Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
  • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
  • H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
  • H02H3/30—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel
  • H02H3/302—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel involving phase comparison
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
  • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/08—Locating faults in cables, transmission lines, or networks
  • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
  • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors

Definitions

• the invention relates to the field of electricity transmission or distribution, and more particularly to a method for identifying the fault direction without voltage measurement information and directional element thereof.
• DGs Distributed Generators
• the traditional over-current (OC) protection relay also directly named “protection”
• P&C protection and control
• a protection is directly composed of directional elements, for example a directional pilot protection.
• the directional element is used as an importantly auxiliary component in a protection, for example the directional element for over-current protection.
• the present invention is to propose methods for identifying the fault direction without voltage measurement information and directional element thereof. Furthermore, the proposed directional element without voltage measurement information can be used in both distribution and transmission systems. Generally, proposed solutions can be used for any applications which need fault direction but the voltage measurements are unavailable.
• the present invention provides a method for identifying the fault direction without voltage measurement information and directional element thereof.
• a method for identifying the fault direction without voltage measurement information comprising: as to any one of protections, measuring the current value of the local line; calculating the fault component current based on said current value, and further calculating the phase angle of said fault component current; obtaining the phase angles of fault component currents from at least other two lines which are connected to the same busbar with said local line; comparing the phase angle of fault component current of said local line with that of the other lines; and identifying the fault direction based on the result of the comparison.
• a method for identifying the fault direction without voltage measurement information comprising: as to any one of protection, measuring the current value of the local line; obtaining current values from at least other two lines which are connected to the same busbar with said local line; calculating the fault component currents based on the current values from said local line and the other lines, and further calculating the phase angles of said fault component currents; comparing the phase angle of fault component current of said local line with that of the other lines; and identifying the fault direction based on the result of the comparison.
• the method further comprises: identifying the fault occurs in the reverse direction for the local protection if the phase angles of fault component currents of said local line and other lines are similar to each other; identifying the fault occurs in the reverse direction for the local protection if the phase angle of the fault component current of said local line is similar to some of the other lines and almost reverse to the others of the other lines; and identifying the fault occurs in the forward direction for the local protection if the phase angle of said local line is almost reverse to all of the other lines.
• the method further comprises: calculating the differences of the phase angles of between said local line and the other lines after getting the phase angles; comparing said differences of the phase angles with a preset threshold; identifying the fault occurs in the reverse direction for the local protection if at least one of said differences of the phase angles is less than a preset threshold; and identifying the fault occurs in the forward direction for the local protection if all differences of the phase angles are much larger than said preset threshold.
• the method further comprises: in the case of the fault in the forward direction for the local protection, calculating each amplitude of the fault component currents on said local line and the other lines respectively; comparing the amplitude of the fault component current on the said local line with that of the fault component currents on the other lines; and determining said amplitude of the fault component current on the said local line is biggest one; otherwise, issuing an alarm or block signal.
• the method is applied in multiple sources connected to the same busbar, multiple sources connected to the different busbars, a distribution system with distributed generation, a distribution network, a transmission network, a traditional substation and/or a digital substation.
• the method can be implemented by the process level, bay level or GOOSE as the communication means in a digital substation.
• a directional element for identifying the fault direction without voltage measurement information comprising: a measuring module, configured to measure the current value of the local line; a calculating module, configured to calculate the fault component current based on said current value, and further calculate the phase angle of said fault component current; a communication module, configured to obtain the phase angles of fault component currents from at least other two lines which are connected to the same busbar with said local line; a comparing module, configured to compare the phase angle of fault component current of said local line with that of the other lines; and an identifying module, configured to identify the fault direction based on the result of the comparison.
• a directional element for identifying the fault direction without voltage measurement information comprising: a measuring module, configured to measure the current value of the local line; a communication module, configured to obtain current values from at least other two lines which are connected to the same busbar with said local line; a calculating module, configured to calculate the fault component currents based on the current values from said local line and the other lines, and further calculate the phase angles of said fault component currents; a comparing module, configured to compare the phase angle of fault component current of said local line with that of the other lines; and a identifying module, configured to identify the fault direction based on the result of the comparison.
