A post-stage detection circuit applied to a single-phase three-wire electric meter and the single-phase three-wire electric meter

Abstract

The application relates to a post-stage detection circuit applied to a single-phase three-wire electric meter, which specifically comprises a first diode and a second diode, the positive pole of the first diode is electrically connected with a first fire wire, the negative pole is electrically connected with a second fire wire, the positive pole of the second diode is electrically connected with the second fire wire, and the negative pole is electrically connected with the first fire wire; the positive pole of the first diode is electrically connected with the negative pole of the second diode; the two poles of the first diode are provided with a reverse first optocoupler circuit, the two poles of the second diode are provided with a reverse second optocoupler circuit, and the first optocoupler circuit and the second optocoupler circuit both have a conduction state output end. The post-stage detection circuit applied to the single-phase three-wire electric meter and the single-phase three-wire electric meter of the application can complete the state detection of the relay post stage without introducing a zero line, can judge electricity stealing events, and have simple overall structures and low production and installation costs.

Description

Technical Field

[0001] This invention belongs to the field of smart meter technology, specifically relating to a post-detection circuit for a single-phase three-wire meter and the single-phase three-wire meter itself. Background Technology

[0002] Currently, smart meters with relays in the field incorporate a relay-based detection function to prevent users from maliciously jumping wires to steal electricity when the relay trips. If such a jump-wire theft occurs, the detection circuit sends an abnormal signal to the meter's main controller, which then identifies and reports the event. Furthermore, this scenario detection prevents short circuits caused by different phase voltages after the circuit breaker is closed, thus protecting electrical equipment.

[0003] Since single-phase three-wire energy meters are powered by two live wires, the neutral wire normally does not need to be connected to the meter. However, in existing technology, to accurately detect the status of downstream circuitry, the neutral wire is introduced into the meter. This downstream status detection in single-phase three-wire meters presents a problem: the need to introduce a neutral wire for circuit reference increases costs. Different meters have different structural designs; to implement neutral wire integration, not only is an additional neutral terminal required, but the PCB layout of the circuit hardware also needs to be modified. Furthermore, since conventional single-phase three-wire energy meters do not require a neutral wire, there may not be a pre-installed neutral wire at the installation site, necessitating a separate neutral wire connection, preventing a plug-and-play solution.

[0004] Therefore, the existing electricity meters mentioned above have drawbacks such as high cost and difficulty in implementation during manufacturing and installation.

[0005] Therefore, a downstream detection circuit and a single-phase three-wire meter are needed that can perform the relay-based state monitoring function without the need to introduce a neutral wire into the meter. Summary of the Invention

[0006] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide a downstream detection circuit for a single-phase three-wire meter and a single-phase three-wire meter that meets one or more of the aforementioned requirements.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a downstream detection circuit for a single-phase three-wire meter, specifically comprising:

[0009] A first diode and a second diode; the positive terminal of the first diode is electrically connected to the first live wire and the negative terminal is electrically connected to the second live wire; the positive terminal of the second diode is electrically connected to the second live wire and the negative terminal is electrically connected to the first live wire; the positive terminal of the first diode is electrically connected to the negative terminal of the second diode.

[0010] The first diode has a first optocoupler circuit in reverse orientation on both sides, and the second diode has a second optocoupler circuit in reverse orientation on both sides. Both the first optocoupler circuit and the second optocoupler circuit have a conducting output terminal.

[0011] In a preferred embodiment, the first diode and the second diode are fast recovery diodes.

[0012] In a preferred embodiment, a first resistor group is provided between the negative terminal of the first diode and the second live wire, and between the negative terminal of the second diode and the first live wire;

[0013] A second resistor group is provided between the positive terminal of the first diode and the first live wire, and between the positive terminal of the second diode and the second live wire.

[0014] As a further preferred embodiment, the first resistor group consists of five 1206 resistors connected in series, and the second resistor group consists of three 1206 resistors connected in series.

[0015] In a second aspect, the present invention also provides a single-phase three-wire meter with a post-stage detection circuit, including a controller and a post-stage detection circuit as described in any of the above claims for use in a single-phase three-wire meter.

[0016] The controller is connected to the on / off output of the first and second optocoupler circuits and to the closed / off pin of the relay. The controller is configured to determine whether there is an electricity theft event based on the closed / off state of the relay and the on / off state of the first and second optocoupler circuits.

[0017] In one preferred embodiment, the single-phase three-wire meter also includes a communication module connected to an MCU controller for reporting electricity theft incidents.

