ADAPTIVE SYSTEM AND METHOD FOR PROTECTION OF ELECTRIC POWER SYSTEMS

BACKGROUND

[0001] The present disclosure relates generally to a protection system for use in an electric power system. In particular, the disclosure relates to an adaptive protection system used in an electric power system.

[0002] Electric power systems have evolved from the historical centralized systems where power generation plants were connected to a transmission network to decentralized systems where pluralities of small distributed generators are connected directly to distribution systems near demand consumption. The pluralities of small distributed generators are sometimes operated using renewable sources of energy such as wind or solar. Notwithstanding, the distributed generators can be based on any energy source, and are commonly used to share either a part of or the entire power load of a system under specific conditions.

[0003] The introduction of distributed power generation in any network greatly impacts network power flows. In particular, the introduction of distributed generators in a power system might interfere with the control of large central generators and eventually impact the behavior of loads in the power system. Further, each power system encounters challenges in the detection of certain faults such as high impedance faults that occur when a conductor of the distribution system makes an inadvertent electrical contact with the ground (or environment such as tree limb) or in the detection of higher than expected loading conditions, especially in the presence of distributed power generators.

[0004] For the safe operation of the power system, protection devices such as protection relays are typically used to protect the electrical devices in the power system against various electrical faults. These protection devices can either be electromechanical or microprocessor based devices. Electromechanical relays are an older technology and require constant calibration to stay within the intended tolerances. Microprocessor or electronic relays generally provide a quicker and more reliable output.

[0005] In general, the microprocessor or electronic relay is typically associated with one or more predefined protection settings that enable the relay device to protect various electrical devices in a power system by tripping and isolating faulty sections from the healthy sections in the power system. The known schemes for defining the protection settings of a relay include configuring the relay with the protection settings at the time of manufacture or using local predictions at the relay location to adjust these protection settings. However, these schemes define the protection parameters of the relay in a static manner. Therefore, these schemes are inefficient and ineffective at enabling the relay to efficiently operate during conditions of high impedance faults or higher than expected load conditions or constantly varying load conditions, especially in the presence of intermittent distributed generators.

[0006] Also, a local measurement at a specific time or a prediction of the expected current or voltage requirement at the relay location does not take into account the actual connected load or power conditions at one or more utilities being served by the distributed generators and the distribution substations and therefore, leads to similar difficulties in the detection of high impedance faults and higher than expected load conditions. In particular, any local measurements at the protection device to obtain protection settings are invariably influenced by fault current or voltage in the network and therefore do not reflect the actual loading conditions at a utility's end. Using such inaccurate local measurements or pre-defined static protection settings leads to false tripping in the power system. False tripping is a fault condition that causes an interrupt in the operation of a network when a sensed current at a protection device exceeds a threshold current at the protection device.

[0007] For example, consider the following scenario: Due to increased power requirements at a user's end, a distribution substation alone is unable to serve a utility because a maximum power capacity of the distribution substation has been reached. Therefore, a distributed generator is used to serve the utility in addition to the distribution substation. However, a traditional relay device with static protection parameter settings may determine an increase in the current drawn by the utility in the presence of the distributed generator as a fault situation when the increased current exceeds a protection parameter current threshold value, leading to a false trip condition. Similarly, a traditional relay device with static protection parameter settings may determine an increase in current drawn by a utility or end user as a fault situation, whereas the increased current at the utility or end user may be due to an increase in the load consumption at the utility or end user. In such and similar scenarios, static protection settings lead to increased false trip situations and other undesired network interrupts such as error messages, shutdown of a network component etc.

[0008] It is therefore desirable to have an improved adaptive protection system for power systems.

BRIEF DESCRIPTION

[0009] In accordance with aspects of the present disclosure, a protection device for electric power systems is disclosed The protection device includes a receiver configured to receive a first sensed load data from at least one corresponding metering system associated with at least one utility in the power system. The protection device further includes at least one processor coupled to the receiver. The processor is configured to reset at least one threshold parameter of the protection device based on the first sensed load data.

[0010] In accordance with another aspect of the present technique, a method for a protection device used in electric power systems is presented. The method includes receiving a sensed load data from at least one metering system associated with at least one corresponding utility in a power system and computing an average value of the sensed load data. Further, to computing the average value of the sensed load data, the method includes comparing a multiple of the average value of the sensed load data with a corresponding threshold parameter of a protection device. The method further includes resetting the corresponding threshold parameter of the protection device to the multiple of the average value of the sensed load data based on the comparison between the multiple of the average value of the sensed load data and the corresponding threshold parameter.

[0011] In accordance with yet another aspect, a power system is disclosed. The power system includes a distribution sub-station and a plurality of metering systems coupled to a plurality of utilities configured to receive electric power from the distribution sub-station, wherein at least one metering system of the plurality of metering systems generates a corresponding sensed load data of a corresponding utility among the plurality of utilities. The power system further includes a feeder system of the distribution network configured to feed the electric power from the distribution sub station to the plurality of utilities. Further, the power system includes at least one protection device coupled to the feeder system. The protection device includes a receiver configured to receive the corresponding sensed load data from the at least one metering system and at least one processor coupled to the receiver, the processor configured to reset at least one threshold parameter of the protection device based on the sensed load data.

[0012] In accordance with yet another aspect of the present technique, a non- transitory computer readable medium for a protection device is disclosed. The non-transitory computer readable medium is encoded with a program to instruct one or more processors to receive a sensed load data from at least one of a plurality of metering systems coupled to a plurality of corresponding utilities in a power system and reset at least one threshold parameter of the protection device based on the sensed load data, wherein the sensed load data is further based upon at least one of an energized state of at least one distributed generator coupled to the at least one metering system, a de-energized state of the at least one distributed generator coupled to the at least one metering system, and a connected load associated with the at least one of the plurality of metering systems.

