Abstract:
A method and system for determining a configuration of a redundant critical control system is provided. The method includes receiving power distribution system operating characteristic information, using a computer, determining a plurality of alternative configurations of the power distribution system that are consistent with the operating characteristic information and determining efficiency characteristics of each of the alternative configurations, and selecting a configuration from the plurality of alternative configurations. The system includes a computer system configured to receive power distribution system operating characteristic information, determine a plurality of alternative configurations of the power distribution system that are consistent with the operating characteristic information and determine life-cycle cost characteristics of each of the alternative configurations, and select a configuration from the plurality of alternative configurations.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is related to U.S. Patent Application No. 60/359,544 filed on Feb. 25, 2002 for “Integrated Protection, Monitoring, and Control” the content of which is incorporated in its entirety herein by reference. This application is also related to U.S. Patent Application No. 60/438,159 filed on Jan. 6, 2003 for “Single Processor Concept for Protection and Control of Circuit Breakers in Low-Voltage Switchgear” the content of which is incorporated in its entirety herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to electrical switchgear and more particularly, to a method and apparatus for facilitating maximizing a power distribution system reliability and system availability through optimizing power distribution system component redundancy and configuration.  
           [0003]    In an industrial power distribution system, power generated by a power generation company may be supplied to an industrial or commercial facility wherein the power may be distributed throughout the industrial or commercial facility to various equipment such as, for example, motors, welding machinery, computers, heaters, lighting, and other electrical equipment. At least some known power distribution systems include switchgear which facilitates dividing the power into branch circuits which supply power to various portions of the industrial facility. Circuit breakers are provided in each branch circuit to facilitate protecting equipment within the branch circuit. Additionally, circuit breakers in each branch circuit can facilitate minimizing equipment failures since specific loads may be energized or de-energized without affecting other loads, thus creating increased efficiencies, and reduced operating and manufacturing costs. Similar switchgear may also be used within an electric utility transmission system and a plurality of distribution substations, although the switching operations used may be more complex.  
           [0004]    Switchgear typically include multiple devices, other than the power distribution system components, to facilitate providing protection, monitoring, and control of the power distribution system components. For example, at least some known breakers include a plurality of shunt trip circuits, under-voltage relays, trip units, and a plurality of auxiliary switches that close the breaker in the event of an undesired interruption or fluctuation in the power supplied to the power distribution components. Additionally, at least one known power distribution system also includes a monitor device that monitors a performance of the power distribution system, a control device that controls an operation of the power distribution system, and a protection device that initiates a protective response when the protection device is activated.  
           [0005]    In at least some other known power distribution systems, a monitor and control system operates independently of the protective system. For example, a protective device may de-energize a portion of the power distribution system based on its own predetermined operating limits, without the monitoring devices recording the event. The failure of the monitoring system to record the system shutdown may mislead an operator to believe that an over-current condition has not occurred within the power distribution system, and as such, a proper corrective action may not be initiated by the operator. Additionally, a protective device, i.e. a circuit breaker, may open because of an over-current condition in the power distribution system, but the control system may interpret the over-current condition as a loss of power from the power source, rather than a fault condition. As such, the control logic may undesirably attempt to connect the faulted circuit to an alternate source, thereby restoring the over-current condition. In addition to the potential increase in operational defects which may occur using such devices, the use of multiple devices and interconnecting wiring associated with the devices may cause an increase in equipment size, an increase in the complexity of wiring the devices, and/or an increase in a quantity of devices installed.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0006]    In one aspect, a method for determining a configuration of a redundant critical control system is provided. The method includes receiving power distribution system operating characteristic information, using a computer, determining a plurality of alternative configurations of the power distribution system that are consistent with the operating characteristic information and determining efficiency characteristics of each of the alternative configurations, and selecting a configuration from the plurality of alternative configurations.  
