Abstract:
Systems and methods for providing and managing high-availability power infrastructures with flexible load prioritization are described. In one embodiment, a system comprises a switch control and monitoring center that monitors and controls a distributed array of remotely controllable switches to optimize power distribution in a high-availability infrastructure according to priority levels. The high-availability comprises an electric battery storage and/or auxiliary generation equipment. In another embodiment a software package performs power quality analysis, ranking, and optimization, thus enabling the assessment of overall local and grid power demand trends. Load priority adjustments may be made in real-time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority benefit of U.S. Provisional Application Ser. No. 60/765,770 entitled “DISTRIBUTED SYSTEM AND METHOD FOR MANAGING LOADS TO MEET ELECTRIC POWER AVAILABILITY AND POWER QUALITY,” filed Feb. 6, 2006, the disclosure of which is hereby incorporated by reference herein. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates, in general, to electrical power systems and, more specifically, to systems and methods for providing and managing high-availability power infrastructures with flexible load prioritization.  
       BACKGROUND  
       [0003]     In recent years, the electric power industry has been burdened by an accelerated increase in demand that threatens the integrity of high-scale generation and transmission systems. As a consequence, customers often experience problems of restricted capacity (“brownouts”) and service interruptions (“blackouts”).  
         [0004]     Even when operating under normal, non-peak conditions, modern power systems deliver services with only 99.9% of reliability, which represents an outage equivalent to about nine hours per year for a typical customer. This level of service is clearly inadequate in the information age, and represents a significant threat to data-processing centers, call centers, telecommunication switching facilities, emergency services, hospitals, and other critical applications. For example, where power is provided at 60 cycles per second, a two-cycle “hiccup” can frequently cause most computers and servers to reboot or lock-up.  
         [0005]     Without immediate and adequate power for computers, communication systems, defense and security systems, appropriate response to terrorist attacks and natural catastrophes can be very difficult. Before the attacks of Sep. 11, 2001, concerns about power interruption focused primarily on the risk of equipment failures, extreme weather conditions, and accidents. Since then, however, there has been a growing concern regarding the possibility of deliberate attacks on the electric power system. Other recent events have further stressed the importance of securing our power supply systems.  
         [0006]     It is generally accepted that satisfactory levels of electrical power services must be provided with at least 99.9999% of availability, or the equivalent of 32 seconds of outages per year. Unfortunately, it has become increasingly difficult for utilities to reach these relatively high levels, particularly due to the fact that power quality is adversely affected as loads increase. It will be virtually impossible to attain the desired degree of availability from current utility transmission and distribution power infrastructures in the foreseeable future.  
         [0007]     A typical solution to these problems involves the local deployment of a distributed generation unit (“DG”) or battery operated, uninterruptible power supply (“UPS”) system. Because information, security, defense, and communications systems are often widely dispersed within a single premises, one of two approaches is commonly followed. First, a large DG and UPS unit may be deployed in order to fulfill the electrical loads of an entire building. Alternatively, a plurality of DG or UPS systems may be installed in different parts of the building, each unit thus servicing a particular portion thereof.  
         [0008]     The deployment of DG or UPS systems often presents itself as a business decision. Customers adopting these solutions are, in fact, generating power on-site in lieu of purchasing power from the local utility and risking production shutdown because of poor power quality. Unfortunately, for many customers, purchasing a local power supply system that supports all building load or a widely dispersed collection of critical load is far too expensive.  
         [0009]     Prior art system  100  shown in  FIG. 1  attempts to reduce emergency power and local generation costs in situations involving high-priority loads. Particularly, utility power line  101  provides power to a customer via a regular infrastructure line  102 , and is also connected to UPS  103 . UPS  103  receives “regular” power from utility power line  101  and provides a reliable, high-availability power source via high-priority infrastructure  104 . Accordingly, the customer may choose to connect low-priority or “regular” loads (not shown) to regular priority line  102 , and high-priority devices or loads  105 - 107  to high-availability infrastructure  104 .  