DRAWINGS

[0013] These and other features and aspects of embodiments of the present system and techniques will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0014] FIG. 1 is a block diagram of an exemplary power system including a protection device in accordance with an embodiment of the present system.

[0015] FIG. 2 is another block diagram of an exemplary power system including a protection device in accordance with an embodiment of the present system.

[0016] FIG. 3 is a block diagram of an exemplary protection device used in an electrical power system in accordance with an embodiment of the present system.

[0017] FIG. 4 is a schematic diagram showing utilities in communication with a protection device according to certain aspects of the system.

[0018] FIG. 5 is a block diagram of an exemplary data repository in a protection device according to certain aspects of the system.

[0019] FIG. 6 is a flowchart representing an exemplary method for the protection of a power system using Advanced Metering Infrastructure (AMI) feedback scheme.

DETAILED DESCRIPTION

[0020] Embodiments discussed herein are generally directed towards protection of power systems. According to one embodiment, the disclosure describes resetting protection parameters for a protection device based on the actual load consumption at a consumer or end user in an electric power system. Particularly, embodiments of the present techniques disclose resetting the threshold values of the protection parameters of the protection device based on an output from the metering devices at various points in the transmission line such as Advanced Metering Infrastructure (AMI) from one or more consumers or end users. Hereinafter, the terms "end users", "clients", "consumers", and "utilities" are used to indicate entities consuming power in the power system. Also, the terms "electric power system", "electrical power system", and "power system" are used interchangeably to refer to the system of power distribution to loads. Although certain embodiments of the present invention are discussed herein with reference to a power distribution system, it should be noted herein that the application of embodiments of the present system may also be suitable for other systems such as power transmission systems or any other systems that require protection from false tripping in the system. This includes various micro grids and other power distribution systems that deliver power from a power source to electrical loads.

[0021] Turning to FIG. 1, a simplified block diagram of an exemplary power system 100 in accordance with aspects of the present system is illustrated. In one embodiment, the power system 100 may be a power distribution system. The power system 100 in this example includes a distribution sub-station 102 that is used to aid in the power distribution. In one example the primary power can be a much higher voltage and the sub-station typically employs a bank of step down transformers disposed proximate to one or more end users for converting voltage obtained from a main generator (not shown) to usable levels of voltage. The power system 100 further includes a plurality of conductors or feeder systems 104, 106, 108 and in some examples one or more sub-feeders (not shown) for feeding electric power from the feeders 104, 106,108 to various loads and end users 110,112,114.

[0022] Electric power may be fed to the end user sections 110, 112, 114 by a plurality of distributed generators 116, 118 in addition to the electric power fed by the distribution sub-station 102. In the illustrated embodiment of FIG. 1, additional electric power is fed to the end sections 110,112 by additional power sources such as distributed generators 116,118 respectively. The distributed generator includes power sources such as solar, wind, geothermal as examples of energy sources that can be part of the distribution system. The distributed generators 116,118 are an auxiliary source of power which is either used to support a part of or the entire load of a power system 100. For example, in case the distribution sub-station 102 is unable to feed electric power to the end user section 110 under conditions when a maximum limit of the distribution sub station 102 is reached or when a utility supply (not shown) is overloaded, the distributed generator 116 may feed electric power to the end user section 110. In another embodiment, the end user section 112 may demand an increased power supply to meet its growing power requirements. In such an embodiment, the distributed power generator 118 may feed electric power to the end user section 112 to support the growing power requirements.

[0023] Further, the end user sections 110, 112, 114 may include one or more utilities or end users. For example, in the embodiment of FIG. 2, the feeder 104 or sub-feeder 140 with protection devices 142, 144, 146 are electrically coupled to end user sections 110, 112, 114 and utilities 120, 122, 124, 126, 128 in the power network 100. The utilities 120, 122, 124, 126, 128 may include any power consuming entity. In one embodiment, the utilities 126,128 may be users with large scale power demands such as factories with multiple functioning units. In yet another embodiment, the utilities 120, 122, 124 may be business workplaces or any other users with power requirements. In other words, the utilities 120, 122, 124, 126, 128 may be domestic loads or industrial loads. In such an embodiment, the utility 120 may include a plurality of electrical appliances (not shown). Likewise, utility 122 may be a factory having equipment (not shown) including refrigerator, microwave ovens, computer systems, etc. Similarly, utilities 124,126,128 may be small shops with one or more electrical equipment. In one example the end users 110,112 include metering systems 148,150 electrically coupled to the sub-feeder 140 and coupled to the end user 110, 112. In one example the end user 114 is a residence or business and the metering system 152 is a smart meter or smart appliance.

[0024] Each of the utilities 120, 122, 124, 126, 128 has a respective electrical metering system 130,132,134,136,138 coupled to its respective electrical appliances or equipment. Similarly, each of the end users 110, 112, 114 has a corresponding metering system 148, 150, 152 coupled to its respective appliances. Each metering system 130, 132, 134, 136, 138, 148, 150, 152 records and accounts for power consumption information at any instant of time at the respective utilities 120, 122, 124, 126, 128 and end users 110, 112, 114. Each of the metering systems 130, 132, 134, 136, 138, 148, 150, 152 is configured to measure a sensed load data at the respective utility or end user at which the metering system 130, 132, 134, 136, 138, 148, 150, 152 is installed. The sensed load data includes one or more of a number of power units consumed or a current value based on the number of power units consumed or a voltage value based on the number of power units consumed at the respective utilities 120, 122, 124, 126, 128 or end users 110, 112, 114 due to one or more "connected loads" at the utilities or end users. A connected load may be referred to as a sum of continuous power ratings of all load consuming devices at a particular utility of end user coupled to the power system 100 or any part thereof at a particular instant of time. For example, in one embodiment, the metering system 130 provides a sensed load data by measuring a number of power units consumed at the utility 120.