           [0007]    In another aspect, a computer system for determining a configuration of a redundant critical control system is provided. The computer system is configured to receive power distribution system operating characteristic information, determine a plurality of alternative configurations of the power distribution system that are consistent with the operating characteristic information and determining efficiency characteristics of each of the alternative configurations, and select a configuration from the plurality of alternative configurations. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is an exemplary schematic illustration of a power distribution system;  
         [0009]    [0009]FIG. 2 is an exemplary schematic illustration of a node power system;  
         [0010]    [0010]FIG. 3 is an exemplary schematic illustration of a central control processing unit that may used with the power distribution system shown in FIG. 1;  
         [0011]    [0011]FIG. 4 is an exemplary schematic illustration of a node electronic unit that may used with the power distribution system shown in FIG. 1;  
         [0012]    [0012]FIG. 5 is an exemplary schematic illustration of a circuit breaker that may used with the power distribution system shown in FIG. 1;  
         [0013]    [0013]FIG. 6 is a simplified block diagram of a power distribution system design computer system that may be used with power distribution system  10  shown in FIG. 1;  
         [0014]    [0014]FIG. 7 is an expanded version block diagram of an exemplary embodiment of a server architecture of power distribution system design computer system shown in FIG. 6;  
         [0015]    [0015]FIG. 8 is a flow chart illustrating an exemplary embodiment of a method for operating power distribution system shown in FIG. 1;  
         [0016]    [0016]FIG. 9 is a flow chart illustrating an exemplary embodiment of a method  900  optimizing a reliability of a plurality of control power sources in the power distribution system shown in FIG. 1;  
         [0017]    [0017]FIG. 10 is a flow chart illustrating an exemplary embodiment of a method for determining a probability that a power distribution system circuit breaker error will not affect the reliability of the power distribution system shown in FIG. 1; and  
         [0018]    [0018]FIG. 11 is a flow chart illustrating an exemplary embodiment of a method for operating power distribution system shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    [0019]FIG. 1 illustrates an exemplary schematic illustration of a power distribution system  10 , used by an industrial facility for example. In an exemplary embodiment, system  10  includes at least one main feed system  12 , a power distribution bus  14 , a plurality of power circuit switches or interrupters, also referred to herein as a circuit breakers (CB)  16 , and at least one load  18 , such as, but not limited to, motors, welding machinery, computers, heaters, lighting, and/or other electrical equipment.  
         [0020]    In use, power is supplied to a main feed system  12 , i.e. a switchboard for example, from a source (not shown) such as, an electric generator driven by a prime mover locally, or an electric utility source from an electrical substation. The prime mover may be powered from, for example, but not limited to, a turbine, or an internal combustion engine. Power supplied to main feed system  12  is divided into a plurality of branch circuits by a plurality of busbars configured to route the power from a branch feed breaker and a bus-tie breaker to a plurality of load circuit breakers  16  which supply power to various loads  18  in the industrial facility. In addition, circuit breakers  16  are provided in each branch circuit to facilitate protecting equipment, i.e. loads  18 , connected within the respective branch circuit. Additionally, circuit breakers  16  facilitate minimizing equipment failures since specific loads  18  may be energized or de-energized without affecting other loads  18 , thus creating increased efficiencies, and reduced operating and manufacturing costs.  
         [0021]    Power distribution system  10  includes a circuit breaker control protection system  19  that includes a plurality of node electronics units  20  that are each electrically coupled to a digital network  22 . Circuit breaker control protection system  19  also includes at least one central control processing unit (CCPU)  24  that is electrically coupled to digital network  22  via a switch  23  such as, but not limited to, an Ethernet switch  23 . In use, each respective node electronics unit  20  is electrically coupled to a respective circuit breaker  16 , such that CCPU  24  is electrically coupled to each circuit breaker  16  through digital network  22  and through an associated node electronics unit  20 .  
         [0022]    In one embodiment, digital network  22  includes, for example, at least one of a local area network (LAN) or a wide area network (WAN), dial-in-connections, cable modems, and special high-speed ISDN lines. Digital network  22  also includes any device capable of interconnecting to the Internet including a web-based phone, personal digital assistant (PDA), or other web-based connectable equipment.  
