Patent Application
20150212138
The present invention relates to methods for detecting open-circuit faults of power distribution line in an electric power distribution system and identifying locations of the open circuit. The invention also relates to systems for managing electric power distribution facilities.
An open-circuit fault in an electric power distribution system is likely to lead to an accident from electrical shock due to human contact with the open-circuit of the power line. It becomes vital, therefore, to detect the open-circuit fault early from a perspective of safety of the power distribution system.
An open-circuit fault in such a power distribution line, however, is difficult to detect. For example, since the distribution line is insulated, the line often fails to form an electrical path to the ground even after sagging down to the ground surface. In this case, the open-circuit fault may not be detectable since the distribution system voltage and current will remain unchanged from respective values that they exhibit under normal conditions.
For these reasons, adopting a variety of sensor-aided methods to detect open-circuit faults has been considered. The open-circuit fault detection system described in Patent Document 1, for example, includes a plurality of meters that each have a communication function, meter the amount of electrical energy supplied from a power distribution line, and include a communication unit that transmits the metered data. The system also includes a management office capable of receiving the data transmitted from the meters having a communication function. The meters are placed on the distribution line, and they, detect a voltage of the distribution line. A location of an open-circuit on the distribution line is determined from a detection result on that voltage.
Patent Document 1: JP-2007-282452-A
The art relating to Patent Document 1, however, makes it necessary to place a plurality of additional meters (sensors) an the distribution line in order to detect an open-circuit fault in the distribution line, which poses a problem of increased equipment investments in distribution facilities management. In addition, where a synchronous generator, an induction generator, and the like are interconnected in or to the distribution system, even after an open-circuit fault has occurred, voltage may not exhibit an abnormal value, in which case the open-circuit fault becomes difficult to detect.
The present invention has been made for solving the above problem, and an object of the invention is to detect an open-circuit fault in an electric power distribution line by use of metering devices (Advanced Meter Infrastructure: AMI) each having a communication function and each placed on a power consumer's circuit connected to an electric power distribution system, and identify a location of the open-circuit.
To solve the above problem, an open-circuit fault detecting method and electric power distribution facilities management system according to the present invention adopts, for example, any one of configurations set forth in CLAIMS accompanying this patent application.
The open-circuit fault detecting method according to claim 1 includes placing sensors, each provided with a communication function, on a consumer connected to an electric power distribution system, and obtaining, via a communication system, meter-reading data detected by the sensors having a communication function; the detecting method further including detecting an open-circuit in the power distribution system in accordance with an unavailable state of the meter-reading data.
In addition, the power distribution system is divided into an appropriate number of sections. The number of those sensors with a communication function each reporting unavailability of meter-reading data in a corresponding section is compared with the number of those sensors with a communication function placed in the corresponding section, thereby determining whether an open circuit has occurred in the electric power distribution system.
In addition, a number of simultaneously unavailable data due to communication trouble is retrieved and retained from a past history, and the detection of the open circuit in the power distribution system is performed when the number of those sensors with a communication function that report the data unavailability is greater than the number of simultaneously unavailable data due to communication trouble.
Furthermore, the sections of the power distribution system are changed in order, thereby successively determining for each sections whether an open circuit has occurred in the electric power distribution system.
Moreover, the unavailable state of the meter-reading data includes a state in which the amount of meter-reading data detected by at least one of the sensors having a communication function is zero.
The electric power distribution facilities management system according to claim 7 obtains, from a power distribution system to which consumers each including a sensor provided with a communication function are connected, meter-reading data within each of the sensors having a communication function, via a communication system. The power distribution facilities management system includes a, number-of-unavailable-data calculation unit that calculates a number of unavailable meter-reading data in accordance with the meter-reading data obtained from the sensors having a communication function, an on-fault number-of-unavailable-data calculation unit that calculates the number of sensors having a communication function, placed in the power distribution system, and a fault determining unit that determines whether an open-circuit fault is occurring in the power distribution system, by comparing the number of placed sensors of the on-fault number-of-unavailable-data calculation unit, and the number of unavailable data calculated by the number-of-unavailable-data calculation unit.
