Grid edge controller for uninterruptible power supply and method of operation thereof

Abstract

A system includes an uninterruptible power supply (UPS) configured to selectively provide power from a power grid and an energy storage device to critical loads; and a grid edge controller configured to communicate with a controller of the UPS and to cause the UPS to operate the energy storage device as a distributed energy source (DER) of the grid while maintaining autonomous operation of the UPS to serve the critical load. The grid edge controller may be configured, for example, to maintain critical reserve in the energy storage device that enables the UPS to maintain the critical load while allowing the energy storage device to also be used for demand management, frequency regulation, and other grid-oriented tasks. The grid edge controller may be configured to control the UPS, for example via an application programming interface (API) of the controller of the UPS.

Description

[0001] This application is a divisional application of the application filed on February 25, 2020, with application number 202080020132.4 and invention title "Grid Edge Controller for Uninterruptible Power Supply and its Operating Method Thereof". Technical Field

[0002] The subject matter of this invention relates to uninterruptible power systems (UPS) and methods of operation thereof, and more particularly to UPS connected to the power grid and methods of operation thereof. Background Technology

[0003] Data center customers typically require uninterruptible power supply (UPS) solutions that provide the power quality and critical power reserves needed for mission-critical operations. However, data center customers may also increasingly require advanced UPS systems that offer energy ancillary services such as demand response in the form of peak and frequency regulation. Such capabilities enable customers to utilize previously undeveloped and unavailable battery capacity, which can improve return on investment (ROI) and reduce total cost of ownership (TCO). Summary of the Invention

[0004] Some embodiments of the subject matter of this invention provide a system comprising: an uninterruptible power supply (UPS) configured to selectively supply power to critical loads from the power grid and energy storage devices; and a grid edge controller configured to communicate with the UPS controller and enable the UPS to operate the energy storage devices as a distributed energy source (DER) of the power grid, while maintaining autonomous operation of the UPS to serve critical loads. The grid edge controller may be configured, for example, to maintain critical reserves in the energy storage devices, which enable the UPS to sustain critical loads while allowing the energy storage devices to also be used for demand management, frequency regulation, and other grid-oriented tasks. The grid edge controller may be configured to control the UPS, for example, via an application programming interface (API) of the UPS controller.

[0005] According to another aspect, the grid edge controller may include a user interface configured to enable users to set criteria for the grid edge controller to operate energy storage devices as DERs. For example, the user interface may include at least one webpage configured to accept at least one user setting for at least one SOC-based threshold for operating energy storage devices as DERs. In some embodiments, the user interface may include at least one webpage configured to accept user settings for a schedule of using energy storage devices as DERs.

[0006] Some implementations provide a system comprising: an uninterruptible power supply (UPS) configured to selectively supply power from the grid and energy storage to a critical load; and a grid edge controller configured to communicate with the UPS controller and enable the UPS to autonomously maintain continuous power from the grid and energy storage to the load, and to selectively transfer power between the grid and energy storage based on the state of charge (SOC) of the energy storage in response to grid control inputs. Grid control inputs may include grid operator commands and / or grid operating parameters. The grid edge controller may be configured to prevent the energy storage from being used as a DER (Demand Provider) of the grid in response to the SOC meeting predetermined criteria, such as a SOC corresponding to critical reserves required to support UPS operation. The grid edge controller may be configured to provide a user interface that provides control over the criteria.

[0007] Other implementations provide methods that include: the UPS operating autonomously to selectively supply power from the grid and energy storage to critical loads, thereby sustaining critical loads; and the grid edge controller selectively interacting with the UPS controller to operate the energy storage as a DER (Demand Response) device for the grid based on the energy storage device's state of charge (SOC). This selective interaction may include maintaining critical reserves in the energy storage device to enable the UPS to sustain critical loads. It may also include the grid edge controller communicating with the UPS via the UPS controller's application programming interface (API). Finally, it may include the grid edge controller enabling the UPS to support frequency regulation and demand response.

[0008] In some implementations, selective interaction between the grid edge controller and the UPS controller may include the grid edge controller enabling the UPS to autonomously maintain continuous power from the grid and energy storage to the load, and selectively transferring power between the grid and energy storage based on the energy storage's state of charge (SOC) in response to grid control inputs. Grid control inputs may include grid operator commands and / or grid operating parameters. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating a system with a UPS and a grid edge controller according to some implementation schemes.

[0010] Figures 2-4 A webpage showing the user interface of a grid edge controller according to some implementation schemes is provided.