         [0023]    In one embodiment, CCPU  24  is a computer and includes a device  26 , for example, a floppy disk drive or CD-ROM drive, to facilitate reading instructions and/or data from a computer-readable medium  28 , such as a floppy disk or CD-ROM. In another embodiment, CCPU  24  executes instructions stored in firmware (not shown). CCPU  24  is programmed to perform functions described herein, but other programmable circuits can likewise be programmed. Accordingly, as used herein, the term computer is not limited to just those integrated circuits referred to in the art as computers, but broadly refers to computers, processors, microcontrollers, microcomputers, programmable logic controllers, application specific integrated circuits, and other programmable circuits. Additionally, although described in a power distribution setting, it is contemplated that the benefits of the invention accrue to all electrical distribution systems including industrial systems such as, for example, but not limited to, an electrical distribution system installed in an office building.  
         [0024]    [0024]FIG. 2 is an exemplary schematic illustration of a node power distribution system  29  that can be used with power distribution system  10  (shown in FIG. 1) and more specifically, with circuit breaker control protection system  19  (shown in FIG. 1). Node power distribution system  29  includes a power source  30  that is electrically coupled to node electronic units  20  through a node power distribution bus  32 . In an exemplary embodiment, power source  30  is an uninterruptible power supply (UPS). In one embodiment, power source  30  receives power from power distribution system  10  and then distributes this power to node electronic units  20  through node power distribution bus  32 . In an alternative embodiment, power is not supplied to power source  30 , but rather, power source  30  supplies power to node electronic units  20  using an internal power supply, such as, but not limited to, a plurality of batteries (not shown). In another alternate embodiment, node electronic units  20  are powered by secondary current available from current sensor  82  and/or voltage sensor  84 . In this embodiment, circuit breaker control protection system  19  would not include node power distribution system  29 , power source  30 , or node power distribution bus  32 .  
         [0025]    [0025]FIG. 3 is an exemplary schematic illustration of CCPU  24 . CCPU  24  includes at least one memory device  40 , such as, but not limited to, a read only memory (ROM)  42 , a flash memory  44 , and/or a random access memory (RAM)  46 . CCPU  24  also includes a central processor unit (CPU)  48  that is electrically coupled to at least one memory device  40 , as well as an internal bus  50 , a communications interface  52 , and a communications processor  54 . In an exemplary embodiment, CCPU  24  is a printed circuit board and includes a power supply  56  to supply power to a plurality of devices on the printed circuit board.  
         [0026]    Additionally, in an exemplary embodiment, internal bus  50  includes an address bus, a data bus, and a control bus. In use, the address bus is configured to enable CPU  48  to address a plurality of internal memory locations or an input/output port, such as, but not limited to communications interface  52  through communications processor  54 , and a gateway interface  58 , through a gateway processor  56 . The data bus is configured to transmit instructions and/or data between CPU  48  and at least one input/output, and the control bus is configured to transmit signals between the plurality of devices to facilitate ensuring that the devices are operating in synchronization. In the exemplary embodiment, internal bus  50  is a bi-directional bus such that signals can be transmitted in either direction on internal bus  50 . CCPU  24  also includes at least one storage device  60  configured to store a plurality of information transmitted via internal bus  50 .  
         [0027]    In use, gateway interface  58  communicates to a remote workstation (not shown) via an Internet link  62  or an Intranet  62 . In the exemplary embodiment, the remote workstation is a personal computer including a web browser. Although a single workstation is described, such functions as described herein can be performed at one of many personal computers coupled to gateway interface  58 . For example, gateway interface  58  may be communicatively coupled to various individuals, including local operators and to third parties, e.g., remote system operators via an ISP Internet connection. The communication in the example embodiment is illustrated as being performed via the Internet, however, any other wide area network (WAN) type communication can be utilized in other embodiments, i.e., the systems and processes are not limited to being practiced via the Internet. In one embodiment, information is received at gateway interface  58  and transmitted to node electronics unit  20  via CCPU  24  and digital network  22 . In another embodiment, information sent from node electronics unit  20  is received at communication interface  52  and transmitted to Internet  62  via gateway interface  58 .  
