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EP-4064492-B1 - SYSTEMS AND METHODS FOR IMPEDANCE-BASED BROKEN CONDUCTOR DETECTION IN ELECTRIC DISTRIBUTION SYSTEMS

EP4064492B1EP 4064492 B1EP4064492 B1EP 4064492B1EP-4064492-B1

Inventors

  • YIN,, Yujie
  • ZAMANI,, Mohammad Amin
  • KRUGER,, Johannes
  • BAYAT,, Hasan

Dates

Publication Date
20260506
Application Date
20220124

Claims (14)

  1. A method (700) for determining the occurrence of a broken conductor condition, comprising: determining, by a processor (242), during a first time period, a first impedance value measured by a first IED 105, wherein the first IED (105) is located at a feeder head (102) of a feeder associated with a distribution substation; determining, by the processor (242), during a second time period, a second impedance value measured by the first IED (105), wherein the second time period is after the first time period; determining, by the processor (242), a first ratio based on dividing a difference between the first impedance value and the second impedance value by the first impedance value; determining, by the processor (242), that the first ratio deviates from a threshold setpoint; and determining, by the processor (242), that a broken conductor condition occurs based on the first ratio deviating from the threshold setpoint, the method characterised by the steps of: determining, by the processor (242), during a third time period, a third impedance value measured by the first IED (105), wherein the third time period is prior to the first time period when the first impedance value is calculated; and determining, by the processor (242), that a fuse blown condition occurs based on determining that the third impedance value is greater than the first impedance value, and the second impedance value is greater than the first impedance value, wherein determining that the fuse blown condition occurs is further based on the first ratio deviating from the threshold setpoint, wherein determining that the broken conductor condition occurs based on determining that the third impedance value is less than the first impedance value and the second impedance value.
  2. The method (700) of claim 1, wherein the first impedance value and the second impedance value are with respect to a ground and are associated with a first phase of a distribution overhead line (110) associated with the feeder, the method (700) further comprising: determining, by the processor (242), during the second time period, a third impedance value measured by the first IED (105), wherein the third impedance value is associated with a second phase of the distribution overhead line (110) with respect to the ground; determining, by the processor (242), a second ratio based on dividing a difference between the second impedance value and the third impedance value by the third impedance value; and determining, by the processor (242), that the second ratio derives from the threshold setpoint, wherein determining that the broken conductor condition occurs is further based on the second ratio deviating from the threshold setpoint.
  3. The method (700) of claim 1, further comprising: determining, by the processor (242), during the first time period, a fourth impedance value measured by the first IED (105), wherein the fourth impedance value is associated with the second phase relative to a third phase of a distribution overhead line (110) associated with the feeder; determining, by the processor (242), during the second time period, a fifth impedance value measured by the first IED, wherein the fifth impedance value is associated with the second phase relative to the third phase; determining, by the processor (242), a third ratio based on dividing a difference between the fourth impedance value and the fifth impedance value by the fourth impedance value; determining, by the processor (242), that the third ratio is less than the threshold setpoint; and determining, by the processor (242), that the broken conductor condition relative to the first phase occurs based on the third ratio being less than threshold setpoint.
  4. The method (700) of claim 1, wherein the threshold setpoint is a first threshold setpoint associated with a first feeder load current of a distribution overhead line (110) associated with the feeder, the method (700) further comprising: determining, by the processor (242), that the first feeder load current is changed with time to a second feeder load current; determining, by the processor (242), a second threshold setpoint based on the second feeder load current; and adjusting, by the processor (242), the first threshold setpoint to the second threshold setpoint.
  5. The method (700) of claim 4, wherein the second feeder load current is greater than the first feeder load current, and wherein the second threshold setpoint is less than the first threshold setpoint.
  6. The method (700) of claim 1, further comprising: storing, by the processor (242), two or more impedance values prior to receiving the second impedance value, wherein the two or more impedance values comprise the first impedance value; determining, by the processor (242), a time interval between the first time period and the second time period based on a sampling rate of an output of the IED (105), wherein the time interval is associated with a number of cycles of time of the output of the IED (105); and retrieving, by the processor (242), the first impedance value based on the time interval.
  7. The method (700) of claim 1, wherein the broken conductor condition is a first broken conductor condition, wherein the first IED (105) is associated with a feeder main (102) of the feeder, the method (700) further comprising: determining, by the processor (242), during the first time period, a third impedance value measured by a second IED (105), wherein the second IED (106) is located at a downstream location of the feeder, and the second IED (106) is associated with a first branch of the feeder; determining, by the processor (242), during the second time period, a fourth impedance value measured by the second IED; determining, by the processor (242), a second ratio based on dividing a difference between the third impedance value and the fourth impedance value by the third impedance value; determining, by the processor (242), that the second ratio deviates from the threshold setpoint; determining, by the processor (242), that a second broken conductor condition occurs in the first branch based on the second ratio deviating from the threshold setpoint; and determining trip time for the second IED (106) associated with the second broken condition in coordination with the first IED (105) associated with the first broken condition.