The power distribution facilities management system further includes a system data storage unit in which the number of sensors with a communication function, existing in the power distribution system when the power distribution system is divided into an appropriate number of sections, is stored for each of the sections; wherein the on-fault number-of-unavailable-data calculation unit accesses the system data storage unit and calculates, on a section-by-section basis, the number of sensors having a communication function, and the fault determining unit determines whether the open-circuit fault in the power distribution system is occurring, by comparing for each section the number of, sensors having a communication function, and the section-specific number of unavailable data, calculated by the number-of-unavailable-data calculation unit.
The power distribution facilities management system further includes an unavailable data storage unit that stores, from the meter-reading data obtained from the sensors with a communication function via the communication system, a number of simultaneously unavailable data due to communication trouble; wherein, when the number of unavailable data calculated by the number-of-unavailable-data calculation unit is smaller than the number of simultaneously unavailable data due to communication trouble, retained in the unavailable data storage unit, the fault determining unit withholds determining whether an open-circuit fault is occurring in the power distribution system.
In addition, the fault determining unit sends an open-circuit fault determination result to a substation that supplies electric power to the distribution system.
Furthermore, each of the sensors with a communication function is placed at an electric power consumer house connected to the distribution system, acquires meter-reading data at predetermined intervals of time, and has a function for communicating wirelessly with at least one other sensor having a communication function and existing in a predetermined region.
Furthermore, the meter-reading data is at least one of electric power consumption, a voltage value, and a current value, detected at an electric power consumer house having one of the sensors provided with a communication function.
Furthermore, meter-reading data from each of the sensors with a communication function is collected in a meter-reading data collection unit, the meter-reading data collection unit being placed in plurality for one feeder, on the power distribution system, and having a function that uses wireless communication to collect at predetermined time intervals the meter-reading data measured by the metering devices placed within a predetermined region.
Furthermore, the system data storage unit retains data about a configuration of the distribution system, data about transformers installed on the distribution system, and data about interconnection between a transformer and metering devices each connecting thereto at a downstream section of the distribution system relative to the transformer.
Moreover, the fault determining unit is configured to: compare an unavailable state of the meter-reading data measured by each of the sensors with a communication function and an unavailable state of the meter-reading data that assumes an open circuit at a suitable location on the distribution system; and when a determination index that is a rate of the two unavailable states of the meter-reading data reaches a predetermined value, determine an open circuit to have occurred in the distribution system.
Besides, the fault determining unit is configured to: compare an unavailable state of the meter-reading data measured by each of the sensors with a communication function, and an unavailable state of the meter-reading data that assumes an open circuit in a line at a suitable location on the distribution system; and when a combination of those sensors with a communication function that are involved in the former unavailable state agrees at a predetermined rate with a combination of metering devices involved in the latter unavailable state under the assumed open circuit in the line, determine an open circuit to have occurred at the assumed location.
The present invention is effective for reducing the number of meters (sensors) placed in the power distribution system, and for saving equipment investments, as well as for detecting open-circuit faults very accurately.
Hereunder, an open-circuit fault detecting method according to an embodiment of the present invention, and an electric power distribution facilities management system including the open-circuit fault detecting method will be described in detail referring to
In the present invention, sensors each having a communication function, placed on a consumer, are used to detect open circuits on power distribution lines. Each of the sensors with a communication function measures and reads the amounts of water, gas, electricity, and other utilities consumed, and then transmits meter-reading data to a host via a power distribution line or a communication route such as a wireless communication channel.
Each sensor with a communication function generally operates on electric power supplied from the power distribution line. If there is an open circuit in power distribution line, therefore, the sensor with a communication function cannot transmit the meter-reading data, which then results in the meter-reading data being unavailable at the host. The present invention uses this, mechanism to detect the open circuit in the power distribution line.
