Electricity meter and method for cold load pickup management

Abstract

Systems and methods for managing the connection of cold loads to an electric grid are disclosed. One system for managing the connection of cold loads to an electric grid includes an electric meter configured to detect the restoration of power after a power outage and, in response to detecting the restoration of power after the power outage, resume operation and enter a service limiter mode. The electric meter remains in the service limiter mode for a predetermined period of time. During the service limiter mode, the electric meter aggregates power, compares the aggregated power with a threshold, and controls a service switch to determine whether to connect or disconnect one or more loads to the electric grid. After another predetermined period of time, the electric meter reconnects the one or more loads to the electric grid and returns to normal operation.

Description

[Technical Field]

[0001] The present invention relates generally to managing the connection of loads to an electrical grid after a power outage. [Background technology]

[0002] An electric power distribution grid consists of a large number of interconnected devices across a large geographic area. The interconnected devices are typically used to monitor and distribute electric power to user premises and may include power assets such as transformers, protection devices such as switches, line sections, and electric meters associated with user premises.

[0003] Electrical distribution networks are typically optimized to handle nominal or standard steady-state loads. This makes them vulnerable to sudden, abnormal increases in demand. A sudden increase in demand can strain or damage devices on the distribution network, causing power outages. If a power outage occurs over a wide area and lasts for a long period of time, restarting the distribution network poses a risk of overloading devices on the network due to cold load pickup. Cold load pickup occurs when a load that has lost power, such as a cold load, is reconnected to the distribution network. Connecting a cold load to the distribution network generates an inrush current. The inrush current can damage power assets and other devices in the distribution network. Sudden demand from large loads, such as electric heating and electric water heaters, can overload the distribution network and cause further power outages. Therefore, a management system is needed to control the connection of loads to the distribution network. Summary of the Invention

[0004] The present disclosure includes an electric meter connectable to an electric grid. The electric meter includes a metering device that measures power from the electric grid, a processing unit that determines whether an outage has occurred and whether power has been restored, and an optional communication module that communicates with a central system. In some implementations, the electric meter may also include one or more service switches, a controller, and a memory that can store operating parameters of the electric meter.

[0005] In one example method for operating an electricity meter, in response to detecting the restoration of power after a power outage, the electricity meter resumes operation and enters a service limiter mode. The electricity meter maintains the service limiter mode for a predetermined period of time. During the service limiter mode, the electricity meter monitors power from the grid to a building through the electricity meter and aggregates the power during a service limiter demand period. The aggregated power during the service limiter demand period is compared to a service limiter threshold. If the aggregated power during the service limiter demand period is within the service limiter threshold, the electricity meter controls a service switch to maintain a connection between the building and the grid. During the service limiter mode, the electricity meter may also determine the elapsed time since entering the service limiter mode. If the elapsed time since entering the service limiter mode reaches or exceeds the predetermined time, the electricity meter exits the service limiter mode and enters a normal operating mode.

[0006] In another example, when the aggregated power for a service limiter demand period exceeds a service limiter threshold, the electricity meter controls a service switch to disconnect the building from the electrical grid, and the electricity meter may wait a second predetermined period before controlling the service switch to connect the building to the electrical grid. [Brief explanation of the drawings]

[0007] These and other features, aspects, and advantages of the present disclosure will become better understood from the following detailed description when taken in conjunction with the accompanying drawings.

[0008] [Figure 1] FIG. 1 is a flow chart illustrating an example method of operating an electricity meter in a service limiter mode. [Figure 2] FIG. 2 is a flow chart illustrating an example method of operating an electricity meter that transitions between a service limiter mode and a normal operating mode. [Figure 3] FIG. 3 is a block diagram illustrating the components of an exemplary electricity meter. [Figure 4] FIG. 4 is a block diagram illustrating a portion of an exemplary electrical grid. [Figure 5] FIG. 5 is a block diagram illustrating an example of a communication network for an electrical grid. DETAILED DESCRIPTION OF THE INVENTION

[0009] Aspects of the present disclosure relate to a system for managing the connection of buildings to an electrical grid after a power outage event occurs. A building may include multiple loads. When a building is disconnected from the electrical grid, the loads associated with the building may become cold loads. A cold load is a load that has lost power for a period of time sufficient to be in a powered-down or low-power state. When a building with a cold load is reconnected to a power source or the electrical grid, the building may experience cold load pickup issues. The power demand of cold loads is generally high when initially connected to the electrical grid. When a power outage occurs, various buildings may lose power for a period of time sufficient to have cold loads, in which case connecting the buildings to the electrical grid may create a higher demand than the electrical grid is normally configured to provide, which may result in strain or damage to the electrical grid and lead to further power outages.

