Priority Date: 04/10/2010
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Schweitzer, Edmund O. III, Donolo, Marcos A., Whitehead, David E.
• Primary Examiner(s): Kasenge, Charles
• Application Number:
  US12/757,995
• Publication Number:
  US 20110251732A1
• Time in Patent Office: 1,473 Days
• Field of Search: 700/22, 700/28, 700/29, 700/31, 700/286, 700/291, 700/292, 700/293, 700/294, 700/295, 700/296, 700/297, 700/298, 703/13, 703/18
• US Class Current: 700/291
• CPC Class Codes: H02J 13/00004 characterised by the power network being locally controlled
• CPC Class Codes: H02J 13/00006 characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 2310/12 The local stationary network supplying a household or a building
• CPC Class Codes: H02J 3/003 Load forecast, e.g. methods or systems for forecasting future load demand
• CPC Class Codes: H02J 3/12 for adjusting voltage in ac networks by changing a characteristic of the network load
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/18 using switches, relays or circuit breakers, e.g. intelligent electronic devices [IED]
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

Disclosed are systems and methods for calculating load models and associated tunable parameters that may be used to describe the behavior of loads connected to an electric power distribution system. The load models may be utilized to predict variations in demand caused by changes in the supply voltage, and may be utilized in determining an optimized control strategy based on load dynamics. Any action which causes a disruption to the electric power distribution system may provide information regarding the composition or dynamics of connected loads. Such actions may be referred to as modeling events. Modeling events may occur with some frequency in electric power distribution systems, and accordingly, a number of data sets may be acquired under a variety of conditions and at a variety of times. Load models may include static load models, dynamic load models, or a combination of static and dynamic load models.

Claims

1. An electric power distribution system to distribute power to at least one load, comprising:

a first load;

a bus connected to the first load;

a capacitor bank in electrical communication with the bus;

a first intelligent electronic device (IED) configured to interface with the electric power distribution system, comprising;

a first network communications interface;

a processor; and

a computer-readable storage medium, comprising;

software instructions executable on the processor that enable the IED to perform operations, including;

determining that the capacitor bank has been connected to the bus;

receiving a first plurality of measurements representing an electrical condition in at least a portion of the electric power distribution system prior to connecting the capacitor bank to the bus and subsequent to connecting the capacitor bank to the bus; and

,

calculating a load model based on the first plurality of measurements, the load model representing a predicted response of the first load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system.

2. The electric power distribution system of claim 1, wherein the software instructions executable on the processor enable the IED to perform operations, including:

identifying that the first load comprises a constant impedance load; and

determining that the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

reducing the voltage provided to the first load.

3. The electric power distribution system of claim 1, wherein the software instructions executable on the processor enable the first IED to perform operations, including:

identifying that the first load comprises a constant power load;

determining that the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

electrically disconnecting the first load from the electric power distribution system.

4. The electric power distribution system of claim 1, wherein the software instructions executable on the first processor further enable the IED to perform operations, including:

adjusting the load model based upon at least one of a season, a day of the week, and a time of the day in which the electrical condition occurs.

5. The electric power distribution system of claim 1, further comprising:

a second IED configured to interface with the electric power distribution system, comprising;

a second network communications interface to communicate with the first IED;

a sensor component configured to make measurements on the bus;

a second processor; and

a second computer-readable storage medium, comprising;

software instructions executable on the second processor that enable the second IED to perform operations, including;

identifying an event based on measurements made by the sensor component;

recording a second plurality of measurements representing electrical conditions in at least a portion of the electric power distribution system prior to the event and subsequent to the event;

generating a load dynamics report comprising the second plurality of measurements; and

transmitting the load dynamics report to the first IED.

6. The electric power distribution system of claim 5, wherein the software instructions executable on the first processor further enable the first IED to perform operations, including:

receiving the load dynamics report;

identifying the second event as a second modeling event;

calculating a second load model based on the second plurality of measurements, the second load model representing a predicted response of the first load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system; and

determining an optimized control strategy based on the first calculated load model and the second calculated load model.

7. The electric power distribution system of claim 5, wherein each of the first IED and the second IED further comprise an external time input configured to receive an external time signal from an external time source;

and

wherein the software instructions executable on each of the first processor and the second processor further enable the first IED and the second IED to perform operations, including;

recording a time based on the external time source and associated with each of the first plurality of measurements and the second plurality of measurements.

8. The electric power distribution system of claim 1, wherein the first load model further represents sensitivity of the first load to variations in voltage of power distributed by the electric power distribution system.

9. An electric power distribution system to distribute power to at least one load, comprising:

a first load;

a first bus connected to the first load;

a primary transformer in electrical communication with the first bus;

a first intelligent electronic device (IED) configured to interface with the electric power distribution system, comprising;

a network communications interface;

a processor; and

a computer-readable storage medium, comprising;

software instructions executable on the processor that enable the IED to perform operations, including;

determining that an adjustment has been made to an output voltage of the primary transformer;

receiving a first plurality of measurements representing an electrical condition in at least a portion of the electric power distribution system prior to the adjustment of the output voltage of the primary transformer and subsequent to the adjustment of the output voltage of the primary transformer; and

,

calculating a first load model based on the first plurality of measurements, the first load model representing a predicted response of the first load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system.