[0018] Thirdly, the present invention also provides a method for detecting electricity theft in a single-phase three-wire meter, applicable to a single-phase three-wire meter having a subsequent detection circuit as described in any of the above claims, specifically including:

[0019] Obtain the conduction state of the first optocoupler circuit and the conduction state of the second optocoupler circuit;

[0020] Obtain the closing status of the relay;

[0021] If the relay has been tripped and the first and second optocoupler circuits are not fully connected, then an electricity theft event is detected.

[0022] Compared with the prior art, the beneficial effects of this invention are:

[0023] The present invention relates to a downstream detection circuit for a single-phase three-wire electricity meter and to a single-phase three-wire electricity meter. It can complete the state detection of the downstream relay without introducing a neutral wire, and determine electricity theft events. At the same time, the overall structure is simple and the production and installation costs are low. Attached Figure Description

[0024] Figure 1 This is a circuit connection diagram of a three-phase electric meter in the prior art;

[0025] Figure 2 This is a circuit connection diagram of the downstream detection circuit of a single-phase three-wire meter according to an embodiment of this application. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0027] Before describing the specific implementation of the method of the present invention, the circuit connection structure of a common single-phase three-wire meter with a neutral wire in the prior art will be described in detail:

[0028] like Figure 1 The diagram shows the circuit connection structure of an existing single-phase three-wire meter. To accurately detect the status of the downstream circuit, the neutral wire is introduced into the meter. The detection principle is as follows: Figure 1 As shown. UN is the neutral line, L1_RELAY is the relay output port for live wire L1, and L2_RELAY is the relay output port for live wire L2. When the relay is open, if a malicious jumper is used, the output stage and the output stage will be at the same potential. At this time, the voltage forms a loop through D700, R700, R701, R702, R703, and U700, and the optocoupler conducts. The RE_TEST signal will show a 50Hz square wave signal. If there is no power to the output stage, the optocoupler does not conduct, and RE_TEST remains in a pulled-up state. The second channel works similarly; the MCU determines the state of the relay output stage by recognizing the different signals.

[0029] The aforementioned electricity meters require a neutral wire for circuit reference, leading to higher costs. The structural designs of various electricity meters differ, and to enable the neutral wire connection, not only are additional neutral terminals needed, but the PCB layout of the circuit hardware also requires modification. Furthermore, since conventional single-phase three-wire electricity meters do not require a neutral wire, a pre-installed neutral wire may not be available at the installation site, necessitating a separate neutral wire connection, preventing a plug-and-play solution.

[0030] To address the aforementioned problems of existing single-phase three-wire meters, this application provides a downstream detection circuit for single-phase three-wire meters and a single-phase three-wire meter itself.

[0031] The following description provides several embodiments of this application. Different embodiments can be substituted or combined. Therefore, this application can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0032] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this application. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0033] In a first aspect, this application provides a downstream detection circuit for a single-phase three-wire meter, specifically comprising:

[0034] A first diode and a second diode; the positive terminal of the first diode is electrically connected to the first live wire and the negative terminal is electrically connected to the second live wire; the positive terminal of the second diode is electrically connected to the second live wire and the negative terminal is electrically connected to the first live wire; the positive terminal of the first diode is electrically connected to the negative terminal of the second diode.

[0035] The first diode has a first optocoupler circuit in reverse orientation on both sides, and the second diode has a second optocoupler circuit in reverse orientation on both sides. Both the first optocoupler circuit and the second optocoupler circuit have a conducting output terminal.

[0036] In one specific embodiment, the circuit connection diagram of the post-stage detection circuit applied to the single-phase three-wire meter is as follows. Figure 2 As shown, it specifically includes the following structure:

[0037] In the upper part of the circuit, the relay output port of the second live wire L2 is connected to the negative terminal of the first diode D701 through five 33K1206 resistors (R700-R704), and the relay output port of the first live wire L1 is connected to the positive terminal of the first diode D701 through three 33K1206 resistors (R710-R712). The input terminal of the optocoupler U700 is connected in parallel to the two ends of the first diode D701 to form the first optocoupler circuit. The output terminal is connected to VCC_3.3V and ground, and the RE_TEST1 port for detecting the conduction status of the optocoupler is led out as the conduction status output terminal.

[0038] In the lower half of the circuit, the relay output port of the first live wire L1 is connected to the negative terminal of the second diode D702 through five 33K1206 resistors (R720-R724), and the relay output port of the second live wire L2 is connected to the positive terminal of the second diode D702 through three 33K1206 resistors (R730-R732). The input terminal of optocoupler U701 is connected in parallel to the two ends of the second diode D702 to form the second optocoupler circuit. The output terminal is connected to VCC_3.3V and ground, and the RE_TEST2 port for detecting the conduction status of the optocoupler is led out as the conduction status output terminal.