[0010] Cold load pickup management is the ability of a utility provider to manage the sudden demand placed on the electric grid by powering a building with a cold load. An electric meter can be used to manage cold load pickup at a building by limiting service to the building so that demand does not exceed the capacity of the electric grid. An electric meter can assist in cold load pickup management by limiting demand once power is restored. In some examples, an electric meter can manage demand by controlling the open or closed state of a service switch so that the electric meter can connect or disconnect the building associated with the electric meter from the electric grid when the grid restores power after a power outage.

[0011] When the electric meter detects that power has been restored after a power outage, the electric meter determines whether the length of the outage was sufficient to create a cold load in the building. If the outage was momentary, the building has no cold load and the electric meter can resume normal metering operation, but if the outage is long enough to create a cold load in the building, the electric meter can enter service limiter mode. Service limiter mode is an operating mode of the electric meter in which the electric meter manages power to the building.

[0012] The electric meter determines whether to connect or disconnect the building from the grid based on electric meter parameters, such as timer values ​​and thresholds. For example, when service limiter mode is enabled, the electric meter may start a cold load pickup timer. While the cold load pickup timer is running, the electric meter may accumulate demand in the building and compare that demand to a threshold, such as a service limiter threshold. The service limiter threshold may be a preset threshold that represents the amount of power allocated by the utility provider for use in the building while the electric meter is in service limiter mode.

[0013] When building demand falls below a threshold, the service switch may remain closed. When building demand exceeds a service limiter threshold, the electric meter may open the service switch to disconnect the building from the electrical grid for a predetermined period of time. After the predetermined period of time has elapsed, the electric meter closes the service switch to reconnect the building to the electrical grid. When the cold load pickup delay timer period expires, the electric meter transitions from the service limiter mode to a normal operating mode, and the electric meter resumes normal metering operation.

[0014] The timers and thresholds may vary from one electric meter to another. Electric meter parameters are determined based on the location of the electric meter in the electrical grid, the type of building or load at the building, the account options associated with the building, etc. Values ​​may be pre-set in the electric meter by the utility provider or a central system. More details about electric meter parameters and operation are provided below.

[0015] Exemplary Methods of Operation 1 and 2 are flowcharts illustrating an example of a method of operating an electricity meter. In some examples, some steps in the flowcharts of FIGS. 1 and 2 are implemented in program code executed by a processor of the electricity meter. In some examples, the steps illustrated in FIGS. 1 and 2 may be performed in a different order, or one or more steps may be skipped. Alternatively, in some examples, additional steps not illustrated in FIGS. 1 and 2 may be performed.

[0016] 1 and 2 show that an electric meter monitors the power consumed from the grid and determines whether to connect or disconnect the building from the grid based on the monitored power information.

[0017] Exemplary Method of Operating an Electric Meter in a Service Limiter Mode 1 is a flowchart illustrating an exemplary method 100 of operating an electricity meter that controls the connection of a load to an electrical grid. The method begins at step 102, where the electricity meter detects the restoration of power after a power outage. Upon detecting that power has been restored after a power outage, the electricity meter resumes operation and enters a service limiter mode for a predetermined period of time (step 104).

[0018] Service limiter mode is an operating mode in which the electric meter allows an allocated amount of power to one or more loads in a building. If the specified amount of power is exceeded, the electric meter can disconnect the building from the electrical grid.

