A device for preventing electricity theft in a pumping unit well

Abstract

The present application relates to the technical field of electrical engineering, and more particularly to a pumping unit well anti-theft device, which comprises: a direct-current variable sequence module, which transmits positive and negative voltages of direct current output by a rectifying module to two wire cores of a cable, randomly switches loops among all wire cores of the cable, and sends wire core information corresponding to the positive and negative voltages after switching to a direct-current inverter decryption module; the direct-current inverter decryption module is connected to a pumping unit well through a frequency converter, and is used to connect wire cores where the positive and negative voltages after switching are located to positive and negative voltage direct-current busbars corresponding to the frequency converter according to the received wire core information. The present application solves the problem that the power transmission cable of the oilfield pumping unit well is stolen, which brings safety hazards to production and causes economic losses. The existing anti-theft method mainly relies on equipment inspection personnel to find the stolen power, and manual cutting is required when the power is stolen, which is delayed and cannot fundamentally solve the problem of power theft.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering technology, and in particular to an anti-theft device for oil pumping wells. Background Technology

[0002] In oilfield production, electricity is an indispensable resource. Using oilfield electricity without permission and metering is considered theft of oilfield electricity, or simply electricity theft. Electricity theft not only causes economic losses to the oilfield but also poses safety hazards such as electric shock. Current methods for preventing electricity theft involve capturing theft information on power lines and then notifying managers to cut off the stolen resources. This is an emergency measure, but due to the time lag between detection and on-site response, and limitations in investigation methods, it cannot immediately and effectively stop electricity theft. Even after theft is stopped, repeated theft often occurs. This method is considered a management-based prevention measure. Existing technical prevention methods mostly employ current limiting, but thieves often damage or enlarge simple current limiting measures. Enlarging current-limiting equipment, if not stopped promptly, often results in equipment burnout. Summary of the Invention

[0003] This invention proposes an anti-theft device for oil pumping wells to solve the problem of electricity theft from oilfield pumping well power cables, which poses safety hazards to production and causes economic losses. Existing anti-theft methods require manual disconnection when electricity theft is detected, which is delayed and cannot fundamentally solve the problem of electricity theft, and also increases labor intensity.

[0004] According to one aspect of the present invention, an anti-theft device for oil pumping wells is provided, comprising: a rectifier module, a DC sequence conversion module, and a DC inverter decryption module;

[0005] The rectifier module is connected to the pumping unit well transformer, the DC sequence conversion module is connected to the rectifier module for converting the AC output of the transformer into DC, and is connected to the DC inverter decryption module via a cable;

[0006] The DC sequence conversion module is used to transmit the positive and negative voltages of the DC power output by the rectifier module to two of the wires of the cable, and randomly switch the circuit between all the wires. At the same time, it sends the wire information corresponding to the positive and negative voltages after the switch to the DC inverter decryption module.

[0007] The DC inverter decryption module is connected to the pumping unit motor via a frequency converter. The DC inverter decryption module is used to connect the cores containing the positive and negative voltages in the switched cable to the corresponding positive and negative voltage DC busbars of the frequency converter according to the received core information.

[0008] Preferably, the rectifier module is further used to boost the voltage output by the transformer to a predetermined voltage and then transmit it to the DC sequence conversion module;

[0009] The frequency converter is used to convert the DC power transmitted through the cable into AC power, and then step it down to a predetermined pressure range before transmitting it to the pumping unit motor.

[0010] Preferably, the DC sequence conversion module includes: a first microcontroller, a first control switch group, and a wireless transmission module;

[0011] The first microcontroller is connected to the first control switch group, which is connected to the positive and negative voltage output terminals of the transformer and to each wire core in the cable. The first microcontroller is used to control the connection or disconnection of the circuit between the positive voltage output terminal and / or negative voltage output terminal of the transformer and each wire core through the first control switch group.