         [0010]     As illustrated in  FIG. 1 , prior art systems use one power distribution system for high-priority loads and another for regular loads. Equipment connected to high-availability distribution lines enjoy more reliable performance than equipment connected o regular lines because they are supported by a UPS or DG system. Nonetheless, high priority loads, regardless of their location, are supported by a redundant distribution infrastructure  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides an electrical power infrastructure cap able of controlling the availability and distribution of power to power lines and devices connected thereto according to a priority system. In one exemplary embodiment, a high-availability “backbone” power line or circuit provided by a high-availability power supply unit (e.g., UPS, DG, etc.) selectively feeds power to one or more flexible priority power lines (collectively referred to as “sub power lines”). Each flexible priority line may serve a single device, a plurality of devices, or an entire site. Remotely controllable switches or power control devices connect the backbone line to one or more flexible priority lines. For example, under normal operating conditions, a switch may be closed and thus provide high-availability power to its respective flexible priority line. Upon the happening of a specific event, a controller may transmit a signal to the switch that opens the circuit and cuts off high-availability power to its flexible priority line.  
         [0012]     In one embodiment of the present invention, each switch may be ranked as to its relative priority depending upon the available power, interaction with other switches, and/or relative importance of the devices connected thereto (e.g., security, communications, safety, protection, etc.). Each switch may provide information as to all sources and loads, and may also provide dynamic “islanding” or the creation of intelligent, interactive “microgrids” within a building or region. Switches may be remotely operated by a single programmable controller such as a computer, for instance, via a communications network. In one alternative embodiment, a controllable switch may be embedded directly into devices that connect directly to the backbone power line.  
         [0013]     The foregoing has outlined rather broadly certain features and technical advantages of the present invention so that the detailed description that follows may be better understood. Additional features and advantages are described hereinafter. As a person of ordinary skill in the art will readily recognize in light of this disclosure, specific embodiments disclosed herein may be utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. Several inventive features described herein will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, the figures are provided for the purpose of illustration and description only, and are not intended to limit the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     For a more complete understanding of the present invention, reference is now made to the following drawings, in which:  
         [0015]      FIG. 1  shows a block diagram of a prior art power distribution system;  
         [0016]      FIG. 2  shows a block diagram of a system for providing and managing a high-availability power infrastructure with flexible load prioritization according to an embodiment of the present invention;  
         [0017]      FIG. 3  shows a circuit diagram of a remotely controllable switch with fault protection according to an embodiment of the present invention;  
         [0018]      FIG. 4  shows a circuit diagram of a remotely controllable switch with fault protection and a controllable override circuit according to an embodiment of the present invention; and  
         [0019]      FIG. 5  shows a block diagram of a programmable computer adapted to implement an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 2  shows a block diagram of system  200  for providing and managing a high-availability power infrastructure with flexible load prioritization according to an exemplary embodiment of the present invention. Utility power line  101  provides power to UPS  103 . As such, UPS  103  receives “regular” power from utility power line  101  and provides a reliable, high-availability power source via high-availability backbone line  201 . In alternative embodiments, any power source (e.g., a DG unit) may be used instead of, or in addition to, UPS  103 . A plurality of flexible-priority branches or lines  206 - 208  are connected to backbone line  201  via remotely controllable switches  203 - 205 . Switch control and monitoring center  202  is connected to each of switches  203 - 205 , either by direct wiring, wirelessly, or by signals communicated via the power grid. Furthermore, switch control and monitoring center  202  may receive power necessary for its own operation from backbone line  201 .  
         [0021]     In one exemplary embodiment, remotely controllable switches  203 - 205  remain closed under normal operating conditions, thus allowing electrical current to flow from backbone line  201  to flexible priority lines  206 - 208 . Each flexible priority line may have a priority level associated therewith. For example, different priority profiles may be programmed into, or associated with, each of switches  203 - 205 . As such, when one of switches  206 - 208  receives a signal from switch control and monitoring center  202  that has a priority profile that is higher than the switch&#39;s priority profile, the switch opens and cuts off high-availability power to its respective flexible priority line. In these cases, each of flexible-priority lines  206 - 207  may be backed up by utility power line  101  to provide regular power to lower priority loads connected thereto. Additionally or alternatively, system  200  may be designed to respond to diminished DG or UPS  103  output when, for example, fuel supply or battery reserves reach a critical level.  