[0019] The electricity meter monitors power from the grid to the building through the electricity meter (step 106) and aggregates the power during a service limiter demand period (step 108). The service limiter demand period is a predetermined time period during which the electricity meter determines whether the load's demand exceeds a service limiter threshold. The service limiter threshold is a preset value set in the electricity meter by the utility provider and represents an allocated amount of grid power that may be used by the building.

[0020] The electric meter compares the aggregated power for the service limiter demand period with the service limiter threshold in step 110. Based on the comparison of the aggregated power with the service limiter threshold, the electric meter controls a service switch of the electric meter so that the building remains connected to the electric grid if the aggregated power or the service limiter demand period is within the service limiter threshold (step 112).

[0021] The electricity meter determines the amount of time that has elapsed since entering the service limiter mode (step 114), and exits the service limiter mode when the elapsed time reaches or exceeds a predetermined time (step 116).

[0022] After exiting the service limiter mode, the electricity meter can enter a normal operation mode, step 118. During the normal operation mode, the electricity meter does not control the service switch based on the service limiter threshold.

[0023] Exemplary Method of Operation of Electric Meter Upon Power Restoration FIG. 2 is a flow chart illustrating an exemplary method 200 of operating an electric meter to connect and disconnect a building from an electrical grid.

[0024] The method begins at step 202 when an electric meter detects a power outage event. The electric meter is configured to measure power associated with an electric grid, and when the electric meter detects a lack of power or power below a predetermined power threshold for a period of time longer than an outage recognition time, the electric meter can determine that a power outage event is occurring in the electric grid (step 204). The outage recognition time is a predetermined period of time that can be set by a utility provider.

[0025] If the electric meter determines that the power outage event did not last longer than the power outage recognition time, the method proceeds to step 218, where the electric meter operates in a normal operating mode. In the normal operating mode, the electric meter performs normal metering operations.

[0026] If the electric meter determines that a power outage event has occurred and lasted longer than the power outage recognition time, the method proceeds from step 204 to step 206, where the electric meter records the power outage event. The electric meter may record the power outage event in a memory of the electric meter or may transmit a record of the power outage event to an edge computing device or a central system.

[0027] Once power is restored (step 207), the electric meter determines whether the power outage event lasted longer than the cold load pickup delay trigger (step 208). The cold load pickup delay trigger is a predetermined period of time that is set in the meter to determine whether the power outage event lasted long enough to cause a cold load to develop in the building.

[0028] If the power outage event does not last for a period longer than the cold load pickup delay trigger, the electric meter resumes normal metering operation (step 218). If the power outage event lasts for a period longer than the cold load pickup delay trigger, the electric meter enters service limiter mode (step 210). Service limiter mode is an electric meter operating mode in which the electric meter manages the building's demand for electricity from the electrical grid. The electric meter can manage the demand for electricity by connecting or disconnecting it from the building.

[0029] Upon entering the service limiter mode, the electricity meter starts a cold load pickup delay timer (step 212). The cold load pickup delay timer is a timer that specifies the amount of time the electricity meter will remain in the service limiter mode.

[0030] The electricity meter determines whether the cold load pickup delay timer has expired (step 214). If the electricity meter determines that the cold load pickup delay timer has expired, it disables the service limiter mode (step 216), transitions to the normal operation mode, and resumes normal metering operation (step 218).

[0031] If the electric meter determines that the cold load pickup timer has not expired, it starts the service limiter demand timer (step 220). If the service limiter demand timer is running, the electric meter may aggregate the demand of the load associated with the electric meter (step 222). If the service limiter demand timer expires, the electric meter determines whether the power demand by the load during the service limiter demand period exceeded the service limiter threshold (step 226). The service limiter threshold is a preset value set in the electric meter and represents the allocated amount of power available to the building during the service limiter demand period. If the load demand does not exceed the service limiter threshold, the electric meter proceeds to step 214.

[0032] When the load demand exceeds the service limiter threshold, the electric meter opens the service switch (step 228). A service switch is a switch configured to connect or disconnect a building from the electrical grid. The service switch may be located on the electric meter. When the service switch is opened (step 228), the electric meter starts an open switch timer (step 230). The open switch timer tracks the amount of time the service switch is open (step 232). When the open switch timer expires, the electric meter closes the service switch (step 234) and returns to step 214.