[0025] Further, in accordance with some embodiments of the invention, one or more of the metering systems 130, 132, 134, 136, 138, 148, 150, 152 is an Advanced Metering Infrastructure (AMI) based metering system. AMI based metering systems are also referred to as smart metering systems or smart meters. AMI based metering systems are capable of having a bidirectional communication with a centralized management site. In some cases, the AMI based metering systems may provide real-time bidirectional communications with the centralized management site. In other case, the AMI based metering systems may provide near real-time communication between the AMI meters and the centralized management site due to limited bandwidth available for communication. In the illustrated embodiment, the AMI based smart meters 130, 132, 134, 136, 138, 148, 150, 152 sense power consumption at their respective utilities 120, 122,124,126, 128 or end users 110,112,114 to obtain the sensed load data and transmit the sensed load data such as a sensed current value or a sensed voltage value to the corresponding protection devices 142, 144, 146. In another example, the AMI based smart meters 130, 132, 134, 136, 138, 148, 150, 152 sense a power consumption at their respective utilities 120, 122, 124, 126, 128 or end users 110, 112, 114 while taking into account the electrical coupling or decoupling of an energized (or de-energized) distributed generator serving the respective utilities 120,122, 124, 126, 128 or end users 110, 112, 114, and transmit the sensed load data based on the sensed power consumption to the corresponding protection devices 142,144,146. For example, in one embodiment, the AMI technology enables a real-time bidirectional communication between the metering systems 130, 132, 134 and the protection device 142, between the metering system 136 and protection device 144, and between the metering system 138 and protection device 146.

[0026] The protection devices 142, 144, 146 may be a relay, or the like devices. The protection devices 142, 144, 146 are used for the protection of the power system 100. In one embodiment, the protection devices 142, 144, 146 are coupled to the feeder system 104 including the sub-feeder 140 of the power system 100 and correspond to end user sections 110, 112, 114. In another embodiment, the protection devices 142, 144, 146 may be coupled to a centralized protection device (not shown) coupled to the feeder system 104 including the sub-feeder 140. In yet another embodiment, there may be only one centralized protection device (not shown) coupled to one or more of the feeder systems 104, 106,108 of the power system 100 shown in FIG. 1.

[0027] Further, each of the protection devices 142, 144, 146 shown in FIG. 2 is associated with one or more protection parameters such as current, voltage, or the like. Each protection parameter of the protection devices 142, 144, 146 includes an associated predetermined threshold value. Typically, the predetermined threshold values are set points or values for a corresponding protection parameter such as current or voltage, beyond which the protection devices 142,144,146 may trip in order to protect the power system 100 or any component thereof from any fault. For example, each protection device 142, 144, 146 may include a predetermined current threshold value, a predetermined voltage threshold value, or the like as protection parameters. Such predetermined threshold values of current and voltage may be preconfigured into the protection devices 142, 144, 146 as the protection parameters either at a time of manufacture or by a network operator of the power system 100 or may be obtained based on the power consumption or connected load measurement at the utilities 120, 122, 124, 126,128 and end users 110, 112, 114 as obtained from metering systems 130, 132, 134, 136,136,138,148,150,152.

[0028] According to some aspects of the disclosure, the protection devices 142, 144, 146 receive a sensed load data from one or more of the respective utilities 120,122, 124, 126,128 or end users 110, 112, 114. As previously explained, the sensed load data include at number of power units consumed, a current value, and a voltage value at the respective utilities 120,122,124,126,128 or end users 110, 112,114 due to one or more "connected loads" at the utilities. In one embodiment, the protection devices 142, 144, 146 may determine a corresponding current value and a corresponding voltage value from the sensed load data, when the sensed load data comprises the number of power units consumed at a respective utility.

[0029] Further, in response to receiving the sensed load data, the protection devices 142, 144, 146 retrieve the predetermined threshold values associated with the corresponding protection parameters. In one embodiment, the protection devices 142, 144, 146 determine one or more of a predetermined current threshold value and a predetermined voltage threshold value from the one or more corresponding protection parameters in response to receiving the sensed load data comprising a current value and a voltage value. Furthermore, the protection devices 142, 144, 146 obtain an average current value based on the current value in the sensed load data. The protection devices 142, 144, 146 may additionally obtain an average voltage value based on the voltage value in the sensed load data.

[0030] The protection devices 142, 144, 146 then compare the predetermined current threshold value with a multiple of the average current value determined from the sensed load data. Similarly, the protection devices the protection devices 142, 144, 146 compare the predetermined voltage threshold value with a multiple of the average voltage value determined from the sensed load data. Accordingly, the protection devices 142, 144, 146 determine whether the predetermined current threshold value is different from the multiple of the average current value determined from the sensed load data. Similarly, the protection devices the protection devices 142, 144, 146 may additionally determine whether the predetermined voltage threshold value is different from the multiple of the average voltage value determined from the sensed load data. In one embodiment, the multiple of the average current value is obtained by multiplying the average current value with a number, hereon referred to as a multiplying factor. The multiplying factor may be preconfigured into the protection device 142, 144, 146 at the time of manufacture or may be updated by an operator of the network 100. It is to be noted that any suitable method may be used for configuring the multiplying factor into the protection device 142, 144, 146. Also, the protection device 142, 144, 146 may include different or same multiplying factors for multiplying with average current value and with average voltage value. In this way, the protection devices 142, 144, 146 determine whether a multiple of the average value of received sensed load data including one or more of the current value and voltage value is different from the threshold value of one or more corresponding protection parameters, that is, a predetermined or predefined current threshold value or/and a predetermined or predefined voltage threshold value.