[0012] The first microcontroller is connected to the DC inverter decryption module via a wireless transmission module. The first microcontroller is used to send the information of the wire cores connected to the first control switch group to the DC inverter decryption module via the wireless transmission module each time a circuit switch is performed.

[0013] Preferably, the random loop switching among all wire cores includes:

[0014] When switching circuits, the positive or negative voltage output terminal of the transformer is first randomly connected to any unenergized core of the cable. After a first predetermined time, the original connected core is disconnected from the positive or negative voltage output terminal of the transformer.

[0015] Preferably, the DC inverter decryption module includes: a second microcontroller and a second control switch group;

[0016] The second microcontroller is connected to the second control switch group, and the second control switch group is connected to each wire core in the cable and the positive and negative DC bus of the frequency converter respectively;

[0017] The second microcontroller is connected to the DC sequence conversion module. When the second microcontroller receives the core information and after a second predetermined time, it controls the cores containing the positive and negative voltages in the cable to connect to the corresponding positive and negative voltage DC bus of the frequency converter through the second control switch group.

[0018] Preferably, connecting the conductors containing the positive and negative voltages in the switched cable to the corresponding positive and negative DC busbars of the frequency converter includes:

[0019] When the second microcontroller receives the core information, and after a second predetermined time, it connects the cores with positive and negative voltages in the control cable to the corresponding positive and negative DC bus of the frequency converter through the second switch group. After a third predetermined time, it disconnects the original connected cores from the positive or negative DC bus of the frequency converter.

[0020] Preferably, before switching the circuit, it is checked whether the core to be switched is grounded or short-circuited. If so, the circuit is not switched to that core.

[0021] Preferably, it also includes a current comparison module;

[0022] The current comparison module is connected to the transformer and the frequency converter respectively. The current comparison module is used to count the total current output by the transformer and the total current received by the frequency converter, and calculate the difference between the two.

[0023] If the difference is greater than a predetermined percentage of the total output current of the transformer, the alarm module is controlled to sound an alarm.

[0024] Preferably, the signal transmission distance of the wireless transmission module is less than or equal to 200 meters.

[0025] Preferably, it also includes: a security box;

[0026] The low-voltage side of the transformer and the DC sequence conversion module are located inside the anti-theft box. The door of the anti-theft box is equipped with a wireless combination lock, and an alarm device connected to the wireless combination lock is installed inside the anti-theft box.

[0027] The present invention has at least the following beneficial effects:

[0028] This invention proposes an anti-electricity theft device for oil pumping wells. By setting up a DC sequence-changing module, the current in the cable is randomly alternating in the cable core, preventing electricity thieves from stealing DC power by installing a bypass circuit in the power circuit. This fundamentally solves the possibility of electricity being used for civilian purposes, ensuring that the power used for production is not affected, and technically solves the problem of electricity theft. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention and, together with the specification, serve to explain the technical solutions of the present invention.

[0030] Figure 1 This diagram illustrates the equipment connection of an anti-theft electrical device for a pumping well according to an embodiment of the present invention.

[0031] Figure 2A circuit diagram of an anti-theft electrical device for a pumping well according to an embodiment of the present invention is shown. Implementation

[0032] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0033] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0034] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0035] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without certain specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0036] Figure 1 This diagram illustrates the equipment connection of an anti-theft electrical device for a pumping well according to an embodiment of the present invention. Figure 2 A circuit diagram of an anti-theft electrical device for a pumping unit well according to an embodiment of the present invention is shown. Figure 1 and 2As shown, an anti-theft device for oil pumping wells includes: a rectifier module, a DC sequence conversion module, and a DC inverter decryption module; the rectifier module is connected to the oil pumping well transformer, the DC sequence conversion module is connected to the rectifier module for converting the AC power output from the transformer into DC power, and is connected to the DC inverter decryption module via a cable; the DC sequence conversion module is used to transmit the positive and negative voltages of the DC power output from the rectifier module to two cores of the cable, and randomly switch the circuit among all cores, while simultaneously sending the core information corresponding to the positive and negative voltages after the switch to the DC inverter decryption module; the DC inverter decryption module is connected to the oil pumping well motor via a frequency converter, and is used to connect the cores containing the positive and negative voltages in the switched cable to the corresponding positive and negative voltage DC busbars of the frequency converter according to the received core information.