[0033] In some examples, the electric meter can receive a resume command while in service limiter mode. Upon receiving the resume command, the electric meter resumes normal metering operation. If the service switch was open when the resume command was received, the electric meter closes the service switch. The resume command may be a command received from an input on the meter, such as pressing a button, pulling a lever, or adjusting a switch. The resume command may be a command sent by an edge computing device or a central system.

[0034] Exemplary Meter As previously mentioned, an electric meter performs various functions, including metering, processing, and communication functions. Depending on the implementation, these functions may be performed by different components. FIG. 3 shows an electric meter 300 that includes two service switches 302, a metering component 304, a processing unit 306, a parameter 308, a controller 310, and an optional communication module 312. The electric meter 300 is connected to a building 314, which may include one or more loads (not shown). The electric meter may be configured to connect to single-phase or polyphase power. In FIG. 3, the electric meter is a two-phase meter with a service switch for each phase.

[0035] One or more service switches 302 are configured to connect and disconnect the building from an electrical grid (not shown). The service switches 302 may also be connected to a controller 310 and a metering component 304. In some examples, the service switches 302 are controlled via the controller 310, which can send control signals configured to adjust the open and closed states of the service switches 302.

[0036] In another example, the electric meter may control one or more load control switches instead of the service switch during the service limiter mode. The load switches may be located outside the electric meter and associated with one or more loads.

[0037] The metering components 304 can measure the voltage, current, power, or other characteristics of the electrical grid. The processing unit 306 can process the measurements by the metering components 304 to determine whether a power outage event has occurred. The processing unit 306, e.g., a processor or other processing device, can also include preset parameters 308. The parameters 308 can be stored in memory located in the processing unit 306 or in memory elsewhere in the electric meter 300. In some examples, the parameters 308 are set and / or changed by a central system, such as a head-end system. The parameters 308 can also be preset at the time of manufacture or installation, or can be set or changed during configuration of the electric meter 300. The parameters 308 can include values ​​associated with timers or thresholds, such as those described in FIGS. 1 and 2. For example, the parameters can include values ​​for a power outage recognition time, a cold load pickup delay trigger, a service limiter demand period, and a service limiter threshold.

[0038] The optional communication module 312 can receive information, commands, and messages from a central system to adjust the parameters 308 when the electric meter 300 is in a normal operating mode. For example, the central system can send information to the optional communication module 312 to adjust the parameters 308 when the meter is in a normal operating mode. The optional communication module 312 can also send parameter 308 information, such as electric meter 300 measurements and parameters 308, to the central system, which can store it in a database or other data management system. In another example, a field service technician may adjust the parameters 308 of the electric meter 300 in the field. In a further example, the service limiter mode parameters 308 of the electric meter 300 may differ based on where the electric meter 300 is located in the electric grid.

[0039] The electric meter may include additional components. For example, the memory may be a separate component or may be included in one or more of the metering device 304, the processing unit 306, the controller 310, or the communication module 312. The processor or processing unit 306 may be included in any of the components. The processor may execute computer-readable instructions to configure the processor to perform the functions of the electric meter, including the metering, processing, and communication functions described herein. The instructions may be stored on a computer-readable medium.

[0040] Exemplary Implementation in an Electrical Distribution Grid 4 illustrates an exemplary electrical grid. The electrical grid may include a generator 410, which may be a power generating facility or a generator at a power generating facility. The generator 410 may generate three-phase alternating current (AC) power and transmit the power to a substation 420 via a transmission line 465.

[0041] Substation 420 includes transformer 430, which steps down the voltage for customer consumption. The stepped-down power is sent by transmission lines 440a, 440b, 440c to transformers 450 and 455, which further step down the voltage for customer consumption.

[0042] Transformers 450 and 455 can provide single-phase or poly-phase power to customer premises through meters 460 and 462. Electricity meters can monitor characteristics such as current, voltage, and power and may be poly-phase meters. Additionally, power assets other than those shown may be included in the electrical grid.