         [0028]    [0028]FIG. 4 is an exemplary schematic illustration of single node electronic unit  20 . In the exemplary embodiment, node electronic unit  20  is a unitary device mounted remotely from CCPU  24  and circuit breaker  16 . In an exemplary embodiment, node electronic unit  20  is separate from, but proximate to circuit breaker  16 . In an exemplary embodiment, node electronic unit  20  is a printed circuit board.  
         [0029]    In one embodiment, node electronics unit  20  receives signals input from a plurality of devices, such as, but not limited to, a current sensor  82 , and a voltage sensor  84 , and/or circuit breaker  16 . Status input device  86  receives a plurality of status signals from circuit breaker  16  can include signals related to one or more conditions of the breaker, such as, but not limited to, an auxiliary switch status, and a spring charge switch status. Additionally, node electronics unit  20  sends signals  86  to at least circuit breaker  16  in order to control one or more states of the breaker.  
         [0030]    In use, signals input from status input device  86 , current sensor  82 , and voltage sensor  84 , are transmitted to CCPU  24  via node electronics unit  20 , and digital network  22 . Node electronics unit  20  receives the input from status input device  86 , current sensor  82 , and voltage sensor  84 , and packages a digital message that includes the input and additional data relating to a health and status of node electronics unit  20 . The health and status data may include information based on problems found by internal diagnostic routines and a status of self checking routines that run locally in node electronics unit  20 . The data transmitted to CCPU  24  via node electronics unit  20  is processed by CCPU  24 , which outputs a signal to node electronics unit  20  via digital network  22 . In the exemplary embodiment, node electronics unit  20  actuates circuit breaker  16  in response to the signal received from CCPU  24 . In one embodiment, circuit breaker  16  is actuated in response to commands sent only by CCPU  24 , i.e., circuit breaker  16  is not controlled locally by node  20 ,but rather is operated remotely from CCPU  24  based on inputs received from current sensor  82 , voltage sensor  84 , and status inputs  86  received from node electronics unit  20  over network  22 .  
         [0031]    [0031]FIG. 5 is an exemplary schematic illustration of circuit breaker  16  that is electrically coupled to node electronics unit  20 . In the exemplary embodiment, circuit breaker  16  includes a switch assembly that includes movable and/or stationary contacts, an arc suppression means, and a tripping and operating mechanism. Circuit breaker  16  auxiliaries include only a trip coil  100 , a close coil  102 , an auxiliary switch  104 , a spring charge switch  106 , and a motor  108 . Circuit breaker  16  does not include a trip unit. Auxiliary switches and sensors are coupled to node electronics unit  20  through a standard wiring harness  110 , which may include both copper wiring and communications conduits. Current sensor  82 , and voltage sensor  84  are coupled to node electronics unit  20  through a cable  112  that may include copper wiring and/or communications conduits. Circuit breaker  16  is a unitary device mounted proximate to CCPU  20 , current sensor  82 , and voltage sensor  84 . The various components of breaker  16  (e.g., trip coil  100 , close coil  102 , auxiliary switch  104 , spring charge switch  106 , motor  108 ) can be powered by node electronics unit  20 . Alternately, breaker  16  can be powered by secondary current available from current sensor  82  and/or voltage sensor  84 . Circuit breaker  16  is in electrical communication with node electronics unit  20  through a wiring harness  110  (not shown in FIG. 5), which may include copper wiring, communications conduits, and any combination thereof. Current sensor  82 , and voltage sensor  84  are in electrical communication with node electronics unit  20  through a cable  112  (not shown in FIG. 5) that may include copper wiring, communications conduits, and any combination thereof.  