[0037] In this invention, the rectifier module is also used to boost the voltage output by the transformer to a predetermined voltage and then transmit it to the DC sequence module; the frequency converter is used to convert the DC power transmitted through the cable into AC power and then step it down to a predetermined pressure range before transmitting it to the pumping unit motor.

[0038] In this embodiment of the invention, the rectifier module can be a rectifier connected to the transformer at the original power supply point of the pumping unit well. The rectifier module boosts the 380V AC output from the transformer to a predetermined voltage, then converts the predetermined voltage AC to DC before transmitting it to the DC conversion module. The predetermined voltage can be 530V.

[0039] The power supply cable has at least three conductors, such as A, B, and C. In the initial state, the positive and negative voltage output terminals of the rectifier module are randomly connected to two conductors in the cable, such as conductors A and B, via a DC sequence conversion module. The DC sequence conversion module transmits the positive and negative voltages output from the rectifier module to conductors A and B respectively. In the initial state, the DC inverter decryption module transmits the 530V DC power from conductors A and B of the cable to the corresponding positive and negative DC busbars of the frequency converter. The frequency converter converts the 530V DC power to AC power, steps it down to a predetermined voltage range, and then transmits it to the pumping unit motor to supply power. The predetermined voltage range is 0~380V.

[0040] When the DC sequence conversion module switches the circuit between the wire cores, it can switch the circuit from the original A and B wire cores to A and C wire cores or B and C wire cores. For example, when switching to A and C wire cores, the positive and negative voltage information (wire core information) corresponding to A and C wire cores needs to be sent to the DC inverter decryption module at the same time as the switching. For example, A wire core corresponds to positive voltage and C wire core corresponds to negative voltage.

[0041] After receiving the information from the conductor, the DC inverter decryption module switches conductors A and C to connect to the corresponding positive and negative DC bus of the inverter, thereby achieving uninterrupted power supply. The DC sequence module can switch circuits at a fixed frequency (predetermined interval) or at irregular intervals (random intervals).

[0042] In this invention, the DC-DC sequence conversion module includes: a first microcontroller, a first control switch group, and a wireless transmission module; the first microcontroller is connected to the first control switch group, which is respectively connected to the positive and negative voltage output terminals of the transformer and to each wire core in the cable; the first microcontroller is used to control the connection or disconnection of the lines between the positive and / or negative voltage output terminals of the transformer and each wire core through the first control switch group; the first microcontroller is connected to the DC-DC inverter decryption module through the wireless transmission module, and the first microcontroller is used to send the information of the wire cores connected to the first control switch group to the DC-DC inverter decryption module through the wireless transmission module each time a circuit switch is performed.

[0043] In the embodiments of the present invention and Figure 2 In the case of a cable with three cores, the first control switch group includes four switching elements, namely X1, X2, X3 and X4.

[0044] X1, X2, X3, and X4 are connected to the first microcontroller. X4 is connected to the positive voltage output terminal of the rectifier module and one end of the A core in the cable. X3 is connected to the negative voltage output terminal of the rectifier module and one end of the C core in the cable. One end of the B core in the cable is connected to the positive voltage output terminal of the rectifier module through X1 and to the negative voltage output terminal of the rectifier module through X2.

[0045] By controlling the opening and closing of four switching elements, the positive and negative voltages output by the rectifier module can be transmitted to any two lines in the cable. For example, if X4 and X3 are closed and X2 and X1 are open, the positive voltage of the rectifier module is transmitted to core A, and the negative voltage to core C. When the first microcontroller controls the switching circuit, to switch the circuit to cores A and B, the first microcontroller opens X3 and closes X2. At this time, the negative voltage output terminal of the rectifier module is connected to core B, and cores A and B form a circuit. To switch the circuit to cores B and C, the first microcontroller opens X4 and closes X1. At this time, the positive voltage output terminal of the rectifier module is connected to core B, and cores B and C form a circuit. If there are more than three cores, more switching elements need to be set accordingly to achieve circuit switching.

