Method for judging whether metering equipment is inaccurate, power distribution system and power distribution equipment

Abstract

A method for judging whether a metering device has mismeasured, a power distribution system, and a power distribution setting, obtaining the forward active power and reverse active power of all metering devices in the metering system, obtaining the net active power of each metering device according to the forward active power and the reverse active power, obtaining the upper and lower level connection relationship of all metering devices, and judging whether the measurement is inaccurate by comparing the relationship between the net active power of the upper level metering device and the sum of the net active power of all lower level metering devices connected to the same upper level metering device in the same time period. The present invention adopts the net active power when judging the measurement, taking both the forward active power and the reverse active power into consideration, and can cover the application when there is a power generation device in the user load, with a high accuracy rate.

Description

Technical Field

[0001] The invention relates to the field of low-voltage power distribution, and in particular to a method for judging whether a metering device has mismeasured, a power distribution system and a power distribution device. Background Art

[0002] The electric energy meter plays an important role in the power work, and the normal operation of the electric energy meter is directly related to the power enterprises and users. At present, the metering system connected to the distribution network is judged by the relationship between the positive active energy of the upper and lower metering equipment. For example, in a metering box, when the positive active energy of the circuit breaker before the meter is equal to the sum of the positive active energy of all the electric energy meters in the metering box (not absolutely equal, but within the specified error range), that is, Figure 3 As shown, the positive active electric energy s1 of the circuit breaker before the meter is equal to the sum of the positive active electric energy of the electric energy meter a1 to the electric energy meter an [Es1+=(Ea1+)+…(Ean+)], and it is judged that there is no metering inaccuracy problem in the metering box.

[0003] However, this judgment method is only applicable when the power flow of each branch in the meter box is from the grid side to the user side. When the user selects power generation equipment (such as photovoltaic power generation equipment), Figure 4 As shown in the figure, at this time, the positive active energy of some electric energy meters in the meter box has two sources, one is from the circuit breaker in front of the meter, and the other is from the power generation equipment in other branches. The positive active energy of this part of the electric energy meter is Ean+, and ΔE is used to represent the energy from other branches. The positive active energy of the circuit breaker in front of the meter in the meter box is still Es1+, and the sum of the positive active energy of all electric energy meters connected to the circuit breaker in front of the meter is (Ea1+)+…(Ean+), and the positive active energy from the circuit breaker in front of the meter is (Ea1+)+…(Ean+). The positive active electric energy flowing from the circuit breaker to the electric energy meter is [(Ea1+)+…(Ean+)-(ΔE)]=Es1+. However, when there is a power generation equipment, since ΔE≠0, [(Ea1+)+…(Ean+)-(ΔE)]≠Es1+. At this time, although the metering system is still operating normally, it has been judged to be inaccurate according to the judgment condition of the positive active electric energy. It can be seen that relying solely on the positive active electric energy as the judgment condition can no longer meet the actual production application. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method, a power distribution system and a power distribution device for judging whether a metering device is mismeasured, which has a wide coverage and is applicable to power generation equipment.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for judging whether a metering device has mismeasured measurement, comprising obtaining the forward active power and the reverse active power of all metering devices in a metering system, obtaining the net active power of each metering device according to the forward active power and the reverse active power, obtaining the upper and lower level connection relationship of all metering devices, and judging whether the measurement is mismeasured by comparing the relationship between the net active power of an upper level metering device and the sum of the net active power of all lower level metering devices connected to the same upper level metering device within the same time period.

[0007] Preferably, when the difference between the net active power of the upper-level metering device and the sum of the net active power of all the lower-level metering devices connected to the same upper-level metering device is less than or equal to an error threshold, it indicates that there is no metering mismatch between the two adjacent metering devices; when the difference between the net active power of the upper-level metering device and the sum of the net active power of all the lower-level metering devices connected to the same upper-level metering device is greater than the error threshold, it indicates that there is a metering mismatch between the two adjacent metering devices.

[0008] Preferably, the metering system includes at least two branch metering systems. When the branch metering system includes at least two levels of metering equipment, each adjacent two levels of metering equipment are divided into a metering group step by step, and each metering group is judged whether it is an inaccurate metering group.

[0009] When a branch metering system has only one inaccurate metering group, it means that the fault level is located at the next level in the inaccurate metering group;

[0010] When there are two consecutive misaligned metering groups in a branch metering system, it means that the common level of the upper misaligned metering group and the lower misaligned metering group in the two consecutive misaligned metering groups is the fault level;

[0011] When there are three or more consecutive misaligned metering groups in a branch metering system, it means that all common levels of the three or more misaligned metering groups are fault levels.