         [0032]    In use, actuation signals from node electronics unit  20  are transmitted to circuit breaker  16  to actuate a plurality of functions in circuit breaker  16 , such as, but not limited to, operating a trip coil  100 , operating a close coil  102 , and affecting a circuit breaker lockout feature. An auxiliary switch  104  and a spring charge switch  106  provide a status indication of circuit breaker parameters to node electronics unit  20 . Motor  108  is configured to recharge a close spring (not shown) after circuit breaker  16  closes. It should be appreciated that the motor  108  can include, for example, a spring charge switch, a solenoid or any other electromechanical device capable of recharging a trip spring. To close circuit breaker  16 , a close coil  102  is energized by a close signal from actuation power module  90 . Close coil  102  actuates a closing mechanism (not shown) that couples at least one movable electrical contact (not shown) to a corresponding fixed electrical contact (not shown). The closing mechanism of circuit breaker  16  latches in a closed position such that when close coil  102  is de-energized, circuit breaker  16  remains closed. When breaker  16  closes, an “a” contact of auxiliary switch  104  also closes and a “b” contact of auxiliary switch  104  opens. The position of the “a” and “b” contacts is sensed by node electronics unit  20 . To open circuit breaker  16 , node electronics unit  20  energizes trip coil (TC)  100 . TC  100  acts directly on circuit breaker  16  to release the latching mechanism that holds circuit breaker  16  closed. When the latching mechanism is released, circuit breaker  16  will open, opening the “a” contact and closing the “b” contact of auxiliary switch  104 . Trip coil  100  is then de-energized by node electronics unit  20 . After breaker  16  opens, with the close spring recharged by motor  108 , circuit breaker  16  is prepared for a next operating cycle. In the exemplary embodiment, each node electronics unit  20  is coupled to circuit breaker  16  in a one-to-one correspondence. For example, each node electronics unit  20  communicates directly with only one circuit breaker  16 . In an alternative embodiment, node electronics unit  20  may communicate with a plurality of circuit breakers  16 .  
         [0033]    [0033]FIG. 6 is a simplified block diagram of a power distribution system design computer system  600  including a server system  612  including a disk storage unit  613  for data storage, and a plurality of client sub-systems, also referred to as client systems  614 , connected to server system  612 . In one embodiment, client systems  614  are computers including a web browser, such that server system  612  is accessible to client systems  614  via the Internet. Client systems  614  are interconnected to the Internet through many interfaces including a network, such as a local area network (LAN) or a wide area network (WAN), dial-in-connections, cable modems and special high-speed ISDN lines. Client systems  614  could be any device capable of interconnecting to the Internet including a web-based phone, personal digital assistant (PDA), or other web-based connectable equipment. A database server  616  is connected to a database  618  containing information on a variety of matters, as described below in greater detail. In one embodiment, centralized database  618  is stored on server system  612  and can be accessed by potential users at one of client systems  614  by logging onto server system  612  through one of client systems  614 . In an alternative embodiment database  618  is stored remotely from server system  612  and may be non-centralized.  
         [0034]    [0034]FIG. 7 is an expanded version block diagram  700  of an example embodiment of a server architecture of power distribution system design computer system  100  shown in FIG. 6. Components in diagram  700 , identical to components of system  600  (shown in FIG. 6), are identified in FIG. 7 using the same reference numerals as used in FIG. 6. System  700  includes server system  612  and client systems  614 . Server system  612  further includes database server  616 , an application server  722 , a web server  723 , a fax server  726 , a directory server  728 , and a mail server  730 . Disk storage unit  732  is coupled to database server  616  and directory server  728 . Servers  616 ,  722 ,  723 ,  726 ,  728 , and  730  are coupled in a local area network (LAN)  734 . In addition, a system administrator&#39;s workstation  738 , a user workstation  740 , and a supervisor&#39;s workstation  742  are coupled to LAN  734 . Alternatively, workstations  738 ,  740 , and  742  are coupled to LAN  734  via an Internet link or are connected through an Intranet.  
         [0035]    Each workstation,  738 ,  740 , and  742  is a personal computer having a web browser. Although the functions performed at the workstations typically are illustrated as being performed at respective workstations  738 ,  740 , and  742 , such functions can be performed at one of many personal computers coupled to LAN  734 . Workstations  738 ,  740 , and  742  are illustrated as being associated with separate functions only to facilitate an understanding of the different types of functions that can be performed by individuals having access to LAN  734 . In an example embodiment, client system  614  includes a workstation  750  which can be used by an internal analyst or a designated outside field engineer to review power distribution system design information relating to a system.  