[0031] Next, the protection devices 142, 144, 146 update or reset the corresponding threshold values of the protection parameters in response to the received sensed load data from one or more of the utilities 120, 122, 124, 126, 128 and/or end users 110, 112, 114. For example, in one embodiment, the protection devices 142, 144, 146 reset the predetermined current threshold value of the one or more protection parameters to the multiple of the average current value, when the predetermined current threshold value is different from the average current value obtained from the sensed load data. The multiple of the average current value is obtained in similar ways, as described above, such as by multiplying the average current value with the multiplying factor. In another example, the protection devices 142, 144, 146 reset the predetermined current threshold value of the one or more protection parameters to a value that is 1.2 times the average current value, when the predetermined current threshold value is different from the multiple of the average current value obtained from the sensed load data, when the multiplying factor is 1.2. In yet another example, when the predetermined current threshold value is different from the multiple of the average current value obtained from the sensed load data, the protection devices 142,144,146 reset the predetermined current threshold value of the one or more protection parameters to the multiple of the average current value by multiplying the current threshold value with the multiplying factor. In this way, the predetermined current threshold value is reset to a new threshold value hereon referred to as reset current threshold value. The above disclosed procedure is similarly used by the protection devices the protection devices 142, 144, 146 to obtain other reset protection parameters such as reset voltage threshold value for the protection devices 142,144,146.

[0032] Further to resetting the predetermined threshold values of the protection parameters, the protection devices 142, 144, 146 may use the reset threshold values of the protection parameters, also referred to as updated protection parameters, to control an operation of the power system 100. For example, in one embodiment, the reset current threshold value is used by the protection devices 142, 144, 146 to determine whether or not to isolate a faulty section of the power system 100. In another embodiment, the reset voltage threshold value is used by the protection devices 142, 144, 146 to transmit a message to an operator at the distribution sub-station 102 who is monitoring the power system 100 so that the operator can select an appropriate action for proper functioning of the power system 100. In yet another embodiment, the protection devices 142, 144,146 use the updated protection parameters to determine whether to transmit a warning signal to an external controlling device which determines an appropriate action for controlling the power system 100.

[0033] The above disclosed system is particularly helpful in ensuring a dynamic updating of the protection parameters of the protection devices based on receiving feedback from the metering systems 130, 132, 134, 136, 138, 148, 150, 152 in the form of sensed loading conditions at particular instants of time. Such dynamic updating of the protection parameters of the protection devices 142, 144, 146 greatly reduces instances of false tripping in the power system 100 to ensure a reliable network operation. As is understood by one of ordinary skill in the art, the power system 100 described in FIGs. 1 and 2 is only exemplary and any other suitable system may be employed for the purposes of this invention. Further, the protection device 142 of FIGs. 1 and 2 is further described herein with reference to FIG. 3. As may be understood by one of ordinary skill in the art, the protection devices 144 and 146 may also have similar components, as described herein below for the protection device 142 in FIG. 3.

[0034] Turning now to FIG. 3, the protection device 142 of a power system is shown. In a typical power system, the protection device 142 is utilized to protect the various components or sections such as any equipment at the end user 110 and utilities 120, 122, 124 illustrated in FIG. 2. Typically, the protection device 142 protects the various components by isolating a faulty component or section of the power system 100 in response to detecting an impending network component failure or other fault situations in the network components such as current overloading at a particular network component etc. Additionally, the protection device 142 may perform a transmission of a message to a controlling entity such as a processor external to the protection device 142 or an operator manning the power system informing the controlling entity of the detected fault situation or impending network component failure,

[0035] The protection device 142 shown in FIG. 3 includes a transceiver 304, a processor 306, and a data repository 308, each of which communicates using an address and data bus 310. The protection device 142 may be a relay protection device. The transceiver 304 can be a unitary transceiver or separate transmitter and receiver that are electrically coupled together. The receiver 304 may receive sensed load data from one or more utilities. For example, in the exemplary illustration in FIG. 2, the protection device 142 receives sensed load data from the end user 110 and utilities 120, 122, 124. In one embodiment, a sensed load data is a measurement of a number of units of power consumed at a particular utility at a particular instant of time, using the smart meters such as the AMI meters. In another embodiment, a sensed load data is a current value or a voltage value indicative of the number of units of power consumed at a particular utility at a particular instant of time. The transmission of sensed loading data from the one or more utilities to a protection device such as the protection device 142 is described more with reference to FIG. 4.

[0036] Referring back to FIG. 3, the metering systems such as AMI meters installed at the corresponding utilities provide the sensed load data such as a maximum instantaneous power consumed or a total instantaneous power consumed based on respective coupled loads or connected loads at the corresponding utility, to the protection device 142. The coupled load or connected load refers to an "aggregated value of power ratings of all load consuming appliances or apparatus coupled to an electric power system" or "any part thereof where the apparatus is coupled through the AMI meter." In another embodiment, a random sampling is performed to obtain samples of sensed load data from some of the AMI meters among the plurality of AMI meters. In certain embodiments, when a distributed network includes a plurality of distributed generators for feeding electric power to the utilities in addition to a distribution sub-station, the random sampling is performed such that at least one of the samples includes sensed load data of a utility served by a distributed generator. In such embodiments having the presence of distributed generators in the power system, the sensed load data is obtained from each AMI meter corresponding to the distributed generators based upon operating condition of the distributed generators. For example, the operating condition of the distributed generator may be an operational state or energized state, or a non-operational state or de-energized state. In an operational state or energized state, the distributed generator is electrically coupled to one or more utilities and provides power to the one or more utilities. In a non-operational state or de-energized state, the distributed generator is non-functional and is not serving the utilities.

[0037] Upon receiving the real time or near real-time sensed load data from the AMI meters, the transceiver 304 transmits the sensed load data to the processor 306. The processor 306 calculates an average value of the sensed load data. In accordance with the particular embodiment of the present invention, the processor 306 obtains the average value of the sensed load data from each of the utilities by calculating an integral summation of the sensed load data from each of the utilities. The processor 306 then determines an average of a sensed load data by dividing the integral summation of the sensed load data from each of the utilities by the number of the utilities to obtain an average sensed load data. The average sensed load data is obtained by the equation: D,vg = (Dun)/Nu where Davg refers to the average load data, Dun refers to sensed load data from a utility n, and Nu refers to the number of utilities transmitting the sensed load data to the protection device 142. In one embodiment, the processor 306 obtains an average sensed load data by obtaining an average value of the maximum power consumption at each of the utilities. In another embodiment, the processor 306 obtains an average value of the sensed load data by obtaining an average current value corresponding to the sensed load data. In yet another embodiment, the processor 306 obtains average value of the sensed load data by obtaining an average voltage value corresponding to the sensed load data. Other techniques to obtain an average of the sensed load data obtained from various utilities may also be envisaged.