• the identifying module further is configured to: identify the fault occurs in the reverse direction for the local protection if the phase angles of fault component currents of said local line and other lines are similar to each other; identify the fault occurs in the reverse direction for the local protection if the phase angle of the fault component current of said local line is similar to some of the other lines and almost reverse to the others of the other lines; and identify the fault occurs in the forward direction for the local protection if the phase angle of said local line is almost reverse to all of the other lines.
• the calculating module is further configured to calculate the differences of the phase angles of between said local line and the other lines after getting the phase angles; said comparing module is further configured to compare said differences of the phase angles with a preset threshold; said identifying module is further configured to identify the fault occurs in the reverse direction for the local protection if at least one of said differences of the phase angles is less than a preset threshold; and identify the fault occurs in the forward direction for the local protection if all differences of the phase angles are much larger than said preset threshold.
• said calculating module is further configured to calculate each amplitude of the fault component currents on said local line and the other lines respectively; said comparing module is further configured to compare the amplitude of the fault component current on the said local line with the amplitudes of the fault component currents on the other lines; and said identifying module is further configured to determine said amplitude of the fault component current on the said local line is biggest one; otherwise, issue an alarm or block signal.
• the directional element is applied in multiple sources connected to the same busbar, multiple sources connected to the different busbars, a distribution system with distributed generation, a distribution network, a transmission network, a traditional substation and/or a digital substation.
• the directional element can use process level, bay level or GOOSE as the communication means in a digital substation.
• the directional element can be used to form directional pilot protection for transmission or distribution network.
• Embodiments of the present invention provide methods for identifying the fault direction without voltage measurement information and directional element thereof, which make the protection operated correctly without voltage measurement information in distribution or transmission network based on the right identification of the forward fault direction, especially for the network with multiple power sources or distributed generators.
• Fig.1 illustrates a typical distribution network with a DG
• Fig.2 illustrates an application of the present invention in distribution network with multiple power sources connected to the same busbar
• Fig.3 illustrates another application of the present invention in distribution network with multiple power sources
• Fig.4 illustrates another application of the present invention in distribution network with at least one DG
• Fig.5 illustrates another two applications of the present invention in transmission network in the case that fault direction is necessary while voltage is unavailable; and a directional pilot protection and an unblocking differential protection shown in Fig.5a and Fig. 5b respectively;
• Fig.6 illustrates another application of the present invention in distribution network with multiple DGs
• Fig.7 illustrates a diagram of fault component circuit corresponding to the circuit shown in Fig.6;
• Fig.8 illustrates the exemplary vector diagram with a fault on line k corresponding to the circuit shown in Fig.7
• Fig.9 illustrates a method for identifying the fault direction without voltage measurement information according to an embodiment of the present invention
• Fig.10 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention
• Fig.11 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention
• Fig.12 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention
• Fig.13 illustrates the vectors of fault component currents in the case of a fault on the busbar instead on lines
• Fig.14 illustrates a directional element for identifying the fault direction without voltage according to an embodiment of the present invention.
• Fig.1 illustrates a typical distribution network with a DG.
• the power-flow direction is from the left to right; and the over-current protection L 2 will not measure any fault currents in the case of occurrence of fault Fi or F 2 .
• the over-current protection L 2 won't mal-trip due to occurrence of fault F-i or F 2 .
• a DG is connected to the network in Fig. 1 , and the situation is much different than that without DG. If the DG is powerful enough, the over-current protection L 2 will measure a large fault current when a fault occurs at Fi or F 2 location.
• the protection L 2 may mal-trip if the fault current is large enough. It's obvious that directional element is necessary for the protections in distribution network with DG. Considering the situation that there is no voltage measurement information in distribution network normally, voltage will not be applied by the directional element. With the directional element proposed in the present invention, even in the distribution network with DGs, the over-current protection will work very well.