First, a functional block configuration of the present invention that relates to the detection of open circuits is described below referring to
The meter-reading data collection unit 12 is placed in plurality for one feeder, on the power distribution system, and has a function that uses wireless communication to collect at predetermined time intervals the meter-reading data measured by the metering devices placed within a predetermined region.
The communication route 20 between the metering devices 6 and the meter-reading data collection unit 12 can be a power distribution line, a wireless communication channel, or the like, and the metering device 6 and the meter-reading data collection unit 12 communicate with each other and exchange the meter-reading data with each other. Thus the meter-reading data within the metering devices 6 is delivered in order from remote metering devices 6 to nearby remote metering devices 6.
Finally the meter-reading data within all metering devices 6 is sequentially aggregated into the meter-reading data collection unit 12 and read into the open circuit detecting section 10.
The communication between each metering device 6 and the meter-reading data collection unit 12 may employ whichever of two methods as follows: a parent device (the meter-reading data collection unit 12) periodically calls a child device (the metering device 6) to collect data; or the child device transmits data at predetermined periods.
An open-circuit fault detection computing function is provided in the open circuit detecting section 10 at the host, as shown in
The meaning of the actual number of unavailable data and that of the case-based number of unavailable data will be described in further detail later. Here, the meanings of both are briefly described. The actual number of unavailable data is an actual number of metering devices 6 in which unavailable meter-reading data has occurred, and the case-based number of unavailable data is a total number of placed metering devices 6 existing in the section when a point of occurrence of an open-circuit fault is assumed.
The open-circuit fault detection computing function of the present invention will be described in further detail hereunder. The power distribution system applying the open-circuit fault detection computing function, and the communication route used are first described by way of example below.
First,
In contrast to this, the pole-mounted transformers 3 convert a high voltage into a low voltage and form a low-voltage power distribution system between the transformers 3 themselves and a consumer 5. A configuration of the low-voltage power distribution system 7b connected to the pole-mounted transformer 3b is shown as an exemplary, configuration of the system connected between the pole-mounted transformers 3 and the consumer 5. Electric power consumer 5b1 and 5b2 are connected to the low-voltage power distribution system 7b via a low-voltage power distribution line 37, and metering devices 6b1 and 6b2 are placed on the power consumer 5b1 and 5b2, respectively.
Although not shown in
An exemplary relation of connection between the pole mounted transformers and metering devices at the power distribution system is shown in
In the example of
In this configuration, the metering devices at a lowermost end of the communication route transmit meter-reading data to the metering devices located at an immediately higher level of the communication route. The metering devices that have thus received the meter-reading data place their own meter-reading data upon the received data and transmit both sets of data together to the metering devises located at an even higher level. For example, the metering device 6b2 at one of fourth-stage hop positions transmits meter reading data to the metering device 6a3 located at one of third-stage hop positions, a level higher than that of the fourth-stage hop positions. The metering device 6a3 at one of the third-stage hop positions places the meter-reading data of the metering device's own upon the meter-reading data that the metering device 6a3 has received from the metering device 6b2 of the immediately lower level, and transmits both sets of data together to the metering device 6c1 located at one of the second-stage hop positions, an even higher level. Similarly, the metering device 6c1 at one of the second-stage hop positions places the meter-reading data of the metering device's own upon the meter-reading data that the metering device 6c1 has received from the metering devices 6b2, 6a3 of the immediately lower level, and transmits both sets of data together to the metering device 6d1 located at one of the first-stage hop positions, an even higher level.
Similarly the metering device 6d1 at one of the first-stage hop positions, the highest level of the communication route, transmits both the data of the metering device's own and the data that the metering device 6d1 has received from the metering devices of lower levels, to the meter-reading data collection unit 12. More specifically, in addition to the data that the metering device 6d1 has received from the metering devices 6b2, 6a3, 6c1 of lower levels, the metering device 6d1 transmits the meter-reading data that it has received from the metering device 6c2 on a separate route, to the meter-reading data collection unit 12.