[0038] In one embodiment, the processor 306 may optionally store the received sensed load data and the average sensed load data in the data repository 308. The processor 306 compares a multiple of the average sensed load data with one or more threshold parameters of the protection device 142 stored in the data repository 308. For the purposes of this invention, the terms "values" and "parameters" may be used interchangeably. In one example, an average sensed load data may include an average sensed current value and a threshold parameter may include a predetermined threshold current value. The multiple of the average sensed load data may be obtained by multiplying the averaged sensed load data with a predefined multiplying factor of the protection device 142. . The multiplying factor of the protection device 142 may be preconfigured into the protection device. In one embodiment, the multiplying factor of the protection device 142 is preconfigured by a manufacturer of the protection device 142. Further, in response to comparing the multiple of the average sensed load data with the corresponding threshold parameter, the protection device 142 may update the threshold parameter. For example, if a first multiple of the average sensed current value is different from the predetermined threshold current value, the processor 306 resets the predetermined threshold current value to the first multiple of the average sensed current value. Similarly, if a second multiple of the average sensed voltage value is different from the predetermined threshold voltage value, the processor 306 resets the predetermined threshold voltage value to the second multiple of the average sensed voltage value. For the purposes of this invention, the first multiple and second multiple refer to any multiple value of the average sensed current value and the averaged sensed voltage value respectively. In one embodiment, the first multiple of the predetermined threshold value is evaluated by multiplying the average sensed current value with the predetermined multiplying factor stored in the data repository 308. For example, in one exemplary scenario, the predetermined multiplying factor is 2, therefore, the processor 306 resets the predetermined threshold value to twice the average sensed current value. In another example, the predetermined multiplying factor is 1.2 and the processor 306 resets the predetermined threshold voltage value to 1.2 times the average sensed voltage value, i.e., multiply average sensed voltage value by 1.2 to reset the predetermined threshold voltage value. In this way, once the new or updated or reset threshold parameters are determined, the processor 306 may perform one or more of an isolating a network component of the power system or intimating a controller of the power system about a possible component failure using the updated threshold parameters using the new or updated threshold parameters. For the purposes of this disclosure, the terms "reset" and "update" and used interchangeably to suggest a reset or updation of the threshold parameters.

[0039] It should be noted herein that the processor 306 may consider any losses such as line loss while resetting the predetermined threshold parameters to the average sensed load value. Also, the resetting of the threshold parameters of the protection device is an iterative process such that the processor 306 continually upgrades the threshold parameters of the protection parameters according to the latest sensed load data as received from the AMI meters at the plurality of utilities in the power system at periodic intervals of time and/or in real time.

[0040] FIG. 4 shows a power system 400 including a plurality of utilities 402, 404, 406, a feeder network 408, and a protection device 410 in accordance with a particular embodiment of the present system. In one embodiment, the protection device 410 may correspond to the protection device 142 of FIG. 2 and the utilities 402,404,406 correspond to the utilities 120,124,126 of FIG. 2. The feeder network 408 of the power system 400 is configured to feed electric power from a distribution sub-station (not shown) to the plurality of utilities 402, 404, 406 and is further coupled to the protection device 410. Further, each of the plurality of utilities 402,404,406 has one or more smart electrical meters such as AMI meters (not shown) installed at the customer premises. The customer premises may be any one or more of a housing society, an apartment, an office complex, a factory, or any other building having a plurality of electrical equipment which consumes electric power. In one embodiment, one AMI meter is coupled to all the electrical appliances or equipment in a premise of a particular utility to obtain real time sensed load data such as the maximum instantaneous load being consumed, or the total instantaneous load consumption value, or the like. In another embodiment, a plurality of AMI meters may be installed in the premises of a utility for each electrical appliance such that each AMI meter provides sensed load data to the protection device 410. In yet another embodiment, a plurality of slave AMI meters sense load data from a plurality of appliances in a customer premise and transmit the information to a master AMI meter which further transmits collated sensed load data to the protection device 410. In yet another embodiment, an AMI meter at a utility receives the sensed load information from the appliances or equipment in the utility over one or more of a wired network, a wireless network, or a combination thereof. Further, the communications between the AMI meters at the utilities 402, 404,406 and the protection device 410 may occur in real-time and/or at periodic intervals of time.

[0041] FIG. 5 is an exemplary representation of the data repository 308 and its contents according to certain aspects of the present invention. As shown in FIG. 5, the exemplary data repository 308 includes a 4X3 matrix haying time instants 500 , average sensed load data 502, initial (or previous) threshold parameters 504, and reset parameters 506 corresponding to a protection device. such as the protection device 142 in FIG. 3. The time instants 500 represents the time instants corresponding to the average sensed load data 502, initial (or previous) threshold parameters 504, and reset parameters 506. As previously described with reference to FIG. 4, an average sensed load data 502 is an average value of the sensed load data received by the protection device 142 from various utilities. FIG. 5 shows two different values for the average sensed load data 502 obtained at two instants of time T1 and T2. For example, a first value of the average sensed load data at time T1 is C2 Amperes and a second value of the average sensed load data at time instant T2 is shown as C3 Amperes and V2 volts.