[0012] Preferably, when the common level of the upper inaccurate metering group and the lower inaccurate metering group is the fault level, any metering device in the fault level is selected in turn as the device to be tested, and the sum of the net active energy of all the next-level metering devices connected to the device to be tested is used as the replacement net active energy and the net active energy of other non-devices to be tested in the fault level are substituted into the upper inaccurate metering group together, and a secondary judgment is made on the upper inaccurate metering group according to the net active energy relationship between the two adjacent levels of metering devices;

[0013] When the upper inaccurate metering group is no longer inaccurate during the secondary judgment process, it indicates that the device under test in the fault level is an inaccurate metering device.

[0014] Preferably, when there is only one misaligned metering group or there are three or more consecutive misaligned metering groups, it is necessary to manually determine the position of the misaligned metering device within the fault level.

[0015] Preferably, the data of all metering devices are frozen at the same time, and the forward active power, reverse active power and net active power of each metering device are metered in the form of frozen records.

[0016] Preferably, the frozen records are read periodically to obtain the electric energy metering status of the metering device, and the electric energy increment of one cycle is obtained by the difference between two frozen records.

[0017] Preferably, time calibration is performed on each metering device periodically through broadcasting.

[0018] A power distribution system includes a control system and a multi-level metering system connected to a power distribution network, wherein the multi-level metering system is electrically connected to a multi-level metering device, and the control system determines whether the metering system is inaccurate by using the method for determining whether the metering device is inaccurate as described above.

[0019] A power distribution device comprises a processor and a memory storing a computer program, wherein the processor executes the computer program to implement the above-mentioned method for determining whether a metering device has metering inaccuracy.

[0020] Compared with the method of relying solely on positive active electric energy for judgment, the present invention adopts net active electric energy when judging whether the measurement is inaccurate, taking both positive active electric energy and reverse active electric energy into consideration, and can cover the application when there is power generation equipment in the user load, with a higher accuracy rate.

[0021] In addition, by comparing the net active power of two adjacent metering devices, the location of the inaccurate metering device can be determined, which helps to accurately obtain the inaccurate location of the metering device and facilitates replacement by staff.

[0022] In addition, by freezing the data acquisition data of all metering devices at the same time, periodically acquiring the electric energy increment and judging whether metering misalignment occurs, metering misalignment can be discovered in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a method for judging whether a metering device is mismeasured according to the present invention;

[0024] Figure 2 It is a structural schematic diagram of a method for judging whether a metering device is mismeasured according to the present invention;

[0025] Figure 3-4 It is a schematic diagram of using positive active electric energy to judge whether there is inaccuracy in the background technology. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1 to 2 The given embodiments further illustrate the specific implementation methods of the method for determining whether a metering device is inaccurate, the power distribution system and the power distribution device of the present invention. The method for determining whether a metering device is inaccurate, the power distribution system and the power distribution device of the present invention are not limited to the description of the following embodiments.

[0027] A method for judging whether a metering device has mismeasured measurement, comprising obtaining the forward active power and the reverse active power of all metering devices in a metering system, obtaining the net active power of each metering device according to the forward active power and the reverse active power, obtaining the upper and lower level connection relationship of all metering devices, and judging whether the measurement is mismeasured by comparing the relationship between the net active power of an upper level metering device and the sum of the net active power of all lower level metering devices connected to the same upper level metering device within the same time period.

[0028] Compared with the method of relying solely on positive active electric energy for judgment, the present invention adopts net active electric energy when judging whether the measurement is inaccurate, taking both positive active electric energy and reverse active electric energy into consideration, and can cover the application when there is power generation equipment in the user load, with a higher accuracy rate.

[0029] The metering system usually includes at least two or more branch metering systems, that is, in the entire metering system, when there are at least two primary metering devices, each primary metering device is divided into at least two branch metering systems, and all metering devices connected to the same primary metering device are divided into the same branch metering system from top to bottom; when there is only one primary metering device, at least two secondary metering devices connected to the primary metering device are divided into at least two branch metering systems, and so on, the metering system can be divided into at least two branch metering systems, each branch metering system includes at least two levels of metering devices, and each adjacent two levels of metering devices are divided into a metering group from top to bottom, and the relationship between the net active power of the upper and lower level metering devices in each metering group is compared to determine whether the metering group is inaccurate.