While the metering devices 6d2, 6d3 at the other first stage positions also form a multi-hop communication route in accordance with the same concept as that described above, detailed description of the data exchanges between the metering devices 6d2, 6d3 and other metering devices is omitted here since the association between these metering devices would be easily understandable from the diagram of
In this way, the wireless communication route for the metering devices in the present invention has a tree-like structure and can use multi-hop communication to collect the meter-reading data within the distribution system by transmitting meter-reading data in order from remote metering devices to the meter-reading data collection unit 12.
An example of a power distribution system configuration has been described above per
However, even when the distribution system configuration and the communication route configuration are established separately and undergo changes as appropriate, the layout relationship between pole-mounted transformers and metering devices, shown in
The transmission and reception of meter-reading data are carried out at fixed periods of time, and are repeatedly performed in line with predetermined metering cycles of time. Thus, the meter-reading data detected at the same time of day at various locations in the distribution system will be collected into the meter-reading data collection unit 12.
An example in which the meter-reading data that has been obtained every 30 minutes is listed in
Table 50 shown in
A blank box (e.g., 54) in the table means that the meter-reading data collection, unit 12 has acquired the meter-reading data measured by the metering device. A shaded box (e.g., 55), on the other hand, means that the meter-reading data collection unit 12 has failed to acquire the meter-reading data measured by the metering device (i.e., the data is unavailable).
Examples are described below referring to the communication route shown in
The meter-reading data that the metering device 6a2 “0002” measured at the time of 2:00 and 4:00, on the other hand, fails to reach the meter-reading data collection unit 12, and the meter-reading data is unavailable in the open circuit detecting section 10. Meter-reading data may also become unavailable in a plurality of metering devices in the same time zone (simultaneously unavailable).
During actual operation, however, the number-of-unavailable-data calculation unit 101 in the open circuit detecting section 10 calculates a number of unavailable meter-reading data, in line with the metering period. That is, in the present embodiment, number of unavailable meter reading data coming in at intervals of 2 minutes is computed each time the data is received. The acquisition and unavailable states of the meter-reading data measured by various metering devices can thus be confirmed.
In the present invention, the table of
The unavailability here means a state in which the data that should be obtained at predetermined time is not collected. Causes of the collecting failure exist at both of the distribution side and the communication side. Among the causes relating to the distribution side is the open circuit in the distribution line. A large portion of the metering devices 6 operate on the power supplied from the distribution system, and these devices therefore do not have other power supplies such as storage cells. For this reason, an open circuit in the distribution system interrupts the supply of power to the metering devices 6, hence rendering these devices unable to transmit data, which means that the data that should be obtained at the predetermined time is not collected into the meter-reading data collection unit 12.
If any communication trouble occurs as a cause relating to the communication side, the data that should be obtained at the predetermined time will not be collected because of receiving trouble.
States to be defined as the unavailable state preferably include a state in which the amount of electric power detection data is zero. For example, assuming that a metering device that measures electric power consumption has any other power supply such as cells, the metering device can communicate even if there is an open circuit in, the distribution system. In this case, power detection data that assigned as zero can be obtained. Accordingly, this case can also be managed.
In the present invention, the association between transformers and metering devices, shown in
First, the number-of-unavailable-data calculation unit 101 in
Next, the on-fault number-of-unavailable-data calculation unit 102 reads in predetermined system data from the system data storage unit 13 and similarly calculates the case-based number of unavailable data in each of predetermined sections. As described earlier herein, the relationship in
The present invention assumes that when a substantial number of metering devices in the section are unavailable, the open circuit is most likely to have been occurred. Under the state of 3:00 in
For these reasons, the fault determining unit 103 in
At this time, a location of the open circuit on the distribution system can also be identified by checking with the determination index values for the sections. Since the determination index ρ ranges from 0.0 to 1.0, any threshold value can be set that falls within a range of 0.0<p≦1.0.