[0043] The electric meters 460 and 462 may operate differently in service limiter mode based on their location on the electrical grid. For example, one or more values ​​for the cold load pickup delay trigger, the cold load pickup delay timer, the service limiter demand timer, and the service limiter threshold may differ based on the location of the electric meters 460, 462 within the electrical grid or the building associated with the electric meters 460, 462.

[0044] In some implementations, the electric meters 460, 462 may be configured to have a shorter cold load pickup delay timer or open switch timer compared to electric meters 460, 462 in other locations. A shorter cold load pickup delay timer reduces the duration that the electric meters 460, 462 remain in service limiter mode, allowing the electric meters 460, 462 to return to normal operating mode and resume normal operation sooner than other electric meters 460, 462. In some implementations, this allows some buildings to be prioritized over others. For example, hospitals and other critical infrastructure may have electric meters 460, 462 with shorter cold load pickup delay timers, allowing the hospitals to return to normal metering operation sooner than residential buildings. In other examples, the cold load pickup delay timer may vary based on the location of the electric meters 460, 462 on the electrical grid or their relationship to other power assets in the electrical grid. For example, the electric meters 460 , 462 may have different cold load pickup delay timer values ​​depending on the distance of the electric meters 460 , 462 from the generator 410 .

[0045] Exemplary Communication Network The central system 504 can communicate with the electric meters 560 via a communication network, as shown in Figure 5. Figure 5 illustrates a wireless mesh network 540 that allows the electric meters 560 to communicate with other meters 560 and the central system 504. The electric meters 560 can transmit information to other meters 560 to reach their respective root nodes 554. The electric meters 560 can communicate with each other via a variety of wireless and wired communication technologies, including RF, WiSUN, satellite, 3g, 4g, UHB, WiFi, and other communication technologies.

[0046] The root node may be a personal area network coordinator, gateway, border router, or other device capable of communicating with the central system 504 and other devices on the mesh network. Additionally, the root node 564 may forward information 522 to the central system 504 over the network 550.

[0047] The information transmitted over the communication network may include parameters of the electric meter 560, such as threshold and timer information. In some implementations, the central system 504 can transmit information to the electric meter 560 to update parameters of the electric meter 560. In other examples, the central system 504 can also query information from the meter 560.

[0048] Further examples In some examples of electricity meters, meter parameters such as timers and thresholds may vary between meters based on a priority system established by the utility provider. For example, a service limiter threshold for a first building may be set to a higher value than a service limiter threshold for a second building based on the first building's customers paying for a higher level of service.

[0049] In another example, an electric meter may transmit information to a central system upon entering a normal operating mode from a service limiter mode. During the normal operating mode, the electric meter may transmit information to the central system, such as information collected while operating in the service limiter mode. The information may include whether a service limiter threshold was exceeded, the amount of energy accumulated during the service limiter mode, or the number of times the service limiter threshold was exceeded during a single service-limited demand period. The information may be received by the central system and recorded in a database.

[0050] In a further example, the electricity meter may be configured to communicate with individual loads to control the service switch of the electricity meter as well as communicate with individual loads in the building to turn them off or operate in a low power mode in order to reduce the demand on the building so that the demand is within the service limiter threshold.

[0051] While the present invention has been described in detail with respect to specific embodiments thereof, it will be understood that those skilled in the art, upon understanding the foregoing, may readily make alternatives, variations, and equivalents of such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of illustration and not limitation, and is not intended to exclude the inclusion of modifications, variations, and / or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

Claims

1. 1. A method of operation of an electricity meter, comprising: Detecting restoration of power after a power outage; In response to detecting restoration of power after a power outage, resuming operation and entering a service limiter mode for a predetermined period of time; During the service limiter mode, monitoring power from a power grid to a building through said electricity meter; aggregating power during a service limiter demand period; comparing the aggregated power for the service limiter demand period to a service limiter threshold; controlling a service switch of the electricity meter to maintain a connection between the building and the electrical grid when the aggregated power for the service limiter demand period is within the service limiter threshold; determining an elapsed time since entering said service limiter mode; exiting the service limiter mode when the elapsed time since entering the service limiter mode reaches or exceeds the predetermined time; Entering normal operating mode; A method comprising:

2. 2. The method of claim 1, further comprising: during the service limiter mode, controlling the service switch to disconnect the building from the electrical grid when the aggregated power for the service limiter demand period exceeds the service limiter threshold.