[0011] Figure 5 A flowchart illustrating the operation of a power grid edge controller according to some implementation schemes is provided.

[0012] Figure 6 To illustrate a schematic diagram of a system according to an alternative implementation, the system utilizes an aggregator to combine multiple grid edge controllers and UPS. Detailed Implementation

[0013] Specific exemplary embodiments of the subject matter of the invention will now be described with reference to the accompanying drawings. However, the subject matter of the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be comprehensive and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, similar reference numerals denote similar items. It should be understood that when an item is referred to as “connected” or “coupled” to another item, the item may be directly connected to or directly coupled to the other item, or there may be an intermediary item. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0014] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the subject matter of the invention. Unless otherwise expressly stated, the singular forms “a,” “an,” and “the” are intended to include the plural forms as used herein. It should also be understood that the terms “comprising” and / or “including” as used in this specification indicate the presence of the stated features, integers, steps, operations, items, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, items, components, and / or combinations thereof.

[0015] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of this invention pertains. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant field, and will not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0016] Figure 1 An exemplary system is shown for enabling UPS 110 to function as such a DER. The input 111 of UPS 110 is coupled to the AC grid, and the UPS is configured to serve critical loads coupled to its output 112 via, for example, a power distribution unit (PDU) 120. A set of batteries 130 is coupled to UPS 110 and is used to support the critical loads in the event of a power outage or degradation from the grid.

[0017] According to some implementations, UPS 110 can be enabled as a DER using grid edge controller 140, which enables energy control schemes supporting ancillary energy services such as peak regulation and frequency control, while allowing UPS 110 to continue operating autonomously as a critical backup power source for IT loads or critical loads. Grid edge controller 140 includes grid edge controller 142 that communicates with the controller API in UPS 110 via, for example, a network switch 144. Grid edge controller 142 may support network connectivity to allow configuration of controller 140 to provide certain ancillary energy services using UPS 110.

[0018] For example, the grid edge controller 142 can implement an operation schedule for the UPS 110, which operates the UPS 110 in various modes to provide grid ancillary services according to the time of day. For instance, the schedule could cause the grid edge controller 142 to operate the UPS in a peak-shaving mode during specific times of the day, thereby allowing the UPS 110 to deliver power from the battery pack 120 to the load to limit the amount of power the UPS 110 draws from the grid during that period. Support for such planned operation could include having the UPS 110 pre-charge the battery pack 120 to a level suitable for supporting peak-shaving operation, which could be the maximum available capacity of the battery pack 120 or a capacity close to its maximum available capacity. Such charging could occur, for example, during lower periods (or off-peak periods) with previously lower energy rates, such as at night or during periods of low energy congestion on the grid.

[0019] In another example, the control schedule of the grid edge controller 142 may also include the time periods during which the UPS will operate in frequency regulation mode. In this mode, the UPS 110 can supply power to and receive power from the grid operator to compensate for frequency variations on the grid. Compared to peak regulation mode, before operating in frequency regulation mode, the grid edge controller 142 can enable the UPS 110 to bring the battery pack 120 to approximately half of its maximum capacity, allowing the battery pack 120 to efficiently supply and receive power sequentially, maximizing the time the UPS participates in grid ancillary services.

[0020] According to another aspect, the grid edge controller 142 may also provide a grid security-compatible interface for using the UPS 110 as a DER. In some modified applications, for example, the UPS 110 may be a UPS not designed to be coupled to the grid control network and may not be grid security compatible to prevent or reduce the possibility of intrusion. The grid edge controller 142 may employ hardware and software that meet grid security requirements, thereby allowing the UPS 110 to be used safely with the grid in DER applications.

[0021] According to another aspect, the grid edge controller 142 may also provide a user interface to allow UPS customers to monitor and control the schedules implemented by the grid edge controller 142, as well as parameters used by the grid edge controller 142, such as the mapping of the capacity of the battery pack 120 for critical power and ancillary services. For example, Figure 2 A webpage hosted by the grid edge controller 142 is shown, which provides a control panel to inform customers of the status of the system and its components, including the current mode of the UPS 110, the current state of charge (SOC) of the battery pack and its current capacity allocation, the input and output power meters, and the current mode of the grid edge controller 142.