[0042] The threshold parameters (or initial threshold parameters) 504 of the protection device 142 define cut-off values at which the protection device 142 takes an appropriate action for the protection of the power system. Each of the threshold parameters 504 may include predefined current threshold value and/or predefined voltage threshold value. The predefined current or voltage threshold value may be either an absolute value or one or more range of values. For example, in the illustrated embodiment in FIG. 5, the data repository 408 includes a first absolute threshold parameter (CI Ampere and VI volts) corresponding to the time instant T1 and a second absolute threshold parameter (C2 Ampere and VI volts) corresponding to the time instant T2. Further, the threshold parameters 504 may be either be pre-configured into the protection device or may be determined based on a previous determination of an average sensed load data received by the protection device from one or more utilities.

[0043] The data repository 308 further includes reset parameters 506 which are the new threshold parameters or cut off values for the operation of the protection device. This process of determining the reset threshold parameters 506 is described in greater detail below.

[0044] A protection device utilizes the average sensed load data 502 and the threshold parameters 504 to determine the reset parameters 506. In particular, the reset parameters 506 are determined based on a comparison between a multiple of the average sensed load data 502 at a particular time instant and the corresponding initial threshold parameters 504 at that time instant.

[0045] For example, consider a particular time instant t1 at which a protection device receives a sensed load data from one or more utilities. The protection device determines an average value of the sensed load data 502 at the time instant T1. For example, in the illustration in FIG. 5, the average value of sensed load data 502 for time instant t1 is recorded as C2 Ampere in terms of current flow. The protection device then retrieves predetermined initial threshold parameter values 504 corresponding to time instant T1. In the exemplary embodiment in FIG. 5, the predetermined threshold parameters 504 at time instant T1 include current threshold value CI and voltage threshold value VI. The protection device then compares a multiple of the average sensed load data 502 at time T1 with the existing threshold values 504 at time T1. In one embodiment the multiple of the average sensed load data is obtained by multiplying the average sensed load data 502 by a multiplying factor (not shown) stored in the data repository 308. In case of FIG. 5, the multiplying factor is considered to be 1. However, it is to be noted that any suitable numeric value may be preconfigured into the protection device to be utilized as the multiplying factor. In the exemplary case depicted in FIG. 5 for time instant T1, the current threshold value CI of the predetermined threshold parameter is different from a multiple (in this case, 1 times) of the current value C2 corresponding to the average sensed load data 502. Therefore, the protection device resets the current threshold value CI of the predetermined threshold parameter 504 to the multiple (in this case, 1 times) of the current value C2 corresponding to the average sensed load data 502, to obtain the reset threshold parameter 506 as C2 Ampere and VI Volts corresponding to time instant T1. It is to be noted that in this case no determination has been performed with respect to a voltage value corresponding to the average sensed load data, and therefore, the reset threshold voltage in the reset parameter 506 is same as the initial threshold voltage VI corresponding to the initial threshold parameter 504 for time instant T1. In another exemplary scenario, a reset threshold voltage value may also vary from the initial threshold voltage value in accordance with the variation in the reset threshold current value from the initial threshold current value.

[0046] In another example, at a time instant T2, the protection device receives another sensed load data from one or more utilities. The protection device compares a multiple of the average value of the sensed load data 502 with the threshold parameters 504 existing at time instant T2. As previously explained, the multiple of the average value of the sensed load data is obtained by multiplying the sensed load data 502 with a multiplying factor preconfigured into the protection device. As shown in FIG. 5, the average value of the sensed load data 502 corresponding to time instant T2 includes a current value C3 Amperes and a voltage value V2 Volts. The protection device compares a multiple of the current value C3 and a multiple of the voltage value V2 obtained as the average sensed load data 502 with the corresponding threshold parameter 504 at the time instant 2, namely, with predetermined current threshold value C2 and predetermined voltage threshold value VI, respectively. In this embodiment, a multiple (1 times) of the current value C3 is compared with the predetermined current threshold value C2 and it is determined that the multiple (1 times) of the current value C3 is different from the predetermined current threshold parameter C2. Accordingly, the current threshold parameter C2 is reset to 1 times the corresponding current value C3 to obtain the reset threshold current parameter as C3 as shown in the reset threshold parameter 506 corresponding to time instant t2 in FIG. 5. Similarly, it is determined that the predetermined voltage threshold value VI is different from the voltage value V2 obtained from a multiple of the average sensed load data 502. Accordingly, the voltage threshold value VI is set to V2, as shown by the reset threshold parameter 506 corresponding to time instant T2. It is to be noted that any other suitable methods of comparing the sensed load data with the predetermined threshold parameter of the protection device may be used. The invention is now described with reference to the flow chart of FIG. 6.

[0047] Referring now to FIG. 6, the method 600 for dynamically updating threshold parameters of a protection device of a power system is disclosed. The method 600 includes receiving a sensed load data from at least one metering system associated with at least one corresponding utility or end user in a power system as represented by the step 602. The sensed load data includes one or more of a current value or a voltage value or a power value at a metering system based on a load at the corresponding utility or end user. In one embodiment, the sensed load data includes a number of consumed power units. The number of power units is also indicative of the current or voltage drawn due to the connected loads at the utility or end user. In a particular embodiment, a connected load refers to a sum of all continuous power ratings of all load consuming entities of the utility or end user. In one embodiment, a corresponding sensed load data is received from a set of utilities among the plurality of utilities of the power system such that the sensed load data is received from at least one utility that is served by at least one distributed generator.

[0048] Upon receiving the corresponding sensed load data, the method includes computing an average value of the sensed load data is computed as indicated by the step 604. As discussed previously, an average value of the sensed load data may be obtained by performing an integral summation of sensed load data received from each utility and dividing the integral summation by the number of utilities that transmitted the sensed load data. Similar processing is performed by performing an integral summation of sensed load data received from each end user and dividing the integral summation by the number of end users that transmitted the sensed load data. Other suitable methods may be used for the computation of the average value of the sensed load data. In one example, the average value of the sensed load data includes an average value of the current consumed at various utilities due to the coupled loads. In another example, the average value of the sensed load data includes an average value of the power consumed at various utilities due to the coupled loads. In yet another, the average sensed load data includes a voltage value.