[0039] The number of resistors in the resistor group connected to the negative and positive terminals of the diode can be adjusted. The selection and series connection of resistors are mainly based on the voltage value of the power grid range and the power that the resistors themselves can handle. Generally, they are required to meet the overvoltage requirement of 1.9 times UN.

[0040] In a preferred embodiment of the above embodiments, the first resistor group connected to the negative terminals of the first and second diodes consists of five 33K1206 resistors, and the second resistor group connected to the positive terminals of the first and second diodes consists of three 33K1206 resistors.

[0041] To protect the optocoupler, diodes D701 and D702 are selected as fast recovery diodes LL4148.

[0042] The working process of the above-mentioned downstream detection circuit applied to a single-phase three-wire meter is as follows, depending on the different operating states of the relay.

[0043] When the relay is normally closed, the positive half-cycle AC voltage passes through five 33K1206 resistors (R700-R704), the first optocoupler (U700), and three 51K1206 resistors (R710-R712) to the mains voltage, forming a circuit. The first optocoupler is turned on, and the potential of the RE_TEST1 port is pulled low to ground. During the negative half-cycle, the fast recovery diode LL4148 protects the optocoupler. Voltage passes through the diode, the optocoupler is not turned on, and the potential of the RE_TEST1 port is pulled high to VCC_3.3V. At this time, the output signal is a 50Hz square wave signal. The second channel RE_TEST2 works similarly.

[0044] When the relay is normally disconnected, there is no voltage after the relay, and neither the first nor second optocoupler is conducting. The potentials of both RE_TEST1 and RE_TEST2 ports are pulled high to VCC_3.3V and remain at a high level. The mains voltage is applied across six 51K1206 resistors (R710-R712, R730-R732) to form a circuit.

[0045] When the relay is open, if the power theft state is in the jumper state of the front and rear stages respectively, the output signals of RE_TEST1 and RE_TEST2 are the same as the relay in the normal closed state, both outputting a 50HZ square wave signal. The rear detection circuit detects the closed state, but at this time the relay is in the open state.

[0046] When the relay is open, if the circuit is in a state of power theft due to jumpers between the front and rear stages, the voltage after the A-stage relay is L2, and the voltage after the B-stage relay is L1. During the positive half-cycle of L1, the voltage passes through resistors R700-R704 (five 33K 1206 resistors), optocoupler U700, and resistors R730-R732 (three 51K 1206 resistors) to form a loop at L2. The first optocoupler U700 is turned on, and the potential of the RE_TEST1 port is pulled low to ground. During the negative half-cycle, the fast recovery diode LL4148 protects the first optocoupler; the voltage passes through the diode, the first optocoupler is not turned on, and the potential of RE_TEST1 is pulled high to VCC_3.3V. The other optocoupler U701 behaves similarly. At this time, the downstream detection circuit detects a closed state, but the relay is in a closed state.

[0047] Based on the above explanation of the working principle, it can be seen that the aforementioned downstream detection circuit can detect the actual energized state of the relay and compare it with the current open and closed states of the relay, thereby providing a basis for judging electricity theft incidents.

[0048] On the other hand, this application also provides a single-phase three-wire meter with a post-stage detection circuit, including a controller and a post-stage detection circuit as described in any of the above claims for use in a single-phase three-wire meter.

[0049] The controller is connected to the on-state output terminals of the first and second optocoupler circuits and to the closing state pin of the relay. The controller is configured to determine whether there is an electricity theft event based on the closing state of the relay and the on-state of the first and second optocoupler circuits.

[0050] The controller mentioned above can be a single-chip microcomputer or an MCU controller.

[0051] Since the controller is connected to the on / off output terminals of the first and second optocoupler circuits and to the closing pin of the relay, it can obtain the on / off states of the first and second optocoupler circuits, i.e., the signals output by RE_TEST1 and RE_TEST2 in the above embodiment. Simultaneously, the controller can also obtain the current closing state of the relay, determine the actual energized state of the relay based on the signals output by RE_TEST1 and RE_TEST2, and compare it with the current open and closed states of the relay to determine if an electricity theft event has occurred.

[0052] Single-phase and three-phase circuits can be used simultaneously or independently, resulting in various wiring configurations. The specific detection and judgment rules of the controller are listed in Table 1 below. Here, AB represents live wire 1 and live wire 2, RE_TEST-0 represents a square wave with 50Hz high and low level changes, and 1 represents a continuously high level.