• the proposed method for identifying the fault direction without voltage measurement information and directional element thereof can be used in both distribution and transmission network, especially the networks with multiple power sources connected to the same busbar, the distribution network with multiple power sources, the distribution network with DGs and so on.
• Fig.2 illustrates an application of the present invention in distribution network with multiple power sources connected to the same busbar.
• Fig.3 illustrates another application of the present invention in distribution network with multiple power sources.
• Fig.4 illustrates another application of the present invention in distribution network with at least one DG.
• Fig.5 illustrates another two applications of the present invention in transmission network wherein the fault direction is necessary while voltage is unavailable.
• the signal of voltage measurement is not submitted to the I ED, and/or the voltage measurement sensor fails for some reasons.
• the directional element provided by the present invention can be used as a directional pilot protection or unblocking differential protection shown in Fig.5a and Fig.5b respectively.
• Fig.6 illustrates another application of the present invention in distribution network with multiple DGs.
• the distribution network module has n lines, and each line connects a protection (L-i , L k L n ) in series. Some DGs are connected to some of the lines individually. And a fault F occurs on the line k.
• Fig.7 illustrates a diagram of fault component circuit corresponding to the circuit shown in Fig.6.
• the fault component circuit shows the case that a fault occurs on the line K.
• the fault component currents on each line in the network can be calculated as shown below.
• ⁇ 5 is the current on the line from power generator to busbar
• Z s is the equivalent impedance on the line from power generator to busbar
• Z S1 is the equivalent impedance of the parallel lines exce t the line from power generator to busbar and the fault line k, and ;
• phase angle of all the impedances in equations (1 ) and (3) are similar (about 70° ⁇ 85°), which means the phase angle of fault component current ⁇ AI k ) on the fault line k is quite different (nearly in reverse direction) from all the other fault component currents ( ⁇ , ⁇ ' ⁇ k) ) in healthy lines.
• Fig.8 illustrates the exemplary vector diagram with a fault on line k corresponding to the circuit shown in Fig.7.
• the present invention is a solution for detecting fault direction without voltage measurement information, wherein the phase angles of fault component currents are different between a fault line and healthy lines.
• the phase angle of the fault component current on a fault line is almost reverse to that of all other fault component currents on healthy lines.
• the one whose phase angle is quite different from the others is regarded as the fault line and its fault direction is regarded as forward direction (fault is at the forward direction to the related protection).
• Fig.9 illustrates a method for identifying the fault direction without voltage measurement information according to an embodiment of the present invention.
• the method for identifying the fault direction without voltage measurement information comprises:
• Step 902 as to any one of protections, measuring the current value of the local line. That's to say, the protection in each line is configured to measure the local current of its local line.
• Step 904 calculating the fault component current based on said current value, and further calculating the phase angle of said fault component current.
• Each local protection calculates the phase angle of the fault component current on the local line.
• Step 906 obtaining the phase angles of fault component currents from at least other two lines which are connected to the same busbar with said local line.
• Each local protection communicates with at least other two protections, and obtains the phase angles of fault component currents from such lines connected to the same busbar with its local line.
• Step 908 comparing the phase angle of fault component current of said local line with that of the other lines.
• Step 910 identifying the fault direction based on the result of the comparison.
• the solutions no longer need voltage measurement information for identifying the fault direction when compared with conventional directional element. Furthermore, the solutions do not need any pre-fault power-flow direction or pre-fault voltages information for identifying the fault direction when compared with the methods proposed by A. K. Pradhan and P.Jena. Thus, the method and direction element thereof are more practical and valuable for identifying the fault direction without voltage measurement information.
• each local protection identifies the fault occurs in the reverse direction for the local protection if the phase angles of fault component currents of its local line and other lines are similar to each other; also identifies the fault occurs in the reverse direction for the local protection if the phase angle of the fault component current of its local line is similar to some of the other lines and almost reverse to the others of the other lines; and identifies the fault occurs in the forward direction for the local protection if the phase angle of its local line is almost reverse to all of the other lines.