[0049] The method further includes comparing a multiple of the average value of the sensed load data with a corresponding value of a predetermined threshold parameter of the protection device as represented by the step 606. The predetermined threshold parameter of the protection device is a set-point or a cut off value at which the protection device performs an appropriate action for the safe operation of the power system. Further, the multiple of the average value of the sensed load data is obtained by multiplying the average value of the sensed load data with a multiplying factor of the protection device. The multiplying factor may be preconfigured into the protection device and may be any suitable numerical value. For example, with reference to FIG. 5, the multiple of the average value of the sensed, load data is obtained by multiplying the average value with the multiplying factor referred to as a "relay multiplier". For example, in one particular embodiment, a current value indicative of a sensed load data is determined. A multiple value of the current value (that is, current multiplied by the multiplying factor of the protection device) is then compared with a corresponding predetermined current threshold value of the threshold parameter.

[0050] Further, the method includes determining whether the multiple of the average value of the sensed load data is different compared to the corresponding threshold parameter as represented by the step 608. For example, a current value is determined from the average sensed load data and a multiple of the current value is compared with the corresponding predetermined current threshold value at that time instant to determine whether the multiple of the current value differs or not with respect to the predetermined current threshold value. If it is determined that the average value of the sensed load data (such as the current value) is different with respect to the corresponding threshold parameter (such as predetermine current threshold value), the corresponding threshold parameter of the protection device is reset to the multiple value of the average value of the sensed load data as represented by the step 610. As previously described, the multiple value of the average value of the sensed load data is typically evaluated by multiplying the averaged value of the sensed load data with the predetermined multiplying factor stored at the protection device. If it is determined that the average value of the sensed load data (such as the current value) is the same as the corresponding threshold value, then the threshold value is not altered. The method 600 is repeated.

[0051] The method 600 ensures that the threshold values of the protection parameters of the protection device are continually upgraded based on the latest load consumption conditions the respective clients associated with the protection device. The upgraded or updated protection parameter threshold values are utilized by the protection device to compare a multiple of the average value of a sensed load data with the latest threshold value of the corresponding protection parameter. The comparison is used as a basis to determine whether or not to isolate a particular system component from the rest of the system by the protection device. In one example, in response to detecting a multiple of the average current value in the power network greater than an updated threshold value of a corresponding current threshold value of the protection parameter, the protection device trips and isolates the faulty section of the system from the rest of the sections of the system. In another example, in response to detecting a multiple of the average current value in the network greater than an updated threshold current value of a corresponding protection parameter, the protection device transmits a message to an operator of the power system for taking an appropriate action. It is understood by one or ordinary skill in the art that the above scenarios are only exemplary and not limiting by nature.

[0052] The above system may be further described using the following exemplary situation: A power system has a distribution sub-station coupled to four utilities and a protection device. Each utility has a respective AMI meter for the measurement of the power consumption at the respective utility. The protection device in a power system is configured with a predefined voltage threshold value of V volts as a threshold load parameter. The protection device is configured to receive periodic sensed load data values at a period of t seconds from each of four utilities. At a time instant t1, the protection device receives sensed load data values corresponding to the voltage from each of the four utilities and obtains an average voltage value (VI) of the sensed load data. The protection device then compares a multiple of the average voltage value of the sensed load data (VI) with the predefined threshold voltage value (V) value in a data repository and determines that the multiple of the average voltage value is x positive units greater than the predefined threshold voltage value. The protection device accordingly updates the predefined voltage threshold value (V Volts) to the multiple value of the average voltage value (VI volts) where the multiple value of the average voltage value (VI) is obtained by multiplying the average voltage value (VI) with a predefined multiplying factor, n, as stored at the protection device. .

[0053] After t seconds, the protection device receives next sensed load data values from each of the four utilities at time instant t2, where t2 is a summation of t1 and t. The protection device obtains a next average sensed load data value (C1). In this case, the average sensed load data value corresponds to a current value. The protection device now compares a multiple of the latest average sensed load data value (C1) with the corresponding threshold current value (C) of the predefined threshold parameter in the data repository. That is, the protection device compares the multiple of the current value C1 to the current threshold value C to determine whether the multiple of the average sensed load data is same or different with respect to predefined threshold parameter. The protection device now resets the current threshold value (C Amperes) to the new current threshold value, which is m times CI Amperes, where m is the multiplying factor for current threshold parameter as stored at the protection device, when the multiple of the average sensed load data, that is, m times CI, is different from the current threshold value C.

[0054] The above process of iteratively updating the threshold values of the protection parameters of the protection device in real time or near real-time will continue at periodic intervals of time. In one embodiment, the threshold values of the protection parameters of the protection device are updated based on a processing capability of the metering systems at the utilities. As is evident, the aforementioned method and system for a protection device greatly reduces cases of false tripping in any power system. Periodic updates in the form of sensed load data from the meters at the utilities enables the protection device to dynamically reset the threshold values of the protection parameters of the protection device based on the actual power consumption at the various utilities in the network. Specifically, in cases of high voltage impedance when a conductor of the feeder network distributing power to a specific utility inadvertently touches the ground, the readings of the respective AMI meters at the utility will decrease. The decrease in the AMI meter reading is reflected back to the protection device that adjusts and updates the threshold values of the protection parameters so as to avoid any unnecessary interruption in the operation of the network. Similarly, in cases of increased power consumption due to coupling of a distributed generator to the network, the respective AMI meter records the increased load and communicates the increased load as sensed load data to the protection device that resets its protection parameters based on the increased load conditions at the particular utility. Again, the ability of the protection device to reset its protection parameters based on the actual load conditions at one or more utilities prevents any undesired tripping thereby providing a smooth operation of the power system.

[0055] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

CLAIMS:

1. A protection device for a power system, the protection device comprising:

a receiver configured to receive a first sensed load data from at least one corresponding metering system associated with at least one utility or end user in the power system; and

at least one processor coupled to the receiver, the processor configured to reset at least one threshold parameter of the protection device based on the first sensed load data.

