Electric energy meter and method for judging whether relay can be switched on or not based on real load detection circuit

Abstract

The invention provides an electric energy meter and method for judging whether a relay can be switched on based on a real load detection circuit, the electric energy meter comprises a detection circuit and a processing module, the detection circuit is used for detecting whether the rear end of the electric energy meter is electrified and whether the time sequence is consistent with that of the front end of the electric energy meter; the processing module performs different actions according to a detection result, the electric energy meter is allowed to be switched on when it is detected that the rear end of the electric energy meter has voltage and the time sequence of the voltage is consistent with the time sequence of the front end of the electric energy meter, and switching on is forbidden when the detected time sequence is inconsistent with the time sequence of the front end of the electric energy meter, so that the short circuit phenomenon is prevented.

Description

Technical Field

[0001] This invention relates to the field of energy meter technology with actual load detection, and more specifically, to an energy meter and method for determining whether a relay can be closed based on an actual load detection circuit. Background Technology

[0002] With the promotion and application of photovoltaic power generation technology, electricity metering devices that can be connected to both the power grid and photovoltaic power generation systems have gradually appeared on the market.

[0003] Currently, common solutions include configuring two independent energy meters or using a single integrated energy meter. However, in the case of using a single energy meter, the installation and wiring process must strictly ensure the correctness of the phase sequence and timing; if the wiring sequence is incorrect, it can easily cause a short circuit, which may lead to safety accidents such as fires.

[0004] In addition, there is another hidden danger: when the electricity meter is in the off state, if the user directly short-circuits the power grid line at the output end, although it only constitutes electricity theft, once the electricity meter is restored, a short circuit risk may still occur immediately due to the incorrect phase sequence, which poses a serious threat to the safety of equipment and personnel. Summary of the Invention

[0005] The purpose of this invention is to address the question of whether to allow the relay to operate in situations involving photovoltaic power generation or direct electricity theft at the back end of the user's electricity meter. This invention proposes an electricity meter and method based on a real load detection circuit to determine whether the relay can be closed. This invention can accurately determine whether the voltage timing at the back end of the electricity meter is normal, and then decide whether the relay can be closed based on the timing status.

[0006] The technical solution of this invention is: This invention provides an energy meter that determines whether a relay can be closed based on a real load detection circuit, including a detection circuit and a processing module; The detection circuit is installed inside the energy meter and is used to detect the AC voltage between the output terminals of each phase line and the neutral line of the energy meter in real time when the relay is in the open state, and generate a zero-crossing signal that reflects whether the output terminal voltage exists and when it exists. The processing module is integrated into the CPU of the electricity meter. It is used to receive and process the signal output by the detection circuit, and combine it with the zero-crossing signal of the grid input voltage provided by the metering chip to perform timing consistency judgment. If the timing is consistent, the relay is allowed to close; if the timing is inconsistent, the relay is prohibited from closing.

[0007] Furthermore, the detection circuit includes three identical single-phase detection channels, corresponding to phase A, phase B, and phase C respectively; each detection channel is composed of a resistor, a diode, an optocoupler, and a signal conditioning resistor network. In the A-phase channel, the A-phase line output terminal L1_OUT is connected to one end of resistor R1. The other end of R1 is connected to both the cathode of diode D1 and the anode of the input side of optocoupler U1. The anode of diode D1 and the cathode of the input side of optocoupler U1 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U1 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R2 and R3. The other end of resistor R2 serves as the A-phase channel detection signal output terminal SCS_FB_L1, which is connected to the interrupt pin of the CPU. The other end of resistor R3 is grounded to DGND. In the B-phase channel, the output terminal L2_OUT of the B-phase line is connected to one end of resistor R4. The other end of R4 is connected to both the cathode of diode D2 and the anode of the input side of optocoupler U2. The anode of diode D2 and the cathode of the input side of optocoupler U2 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U2 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R5 and R6. The other end of resistor R5 serves as the B-phase channel detection signal output terminal SCS_FB_L2, which is connected to the interrupt pin of the CPU. The other end of resistor R6 is grounded to DGND. In the C-phase channel, the C-phase line output terminal L3_OUT is connected to one end of resistor R7. The other end of R7 is connected to both the cathode of diode D3 and the anode of the input side of optocoupler U3. The anode of diode D3 and the cathode of the input side of optocoupler U3 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U3 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R8 and R9. The other end of resistor R8 serves as the C-phase channel detection signal output terminal SCS_FB_L3, which is connected to the interrupt pin of the CPU. The other end of resistor R9 is grounded to DGND.

[0008] This invention provides a method for determining whether a relay can close based on a real load detection circuit, applied to the aforementioned energy meter, comprising the following steps: When the relay is in the open state, continuously acquire the signal status of the three detection channel output terminals SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3 of the detection circuit; When any signal has a high-level pulse, record the timestamp T_out of the rising edge of the signal, and obtain the timestamp T_in of the rising edge of the zero-crossing signal ZC_L at the corresponding phase input terminal provided by the metering chip; calculate the time difference ΔT = |T_out -T_in|, and compare it with the preset phase tolerance threshold T_tol; If the corresponding ΔT for all energized circuits is not greater than T_tol, the timing is considered consistent, and relay closing is allowed; otherwise, the timing is considered inconsistent, and relay closing is prohibited.