[0030] In each metering group, the relationship between the net active electric energy between the metering devices of two adjacent levels is compared. When the net active electric energy of the metering device of the upper level is equal to the sum of the net active electric energy of all the metering devices of the lower level connected to the same metering device of the upper level, that is, the difference between the two is less than or equal to the error threshold (not absolutely equal, but only refers to the equality of the error within the allowable range), it indicates that there is no metering mismatch between the two adjacent metering devices, that is, there is no mismatch in the metering group; when the net active electric energy of the metering device of the upper level is not equal to the sum of the net active electric energy of all the metering devices of the lower level connected to the same metering device of the upper level, that is, the difference between the two is greater than the error threshold (referring to the error exceeding the allowable range), it indicates that there is a metering mismatch between the two adjacent metering devices, and the metering group is an inaccurate metering group.

[0031] When there are inaccurate metering groups in a branch metering system, the fault level and the location of the inaccurate metering equipment can be determined based on the number and location of the inaccurate metering groups. The specific process is as follows:

[0032] When all branch metering systems include primary metering equipment and secondary metering equipment connected to the primary metering equipment, all branch metering systems are divided into a metering group. When the metering group is misaligned, manual inspection is required to determine the specific misalignment location. Since the primary metering equipment is usually inspected regularly, the possibility of metering misalignment is small, so the fault level is usually located in the secondary metering equipment, and manual inspection is required to determine the specific misalignment location.

[0033] When there are only third-level metering devices in all branch metering systems, the branch metering systems are divided into two metering groups, upper and lower. When only the lower metering group is inaccurate, since the upper metering group is not inaccurate, it means that the first-level metering devices and the second-level metering devices are normal. Therefore, the fault level is the third-level metering device, and manual inspection is required to determine the location of the specific inaccurate metering device; when both the upper and lower metering groups are inaccurate, it means that the fault level may occur in the two second-level devices, or there are inaccurate metering devices in both the second-level metering devices and the third-level metering devices. Since it is impossible to accurately determine the location of the fault level, manual inspection is required to determine the specific inaccurate location.

[0034] When there are four or more levels of metering equipment in a branch metering system, this is the main situation targeted by the improvement of this application, which can improve the efficiency of determining the location of the fault level and find the inaccurate metering equipment. Each branch metering system is divided into multiple metering groups step by step. When there is only one inaccurate metering group in a branch metering system, it means that the inaccurate metering group is located in the first metering group or the last metering group of the branch metering system. The possibility of inaccuracy of the first-level metering equipment is low. Usually, the inaccurate metering group is the last metering group. The fault level is located at the next level of the inaccurate metering group, that is, the last level of metering equipment in the branch metering system. Manual inspection is required to determine the specific location.

[0035] When there are two consecutive inaccurate metering groups in a branch metering system, it means that the inaccurate metering group is located in the middle position of the branch metering system. The metering group at the upper level of the two consecutive inaccurate metering groups is the upper inaccurate metering group, and the metering group at the lower level is the lower inaccurate metering group. At this time, the common level of the upper inaccurate metering group and the lower inaccurate metering group is the fault level. If there is only a single inaccurate metering device in the fault level, any metering device can be selected in the fault level as the device to be tested, and the sum of the net active energy of all the next-level metering devices connected to the device to be tested is used as the replacement net active energy and the net active energy of other non-devices to be tested in the fault level are substituted into the upper inaccurate metering group. According to the net active energy relationship between the two adjacent metering devices, the upper inaccurate metering group is secondary judged to determine the position of the inaccurate metering device. The secondary judgment requires replacing the metering devices in the fault level one by one. Therefore, the upper inaccurate metering group needs to be secondary judged multiple times until the upper inaccurate metering group is no longer inaccurate during the secondary judgment process, which indicates that the device to be tested in the fault level is an inaccurate metering device. In addition, when there are two or more misaligned metering devices in the fault stage, it is preferred to determine the specific locations through manual detection or other means.

[0036] When there are three or more consecutive misaligned metering groups in a branch metering system, it means that all common levels of the three or more misaligned metering groups are fault levels, which means that there are multiple misaligned metering devices in the branch metering system. It is preferred to determine the misaligned metering devices through manual detection or other methods.

[0037] In practical applications, a branch metering system usually includes multiple branches. The number of metering equipment levels in each branch may be different. The metering equipment of the entire branch metering system is divided into multiple metering groups from top to bottom. The longest branch has the largest number of metering groups, and the number of metering groups of the shortest branch can be one, two, three or more. However, the metering groups of the longest branch are divided in the same way as the metering groups of other branches, and there is no misalignment. Therefore, it can be used in combination with the above situation.