         [0022]     Even though switches  203 - 205  have been shown as on/off switches, they alternatively be controllable power limiting devices such as, for example, variable current limiters, or the like. When power control devices are used in place of switches  203 - 205 , system  200  is capable of controlling the maximum consumption of power distributed to each flexible priority line. Therefore, rather than turning low priority lines completely off, system  200  can allocate varying amounts of power to each line (or device) as a function of, or in proportion to, their respective priority profiles.  
         [0023]     The term “high or higher priority load or device” is used throughout this disclosure to identify loads that must preferably be supplied electrical power to the detriment of “low or lower priority loads or devices” (when necessary), due to the relative importance of their operation. As shown in  FIG. 2 , high priority device  209  is directly connected to backbone line  201 . Lower priority devices (not shown) may be connected to one of flexible priority lines  206 - 208 , depending on their level of importance. In the exemplary embodiment of system  200 , first flexible-priority line  206  has a higher priority than second flexible-priority line  207 , and second flexible-priority line  207  has a higher priority than third flexible-priority line  205 .  
         [0024]     Still referring to  FIG. 2 , second priority device  210  is connected to backbone line  201  via internal switch  211 , thus making its access to backbone line  201  controllable via switch control and monitoring center  202 . In this case, internal switch  211  may be embedded into the power input circuitry of device  210  and operable to communicate with switch control and monitoring center  202  wirelessly or via the power line. As will be readily recognized by a person of ordinary skill in the art in light of this disclosure, system  200  may be added to an existing infrastructure such as the one depicted in  FIG. 1 , in order to advantageously provide the flexible prioritization of loads and other advantages described herein.  
         [0025]     Turning now to  FIG. 3 , circuit diagram  300  of a remotely controllable switch with fault protection is depicted according to an exemplary embodiment of the present invention. In this embodiment, switch  300  may be used as any of switches  203 - 205  and/or  211  shown in  FIG. 2 , and is operable to connect backbone line  201  to flexible-priority lines  206 - 208  and/or device  210 . Exemplary switch  300  comprises four toggle switches (S 1 -S 4 ), two master switches (MS 1  and MS 2 ), and three current sensors (CS 1 -CS 3 ). Switch  300  also comprises switch control module  301 . Switch control module  301  may comprise a communications unit (not shown) for exchanging signals with switch control and monitoring center  202  and a controller (not shown) for controlling the operation of toggle switches S 1 -S 4 .  
         [0026]     In operation, switches S 1 -S 4  maintain identical status (i.e., they are either all open or all closed). The status of switches S 1 -S 4  is controlled by switch control module  301 . Master switches MS 1  and MS 2  may be used for performance and reliability testing and provide normal condition override functionality by forcing switch  300  to be either open or closed regardless of the status of toggle switches S 1 -S 4 . In the embodiment shown in  FIG. 3 , master switches MS 1  and MS 2  are manually operated.  FIG. 4  shows alternative circuit  400  having remote override module  401  for remotely controlling master switches MS 1  and MS 2 . In an alternative embodiment (not shown), the functionality of remote override module  401  may be built into switch control module  301 .  
         [0027]     Table I depicted below shows the overall functionality of switches  300  and/or  400  under a variety of S 1 -S 4  switch faults:  
                                     TABLE I                           Overall Functionality                Functionality   Faults   Functionality   Faults                       Closed   S1   Open   S1               S2       S2               S3       S3               S4       S4               S1 and S4       S1 and S2               S1 and S3       S4 and S3               S2 and S3       —               S2 and S4       —                      
 
         [0028]     The embodiments described above with respect to  FIGS. 3 and 4  allow the testing of toggle switches S 1 -S 4 &#39;s functionality during service, in addition to providing redundant failure protection. The in-service testing may be scheduled in advance. For example, switch control and monitoring center  202  may send an “open S 4 ” command to switch control center  301  for toggling switch S 1 . If S 1  opens on command, current sensor CS 3  reports a current increase to switch control center  301 , which in turn sends a response message to switch control and monitoring center  202 . Current sensors CS 1 -CS 3  may also report energy usage and other parameters to switch control and monitoring center  202  for energy management or any other purposes.  