• the solution only needs at least three current measurement information (such as the current of local line with the specific protection, and currents of at least two other lines connected to the same busbar) to detect and identify the fault direction of the. While in prior art, especially in Jia Wei's solution, the current measurement information of all lines connected to the same busbar is necessary for identifying the fault direction. Furthermore, the solution in the present invention simplifies the requirements of the hardware, software and communication flow of the system.
• Fig.10 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention.
• the method for identifying the fault direction without voltage measurement information comprises: steps 1002-1014; in which steps 1002-1006 are the same or similar to the corresponding steps 902-906 in Fig.9. In order to keep the description brief, the same or similar steps will not be described again.
• Step 1008 calculating the differences of the phase angles of between said local line and the other lines after the obtaining step;
• Step 1010 comparing said differences of the phase angles with a preset threshold. If at least one of said differences of the phase angles is less than a preset threshold, go to step 1012; otherwise, go to step 1014.
• Step 1012 identifying the fault occurs in the reverse direction for the local protection.
• Step 1014 identifying the fault occurs in the forward direction for the local protection. If all differences of the phase angles are much larger than said preset threshold, the fault is in the forward direction of the local protection.
• a threshold, 40 degree and alike can be preset. If at least one of the differences of the phase angles is less than 40 degree, then the local protection can identify the fault occurs in the reverse direction (that means the fault is not in the forward direction of the local line). So the local protection will not respond to the fault even if the current is larger than the setting in the over-current protection. That's to say, if the difference is less than a specified threshold, we can say such phase angles are similar to each other. Otherwise, if all the differences are larger than the 40 degree, the fault occurs in the forward direction of the local protection. So the protection shall respond to the fault if the current is larger than the setting at the same time. It shall be noted that the person skilled in art can select and adjust the preset threshold according to the specified applications; 40 degree is exemplified as a preset threshold, but not used to limit the threshold.
• the other healthy lines are connected to the same busbar with the fault line.
• the amplitude of the fault component current on the fault line is different to the ones on all the other healthy lines; furthermore, the amplitude of the fault component current is the largest one among all the fault component currents on the lines connected to the same busbar. Consequently, the amplitude difference can also be used as auxiliary criteria and algorithm to enhance the reliability of the solution.
• the present invention in order to double check the accuracy on identifying the fault direction, provides another method to identify the fault direction without voltage measurement information. After identifying the fault in the forward direction for the local protection in the embodiment as shown in for example Fig.9 or 10, the method further comprises a double check procedure comprising:
• Step A01 calculating each amplitude of the fault component currents on said local line and the other lines respectively.
• the local protect calculates every amplitude of the fault component currents previously used to identify the fault in the forward direction.
• Step A02 comparing the amplitude of the fault component current on the said local line with that of the fault component currents on the other lines.
• Step A03 determining the amplitude of the fault component current on its local line is biggest one. Then the fault can be confirmed in the forward direction for the local protection again. Otherwise, there is something wrong with the system, maybe a communication error, measurement mistake or current transformer error and so on; then the local protection issues an alarm or block signal.
• the further steps "comparing the amplitudes of all the fault component currents and determining the largest amplitude of the fault component current is from the same fault line where the phase angle of the fault component current represents a nearly reverse direction to the others” are used as an auxiliary means for final confirmation.
• Such auxiliary means based on the amplitude is benefit to enhance the reliability of the proposed method for identifying the fault direction without voltage measurement information.
• the auxiliary means are not necessary in theory.
• the steps based on phase angle for example "identifying one of the phase angles is almost reverse to the others” or “identifying some differences of the phase angles are much larger than said preset threshold" has already determined the corresponding phase angle of fault component current is from the fault line. Without the auxiliary means, the method is also a completed one for identifying the fault direction without voltage measurement information.
• Fig.11 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention.