[0038] Combination Figure 1 An embodiment is provided, in which a multi-level metering system is connected to one side of the distribution network, and a multi-level metering device is electrically connected to the multi-level metering system. Figure 1 In the process, the incoming main switch is used as the primary metering device, and the net active energy of the primary metering device is recorded as E 总, a plurality of distribution switches are connected in parallel to the primary metering device, namely distribution switch 1, distribution switch 2...distribution switch n, and the distribution switches serve as secondary metering devices, and the net active energy of the secondary metering devices is recorded as E1, E2...En; a plurality of branch switches are connected in parallel to one of the distribution switches (distribution switch 1 in the figure) as tertiary metering devices, namely branch switch 1-1, branch switch 1-2...branch switch 1-n, and the net active energy of the tertiary metering devices is recorded as E1-1, E1-2...E1-n; a plurality of meter box incoming line switches are connected in parallel to one of the branch switches (branch switch 1-1 in the figure), namely meter box incoming line switch 2-1-1, meter box incoming line switch 2-1-2...meter box incoming line switch 2-1-n. The meter box incoming line switch is used as a fourth-level metering device, and the net active electric energy of the fourth-level metering device is recorded as E2-1-1, E2-1-2...E2-1-n; on one of the meter box incoming line switches (the meter box incoming line switch 2-1-1 in the figure), multiple meter box electric energy meters are connected as fifth-level metering devices, namely meter box electric energy meter 3-1-1, meter box electric energy meter 3-1-2 and meter box electric energy meter 3-1-n, and the net active electric energy of the fifth-level metering device is recorded as E3-1-1, E3-1-2...E3-1-n; the fusion terminal, concentrator or operation and procurement main station obtains the electrical parameters and electric energy data of the incoming line main switch through sensors. The fusion terminal, concentrator or operation and procurement main station can also communicate with each metering device in the substation to obtain the data and status of each metering device. The fusion terminal, concentrator or operation and procurement master station stores the upper and lower connection relationship of all metering devices. The fusion terminal, concentrator or operation and procurement master station periodically obtains the forward active power, reverse active power and net active power of all metering devices. It is preferred that the fusion terminal, concentrator or operation and procurement master station calibrates the time of each metering device in the substation area through broadcasting every day to ensure the timing consistency of each metering device. Each metering device in the substation area freezes data at zero o'clock every day according to its own clock, obtains forward active power, reverse active power and net active power and records data in the form of frozen measurement, and obtains the daily increment of electric energy through the difference between the frozen measurements of two consecutive days.

[0039] When the fusion terminal, concentrator or operation and procurement master station divides each adjacent two-level metering device into a metering group step by step according to the acquired data records, the relationship between the net active electric energy between the adjacent two-level metering devices is compared step by step, that is, the relationship between the net active electric energy of the two-level metering devices in the metering group is compared. In the process of judging the metering group, the electric energy belongs to the daily increment of electric energy in the same time period, rather than the absolute value of the electric energy. When the net active electric energy of the upper-level metering device is equal to the sum of the net active electric energy of all the lower-level metering devices connected to the same upper-level metering device, that is, when the difference between the two is less than or equal to the error threshold (not absolutely equal, but only refers to the equality of the error within the allowable range), it means that there is no metering inaccuracy between the adjacent two-level metering devices, that is, when E 总 =E1+E2+…+En, it means that there is no metering mismatch between the primary metering device and the secondary metering device. Similarly, when E1=E1-1+E1-2+…+E1-n, it means that there is no metering mismatch between the secondary metering device and the tertiary metering device. When the net active energy of the upper metering device is not equal to the sum of the net active energy of all the lower metering devices connected to the same upper metering device, that is, when the difference between the two is greater than the error threshold (the error is beyond the allowable range), it means that there is a metering mismatch between the adjacent two metering devices, that is, when E 总 ≠E1+E2+…+En, it indicates that there is measurement inaccuracy in the primary and secondary measuring equipment.

[0040] After determining that there is misalignment in two adjacent metering devices, the position of the misaligned metering device can be further determined according to the misalignment. In this embodiment, there is only one primary metering device, so the branch metering system is divided according to the secondary metering device connected to the primary metering device, and there are n branch metering systems, wherein all metering devices connected to the distribution switch 1 and the primary metering device constitute the first branch metering system, and the first branch metering system is divided into metering groups step by step from the primary metering device to the fifth metering device, wherein the primary metering device and the secondary metering device are the first metering group, the secondary metering device and the third metering device are the second metering group, the third metering device and the fourth metering device are the third metering group, and the fourth metering device and the fifth metering device are the fourth metering group; correspondingly, other branch systems are also divided into multiple metering groups.