         [0036]    Server system  612  is configured to be communicatively coupled to various individuals, including employee workstation  744  and to design engineer workstation  746  via an ISP Internet connection  748 . The communication in the example embodiment is illustrated as being performed via the Internet, however, any other wide area network (WAN) type communication can be utilized in other embodiments, i.e., the systems and processes are not limited to being practiced via the Internet. In addition, and rather than WAN  736 , local area network  734  could be used in place of WAN  736 .  
         [0037]    In the exemplary embodiment, any authorized individual having a workstation  744  can access power distribution system design computer system  600 . At least one of the client systems includes a manager workstation  750  located at a remote location. Workstations  744  and  750  are personal computers having a web browser. Also, workstations  744  and  750  are configured to communicate with server system  612 . Furthermore, fax server  726  communicates with remotely located client systems, including a client system  750  via a telephone link. Fax server  726  is configured to communicate with other client systems  738 ,  740 , and  742  as well.  
         [0038]    [0038]FIG. 8 is a flow chart illustrating an exemplary embodiment of a method  800  for operating power distribution system  10  shown in FIG. 1. Method  800  includes an algorithm that determines the redundancy level of each critical component in power distribution system  10 . This algorithm is controlled by minimizing the life cycle cost, subjected to a system availability constraint. This availability constraint is for circuit breaker control protection system  19  to have a greater availability than that of current local control protection systems.  
         [0039]    Failure rate prediction methods provide a tool with which components may be selected. A set of conditions in which the components operate, such as, the temperature or environmental conditions is defined. The prediction methodology carries out a failure rate calculation as defined by predetermined parameters selected based on known and desired performance goals. For example, components that make up power distribution system  10  can be defined in a tree structure. The tree may be composed entirely of components or it could be subdivided into blocks each of which could hold other blocks or components. In this way power distribution system  10  can easily be represented as a combination of system and subsystems. A failure rate model for each component is made up of a base failure rate for that particular type of component and multiplying factors that depend on the operating conditions experienced by the component.  
         [0040]    Method  800  utilizes an optimization procedure that receives  802  a set of parameters that describe power distribution system  10 . In one embodiment, the parameters include a number and/or reliability of available power sources, a number and/or configuration of branch circuits, a number and rating of a plurality of loads. The procedure then varies  804  the redundancy of each component in system  10  for a given set of parameters, while meeting predetermined requirements and expectations. The redundancy is limited to integer values only; thus resulting in realistic parameters that can be physically implemented. For each level of redundancy for each component, a power distribution system reliability is determined  806 . An associated life cycle cost, reliability and availability of each level of redundancy is considered  808 . A level of redundancy that yields an optimum level of redundancy for each component is determined  810  for the given set of parameters. In one embodiment used for circuit breaker control and protection system  19 , the resulting architecture is doubly redundant in the various components that constitute the centralized control architecture. For the particular example considered, these included the CCPU  24 , communication network  22 , and the power supply connections. Some features include redundancy determined in view of optimizing an application dependent cost function. In one embodiment, the calculation is fast by using a programmed Excel file, in which a “solver” function is employed. Features also include the ability to have any number of requirements or limitations, as well as any number of items that can be redundant. The only portion that needs to be updated for each particular system is its layout.  
         [0041]    Accordingly, an ability to provide quick results that are able to be physically and realistically implemented is provided. Thus, resulting in “true” optimizations within a short period of time. One advantage is the optimally determined redundant architecture. In addition, the calculation is rigorous, fast, and simple, resulting in a structure that is able to be physically &amp; realistically implemented. Additionally, a quick and easy procedure for determining the optimal redundancy of a complex system for a given set of constraints is provided. For example, one implementation considered the constraints to include overall life cycle costs and the systems availability. This procedure resulted in a doubly redundant circuit breaker control protection system architecture.  