[0022] Figure 2 A webpage is displayed indicating the status of the UPS and associated energy storage batteries, indicating, for example, the mode in which the UPS is operating, the state of charge of the batteries and their operating mode, and the status of various input and output parameters monitored by the grid edge controller 142. Figure 3 A webpage hosted by grid edge controller 142 is shown, which customers can use to set or allocate battery capacity for critical power and energy ancillary services. As illustrated, for example, a customer can set a critical reserve state of charge (SOC) threshold 310, which represents the minimum capacity required to ensure that critical loads can be serviced for a specified amount of time (shown here as five minutes). Grid edge controller 142 can be programmed to ensure that the battery pack SOC never drops to this level under normal (non-emergency) operation. To help preserve critical reserves, customers can set a higher minimum effective SOC level 320, which can be used as a threshold to disable ancillary energy services; that is, if the battery pack SOC drops below this level, service can be suspended. Similarly, customers can establish a maximum effective SOC 330, which can be used as a threshold to disable effective services (such as frequency regulation) that could cause the battery pack to exceed this level. Customers can also establish a maximum SOC 340 and a minimum SOC, where the maximum SOC represents a threshold to reduce the likelihood of overcharging, and the minimum SOC is used to reduce the likelihood of deep discharge of the battery pack. The target SOC is related to energy ancillary services and represents the initial or ideal SOC level for upcoming or planned grid ancillary services; the grid edge controller charges or discharges the battery to the target SOC just before grid ancillary services.

[0023] The dynamic capability of specific grid edge controller parameters allows data center operators to adjust / adapt the operation of the UPS DER as needed to maximize DER battery capacity utilization. Without this ability to perform runtime adjustments, the operation of the grid edge controller and UPS would essentially be static, forcing users to accept specific settings or combinations of parameters established at initialization. A data center DER with dynamic capabilities also maximizes UPS availability as a DER by avoiding UPS shutdowns that would reinitialize edge controller parameters to align with the inherently dynamic nature of data center operation plans. Additionally, dynamic capabilities can be selectively enabled or disabled, as indicated by checkbox 350 for enabling and disabling dynamic capabilities parameter by parameter; this provides DER operators with another degree of control.

[0024] The grid edge controller 142 supports various types of energy ancillary services, such as time-of-use (TOU) demand management. Demand charges can constitute a significant portion of a commercial customer's monthly energy bill. Rate structures vary by geographic location, and rates can change due to changes in rate policies and energy plans. Unmanaged electricity demand can result in peak-hour penalties and unexpected / adverse site power ratings, as well as undesirable rate reclassifications. See above for some implementation schemes. Figure 1 The described setup can be used to convert UPS and battery equipment resources into demand charge management devices and reduce energy bills and avoid costly penalties.

[0025] Figure 4 An exemplary webpage supported by the grid edge controller 142 is shown as part of providing such TOU (Demand Usage and Charges) management. This webpage allows customers to input parameters for the operation of the grid edge controller 142, enabling them to set values ​​such as seasonal date ranges 410, peak and off-peak periods 420 for each season, and energy charges 430 for each time period. These parameters allow the grid edge controller 142 to be configured to meet the specific needs of the application. Figure 3 Similar to the parameters shown, checkbox 440 or similar input features can be used to selectively allow dynamic reconfiguration of these parameters.

[0026] according to Figure 1 The configuration can also be used to support real-time pricing demand response. Data center customers can participate in the wholesale energy market to obtain the lowest energy prices. However, at critical times, customers may experience the high price volatility typical of wholesale pricing. Figure 1The system's grid edge controller 142 can process real-time pricing commands from the customer network, such as alert emails or other pricing signals from utility operators, and in response, cause the UPS 110 to use energy stored in the battery pack 130 to reduce demand. For example, the grid edge controller 142 can modify its time-of-use demand management profile (e.g., Figure 4 This reflects such real-time pricing inputs. The grid edge controller 142 can utilize the low real-time energy prices during off-peak periods to restore energy to battery banks. In this way, the data center can avoid the higher real-time prices that are common near periods of high grid congestion and stress. This can reduce total operating costs and also allow the data center to utilize capacity reserve payments granted to eligible loads under specific short- and medium-term distributed resource contracts.

[0027] Figure 5 To illustrate according to some implementation schemes Figure 1 The flowchart illustrates exemplary operation of the system. UPS 110 operates in normal mode, where it autonomously responds to power outages or degradation to maintain service to critical loads (box 510). When determining whether to provide auxiliary grid service (box 520), the system determines whether the battery SOC is suitable for performing the service without reducing the UPS 110's ability to serve critical loads, for example, in the event of service interruption or other degradation (box 530). If the SOC is unsuitable, auxiliary grid service may not be provided, and the UPS may continue its normal autonomous operation. If the SOC is suitable, the grid edge controller 142 may enable the UPS to provide auxiliary grid service (box 540). If the battery SOC becomes unsuitable while providing auxiliary grid service, the system may terminate the service and return to autonomous UPS operation (boxes 550, 530, 510). Similarly, if the service is completed, the system may also return to autonomous UPS operation (boxes 550, 510).