[0041] This embodiment takes the inaccurate measurement of the first three-level metering device as an example. When the fusion terminal, concentrator or operation and procurement master station obtains the frozen record, the relationship between the net active power between the two adjacent metering devices is compared step by step according to the data. At this time, there is no inaccuracy in the first metering group and the fourth metering group. 总=E1+E2+…+En, indicating that there is no measurement inaccuracy in the first-level metering equipment and the second-level metering equipment. In the fourth metering group, E2-1-1=E3-1-1+E3-1-2+…+E3-1-n, indicating that there is no measurement inaccuracy in the fourth-level metering equipment and the fifth-level metering equipment. Since the measurement inaccuracy occurs in the third-level metering equipment, the second and third metering groups are both inaccurate. At this time, E1≠E1-1+E1-2+…+E1-n in the second metering group, indicating that the second-level metering equipment and the third-level metering equipment are There is a measurement inaccuracy in the measuring equipment. In the third measurement group, E1-1≠(E2-1-1)+(E2-1-2)+…+(E2-1-n), which means that there is a measurement inaccuracy in the tertiary and quaternary measuring equipment. It can be seen from the first and fourth measurement groups that the primary, secondary, fourth and fifth measurement equipment are normal, and the third measurement equipment, as the common level of the second and third measurement groups, can affect the two measurement groups. Therefore, the fault level is the level where the third measurement equipment is located.

[0042] Subsequently, the specific location of a single inaccurate metering device is obtained by performing a secondary judgment on the upper inaccurate metering group. In this embodiment, the upper inaccurate metering group is the second metering group, and the lower inaccurate metering group is the third metering group. When performing a secondary judgment on the upper inaccurate metering group, the first three-level metering device in the fault level is selected as the device to be tested, and the sum of the net active energy of all the four-level metering devices connected to the device to be tested is used as the replacement net active energy. The replacement net active energy and the net active energy of other non-tested devices are substituted into the second metering group. At this time, the relationship between the net active energy of the upper and lower metering devices in the second metering group is judged. When the second metering group is no longer inaccurate during the secondary judgment process, it means that the device to be tested in the fault level (i.e., the first three-level metering device) is an inaccurate metering device. At this time, in the second metering group, E1=(E2-1-1)+(E2-1-2)+…+(E2-1-n)+E1-2+…+E1-n.

[0043] Of course, if the second metering device in the three-level metering device is inaccurate, first only the first three-level metering device is replaced as the device to be tested, and then the first secondary judgment is performed on the second metering group. At this time, E1≠(E2-1-1)+(E2-1-2)+…+(E2-1-n)+E1-2+…+E1-n in the second metering group is not established; then only the second three-level metering device is replaced as the device to be tested, and then the second secondary judgment is performed on the second metering group. When the net active energy equation in the second metering group is within the error threshold range, it means that the second metering device in the three-level metering device is inaccurate. Similarly, by gradually replacing all metering devices in all fault levels until the second metering group is no longer inaccurate, the specific location of the inaccuracy of a single metering device in the fault level can be determined.

[0044] It should be noted that this method is applicable to a single metering inaccuracy problem in the metering system. When there are multiple inaccurate metering devices in the fault level, their locations cannot be accurately determined through secondary judgment, and manual inspection is required to determine them.

[0045] Combination Figure 1 It can be seen that when there is only one inaccurate metering group, the inaccurate metering group is the fourth metering group. At this time, the relationship between the net active energy between the first-level metering device and the second-level metering device, the second-level metering device and the third-level metering device, and the third-level metering device and the fourth-level metering device satisfies E 总 =E1+E2+…+En, E1=E1-1+E1-2+…+E1-n, E1-1=(E2-1-1)+(E2-1-2)+…+(E2-1-n), however, the relationship between the net active energy between the fourth-level metering equipment and the fifth-level metering equipment is E1-1≠(E2-1-1)+(E2-1-2)+…+(E2-1-n), since there is no metering inaccuracy in the third-level metering equipment and the fourth-level metering equipment, the metering inaccuracy can only exist in the fifth-level metering equipment, but since the fifth-level metering equipment is the last level, it is impossible to make a secondary judgment. At this time, it is necessary to manually check one by one on site to determine the location of the inaccurate metering equipment. Similarly, when the last-level metering equipment in each branch of the branch metering system fails, manual inspection is also required to determine the specific location.