         [0042]    [0042]FIG. 9 is a flow chart illustrating an exemplary embodiment of a method  900  for operating power distribution system  10  shown in FIG. 1. Method  900  facilitates optimizing a reliability of a plurality of control power sources in power distribution system  10 . The control power sources supply, for example, node electronics units  20  with power to energize node electronic unit  20  circuits and drive node electronic unit  20  outputs. Method  900  begins by determining  902  a user reliability goal. In one embodiment, the reliability goal may be mandated by a customer preference. In another embodiment, the reliability goal may be determined  902  by applying known standards or specifications to system  10  design inputs. An analysis of the control power supply for circuit breaker control protection system  19  is performed. In this analysis, the control power is optimized to yield a customer&#39;s expected reliability, or reliability goal. A reliability of the facility&#39;s available power supplies is determined  904  individually. A reliability of various combinations of these power supplies is determined  906  based on the reliability of the individual power supplies. The determined reliability of the combinations of power supplies is compared  908  to the reliability goal. If the determined reliability does not meet the reliability goal, the algorithm determines  906  a reliability of a different combination of power supply combinations. If the determined  606  reliability meets the reliability goal, the algorithm outputs the combination of power supply so that it may be implemented  910 . In the exemplary embodiment, the determined combination of available power supplies is implemented in the design phase of a new power distribution system  10 . In another embodiment, system  10  implements  910  the determined  906  combination of power supplies by generating commands and actions to appropriate circuit breakers  16  to achieve the optimum lineup determined  906 . In another embodiment, system  10  outputs recommended commands and actions for appropriate circuit breakers  16  for an operator to implement  910  to achieve the optimum lineup determined  906 .  
         [0043]    Accordingly, a designer is enabled to quickly and accurately configure what power supplies should be utilized for the critical control system, thus allowing for quicker design time than at least some other methods. Additionally, any unneeded power supply redundancy is eliminated, thus reducing the quantity of equipment needed, the maintenance that the equipment might require, the cost of supplying such equipment. One aspect includes an ability to determine what combination of the facilities available power supplies are needed to obtain the desired system reliability. This procedure enables this result to be obtained in a short period of time.  
         [0044]    [0044]FIG. 10 is a flow chart illustrating an exemplary embodiment of a method  1000  for operating power distribution system  10  shown in FIG. 1. Method  1000  facilitates determining a probability that a circuit breaker error will not affect the power distribution system reliability. Because all power distribution system monitored parameters are available to CCPU  24  at all times, a circuit breaker error detected by CCPU  24  can be compensated for by reconfiguring the operation of circuit breakers  16  supplying power to the affected circuit breaker  16 . Method  1000  includes detecting  1002  a circuit breaker  16  error in any of the circuit breaker in power distribution system  10 . An error is defined as a power distribution system component malfunction that occurs when the protection features of power distribution system  10  are not needed. The protection features of power distribution system  10  are needed when a power line fault occurs. A power line fault is defined as a malfunction of the power delivery components of power distribution system  10  and loads  18 , such as, for example, but, not limited to, instantaneous over current, short and long time over current, ground fault, differential fault, and under and over frequency. A system failure is defined as a component error that coincides with a line fault. In such a situation, the protection features of power distribution system  10  would be needed to clear the line fault but, because of a component error, the protection features may be unavailable. When a component error is detected  1002 , power distribution system  10  responds by determining  1004  an alternative trip scheme for the affected circuit breaker  16  to enable clearing a fault, should one occur, necessitating operation of the affected circuit breaker  16 . For example, in a hierarchical power system, a plurality of supply circuit breakers each supply power from a power source to a power distribution system. The supply circuit breakers may supply a distribution bus that includes switchgear, such as, a plurality of feeder breakers that each supply power to an electrical load. Each bus may also be coupled to other buses through a bus-tie breaker. The system as described is hierarchical in that each circuit breaker is supplied from another circuit breaker usually with a larger current carrying capability and usually supplying other circuit breaker as well. The supply circuit breaker usually has the largest current carrying capability whereas individual load circuit breaker usually have the lowest current carrying capability. After the circuit breakers that supply the affected circuit breaker are determined, the operation of the determined supply circuit breakers may be adjusted  1006 . This may be done by adjusting  1008  trip curves for the supplying circuit breakers so that they will trip at a current level that will compensate for the loss of the affected breaker&#39;s functionality. Additionally, the global information set of power distribution system  10  electrical parameters may be used to calculate electrical parameters at the affected circuit breaker and a compensatory monitoring  1010  regime may be used to trip the determined supply circuit breakers to facilitate limiting current flow to the affected circuit breaker.  