• the method for identifying the fault direction without voltage measurement information comprises: steps 1102-1110; in which steps 1002, 1108 and 1110 are the same or similar to the corresponding steps 902, 908 and 910 in Fig.9. In order to keep the description brief, the same or similar steps will not be described again.
• Step 1104 obtaining current values from at least other two lines which are connected to the same busbar with said local line. After each protection measures the current value on its local line, any local protection can directly measured current values from other lines, for example at least other two lines connected to the same busbar with its local line.
• Step 1106 calculating the fault component currents based on the current values from said local line and the other lines, and further calculating the phase angles of said fault component currents.
• each local protection identifies the fault occurs in the reverse direction for the local protection if the phase angles of fault component currents of its local line and other lines are similar to each other; also identifies the fault occurs in the reverse direction for the local protection if the phase angle of the fault component current of its local line is similar to some of the other lines and almost reverse to the others of the other lines; and identifies the fault occurs in the forward direction for the local protection if the phase angle of its local line is almost reverse to all of the other lines.
• Fig.12 illustrates a method for identifying the fault direction without voltage measurement information according to another embodiment of the present invention.
• the method for identifying the fault direction without voltage measurement information comprises: steps 1202-1214; in which
• Steps1204 and 1206 are the same or similar to the corresponding steps 1104 and 1106 in Fig.11
• steps 1202, 1208-1214 are the same or similar to the corresponding steps 1002, 1008-1014 in Fig.10. In order to keep the description brief, the same or similar steps will not be described again.
• the method after identifying the fault in the forward direction for the local protection in the embodiment as shown in for example Fig.11 or 12, the method also comprises a double check procedure comprising:
• Step A01 calculating each amplitude of the fault component currents on said local line and the other lines respectively.
• the local protect calculates every amplitude of the fault component currents previously used to identify the fault in the forward direction.
• Step A02 comparing the amplitude of the fault component current on the said local line with that of the fault component currents on the other lines.
• Step A03 determining the amplitude of the fault component current on its local line is biggest one. Then the fault can be confirmed in the forward direction for the local protection again. Otherwise, there is something wrong, maybe a communication error or measurement mistake and so on; then the local protection issues an alarm or block signal.
• the methods mentioned above are applied in multiple sources connected to the same busbar, multiple sources connected to the different busbars, a distribution system with distributed generation, a distribution network, a transmission network, a traditional substation and/or a digital substation.
• the methods mentioned above can be implemented by the process level, bay level or GOOSE as the communication means in a digital substation.
• the method directly obtaining current values from at least other two lines is easy to be implemented by digital substation with Standard IEC61850-9-2.
• Fig.13 illustrates the vectors of fault component currents in the case of a fault on the busbar instead on the lines.
• Fig.13 when a fault occurring on the busbar, the phase angles of all the lines connected on the same busbar are similar to each other.
• the characteristics represented in Fig.13 show that the methods provided by the present invention are immune to the fault on busbar. That's to say, the method proposed in the present invention can take advantage of phase angles to correctly identify the fault occurring in fault line and the direction thereof. And the proposed methods don't need any additional process for identifying the fault direction without voltage measurement information in the condition of a fault on busbar. On the contrary, a whole busbar protection is embedded into the directional element to resolve the case of fault on busbar in the existing art proposed by Jia Wei.
• Fig.14 illustrates a directional element for identifying the fault direction without voltage according to an embodiment of the present invention.
• the directional element 1400 comprises a measuring module 1402, a calculating module 1404, a communication module 1406, a comparing module 1408 and an identifying module 1410.
• the measuring module 1402 is configured to measure the current value of the local line; the calculating module 1404 is configured to calculate the fault component current based on said current value and further calculate the phase angle of said fault component current; the communication module 1406 is configured to obtain the phase angles of fault component currents from at least other two lines which are connected to the same busbar with said local line; the comparing module 1408 is configured to compare the phase angle of fault component current of said local line with that of the other lines; and the identifying module 1410 is configured to identify the fault direction based on the result of the comparison.