[0046] Combination Figure 1 It can be seen that when there are three or more consecutive inaccurate metering groups, for example, the second, third and fourth metering groups are all inaccurate, since the first metering group is not inaccurate, it means that the first-level metering equipment and the second-level metering equipment are operating normally, so the fault level must be located in the common level of the second metering group, the third metering group and the fourth metering group, that is, there must be inaccurate metering equipment in the third-level metering equipment and the fourth-level metering equipment. At the same time, in this embodiment, the fourth metering group is the last metering group, and it is impossible to determine whether the fifth-level metering equipment is inaccurate. Due to the existence of multiple fault levels and the inability to determine whether the last level is inaccurate, manual on-site investigation is required.

[0047] In addition, it should be noted that the error threshold of each branch metering system is not consistent. The closer to the top level, the greater the daily increase in electric energy, so the error threshold of the judgment is also larger. The closer to the bottom level, the smaller the daily increase in electric energy, and the corresponding error of the judgment is also smaller. Configuration adjustment is required according to the actual electricity consumption on site.

[0048] The principle that this method is applicable to users using power generation devices is as follows:

[0049] For example, a circuit breaker and two electric energy meters are installed in the meter box. Figure 2As shown, the circuit breaker before the meter is denoted as S1, two electric energy meters are connected in parallel to the circuit breaker before the meter, denoted as a1 and a2 respectively, and the user loads connected to the two electric energy meters are denoted as U1 and U2 respectively. There are electrical equipment and power generation equipment in the user load U1 and the user load U2.

[0050] Among them, the forward active energy of the circuit breaker s1 before the meter is Es1+, the reverse active energy is Es1-, and the net active energy is Es1; the forward active energy of the energy meter a1 is Ea1+, the reverse active energy is Ea1-, the net active energy is Ea1, and the energy flowing from the energy meter a1 to the energy meter a2 is ΔE1; the forward active energy of the energy meter a2 is Ea2+, the reverse active energy is Ea2-, the net active energy is Ea2, and the energy flowing from the energy meter a2 to the energy meter a1 is ΔE2.

[0051] like Figure 2 As shown, the positive active energy Ea1+ of the energy meter a1 consists of two parts, one part is ΔE2, and the other part comes from the circuit breaker before the meter. The energy from the circuit breaker before the meter is (Ea1+)-ΔE2;

[0052] The positive active energy Ea2+ of the energy meter a2 consists of two parts, one is ΔE1, and the other comes from the circuit breaker before the meter. The energy from the circuit breaker before the meter is (Ea2+)-ΔE1;

[0053] The positive active energy Es1+ of the circuit breaker before the meter and the energy meter a1 and energy meter a2 satisfy the following formula:

[0054] Es 1+=(Ea1+)-ΔE2+(Ea2+)-ΔE1①;

[0055] The reverse active electric energy Ea1- of the electric energy meter a1 flows to two parts, one part is ΔE1, and the other part flows to the circuit breaker before the meter. The electric energy flowing to the circuit breaker before the meter is (Ea1-)-ΔE1;

[0056] The reverse active electric energy Ea2- of the electric energy meter a2 flows to two parts, one part is ΔE2, and the other part flows to the circuit breaker before the meter. The electric energy flowing to the circuit breaker before the meter is (Ea2-)-ΔE2;

[0057] The reverse active energy Es1- of the circuit breaker before the meter and the energy meter a1 and energy meter a2 satisfy the following formula:

[0058] Es1-=(Ea1-)-ΔE1+(Ea2-)-ΔE2②;

[0059] According to the expression of net active energy: net active energy = positive active energy - negative active energy, we can know that

[0060] Es1=(Es1+)-(Es1-)③;

[0061] Substituting formula (1) (2) into formula (3),

[0062] Es1=(Ea1+)-ΔE2+(Ea2+)-ΔE1-(Ea1-)+ΔE1-(Ea2-)+ΔE2

[0063] =(Ea1+)+(Ea2+)-(Ea1-)-(Ea2-)

[0064] =[(Ea1+)-(Ea1-)]+[(Ea2+)-(Ea2-)]④;

[0065] According to the expression of net active energy, in formula (4), Ea1 = [(Ea1+) - (Ea1-)], Ea2 = [(Ea2+) - (Ea2-)],

[0066] Therefore, Es1=Ea1+Ea2.