(Numerical expression 1)
ρ=LER/LAC (1)
where LER, the numerator, is the actual number of unavailable data and LAC, the denominator, is the case-based number of unavailable data. Basically a relation of LAC≧LER exists and as can be seen from expression (1), the determination index ρ can take any value falling within a range shown in expression (2).
(Numerical expression 2)
0.0≦ρ≦1.0 (2)
In an example of the determination according to the present invention, as can be seen from expression (1), if the determination index ρ is smaller than 1.0, an open-circuit fault is determined not to be occurring, and if the determination index ρ is 1.0, then LER=LAC, in which case an open-circuit fault is determined to be occurring. Whether the fault is occurring is determined on the basis of these criteria. In a case of the graph 60, a state of determination index values 606 and 607 circle-marked with a solid line atop indicates that an open-circuit fault is occurring.
In states of determination index values 608 circle-marked with a dotted line atop, determination index values 604 and 605 lie in a 0.6 to 0.8 range and are not 1.0. Thus, this state is determined not to be an open-circuit fault, but that a plurality of unavailable data have simultaneously occurred due to communication trouble.
A criterion for fault determination based upon the determination index ρ can be set to lie in any range as in expression (3), wherein ρACC is a lower-limit value of the fault determination criterion.
(Numerical expression 3)
ρACC≦ρ≦1.0 (3)
In another example of the determination according to the present invention, although the determination index is not 1.0, when the index is a large value, open circuit at a downstream side is considered to be most likely. In other words, when the determination index ρ is calculated assuming the open circuit in the distribution line 4a in
As described above, open-circuit faults in the power distribution system can be detected by comparing, as in expression (1), the actual number of unavailable meter-reading data and the case-based number of unavailable data in each of the predetermined sections.
Next, a functional block configuration of an open-circuit fault detecting method provided in the electric power distribution facilities management system, another embodiment of the present invention, is described below referring to
The open circuit detecting section 10 in this case, as with that of the embodiment in
In addition to the system data storage unit 13 as an external database in
The meter-reading data storage unit 21, one of the external databases, stores meter-reading data that the meter-reading data collection unit 12 has collected. In addition to a configuration of the power distribution system, the system data storage unit 13 stores equipment data about distribution lines, pole-mounted transformers, switchgears, and other pieces of distribution equipment installed in the distribution system. The equipment data includes specifications, IDs, and other management numbers of the distribution equipment. Other elements of the equipment data are, for example, installation locations for the equipment, the number of years passed after installation of the equipment, and the number of years of operation of the equipment. The unavailable data storage unit 22 stores an unavailable state of past meter-reading data relating to predetermined metering devices 6.
The unavailable state stored into the unavailable data storage unit 22 refers to the actual number of unavailable data and to a combination and number of metering devices (simultaneous acquisition failure patterns) in which necessary data has become unavailable at the same time (simultaneous acquisition failures). In addition, causes of data acquisition failures are stored in two separate categories: failures due to a fault such as open circuit, and failures due to communication trouble.
The correction term computing unit 201 reads in, among all past simultaneous acquisition failure patterns stored into the unavailable data storage unit 22, only a simultaneous acquisition failure pattern maximized in the actual number of unavailable data due to communication trouble, and sets a correction term σ for the distribution system.
The correction term computing unit 201 accesses the unavailable data storage unit 22 and recognizes that the maximum number of simultaneously unavailable data caused by communication trouble in the past is eight (in other words, eight metering devices). In this case, the correction term computing unit 201 determines that although caused by communication trouble, the simultaneous unavailable data in up to eight metering devices will frequently occur, and sets the correction term σ that corrects a determination index ρ. This setting prevents the fault determining unit 103 from determining the state of simultaneous acquisition failures in not more than eight metering devices, to be due to open circuit.