[0028] Like other DERs, UPSs can be widely distributed as part of the complex electrical infrastructure typical of data center operations. According to some implementations, these can be coordinated and dispatched to form / create total power for target energy ancillary services by creating an aggregation of a group of UPSs (2, 4, 6, and possibly even more) that act as a unified resource.

[0029] A typical data center electrical infrastructure consists of numerous power distribution branches and sub-branches, which are powered by incoming transformers and switchboards. Branches are designated as feeder lines and sub-feeders that ultimately power (support) downstream information technology equipment (ITE).

[0030] ITE load can vary depending on data center IT operations and is not necessarily coordinated on a feeder-by-feeder basis. Due to the randomness of ITE activity and traffic, the load level on one feeder may differ significantly from that on another. However, IT load can be controlled / managed through virtualization based on energy economics.

[0031] A key component on ITE feeder lines is the UPS, which is used to ensure power quality and critical power targets for data centers. Protecting critical loads is a primary task of the UPS, and if properly designed, it will protect those loads from power disturbances, including complete power outages, at all times. ITE loads are combined with mechanical loads on these feeder lines. Mechanical loads can be located downstream or upstream of the UPS (more typically upstream).

[0032] Typically, there are also parallel redundant feeders and UPS systems that do not actively support loads and remain standby for most of their lifespan. These feeders can be considered as shelved capacity or capacity that will not be used or exploited except for some energy reduction / storage purposes. If redundant investments are used to support energy services of potential interest while idle, then the redundant investments may incur their own costs.

[0033] As described above, a UPS on a specific feeder line can serve a dual purpose: supporting the energy services and critical load backup required by data center operators. One exemplary service is demand management (DCM). DCM operating logic can be viewed as key input information regarding load level, source voltage, and battery state of charge. Each feeder line and sub-feeder line can have dedicated power meters to provide metering values ​​(power data).

[0034] Data center power infrastructure feeders are often not coordinated. For example, electrical infrastructure may include sub-meters that maintain independent / autonomous readings (data) without being combined or associated in any way. Aggregation systems can identify portions of the data center electrical infrastructure that are operating (consuming meaningful power) and have the potential to generate net energy savings or other energy characteristics or performance metrics. Aggregators can associate (coordinate) target feeders / UPS (data) so that they operate as one or more capacity groups.

[0035] For example, Figure 6An example of a data center power infrastructure including a first capacity cluster and a second capacity cluster is shown, each comprising multiple UPS units in corresponding groups, each group controlled by a corresponding grid edge controller 142a, 142b. Aggregator 510 can interact with the multiple grid edge controllers 142a, 142b to enable the use of the two capacity clusters and their treatment as combined energy resources, for example, by coordinating time-of-use pricing, battery capacity, and other parameters used by the grid edge controllers 142a, 142b.

[0036] Time-of-use pricing demand management and autonomous frequency regulation, according to some implementation schemes, can simplify the control network, where DER UPSs operate both critical backup and grid ancillary services without input from the grid (e.g., "set and forget"). Autonomous FR mode is achieved by the UPS sensing the local frequency and pulling / pushing power to some preset frequency / power thresholds (known as frequency-watt pairs in the US and frequency control reserves in Europe).

[0037] Aside from some cooling or facility loads, data center loads, and especially IT loads, loads are also resilient, albeit relatively constant; load resilience means the ability of data center operations to shift loads to different computing levels. A UPS-based DER, according to some implementations, can inform this process, and vice versa. Upstream loads can be controlled / informed / used for “selective self-consumption,” where the downstream DER (such as a UPS DER as described above) can be restricted (by the grid operator and its grid connection rules) to not discharge power from the facility’s point of common connection (POC or PCC). The UPS DER can interact with these loads to maintain compliance with such grid connection rules / regulations. Regarding grid ancillary services, as seen by the grid, the facility’s power rises or falls as expected; the requirement for net power generation (flow from the DER to the grid) is not mandatory and may even be violated. Upstream loads of the DER UPS, as described herein, can help address this compliance issue.