[0067] When expanded to n devices in parallel (i.e., energy meter a1, energy meter a2...energy meter an), the forward active energy of the circuit breaker s1 before the meter is Es1+, the reverse active energy is Es1-, and the net active energy is Es1; the forward active energy of the energy meter a1 is Ea1+, the reverse active energy is Ea1-, and the net active energy is Ea1; the forward active energy of the energy meter a2 is Ea2+, the reverse active energy is Ea2-, and the net active energy is Ea2. The forward active energy of the energy meter an is Ean+, the reverse active energy is Ean-, and the net active energy is Ean; ΔE1n represents the energy flowing from Ea1- to Ean+; ΔEn1 represents the energy flowing from Ean- to Ea1+.

[0068] Ea1+ is composed of n parts, one part comes from Es1+, and the other (n-1) parts come from ΔE21…ΔEn1. Therefore, the part of Ea1+ coming from Es1+ can be expressed as: (Ea1+)-ΔE21-…-ΔEn1;

[0069] Similarly,

[0070] The part of Ean+ coming from Es1+ can be expressed as: (Ean+)-ΔE1n-…-ΔE(n-1)n;

[0071] Es1+ is composed of the above n parts, so Es1+ can be expressed as:

[0072] Es1+=[(Ea1+)-ΔE21-…-ΔEn1]+…+[(Ean+)-ΔE1n-…-ΔE(n-1)n]⑤;

[0073] In formula ⑤, there are n positive terms: Ea1+, Ea2+,…,Ean+.

[0074] There are n(n-1) negative items, recorded in the following table (Table 1):

[0075] / ΔE21 … ΔE(n-1)1 ΔEn1 ΔE12 / … ΔE(n-1)2 ΔEn2 … … … … ΔE1(n-1) ΔE2(n-1) … / ΔEn(n-1) ΔE1n ΔE2n … ΔE(n-1)n /

[0076] Ea1- is divided into n parts and flows in n directions, one part flows to Es1-, and the other (n-1) parts flow to ΔE12…ΔE1n respectively. The part of Ea1- flowing to Es1- can be expressed as: (Ea1-)-ΔE12-…-ΔE1n;

[0077] Similarly,

[0078] The part of Ean- flowing to Es1- can be expressed as: (Ean-)-ΔEn1-…-ΔEn(n-1);

[0079] Es1- is composed of the above n parts, so Es1- can be expressed as:

[0080] Es1-=[(Ea1-)-ΔE12-…-ΔE1n]+…+[(Ean-)-ΔEn1-…

[0081] -ΔEn(n-1)]⑥;

[0082] In formula ⑥, there are n positive terms: Ea1-, Ea2-,…,Ean-.

[0083] There are n(n-1) negative items, recorded in the following table (Table 2):

[0084] / ΔE12 … ΔE1(n-1) ΔE1n ΔE21 / … ΔE2(n-1) ΔE2n … … … … ΔE(n-1)1 ΔE(n-1)2 … / ΔE(n-1)n ΔEn1 ΔEn2 … ΔEn(n-1) /

[0085] By comparison, it can be seen that each negative term in Table 1 corresponds to each negative term in Table 2 one by one and the magnitudes are equal, so the sum of all negative terms is recorded as ΔE.

[0086] Therefore, formula ⑤ can be simplified to: Es1+=(Ea1+)+…+(Ean+)-ΔE ⑦;

[0087] Formula ⑥ can be simplified as: Es1-=(Ea1-)+…+(Ean-)-ΔE ⑧;

[0088] Combining formula ⑦⑧ and the expression of net active energy: net active energy = forward active energy - reverse active energy, we can know that:

[0089] Es1=(Es1+)-(Es1-)

[0090] =(Ea1+)+…+(Ean+)-ΔE-(Ea1-)-…-(Ean-)+ΔE

[0091] =[(Ea1+)-(Ea1-)]+…+[(Ean+)-(Ean-)]

[0092] That is, Es1=Ea1+…+Ean⑨.

[0093] The present invention is applicable to the case where the user load does not include power generation equipment as follows:

[0094] When the user load does not include power generation equipment, but only power consumption equipment, then Es1-=Ea1-=Ea2-=……=Ean=ΔEn=0, and formula ⑤ is simplified to the following formula:

[0095] Es1+=(Ea1+)+(Ea2+)+……+(Ean+)

[0096] In formula 9, subtract 0 from both sides of the equation to get:

[0097] Es1+-0=(Ea1+)-0+(Ea2+)-0+……+(Ean+)-0

[0098] Es1=Ea1+Ea2+……+Ean。

[0099] It can be seen that the method can be applied to environments where the user load includes or does not include power generation equipment, and has a wide range of applications.