[0009] Furthermore, the phase tolerance threshold T_tol is 1 millisecond.

[0010] Furthermore, when any signal experiences a high-level pulse, a data record containing the output voltage anomaly event and timing comparison results is generated, and the data record is reported to the main station.

[0011] The beneficial effects of this invention are: This invention provides an energy meter that uses a real load detection circuit to determine whether a relay can be closed. The hardware detection circuit monitors the output voltage and phase sequence in real time, and uses optocoupler isolation and resistor current limiting protection to ensure that the signal is safely transmitted to the controller processing module. The processing module compares the zero-crossing signal timing of the input and output terminals to determine whether the switch can be closed. In case of abnormality, it prohibits closing the switch and reports the data to the main station, which facilitates on-site verification of the cause of the abnormality.

[0012] This invention uses the coordinated operation of hardware circuits and software judgment to accurately identify abnormal states at the output end, ensuring the safe operation of the power metering device. At the same time, it effectively addresses complex scenarios such as electricity theft or photovoltaic access, improving the system's intelligent management level and security protection capabilities.

[0013] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0014] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0015] Figure 1 A detection circuit diagram according to an embodiment of the present invention is shown. Detailed Implementation

[0016] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0017] This invention provides an energy meter that determines whether a relay can be closed based on a real load detection circuit, including a detection circuit and a processing module; The detection circuit is installed inside the energy meter and is used to detect the AC voltage between the output terminals of each phase line and the neutral line of the energy meter in real time when the relay is in the open state, and generate a zero-crossing signal that reflects whether the output terminal voltage exists and when it exists. The processing module is integrated into the CPU of the electricity meter. It is used to receive and process the signal output by the detection circuit, and combine it with the zero-crossing signal of the grid input voltage provided by the metering chip to perform timing consistency judgment. If the timing is consistent, the relay is allowed to close; if the timing is inconsistent, the relay is prohibited from closing.

[0018] Figure 1 A detection circuit diagram according to an embodiment of the present invention is shown.

[0019] like Figure 1 As shown, the detection circuit includes three identical single-phase detection channels, corresponding to phase A, phase B, and phase C respectively; each detection channel is composed of a resistor, a diode, an optocoupler, and a signal conditioning resistor network. In the A-phase channel, the A-phase line output terminal L1_OUT is connected to one end of resistor R1. The other end of R1 is connected to both the cathode of diode D1 and the anode of the input side of optocoupler U1. The anode of diode D1 and the cathode of the input side of optocoupler U1 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U1 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R2 and R3. The other end of resistor R2 serves as the A-phase channel detection signal output terminal SCS_FB_L1, which is connected to the interrupt pin of the CPU. The other end of resistor R3 is grounded to DGND. In the B-phase channel, the output terminal L2_OUT of the B-phase line is connected to one end of resistor R4. The other end of R4 is connected to both the cathode of diode D2 and the anode of the input side of optocoupler U2. The anode of diode D2 and the cathode of the input side of optocoupler U2 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U2 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R5 and R6. The other end of resistor R5 serves as the B-phase channel detection signal output terminal SCS_FB_L2, which is connected to the interrupt pin of the CPU. The other end of resistor R6 is grounded to DGND. In the C-phase channel, the C-phase line output terminal L3_OUT is connected to one end of resistor R7. The other end of R7 is connected to both the cathode of diode D3 and the anode of the input side of optocoupler U3. The anode of diode D3 and the cathode of the input side of optocoupler U3 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U3 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R8 and R9. The other end of resistor R8 serves as the C-phase channel detection signal output terminal SCS_FB_L3, which is connected to the interrupt pin of the CPU. The other end of resistor R9 is grounded to DGND.

[0020] This invention provides a method for determining whether a relay can close based on a real load detection circuit, applied to the aforementioned energy meter, comprising the following steps: When the relay is in the open state, continuously acquire the signal status of the three detection channel output terminals SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3 of the detection circuit; When any signal has a high-level pulse, record the timestamp T_out of the rising edge of the signal, and obtain the timestamp T_in of the rising edge of the zero-crossing signal ZC_L at the corresponding phase input terminal provided by the metering chip; calculate the time difference ΔT = |T_out -T_in|, and compare it with the preset phase tolerance threshold T_tol; If the corresponding ΔT for all energized signals is not greater than T_tol, the timing is considered consistent, and relay closing is allowed; otherwise, the timing is considered inconsistent, and relay closing is prohibited. When any signal has a high-level pulse, a data record containing the output voltage abnormality event and timing comparison results is generated, and the data record is reported to the master station.

[0021] In practice: This solution detects whether there is voltage at the output terminal of the electricity meter. If there is voltage, it can also detect whether the voltage timing is consistent with the input terminal. It includes the following steps: Step 1: When the meter is in the off state, the input and output terminals of the meter are disconnected. Under normal circumstances, there is no voltage at the output terminal. At this time, SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3 are at low level.