[0038] Some implementation schemes can be used to implement stacked services, where priority parameters found on the user interface described above can begin to take effect. Stacked services refer to the ability to enable (planned for) one or more types of ancillary services to operate during a period of interest, where one service is known to have a higher priority than another. Priority can be a function of the economic value of one ancillary service relative to another; economic value can vary across time periods, and therefore priority can also vary across time periods. Generally, stacked services can improve system ROI because they can increase the system's realized revenue or savings (positive cash flow).

[0039] The accompanying drawings and description have disclosed exemplary embodiments of the subject matter of this invention. Although specific terminology has been used, it is used in a general and descriptive sense only and not for limiting purposes, and the scope of the subject matter of this invention is defined by the following claims.

Claims

1. A system comprising: An uninterruptible power supply (UPS) configured to selectively provide power to critical loads from the grid and energy storage devices; and A grid edge controller, configured to communicate with the controller of the UPS, further configured to: The UPS operates the energy storage device as a distributed energy source (DER) of the power grid, while maintaining autonomous operation to serve the critical load. A user interface is provided, comprising at least one webpage configured to allow a user to define and adjust multiple state-of-charge (SOC) thresholds associated with using the energy storage device as the DER operation at runtime. The UPS maintains the SOC of the energy storage device based on the plurality of SOC thresholds, including selectively prohibiting the energy storage device from operating as the DER when the SOC meets a threshold condition defined by the plurality of SOC thresholds.

2. The system of claim 1, wherein the grid edge controller is configured to maintain a critical reserve in the energy storage device, the critical reserve enabling the UPS to maintain the critical load.

3. The system of claim 1, wherein the grid edge controller is configured to operate the UPS to support frequency regulation and demand response.

4. The system of claim 1, wherein the user interface is configured to accept user settings for using the energy storage device as a schedule for the DER.

5. The system of claim 1, wherein the grid edge controller includes a first grid edge controller and further includes an aggregator configured to control the first grid edge controller in concert with at least one second grid edge controller to control a first capacity cluster associated with the first grid edge controller and at least one second capacity cluster associated with the at least one second grid edge controller as a combined energy resource operation control.

6. The system of claim 1, wherein the grid edge controller is configured to communicate with the controller of the UPS and to enable the UPS to autonomously maintain continuous power from the grid and the energy storage device to the load, and to selectively transfer power between the grid and the energy storage device in response to grid control input based on the state of charge (SOC) of the energy storage device.

7. The system of claim 6, wherein the power grid control input includes power grid operator commands and / or operating parameters of the power grid.

8. The system of claim 6, wherein the grid edge controller prevents the energy storage device from being used as a DER of the grid in response to the SOC meeting a predetermined criterion.

9. The system of claim 1, wherein the grid edge controller includes a first grid edge controller and further includes an aggregator configured to control the first grid edge controller in concert with at least one second grid edge controller to control a first capacity cluster associated with the first grid edge controller and at least one second capacity cluster associated with the at least one second grid edge controller as a combined energy resource operation control.

10. The system of claim 1, wherein the grid edge controller is configured to change the SOC threshold in response to user input to the user interface without requiring reinitialization of the grid edge controller.

11. The system of claim 10, wherein the user interface is configured to accept user input that enables and disables changes to the SOC threshold.

12. A method comprising: The UPS operates autonomously to selectively supply power from the grid and energy storage devices to critical loads, thereby maintaining those critical loads; The grid edge controller provides a user interface including at least one webpage configured to allow users to define and adjust multiple state of charge (SOC) thresholds associated with using the energy storage device as a distributed energy source (DER) during runtime. and The grid edge controller selectively interacts with the UPS controller to: The UPS operates the energy storage device as a DER for the power grid, while maintaining autonomous operation of the UPS to serve the critical load. and The UPS maintains the SOC of the energy storage device based on the plurality of SOC thresholds, including selectively prohibiting the energy storage device from being used for the DER operation when the SOC meets a threshold condition defined by the plurality of SOC thresholds.

13. The method of claim 12, wherein selectively interacting with the controller of the UPS by the grid edge controller includes maintaining critical reserves in the energy storage device to enable the UPS to sustain the critical load.

14. The method of claim 12, wherein selective interaction between the grid edge controller and the controller of the UPS includes the grid edge controller enabling the UPS to support frequency regulation and demand response.

15. The method of claim 12, wherein the selective interaction between the grid edge controller and the controller of the UPS includes the grid edge controller enabling the UPS to autonomously maintain continuous power from the grid and the energy storage device to the load, and selectively transferring power between the grid and the energy storage device in response to a grid control input based on the SOC of the energy storage device.

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