If the open circuit detecting section 10 determines open circuit to have occurred, this result is output to an alarm issuance unit 202 and an open-circuit location display unit 203. The alarm issuance unit 202 is disposed in, for example, a consumer service operations office with resident service personnel, and upon receiving a determination result message “Open-circuit fault occurring” from the open circuit detecting section 10 in the distribution facilities management system, the alarm issuance unit 202 can issue an alarm and audibly inform the open-circuit fault to the service personnel. The open-circuit location display unit 203 is also disposed in the consumer service operations office or the like, and can visually inform the open-circuit fault to the service personnel. The open-circuit location display unit 203 is for example, a display of a terminal PC or cell phone or large-size monitor that connects with the distribution facilities management system.
Table 70 of
Suppose, for example, that an open-circuit fault occurred as a first open-circuit fault case in a time zone of 3:00-3:30 at the location F2 on a section of a distribution line 4C lying between pole-mounted transformers A (3a) and C (3c) in
Therefore, the acquisition of meter-reading data in the time zone of 3:00 in Table 70 of
In other words, if a plurality of meter-reading data simultaneously become unavailable in a time zone as described above, it can be determined that an open-circuit fault has occurred. In addition, as shown in Table 70, a location of the open circuit can be identified from factors such as simultaneous unavailable data pattern 704 of the metering devices, according to the metering devices and the pole mounted transformer to which the metering devices are connected.
In the present example, data is not unavailable in the metering devices 6 connected between pole-mounted transformers A (3a) and B (3b), and data is unavailable in all of the metering devices 6 connected between pole-mounted transformers C (3c), D (3d), E (3e). These results indicate that electricity is flowing through the distribution lines 4a, 4b and that electricity is not flowing through the distribution lines 4c, 4d, 4e. The location of the open circuit can therefore be identified as F2.
Next, suppose that an open-circuit fault occurred as a second open-circuit fault case in a time zone of 6:00-6:30 at the location F1 on the distribution line 4b lying upstream relative to pole-mounted transformer B (3b). In this case, electricity does not flow into pole-mounted transformer B (3b) located downstream relative to the open-circuit location F1 in the distribution system. This means that the metering devices 0004 and 0005 connected to pole-mounted transformer B (3b) do not operate and thus that meter-reading data from these metering devices cannot be acquired. Therefore, the acquisition of meter-reading data in the time zone of 6:00-6:30 in Table 70 of
Similarly, suppose that an open-circuit fault occurred as a third open-circuit fault case in the time zone of 6:00-6:30 at the location F3 on the distribution line 4e. In this case, since electricity does not flow into pole-mounted transformer E (3e) located downstream relative to the open-circuit location F3, electricity does not flow into the metering device 0013 connected to pole-mounted transformer E (3e) and this metering device fails to operate. That is to say, meter-reading data from the metering device 0013 cannot be acquired. The acquisition of meter-reading data in the time zone of 6:00-6:30 in Table 70 of
As set forth above, an open-circuit fault can be determined from the interconnection relationship between a pole-mounted transformer and metering devices connected to the pole-mounted transformer, and from certain of the meter-reading data in the metering devices being in an unavailable state, and the location of the open circuit can be identified as a result.
(Numerical expression 4)
σ=0 (N≦8)
σ=1 (N>8) (4)
A threshold value 804 of the step function is described below. The present example employs a maximum number of simultaneously unavailable metering device (maximum number of simultaneously unavailable data) due to communication trouble. In the distribution system for which the present example is intended, the maximum number of the simultaneously unavailable data, NMAX, is 8, which means that an unavailable meter-reading data due to communication trouble is likely to occur in up to eight metering devices at the same time. Therefore, the determination index in expression (1) is corrected as follows using the correction term σ to prevent the state of not more than eight simultaneous acquisition failures due to communication trouble from being erroneously determined to be an open-circuit fault:
(Numerical expression 5)
ρ=LER/LAC×σ(5)
From expressions (4) and (5), the correction term a equals 0 for not more than eight simultaneous acquisition failures.