  8. The method (700) of claim 1, wherein the feeder head is a first feeder head, the feeder is a first feeder, the threshold setpoint is a first threshold setpoint, and the broken conductor condition is a first broken conductor condition, the method (700) further comprising: determining, by the processor (242), during the first time period, a third impedance value measured by a second IED (106), wherein the second IED (106) is located at a second feeder head of a second feeder associated with the distribution substation; determining, by the processor (242), during the second time period, a fourth impedance value measured by the second IED (106); determining, by the processor (242), a second ratio based on dividing a difference between the third impedance value and the fourth impedance value by the third impedance value; determining, by the processor (242), that the second ratio deviates from a second threshold setpoint; and determining, by the processor (242), that a second broken conductor condition occurs based on the second ratio deviating from the second threshold setpoint.
  9. The method (700) of claim 1, further comprising: sending an alarm signal indicative of the occurrence of the broken conductor condition to one or more monitoring and computing devices (280); and performing one or more corrective actions in response to the occurrence of the broken conductor condition, wherein the one or more corrective actions comprise sending a trip signal to the first IED (105).
  10. A system (100) for determining the occurrence of a broken conductor condition, comprising: a feeder; a first IED (105) configured to measure one or more impedance values, wherein the first IED (105) is located at a feeder head (102) of the feeder associated with a distribution substation; a memory (250) coupled to at least one processor (242); the at least one processor (242) configured to: during a first time period, determine a first impedance value measured by the first IED (105), wherein the first IED (105), determine, during a second time period, a second impedance value measured by the first IED (105), wherein the second time period is after the first time period; determine a first ratio based on dividing a difference between the first impedance value and the second impedance value by the first impedance value; determine that the first ratio deviates from a threshold setpoint; and determine that a broken conductor condition occurs based on the first ratio deviating from the threshold setpoint, characterised by the processor being further configured to: determine, during a third time period, a third impedance value measured by the first IED (105). wherein the third time period is prior to the first time period when the first impedance value is calculated; and determine, that a fuse blown condition occurs based on determining that the third impedance value is greater than the first impedance value, and the second impedance value is greater than the first impedance value, wherein determining that the fuse blown condition occurs is further based on the first ratio deviating from the threshold setpoint, wherein determining that the broken conductor condition occurs based on determining that the third impedance value is less than the first impedance value and the second impedance value.
  11. The system (100) of claim 10, wherein the first impedance value and the second impedance value are with respect to a ground and are associated with a first phase of a distribution overhead line (110) associated with the feeder, wherein the at least one processor (242) is further configured to: determine, during the second time period, a third impedance value measured by the first IED (105), wherein the third impedance value is associated with a second phase of the distribution overhead line (110) with respect to the ground; determine a second ratio based on dividing a difference between the second impedance value and the third impedance value by the third impedance value; and determine that the second ratio derives from the threshold setpoint, wherein determining that the broken conductor condition occurs is further based on the second ratio deviating from the threshold setpoint.
  12. The system (100) of claim 11, wherein the at least one processor (242) is further configured to: determine, during the first time period, a fourth impedance value measured by the first IED (105), wherein the fourth impedance value is associated with the second phase relative to a third phase of a distribution overhead line (110) associated with the feeder; determine, during the second time period, a fifth impedance value measured by the first IED (105), wherein the fifth impedance value is associated with the second phase relative to the third phase; determine, a third ratio based on dividing a difference between the fourth impedance value and the fifth impedance value by the fourth impedance value; determine that the third ratio is less than the threshold setpoint; and determine that the broken conductor condition relative to the first phase occurs based on the third ratio being less than threshold setpoint.
  13. The system (100) of claim 10, wherein the threshold setpoint is a first threshold setpoint associated with a first feeder load current of a distribution overhead line (110) associated with the feeder, wherein the at least one processor (242) is further configured to: determine that the first feeder load current is changed with time to a second feeder load current; determine a second threshold setpoint based on the second feeder load current; and adjust the first threshold setpoint to the second threshold setpoint.
  14. The system (100) of claim 13, wherein the second feeder load current is greater than the first feeder load current, and wherein the second threshold setpoint is less than the first threshold setpoint.