3. Detecting a power outage; in response to detecting a power outage, controlling the service switch to disconnect the building from the electrical grid; In response to detecting a restoration of power after a power outage, maintaining the service switch in a disconnected state until a second predetermined period of time expires or a resume command is received; The method of claim 1 further comprising:

4. receiving a resume command over a wireless network; controlling the service switch to connect the building to the electrical grid; The method of claim 2 further comprising:

5. 10. The method of claim 1, wherein the predetermined time in the service limiter mode is based on one or more of a location of the electric meter on the electrical grid, a demand of a load associated with the electric meter, and input from a utility provider.

6. 2. The method of claim 1, comprising, in response to entering the service limiter mode, controlling the building to prevent the building from receiving power from the electrical grid while the electric meter is operating in the service limiter mode.

7. 10. The method of claim 1, including causing a message to be sent to a remote system in response to entering the normal operating mode.

8. 1. A system for restoring power to one or more loads, comprising: Equipped with an electric meter, The electricity meter comprises: detecting a restoration of power after an outage, and in response to detecting the restoration of power after an outage, resuming operation and entering a service limiter mode for a predetermined time based on the connection of one or more power assets of an electric grid and the electric meter; In the service limiter mode, monitoring power from the grid to the building through the electricity meter; The power consumption during the service limiter demand period is calculated. comparing the aggregated power for the service limiter demand period to a service limiter threshold; controlling a service switch of the electricity meter to maintain a connection between the building and the power grid when the aggregated power for the service limiter demand period is within the service limiter threshold; determining an elapsed time since entering said service limiter mode; when the elapsed time since entering the service limiter mode reaches or exceeds the predetermined time, exiting the service limiter mode; Enter normal operation mode, The system is configured as follows:

9. 9. The system of claim 8, wherein during the service limiter mode, when the aggregated power for the service limiter demand period exceeds the service limiter threshold, the electric meter controls the service switch to disconnect the building from the electrical grid.

10. the electricity meter detecting a power outage and, in response to detecting the power outage, controlling the service switch to disconnect the building from the electrical grid; In response to detecting a restoration of power after a power outage, maintaining the service switch in a disconnected state until a second predetermined time period expires or a resume command is received. The system of claim 8.

11. the electricity meter receives the restart command via a wireless network; controlling the service switch to connect the building to the electrical grid; The system of claim 10.

12. The electricity meter determines that the second predetermined time has expired, controlling the service switch to connect the building to the electrical grid; The system of claim 10.

13. 9. The system of claim 8, wherein in response to entering the service limiter mode, the electric meter controls the building to prevent the building from receiving power from the electrical grid while the electric meter is operating in the service limiter mode.

14. 10. The system of claim 8, wherein in response to entering a normal operating mode, the electricity meter causes a message to be sent to a remote system.

15. 1. A method of operation of an electricity meter, comprising: entering a service limiter mode, wherein the electric meter limits power to the building; During the service limiter mode, determining a demand associated with the building; comparing the demand to a threshold; setting a service switch to an open state when the demand for the building exceeds the threshold; setting the service switch to a closed state when the demand is within the threshold; and determining an elapsed time since entering the service limiter mode. exiting the service limiter mode when the elapsed time since entering the service limiter mode reaches or exceeds a predetermined time; Entering normal operating mode; A method comprising:

16. The method of claim 15 , wherein the threshold value varies based on the location of the electric meter on a distribution network.

17. The method of claim 15 , wherein the predetermined time is based on a location of the electric meter on a distribution network.

18. The method of claim 15 , wherein the predetermined time or the threshold is preset in the electric meter by the utility provider.

19. 16. The method of claim 15, further comprising transmitting a message to a remote system when the electric meter enters a normal operating mode.

20. 20. The method of claim 19, wherein the electric meter enters a service limiter mode upon detecting the restoration of power from a power outage event that lasted longer than a predetermined time.

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