[0022] Step 2: When the electricity meter is in a tripped-off state, if the meter is connected to a photovoltaic power generation system or there is electricity theft at the back end, the SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3 signals will still output waveforms even when the power is off. The meter then compares the zero-crossing signals at the input terminal collected by the metering chip with the zero-crossing signals of SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3. If they match, the output timing is considered normal, and the relay is allowed to close. However, data is also reported to the master station, and personnel go to the site to confirm whether it is electricity theft or photovoltaic power generation. But if the output phase sequence is inconsistent with the input phase sequence, the meter will not allow the relay to close, and data will be reported to the master station for personnel to investigate the cause of the problem. This avoids faults caused by short circuits after the power is off.

[0023] When the output phase A and phase B of the electricity meter are reversed, the zero-crossing time of phase A collected by the meter's CPU differs from the zero-crossing time of phase A internally stored in the metering chip. This indicates a problem with electricity theft or incorrect phase sequence at the downstream end. In this case, the meter remains in a closed state until the downstream state is correct, at which point it is allowed to close. If the downstream voltage matches the input voltage, closing is permitted without any risk. Since the relays in a three-phase electricity meter are only on the phase lines, and there is no relay on the neutral line, the neutral line's N_OUT is guaranteed to exist, and there is no need to consider the case where N_OUT is not connected.

[0024] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An energy meter that determines whether a relay can be closed based on a real load detection circuit, characterized in that, Includes detection circuitry and processing modules; The detection circuit is installed inside the energy meter and is used to detect the AC voltage between the output terminals of each phase line and the neutral line of the energy meter in real time when the relay is in the open state, and generate a zero-crossing signal that reflects whether the output terminal voltage exists and when it exists. The processing module is integrated into the CPU of the electricity meter. It is used to receive and process the signal output by the detection circuit, and combine it with the zero-crossing signal of the grid input voltage provided by the metering chip to perform timing consistency judgment. If the timing is consistent, the relay is allowed to close; if the timing is inconsistent, the relay is prohibited from closing.

2. The electricity meter as described in claim 1, characterized in that, The detection circuit includes three identical single-phase detection channels, corresponding to phase A, phase B, and phase C respectively; each detection channel consists of a resistor, a diode, an optocoupler, and a signal conditioning resistor network.

3. The electricity meter as described in claim 2, characterized in that, In the A-phase channel, the A-phase line output terminal L1_OUT is connected to one end of resistor R1. The other end of R1 is connected to both the cathode of diode D1 and the anode of the input side of optocoupler U1. The anode of diode D1 and the cathode of the input side of optocoupler U1 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U1 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R2 and R3. The other end of resistor R2 serves as the A-phase channel detection signal output terminal SCS_FB_L1, which is connected to the interrupt pin of the CPU. The other end of resistor R3 is grounded to DGND.

4. The electricity meter as described in claim 2, characterized in that, In the B-phase channel, the B-phase line output terminal L2_OUT is connected to one end of resistor R4. The other end of R4 is connected to both the cathode of diode D2 and the anode of the input side of optocoupler U2. The anode of diode D2 and the cathode of the input side of optocoupler U2 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U2 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R5 and R6. The other end of resistor R5 serves as the B-phase channel detection signal output terminal SCS_FB_L2, which is connected to the interrupt pin of the CPU. The other end of resistor R6 is grounded to DGND.

5. The electricity meter as described in claim 2, characterized in that, In the C-phase channel, the C-phase line output terminal L3_OUT is connected to one end of resistor R7. The other end of R7 is connected to both the cathode of diode D3 and the anode of the input side of optocoupler U3. The anode of diode D3 and the cathode of the input side of optocoupler U3 are connected to the neutral line N_OUT. The collector of the output side of optocoupler U3 is connected to the power supply VDD3V3, and the emitter is connected to one end of resistors R8 and R9. The other end of resistor R8 serves as the C-phase channel detection signal output terminal SCS_FB_L3, which is connected to the interrupt pin of the CPU. The other end of resistor R9 is grounded to DGND.

6. A method for determining whether a relay can close based on a real load detection circuit, applied to an energy meter as described in any one of claims 1 to 5, characterized in that, Includes the following steps: When the relay is in the open state, continuously acquire the signal status of the three detection channel output terminals SCS_FB_L1, SCS_FB_L2, and SCS_FB_L3 of the detection circuit; When any signal has a high-level pulse, record the timestamp T_out of the rising edge of the signal, and obtain the timestamp T_in of the rising edge of the zero-crossing signal ZC_L at the corresponding phase input terminal provided by the metering chip; calculate the time difference ΔT = |T_out - T_in|, and compare it with the preset phase tolerance threshold T_tol; If the corresponding ΔT for all energized circuits is not greater than T_tol, the timing is considered consistent, and relay closing is allowed; otherwise, the timing is considered inconsistent, and relay closing is prohibited.

7. The method as described in claim 6, characterized in that, The phase tolerance threshold T_tol is 1 millisecond.

8. The method as described in claim 6, characterized in that, When any signal experiences a high-level pulse, a data record containing the output voltage anomaly event and timing comparison results is generated and reported to the main station.

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