         [0045]    [0045]FIG. 11 is a flow chart illustrating an exemplary embodiment of a method  1100  for operating power distribution system  10  shown in FIG. 1. Method  1100  facilitates determining an optimized power distribution system  10  configuration based on a predetermined power distribution system  10  configuration modified to incorporate software considerations into the determination. As discussed above, a configuration of power distribution system  10  is determined using optimization techniques that include optimizing system component reliability based on a redundancy of critical components, an inherent failure probability of components, i.e. mean time between failures (MTBF), mean time to failure (MTTF), and mean time to repair (MTTR), optimizing system component availability, and optimizing total system reliability and availability. In one embodiment, MTBF, is defined as being equal to the sum of MTTF and MTTR. The MTTF for a component may be obtained by analyzing historical data or using standard prediction methods. Once an optimum configuration based on reliability, availability and cost is determined, an additional, constructability evaluation is conducted. Constructability optimizes component availability, manufacturing, and power distribution system maintenance considerations. Additionally, an optimum power distribution system may include a level of redundancy that complicates constructability disadvantageously, necessitating a further review of the determined power distribution system  10  configuration. One area of review is the software which will be controlling power distribution system  10 . Software considerations for power distribution system  10  include the level of redundancy of the plurality of node electronics units  20 , redundancy of network  22  and the redundancy of CCPU  24 . For each level of redundancy software running on power distribution system  10  will manage communications and resolve conflicts. In one embodiment, conflict resolution solutions will use a safety priority resolution methodology. In another embodiment, software voting will resolve command conflicts in power distribution system  10 . Latency considerations influence the conflict resolution solution determined.  
         [0046]    Once an optimized hardware configuration of power distribution system  10  is determined, a corresponding software configuration is determined  1102 . A cost to implement such a corresponding software configuration is determined  1104 . The determination includes labor, schedule, production resource variables. The determined hardware configuration and the corresponding software configuration are varied  1106  to establish an optimum hardware configuration/software configuration solution. For each configuration variation, cost is evaluated  1108  based on at least one of schedule, resources, reliability, availability and labor. Schedule, resource, and labor cost may be interrelated in that shortening a production or design schedule may increase labor costs due to increased numbers of people performing the work in a shorter time span and increased overtime costs. Resource cost also includes an opportunity cost for alternative uses of resources. Reliability and availability costs include costs associated with redundancy, component quality, and testing costs. After each evaluation, the process iterates to a subsequent configuration and evaluated again.  
         [0047]    The above-described power distribution systems are cost-effective and highly reliable. Each system includes a central control unit and networked devices to facilitate protecting a set of switchgear. Devices local to each circuit breaker monitor voltage and current signals from sensors located proximate each circuit breaker. The central control receives all monitored signals from all devices over the high-speed network. The central control implements protection and optimization algorithms for each breaker node based on global voltage and current signals. This method offers performance advantages over existing local, non-networked protection. In many overcurrent faults, the fault level may appear at multiple levels in the electrical protection hierarchy. Branch, feeder and main circuit breakers may all “see” the fault. Protection engineers can partially avoid the problem by setting longer delays. This results in faults at high levels in the hierarchy causing more damage and still can result in multiple devices interrupting, removing electrical service from circuits that do not have a fault. Additionally the system components and configuration are facilitated to be optimized to provide high reliability and high availability. Accordingly, power distribution system  10  facilitates protection and optimization of power system operation in a cost-effective and reliable manner.  
         [0048]    Exemplary embodiments of power distribution system components are described above in detail. The components are not limited to the specific embodiments described herein, but rather, components of each system may be utilized independently and separately from other components described herein. Each power distribution system component can also be used in combination with other power distribution system components.  
         [0049]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.