• the proposed solution in the present invention is much more practical and easier for implementation than existing arts, especially when the amount or status of the lines in the distribution/transmission networks is variable. If more lines are connected into the busbar according to the present invention, all configurations and the embedded arithmetic strategy in the existing protections do not need any modification. While in Jia Wei's solution, the settings and arithmetic strategy of all protections need be changed in this condition.
• the communication module 1406 is configured to obtain current values from at least other two lines which are connected to the same busbar with said local line; the calculating module 1404 is configured to calculate the fault component currents based on the current values from said local line and the other lines, and further calculate the phase angles of said fault component currents.
• the identifying module 1410 further is configured to identify the fault occurs in the reverse direction for the local protection if the phase angles of fault component currents of said local line and other lines are similar to each other; identify the fault occurs in the reverse direction for the local protection if the phase angle of the fault component current of said local line is similar to some of the other lines and almost reverse to that of the other lines; and identify the fault occurs in the forward direction for the local protection if the phase angle of said local line is almost reverse to that of all the other lines.
• the calculating module 1404 is further configured to calculate the differences of the phase angles of between said local line and the other lines after getting the phase angles; the comparing module 1408 is further configured to compare said differences of the phase angles with a preset threshold; the identifying module 1410 is further configured to identify the fault occurs in the reverse direction for the local protection if at least one of said differences of the phase angles is less than a preset threshold; and identify the fault occurs in the forward direction for the local protection if all differences of the phase angles are much larger than said preset threshold.
• the calculating module 1404 is further configured to calculate each amplitude of the fault component currents on said local line and the other lines respectively; the comparing module 1408 is further configured to compare the amplitude of the fault component current on the said local line with the amplitudes of the fault component currents on the other lines; and the identifying module 1410 is further configured to determine said amplitude of the fault component current on the said local line is biggest one; otherwise, issue an alarm or block signal.
• the directional element is applied in multiple sources connected to the same busbar, multiple sources connected to the different busbars, a distribution system with distributed generation, a distribution network, a transmission network, a traditional substation and/or a digital substation. Furthermore, the directional element can use process level, bay level or GOOSE as the communication means in a digital substation.
• said directional element can also be used to form directional pilot protection for transmission or distribution network.
• the solutions no longer need voltage measurement information for identifying the fault direction when compared with conventional directional element.
• the solutions do not need any pre-fault power-flow direction or pre-fault voltages information for identifying the fault direction when compared with the methods proposed by A. K. Pradhan and P.Jena.
• the method and direction element thereof are more practical and valuable for identifying the fault direction without voltage measurement information.
• the solution only needs at least three current measurement information (such as the current of a line with a protection, and currents of at least two other lines connected to the same busbar) to detect and identify the fault direction of the line with such protect device. While in prior art, especially in Jia Wei's solution, the current measurement information of all lines connected to the same busbar is necessary for identifying the fault direction. Furthermore, the solutions in the present invention simpliyies the requirements of the hardware, software and communication flow of the system.
• the proposed solutions in the present invention are much more practical and easier for implementation, especially when the amount or status of the lines in distribution/transmission networks are variable. If more lines are connected into the busbar according to the present invention, all configurations and the embedded arithmetic strategy in the existing protections do not need any modification. While in Jia Wei's solution, the settings and arithmetic strategy of all protections need be changed in this condition.
• the current transformer (CT) saturation has less impact on phase than the amplitude of a current normally. That's to say, the solutions provided by the present invention will be more reliable in case of CT saturation than the one disclosed by Jia Wei.

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• Locating Faults (AREA)

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• 2012
  • 2012-01-16 IN IN4230CHN2014 patent/IN2014CN04230A/en unknown
  • 2012-01-16 WO PCT/CN2012/070424 patent/WO2013106985A1/en not_active Ceased
  • 2012-01-16 CN CN201280067228.1A patent/CN104054001B/zh active Active

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