[0100] The present invention also provides a power distribution system, including a control system and a multi-level metering system connected to a distribution network, wherein the multi-level metering system is electrically connected to a multi-level metering device, and the control system determines whether the metering system is inaccurate by using the method of determining whether the metering device is inaccurate according to the present invention. In the present application, the control system is a fusion terminal, a concentrator or an operation and procurement master station.

[0101] The present invention further provides a power distribution device, comprising a processor and a memory storing a computer program, wherein the processor executes the computer program to implement the method of the present invention for determining whether a metering device has metering mismatch.

[0102] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for determining whether a measuring device is inaccurate, characterized in that: The forward active energy and reverse active energy of all metering devices in the metering system are obtained, the net active energy of each metering device is obtained according to the forward active energy and the reverse active energy, the upper and lower connection relationship of all metering devices is obtained, and whether the metering is inaccurate is determined by comparing the relationship between the net active energy of the upper-level metering device and the sum of the net active energy of all lower-level metering devices connected to the same upper-level metering device in the same time period; when the difference between the net active energy of the upper-level metering device and the sum of the net active energy of all lower-level metering devices connected to the same upper-level metering device is less than or equal to an error threshold, it indicates that no metering inaccuracy occurs in the two adjacent metering devices; when the difference between the net active energy of the upper-level metering device and the sum of the net active energy of all lower-level metering devices connected to the same upper-level metering device is greater than the error threshold, it indicates that metering inaccuracy occurs in the two adjacent metering devices.

2. A method for determining whether a measuring device is inaccurate in measurement according to claim 1, characterized in that: The metering system includes at least two branch metering systems. When the branch metering system includes at least two levels of metering equipment, each adjacent two levels of metering equipment are divided into a metering group step by step, and each metering group is judged whether it is an inaccurate metering group. When a branch metering system has only one inaccurate metering group, it means that the fault level is located at the next level in the inaccurate metering group; When there are two consecutive misaligned metering groups in a branch metering system, it means that the common level of the upper misaligned metering group and the lower misaligned metering group in the two consecutive misaligned metering groups is the fault level; When there are three or more consecutive misaligned metering groups in a branch metering system, it means that all common levels of the three or more misaligned metering groups are fault levels.

3. A method for determining whether a measuring device is inaccurate in measurement according to claim 2, characterized in that: When the common level of the upper inaccurate metering group and the lower inaccurate metering group is the fault level, any metering device in the fault level is selected in turn as the device to be tested, and the sum of the net active energy of all the next-level metering devices connected to the device to be tested is used as the replacement net active energy and the net active energy of other non-devices to be tested in the fault level are substituted into the upper inaccurate metering group. According to the net active energy relationship between the two adjacent metering devices, a secondary judgment is made on the upper inaccurate metering group; When the upper inaccurate metering group is no longer inaccurate during the secondary judgment process, it indicates that the device under test in the fault level is an inaccurate metering device.

4. A method for determining whether a measuring device is inaccurate in measurement according to claim 2, characterized in that: When there is only one misaligned metering group or there are three or more consecutive misaligned metering groups, it is necessary to manually determine the position of the misaligned metering device within the fault level.

5. The method for determining whether a measuring device is inaccurate in measurement according to claim 1, characterized in that: The data of all metering devices are frozen at the same time, and the forward active energy, reverse active energy and net active energy of each metering device are measured in the form of frozen records.

6. A method for determining whether a measuring device is inaccurate in measurement according to claim 5, characterized in that: The frozen records are read periodically to obtain the electric energy measurement status of the metering device, and the electric energy increment of one cycle is obtained by the difference between two frozen records.

7. A method for determining whether a measuring device is inaccurate in measurement according to claim 1, characterized in that: The time of each metering device is calibrated regularly through broadcasting.

8. A power distribution system, comprising a control system and a multi-level metering system connected to a distribution network, wherein the multi-level metering system is electrically connected to a multi-level metering device, characterized in that: The control system determines whether there is an inaccuracy in the metering system by using the method for determining whether the metering device is inaccurate as described in any one of claims 1 to 7.

9. A power distribution device comprising a processor and a memory storing a computer program, characterized in that: The processor executes the computer program to implement the method for determining whether a measuring device is mismeasured as described in any one of claims 1 to 7.

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