2. The protection device of claim 1, wherein the at least one threshold parameter comprises a second sensed load data, wherein the second sensed load data is obtained prior to obtaining the first sensed load data.

3. The protection device of claim 2, wherein each of the first sensed load data and the second sensed load data comprises at least one of a current value, a voltage value, and a power value at the at least one corresponding metering system.

4. The protection device of claim 1, wherein the at least one threshold parameter comprises at least one of a predetermined current threshold value and a predetermined voltage threshold value.

5. The protection device of claim 1, wherein the processor is further configured to reset the at least one threshold parameter of the protection device based on:

determining at least one of a predetermined current threshold value and a predetermined threshold voltage value from the at least one threshold parameter;

computing at least one of an average current value based on a plurality of current values and an average voltage value based on a plurality of voltage values, wherein the plurality of current values and the plurality of voltage values are obtained from the first sensed load data;

resetting the predetermined current threshold value to a first multiple of the average current value, when the first multiple of the average current value is different from the predetermined current threshold value; and

resetting the predetermined voltage threshold value to a second multiple of the average voltage value, when the second multiple of the average voltage value of the plurality of voltage values is different from the predetermined voltage threshold value.

6. The protection device of claim 1, wherein the at least one threshold parameter is different from a multiple of an average value of the first sensed load data when at least one distributed generator is electrically coupled or de-coupled from the power system.

7. The protection device of claim 1, wherein each of the at least one utility or end user comprises at least one power consuming entity.

8. The protection device of claim 1, wherein the receiver is further configured to receive the first sensed load data in real time.

9. The protection device of claim 1, wherein the receiver is further configured to receive the first sensed load data at periodic intervals of time.

10. The protection device of claim 1 further comprising:

a data repository coupled to the processor, wherein the data repository stores the at least one threshold parameter.

11. The protection device of claim 1, wherein the at least one corresponding metering system comprises an advanced metering infrastructure (AMI) system.

12. The protection device of claim 1, wherein the protection device comprises at least a protection relay, further wherein the protection device is coupled to a feeder system in the power system.

13. The protection device of claim 1, wherein the first sensed load data is further based upon at least one of an energized state of at least one corresponding distributed generator coupled to the at least one corresponding metering system, a de-energized state of the at least one corresponding distributed generator coupled to the at least one corresponding metering system, and a connected load associated with the at least one corresponding metering system.

14. A method, comprising:

receiving a sensed load data from at least one metering system associated with at least one corresponding utility in a power network;

computing an average value of the sensed load data;

comparing a multiple of the average value of the sensed load data with a corresponding threshold parameter of a protection device; and

resetting the corresponding threshold parameter of the protection device to the multiple of the average value of the sensed load data based on the comparison between the multiple of the average value of the sensed load data and the corresponding threshold parameter.

15. The method of claim 14 further comprising:

receiving the sensed load data in real time at periodic intervals of time.

16. The method of claim 14, wherein the resetting further comprises:

resetting the corresponding threshold parameter of the protection device to the multiple of the average value of the sensed load data when the multiple of the average value of the sensed load data is different from the corresponding threshold parameter.

17. The method of claim 14, wherein the sensed load data is further based upon at least one of an energized state of at least one corresponding distributed generator coupled to the at least one metering system, a de-energized state of the at least one corresponding distributed generator coupled to the at least one metering system, and a connected load at the corresponding utility associated with the at least one metering system.

18. A power system comprising:

a distribution sub-station;

a plurality of metering systems coupled to a plurality of utilities configured to receive electric power from the distribution sub-station, wherein at least one metering system of the plurality of metering systems generates a corresponding sensed load data of a corresponding utility among the plurality of utilities;

a feeder system of the network configured to feed the electric power from the distribution sub-station to the plurality of utilities; and

at least one protection device coupled to the feeder system, the protection device comprising:

a receiver configured to receive the corresponding sensed load data from the at least one metering system; and

at least one processor coupled to the receiver, the processor configured to reset at least one threshold parameter of the protection device based on the sensed load data.

19. The power system of claim 18, wherein the at least one metering system of the plurality of metering systems is further configured to:

measure an instantaneous power consumption by the corresponding utility; and generate the sensed load data based on the instantaneous power consumption by the corresponding utility.

20. The power system of claim 18, further comprising at least one distributed power generator configured to feed the electric power to the corresponding utility among the plurality of utilities.

21. The power system of claim 20, wherein the sensed load data is further based upon at least one of an energized state of the at least one distributed generator coupled to the at least one metering system, a de-energized state of the at least one distributed generator coupled to the at least one metering system, and a connected load at the corresponding utility associated with the at least one metering system.

22. The power system of claim 18, wherein the at least one processor coupled to the receiver resets the at least one threshold parameter of the protection device based on:

determining at least one of a predetermined current threshold value and a predetermined voltage threshold value from the at least one threshold parameter;

computing at least one of an average current value based on a plurality of current values and an average voltage value based on a plurality of voltage values, wherein the plurality of current values and the plurality of voltage values are obtained from the sensed load data;

resetting the predetermined current threshold value to a first multiple of the average current value, when the first multiple of the average current value is different from the predetermined current threshold value; and

resetting the predetermined voltage threshold value to a second multiple of the average voltage value of the plurality of voltage values, when the second multiple of the average voltage value is different from the predetermined voltage threshold value.

23. A non-transitory computer readable medium for a protection device encoded with a program to instruct one or more processors to:

receive a sensed load data from at least one of a plurality of metering systems coupled to a plurality of corresponding utilities in a power network; and

reset at least one threshold parameter of the protection device based on the sensed load data, wherein the sensed load data is further based upon at least one of an energized state of at least one distributed generator coupled to the at least one metering system, a de-energized state of the at least one distributed generator coupled to the at least one metering system, and a connected load associated with the at least one of the plurality of metering systems.