10. The electric power distribution system of claim 9, further comprising:

a second IED configured to interface with the electric power distribution system, comprising;

a network communications interface to communicate with the first IED;

a sensor component configured to make measurements on the bus;

a second processor; and

a second computer-readable storage medium, comprising;

software instructions executable on the second processor that enable the second IED to perform operations, including;

identifying an event based on measurements made by the sensor component;

recording a second plurality of measurements representing electrical conditions in at least a portion of the electric power distribution system prior to the event and subsequent to the event;

generating a load dynamics report comprising the second plurality of measurements; and

transmitting the load dynamics report to the first IED.

11. The electric power distribution system of claim 10, wherein the software instructions executable on the first processor further enable the first IED to perform operations, including:

receiving the load dynamics report;

identifying the event as a modeling event;

calculating a second load model based on the second plurality of measurements, the second load model representing a predicted response of the first load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system; and

determining an optimized control strategy based on the first calculated load model and the second calculated load model.

12. The electric power distribution system of claim 10, wherein each of the first IED and the second IED further comprise an external time input configured to receive an external time signal from an external time source;

and

wherein the software instructions executable on each of the first processor and the second processor further enable the first IED and the second IED to perform operations, including;

recording a time based on the external time source and associated with each of the first plurality of measurements and the second plurality of measurements.

13. The electric power distribution system of claim 9, further comprising:

a second bus; and

a secondary transformer in electrical communication with the first bus and the second bus;

wherein the software instructions executable on the first processor further enable the first IED to perform operations comprising;

determining that the secondary transformer has been connected to the first bus and the second bus;

receiving a second plurality of measurements representing an electrical condition in at least a portion of the electric power distribution system prior to the connection of the secondary transformer and subsequent to the connection of the secondary transformer; and

,

adjusting the load model based on the second plurality of measurements.

14. The electric power distribution system of claim 9, wherein the software instructions executable on the first processor enable the first IED to perform operations, comprising:

identifying that the load comprises a constant impedance load; and

determining that the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

reducing the voltage provided to the load.

15. The electric power distribution system of claim 9, wherein the software instructions executable on the first processor enable the first IED to perform operations, comprising:

identifying that the first load comprises a constant power load;

determining that the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

electrically disconnecting the first load from the electric power distribution system.

16. The electric power distribution system of claim 9, wherein the software instructions executable on the first processor further enable the first IED to perform operations comprising:

adjusting the load model based upon at least one of a season, a day of the week, and a time of the day in which the electrical condition occurs.

17. The electric power distribution system of claim 9, further comprising:

identifying that the first load comprises a constant impedance load;

wherein the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

determining a first optimized control strategy based on the first calculated load model;

wherein the first optimized control strategy comprises reducing voltage provided to the first load.

18. The electric power distribution system of claim 9, further comprising:

identifying that the first load comprises a constant power load;

wherein the electrical condition comprises the electric power distribution system exceeding a ratio of power consumption to power generation; and

determining a first optimized control strategy based on the first calculated load model;

wherein the first optimized control strategy comprises electrically disconnecting the first load from the electric power distribution system.

19. The electric power distribution system of claim 9, wherein the software instructions executable on the first processor further enable the first IED to perform operations, including:

adjusting the first load model based upon at least one of a season, a day of the week, and a time of the day in which the electrical condition occurs.

20. An electric power distribution system to distribute power to at least one load, comprising:

a load;

a first bus connected to the load;

a second bus;

a primary transmission line in electrical communication with the first bus and the second bus;

a secondary transmission line; and

an intelligent electronic device (IED) configured to interface with the electric power distribution system, comprising;

a network communications interface;

a processor; and

a computer-readable storage medium, comprising;

software instructions executable on the processor that enable the IED to perform operations comprising;

determining that the secondary transmission line has been connected to the first bus and the second bus;

receiving a plurality of measurements representing an electrical condition in at least a portion of the electric power distribution system prior to the connection of the secondary transmission line to the first bus and the second bus and subsequent to the connection of the secondary transmission line to the first bus and the second bus; and

,

calculating a load model based on the plurality of measurements, the load model representing a predicted response of the load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system.

21. An electric power distribution system to distribute power to at least one load, comprising:

a first load;

a second load;

a breaker for selectively connecting the second load to the electric power distribution system; and

a first intelligent electronic device (IED) configured to interface with the electric power distribution system, comprising;

a first network communications interface;

a first processor; and

a first computer-readable storage medium, comprising;

software instructions executable on the first processor that enable the first IED to perform operations, including;

determining that second load has been connected to the electric power distribution system;

receiving a first plurality of measurements representing an electrical condition in at least a portion of the electric power distribution system prior to the connection of the second load and subsequent to the connection of the second load; and

,

calculating a first load model based on the first plurality of measurements, the first load model representing a predicted response of the first load to a variation in at least one electrical characteristic of power distributed by the electric power distribution system.

22. A method of controlling an electric power distribution system, the method comprising:

identifying a plurality of modeling events;

collecting a plurality of measurements associated with each of the plurality of modeling events, each of the plurality of measurements representing electrical conditions in at least a portion of the electric power distribution system prior to each modeling event and subsequent to each modeling event;

calculating a load model based on the plurality of measurements and representing a predicted response of a plurality of loads to a variation in at least one electrical characteristic of power distributed by the electric power distribution system; and

identifying that the plurality of loads comprises a specified ratio of constant impedance loads.