This means that the correction term σ is corrected so that even if simultaneous acquisition failures occur in not more than eight metering devices, this state will not be determined to be an open-circuit fault. Correcting the correction term σ in this manner will prevent an event of frequent unavailable data due to communication trouble or the like, from being determined to be an open-circuit fault.
The open-circuit fault scale N, adopted as the threshold value in the present example, can be optionally set. That is, any value can be assigned on the basis of the number of simultaneously unavailable metering devices located in the distribution system or feeder of interest. Alternatively, any value may be assigned, irrespective of the number of the simultaneously unavailable metering devices.
If it is possible to reduce a likelihood that the unavailable state of meter-reading data due to communication trouble may be determined to be an open-circuit fault, the step function of the correction term σ can be any value other than 0 and 1, or alternatively can be replaced by a linear function, a quadratic function, a high-dimensional function, an exponential function, a logarithmic function, or the like.
Next, open-circuit fault detection by the open circuit detecting section 10 is described below referring to
The open-circuit fault detection process is started upon input of the meter-reading data from the metering devices to the open circuit detecting section 10, and is repeatedly performed in line with the metering period or communication period of the metering devices. The open-circuit fault detection process is performed to detect a open circuit in the distribution lines which form part of the distribution system, and identify a location of the open circuit.
Meter-reading data that the meter-reading data collection unit 12 has collected from each metering device 6 is loaded and acquired in first step S901 of the open-circuit fault detection process shown in
In step S902 following the above acquisition step, the number-of-unavailable-data calculation unit 101 computes the actual number of unavailable meter-reading data, except for the metering readings data that was acquired in step S901.
During this computation, the count of data acquisition failures is computed for each predetermined section into which the distribution system has been divided at each pole-mounted transformer. The actual number of unavailable data is computed by, for example, counting the number of unavailable data flag signals (fDATALACK=1) that are transmitted to indicate a lack of necessary data.
In step S903, system data is read in and acquired from the system data storage unit 13, one of the databases. The system data is data relating to the distribution system and the constituent elements of the distribution system. For example, the system data include the configuration of the distribution system, the installation locations for the equipment constituting the distribution system, the number of years passed after installation of the equipment, and the specifications and operation parameters of the equipment. More particularly, the system data here includes the bound data shown in Table 13 of
In step S904 following the above acquisition step, the on-fault number-of-unavailable-data calculation unit 102 computes the number of unavailable data in the particular predetermined section of the distribution system or in a previously assumed case of an open-circuit fault.
In step S905, the correction term computing unit 201 reads in and acquires the maximum number of simultaneously unavailable data in the past, NMAX, from the unavailable data storage unit 22, one of the databases.
In step S906 following the above acquisition step, the correction term computing unit 201 defines the correction term σ on the basis of the maximum number of simultaneously unavailable data, NMAX, that was loaded and acquired in step S905 (see
In step S907 following the above series of data input and processing steps, the fault determining unit 103 computes the determination index ρ in accordance with expression (5). This computation uses the actual number of unavailable data, LER, that was computed in step S902, the case-based number of unavailable data LAC, that was computed in step S904, and the correction term σ that was computed in step S906.
In step S908, the fault determining unit 103 determines whether the computed correction term σ satisfies an open-circuit fault determination criterion defined in expression (6) or (7).
(Numerical expression 6)
ρ=1.0 (6)
(Numerical expression 7)
ρACC≦ρ≦1.0 (7)
Of these expressions, expression (6) derived from the relationship between LER that is the actual number of unavailable data, and LAC that is the case-based number of unavailable data, becomes expression (8), which means that an open-circuit fault has occurred.