[0053]

[0054]

[0055] Table 1. Detection status of various wiring connections when the relay is disconnected.

[0056] In a preferred embodiment, the single-phase three-wire meter of this application further includes a communication module connected to an MCU controller for reporting electricity theft incidents.

[0057] The aforementioned downstream detection circuit and single-phase three-wire meter detect the actual energization state of the relay and compare it with the current on / off state of the relay to confirm whether electricity theft has occurred. In the absence of a neutral wire connected to the meter, the electricity theft detection function is implemented using components of the same cost as a conventional single-phase three-wire meter.

[0058] On the other hand, this application also provides a method for detecting electricity theft in a single-phase three-wire meter, applied to a single-phase three-wire meter with a subsequent detection circuit as described in the above embodiments, specifically including:

[0059] Obtain the conduction state of the first optocoupler circuit and the conduction state of the second optocoupler circuit;

[0060] Obtain the closing status of the relay;

[0061] If the relay has been tripped and the first and second optocoupler circuits are not fully connected, then an electricity theft event is detected.

[0062] The specific judgment rules for this electricity theft detection method are shown in Table 1 above.

[0063] Specifically, when the relay is disconnected, the software identifies the RE_TEST signal given by the hardware circuit through the controller's I / O port. The controller checks RE_TEST once every 1 / 2048s. If the number of low-level signals within 1 second is greater than or equal to 200, then an electricity theft event is determined to have occurred.

[0064] In another embodiment of this application, the following detection method can also be used: the controller detection port performs a level scan on the RE_TEST signal provided by the hardware every 5ms, for a total of 20 scans. If a high level is continuously detected, it indicates that the relay is open, and RE_TEST is pulled high by the pull-up resistor. If a low level appears during the detection process, it indicates that the relay is closed, the optocoupler is conducting, and RE_TEST is pulled low.

[0065] Using the above method, the single-phase three-wire meter of this application detects the actual energization state of the relay and compares it with the current open and closed states of the relay to confirm whether there is an electricity theft incident.

[0066] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0067] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0068] The foregoing description is merely an exemplary embodiment of this disclosure and should not be construed as limiting the scope of this disclosure. Any equivalent changes and modifications made in accordance with the teachings of this disclosure shall still fall within the scope of this disclosure. Those skilled in the art will readily conceive of embodiments of this disclosure upon considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of this disclosure are defined by the claims.

Claims

1. A downstream detection circuit for a single-phase three-wire meter, characterized in that, Specifically, it includes: A first diode and a second diode, wherein the anode of the first diode is electrically connected to the first live wire and the cathode is electrically connected to the second live wire, and the anode of the second diode is electrically connected to the second live wire and the cathode is electrically connected to the first live wire; the anode of the first diode is electrically connected to the cathode of the second diode. The first diode has a first optocoupler circuit in reverse orientation on its two terminals, and the second diode has a second optocoupler circuit in reverse orientation on its two terminals. Both the first optocoupler circuit and the second optocoupler circuit have a conducting output terminal. The first diode and the second diode are fast recovery diodes; A first resistor group is provided between the negative terminal of the first diode and the second live wire, and between the negative terminal of the second diode and the first live wire; A second resistor group is provided between the positive terminal of the first diode and the first live wire, and between the positive terminal of the second diode and the second live wire.

2. The downstream detection circuit for a single-phase three-wire meter as described in claim 1, characterized in that, The first resistor group consists of four 1206 resistors connected in series, and the second resistor group consists of three 1206 resistors connected in series.

3. A single-phase three-wire meter with a post-stage detection circuit, characterized in that, The device includes a controller and a downstream detection circuit for a single-phase three-wire meter as described in any one of claims 1-2; the controller is connected to the on-state output terminals of the first optocoupler circuit and the second optocoupler circuit, and is also connected to the closing state pin of the relay; the controller is configured to determine whether there is an electricity theft event based on the closing state of the relay and the on-state of the first optocoupler circuit and the second optocoupler circuit.

4. A single-phase three-wire meter with a post-stage detection circuit as described in claim 3, characterized in that, It also includes a communication module, which is connected to the controller, for reporting electricity theft incidents.

5. A method for detecting electricity theft in a single-phase three-wire meter, applicable to a single-phase three-wire meter with a subsequent detection circuit as described in any one of claims 3-4, characterized in that, Specifically, it includes: Obtain the conduction state of the first optocoupler circuit and the conduction state of the second optocoupler circuit; Obtain the closing status of the relay; If the relay has been tripped and the first and second optocoupler circuits are not fully connected, then an electricity theft event is detected.

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