Description

FIELD OF DISCLOSURE The present disclosure related to power distribution, and more particularly to systems and methods for impedance-based broken conductor detection. BACKGROUND An energized overhead power distribution line, also known as a conductor, may break and fall to the ground for a variety of reasons such as severe weather conditions, natural disasters, conductor clamp failures, tree fall, and/or fallen poles. When a falling conductor touches the earth or other grounded objects, it may cause a high-impedance (Hi-Z) fault which may not be reliably detected by conventional overcurrent protection schemes. Moreover, as the live conductor contacts the ground, it produces electrical arcing which may ignite flammable materials or vegetation and start a fire. An undetected Hi-Z fault is a risk to people and their properties as well as having a potential to evolve into a full-blown fault. Most of conventional methods may not detect all Hi-Z faults, and operation of an associated relay for downed conductor faults is not guaranteed. In addition, for such broken or falling conductors, conventional solutions may not be capable of detecting the condition and tripping the corresponding breaker(s) before the conductor touches the ground. Examples of known techniques for the detection of broken conductor are disclosed in the patent publications US 2009/289637, US 2021/025929 and US 2021/048486. DISCLOSURE OF INVENTION An aspect of the invention is to provide a method as defined in the claims. According to another aspect, the invention provides a system as defined in the claims. BRIEF DESCRIPTION OF THE DRAWINGS The detailed description is set forth with reference to the accompanying drawings. The drawings are provided for purposes of illustration only and merely depict example embodiments of the disclosure. The drawings are provided to facilitate understanding of the disclosure and shall not be deemed to limit the breadth, scope, or applicability of the disclosure. In the drawings, the leftmost digit(s) of a reference numeral may identify the drawing in which the reference numeral first appears. The use of the same reference numerals indicates similar, but not necessarily the same or identical components. However, different reference numerals may be used to identify similar components as well. Various embodiments may utilize elements or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. The use of singular terminology to describe a component or element may, depending on the context, encompass a plural number of such components or elements and vice versa. FIG. 1 is a schematic diagram of an example system and method illustrating impedance-based broken conductor detection in accordance with one or more example embodiments of the disclosure.FIG. 2 is a schematic illustration of another example system and method for impedance-based broken conductor detection in accordance with one or more example embodiments of the disclosure.FIG. 3 is a schematic diagram of an example impedance calculation with a moving window in accordance with one or more example embodiments of the disclosure.FIG. 4 is a schematic diagram illustrating an example relationship between adaptive threshold setpoints and feeder load in accordance with one or more example embodiments of the disclosure.FIG. 5 is a schematic diagram illustrating system parameter variation for an example single-phase fuse blown condition in accordance with one or more example embodiments of the disclosure.FIG. 6 is a schematic diagram illustrating an example logic diagram for broken conductor detection in accordance with one or more example embodiments of the disclosure.FIG. 7 is an example process flow diagram of an illustrative method for impedance-based broken conductor detection in accordance with one or more example embodiments of the disclosure.FIG. 8 is a schematic illustration of an example system and method illustrating multiple feeders controlled by a single controller for broken conductor detections in distribution systems in accordance with one or more example embodiments of the disclosure.FIG. 9 is a block diagram of an example of a machine or system for broken conductor detection in accordance with one or more example embodiments of the disclosure. DETAILED DESCRIPTION OVERVIEW The present invention, as defined by the appended claims, relates to a method and a system for impedance-based broken conductor detection to effectively detect broken or falling conductors and improve the performance of overhead distribution power lines. When an overhead power line, known as a conductor, breaks, an energized conductor falls to the ground causing a high-impedance fault and arcing, which may be difficult to detect via conventional protection elements. This may potentially cause wildfires if a protection system does not operate adequately fast. Conventional systems and methods may detect brok