         [0029]     Table II depicted below shows current sensor (CS 1 -CS 3 ) status as a function of toggle switch (S 1 -S 4 ) status:  
                                                       TABLE II                           Current Sensor Status as a Function of Toggle Switch Status            Toggle Switch Position   Current Sensor Indicator            S1   S2   S3   S4   CS1   CS2   CS3               Closed   Closed   Closed   Closed   Middle   Middle   Low       Open   Closed   Closed   Closed   Middle   Middle   Middle       Closed   Open   Closed   Closed   Middle   Middle   Middle       Closed   Closed   Open   Closed   High   0   Middle       Closed   Closed   Closed   Open   0   High   Middle       Open   Open   Closed   Closed   0   0   0       Open   Closed   Open   Closed   High   0   0       Open   Closed   Closed   Open   0   High   High       Closed   Open   Open   Closed   High   0   High       Closed   Open   Closed   Open   0   High   0       Open   Open   Open   Closed   0   0   0       Open   Open   Open   Open   0   0   0                  
 
         [0030]     Turning now to  FIG. 5 , a block diagram of programmable computer  500  adapted to implement switch control and monitoring center  202  of  FIG. 2  is depicted according to an embodiment of the present invention. Central processing unit (“CPU”)  501  is coupled to system bus  502 . CPU  501  may be any general purpose CPU. However, the embodiments of the present invention are not restricted by the architecture of CPU  501  as long as CPU  501  supports the inventive operations as described herein. Bus  502  is coupled to random access memory (“RAM”)  503 , which may be SRAM, DRAM, or SDRAM. ROM  504  is also coupled to bus  502 , which may be PROM, EPROM, or EEPROM.  
         [0031]     Bus  502  is also coupled to input/output (“I/O”) controller card  505 , communications adapter card  511 , user interface card  508 , and display card  509 . I/O adapter card  505  connects storage devices  506 , such as one or more of a hard drive, a CD drive, a floppy disk drive, a tape drive, to computer system  500 . I/O adapter  505  is also connected to a printer (not shown), which would allow the system to print paper copies of information such as documents, photographs, articles, and the like. The printer may be a printer (e.g., dot matrix, laser, and the like), a fax machine, scanner, or a copier machine. Communications card  511  is adapted to couple the computer system  500  to network  512 , which may be one or more of a telephone network, a local (“LAN”) and/or a wide-area (“WAN”) network, an Ethernet network, and/or the Internet. User interface card  508  couples user input devices, such as keyboard  513 , pointing device  507 , and the like, to computer system  500 . Display card  509  is driven by CPU  501  to control the display on display device  510 .  
         [0032]     In one embodiment, computer  500  sends instructions to switches  203 - 205  using communications adapter  511  via network  512 . Alternatively, computer  500  may comprise remote switch interface  514  operable to exchange messages, signals, or instructions with remote switches  203 - 205  and/or  211  shown in  FIG. 2  via bus  515 . Bus  515  may comprise any medium, such as, for instance, a power line (e.g., backbone  201 ), an optical fiber, a wireless medium (i.e., air), any other medium (e.g., twisted pair, coaxial cable, etc.). Remote switch interface  514  may comprise, for instance, a data acquisition card having input and output (analog or digital) channels capable of communicating with switch control modules  301  and/or  401 .  
         [0033]     In operation, computer  500  communicates with each of remotely controllable switches  203 - 205  and/or  211  individually or in groups. Command messages are sent from computer  500  to open or close remotely controllable switches based on their priority profiles. In one non-limiting example, a “priority 3” command opens all switches with a priority profile of 3 or lower (i.e., “priority 3,” “priority 4,” “priority 5,” etc.) without affecting the operation of switches with a higher priority profile (i.e., “priority 1” and “priority 2”). If, for any reason, any of remotely controlled switches  203 - 205  does not correctly respond to a command from computer  500 , the faulty switch reports the problem to computer  500  via bus  515  (or network  512 ).  
         [0034]     In one embodiment of the present invention, computer  500  executes software that allows users to monitor and manage the high-availability infrastructure. For instance, the software may have a graphical user interface (GUI) that presents a block diagram of the infrastructure, such as the one shown in  FIG. 2 . The user may assign priority profiles to each switch of the infrastructure using the GUI. The software may also provide alerts and reports periodically, upon request, or when a critical condition is reached (e.g., faulty switch is detected).  