(Numerical expression 8)
LER=LAC (8)
The above assumes that either expression (6) or (7) is set as the open-circuit fault determination criterion.
Any value based upon expression (9) can be assigned to ρACC.
(Numerical expression 9)
0.0<ρACC<1.0 (9)
If it is determined in step S908 that expression (6) or (7) is satisfied and that an open-circuit fault has occurred, the open-circuit location display unit 203 displays a location of the open circuit in step S909 and then an alarm is issued in step S910 to notify that the open-circuit fault occurred.
Conversely if it is determined in step S908 that, expression (6) or (7) is not satisfied and that an open-circuit fault is not occurring, process control is returned to the first step of the open-circuit fault detection process and this process is resumed from steps S901, S903, and S905.
During the open-circuit fault detection process in the above-described open circuit detecting section 10, alarm issuance unit 202, and open-circuit location display unit 203, whether an open-circuit fault has occurred is determined in accordance with certain of the meter-reading data being in an unavailable state, as described above. Accordingly, the metering devices with a communication function, placed at the electric power consumer houses, can be used to detect the open circuit.
Next, the open-circuit fault determination process in the fault determining unit 103 is described below referring to
The open-circuit fault determination process is started upon input of the computed section-specific actual number of unavailable data from the number-of-unavailable-data calculation unit 101 to the fault determining unit 103, and is repeatedly performed in line with the metering period or communication period of the metering devices. The fault determination process is performed to detect an open circuit in the distribution lines which form part of the distribution system.
In step S1001, the actual number of unavailable data, LER, that the number-of-unavailable-data calculation unit 101 has computed is read in and acquired.
In step S1002, the case-based number of unavailable data, LAC, that the on-fault number-of-unavailable-data calculation unit 102 has computed is read in and acquired.
In step S1003, the correction term σ that the correction term computing unit 201 has computed is read in and acquired.
In step S1004, the determination index ρ for the particular predetermined section is computed as per expression (5).
In step S1005, it is determined whether the determination index ρ that was computed in step S1004 meets the fault determination criterion represented by expression (6) or (7).
If it is determined in step S1005 that the fault determination criterion in expression (6) or (7) is met and that an open-circuit fault has occurred, an open-circuit fault flag fLINEBREAK is set to ON (fLINEBREAK=1). The open-circuit fault flag ON signal is output to the alarm issuance unit 202 and the open-circuit location display unit 203, thereby to complete the fault determination process.
If it is determined in step S1005 that the fault determination criterion in expression (6) or (7) is not met and that an open-circuit fault is not occurring, the open-circuit fault flag fLINEBREAK is set to OFF (fLINEBREAK=0), with which the fault determination process terminates.
The above-detailed power distribution facilities management system of the present invention has much in common with a metering system that measures the amounts of electricity, gas, supply water, and/or other utilities consumed, from the meter-reading data within the sensors placed with a communication function at consumers. For this reason, for example an electrical energy consumption metering system that measures the consumption of electricity will be installed and used, along with the power distribution facilities management system, at a customer service operations office of the power company.
However, since open-circuit fault data will be actually used in the substation, not the customer service operations office, open-circuit fault detection data will be transferred to the substation and used thereat. In consideration of this, the alarm issuance unit 202 and open-circuit location display unit 203 shown in
10: Internal-open-circuit detecting section (minimum configuration) of power distribution facilities management system, 6: Metering device, 12: Meter-reading data collection unit, 13: System data storage unit, 20: Internal-open-circuit detecting section of power distribution facilities management system, 21: Meter-reading data (meter readings) storage unit, 22: Unavailable data storage unit, 101: Number-of-unavailable-data calculation unit, 102: On-fault number-of-unavailable-data calculation unit, 103: Fault determining unit, 201: Correction term computing unit, 202: Alarm issuance unit, 203: Open-circuit location display unit
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-175764 | Aug 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/069766 | 7/22/2013 | WO | 00 |