         [0035]     A user may assign priority profiles to each of switches  203 - 205  and/or  211 , for example, in order to fulfill optimization objectives such as maximizing run times, available DG fuel supply, UPS battery reserves, peak load mitigation for overall improved electric load management, or the like. The user may also use a set of operations defined in natural language to manage and control switches  203 - 205  and/or  211  according to its individual requirements and priorities.  
         [0036]     In one exemplary embodiment, the following set of operations is provided: (a) never turn off; (b) turn off instantly after utility power supply is lost; (c) turn off n seconds after utility power supply is lost; (d) never turn on equipment that is being threatened by utility power quality or power loss (imminent utility brownout or blackout); (e) turn off when the unit price of power exceeds a given amount; (f) turn off on utility demand response signal; (g) and change (reset) remote switch priority on ranked optimization signal(s) including fuel availability, occupancy levels, security threats, communication requirements, etc.  
         [0037]     Using the aforementioned exemplary operators, priority profiles may be assigned to each switch, for instance, on a scale of 1 to 5. For example, a switch may be assigned a “priority level 1” when the user desires it to never be turned off. The user may assign a “priority level 2” to switches that cannot turn on equipment threatened by utility power quality or power loss. Another switch may be assigned a “priority level 3” when the user wants to turn it off 2 minutes after power supply is lost or when the unit price of power exceeds a preset limit, such as $200.00. Another switch may be assigned a “priority level 4” when the user wants to turn it off 30 seconds after power supply is lost or when the unit price of power exceeds $100.00. The user may assign a “priority level 5” to switches that should turn off instantly after power supply is lost or when the unit price of power exceeds $50.00.  
         [0038]     The user may arbitrarily assign priority levels to each switch or group of switches. Further, the user may create, modify, or define the operations upon which the priority levels may be based. Additionally or alternatively, switch control and monitoring center  202  may be programmed to fulfill optimization by monitoring the operating conditions of switches  203 - 205  and/or  211  by adjusting their priority profiles without further user input.  
         [0039]     The functions and/or algorithms described above may be implemented for example, in software or as a combination of software and human procedures. Software may comprise computer executable instructions stored on a computer readable medium such as memory or other type of storage device. Further, functions may correspond to modules, which may be software, hardware, firmware or any combination thereof. Multiple functions may be performed in one or more modules as desired, and the embodiments described are merely examples. Software may be executed on a digital signal processor, microprocessor ASIC, or other type of processor or controller.  
         [0040]     Particularly in view of the foregoing, a person of ordinary skill in the art will readily recognize that the present invention provides numerous advantages over the prior art. For instance, a prior art system such as the one shown in  FIG. 1  requires two expensive separate power distribution lines. Also, designing two separate power distribution systems requires long term planning with little flexibility for future changes. Further, because regular distribution lines typically run together with high-priority lines, unsophisticated customers often overwhelm DG and UPS units by connecting regular loads to high-priority lines, thus reducing the quality of the high priority infrastructure. Conversely, high-priority loads may also inadvertently be connected to regular lines, thus putting important equipment at risk.  
         [0041]     Meanwhile, the systems and methods of the present invention allow the provisioning of power using a flexible power priority principles that obviate the need for redundant power lines. The present invention also allows small, economical DG and UPS systems, to meet the exigent requirements of the information, security, defense, and telecommunications industries. In addition, the present invention successfully addresses the need for reliable power supply that is critical to public facilities during emergencies, avoids detrimental demand peaks that would otherwise lead to brownouts or service interruptions, lowers security risks involved in the operation of the electric power grid, improves grid reliability and efficiency, and reduces reliance on higher cost “must-run” generators. As will be readily recognized by a person of ordinary skill in the art in light of this disclosure, systems according to the present invention may also be advantageously adapted to fit existing infrastructures, thus allowing standard power lines to support a flexible, high-availability power infrastructure.  
         [0042]     Although certain embodiments of the present invention and their advantages have been described herein in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present invention is not intended to be limited to the particular embodiments of the processes, machines, manufactures, means, methods, and steps described herein. As a person of ordinary skill in the art will readily appreciate from this disclosure, other processes, machines, manufactures, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufactures, means, methods, or steps.