[0046] At the same time as or in advance of the first microcontroller switching circuit, the information of the wire core to be switched is sent to the DC inverter decryption module via the wireless transmission module.

[0047] In this invention, the random circuit switching among all wire cores includes: when switching the circuit, first randomly connecting the positive voltage output terminal or negative voltage output terminal of the transformer to any unenergized wire core in the cable, and after a first predetermined time, disconnecting the original connected wire core from the positive voltage output terminal or negative voltage output terminal of the transformer.

[0048] In this embodiment of the invention, before the circuit switching, the cores connected to the rectifier module are the original circuit cores. For example, X1 and X2 are in an open state, and X3 and X4 are in a closed state. The original circuit connection is that core A is connected to the positive voltage output terminal of the rectifier module, and core C is connected to the negative voltage output terminal of the rectifier module. Therefore, during the circuit switching, if the circuit is to be switched to cores A and B, the first microcontroller first controls X2 to close, that is, to connect the negative voltage output terminal of the rectifier module to the unenergized core B in the cable cores. After a first predetermined time, the first microcontroller controls X3 to open, that is, to disconnect the connection between the negative voltage output terminal of the rectifier module and the original circuit cores. The first predetermined time is 10-20 seconds.

[0049] During circuit switching, the circuit to be switched is connected first to ensure current in the conductor, and then the original connection is delayed before disconnecting the conductor. This allows the DC inverter decryption module to smoothly receive the current transmitted by the positive and negative conductors, preventing instantaneous voltage fluctuations when switching between positive and negative voltages simultaneously, which would affect the continuous operation of the pumping unit motor.

[0050] In this invention, the DC inverter decryption module includes: a second microcontroller and a second control switch group; the second microcontroller is connected to the second control switch group, which is respectively connected to each wire core in the cable and the positive and negative DC bus of the inverter; the second microcontroller is connected to the DC sequence module, and the second microcontroller is used to control the wire cores containing the positive and negative voltages in the cable to connect to the corresponding positive and negative DC bus of the inverter through the second control switch group after receiving the wire core information and after a second predetermined time.

[0051] In this embodiment of the invention, when there are 3 cable cores, the second control switch group includes four switching elements, namely Y1, Y2, Y3 and Y4.

[0052] Y1, Y2, Y3, and Y4 are connected to the second microcontroller. Y4 is connected to the positive voltage DC bus of the frequency converter and the other end of the A core of the cable. Y3 is connected to the negative voltage DC bus of the frequency converter and the other end of the C core of the cable. One end of the B core of the cable is connected to the positive voltage DC bus of the frequency converter through Y1 and to the negative voltage DC bus of the frequency converter through Y2.

[0053] By controlling the closing or opening of four switching elements, the positive and negative voltages of any two wires can be transmitted to the frequency converter. For example, if Y4 and Y3 are controlled to be closed and Y2 and Y1 are controlled to be open, then the positive and negative voltages will be transmitted to the frequency converter by wires A and C.

[0054] When the first microcontroller controls the switching circuit, it sends the core information after the switch to the second microcontroller via a wireless transmission module. For example, the core information is the positive voltage of core A and the negative voltage of core B. After sending the core information, the first microcontroller controls the positive and negative voltage output terminals of the rectifier module to connect with the corresponding cores A and B. After receiving the core information, the second microcontroller times and determines that after a second predetermined time, it controls Y3 to disconnect and Y2 to close, so that cores A and B form a circuit, completing the circuit switching. The second predetermined time is 10 seconds. The second predetermined time is used to ensure that during the switching, one end of the core to be switched is connected to the rectifier module first, and the other end of the core is connected to the inverter after a predetermined second time delay. This allows the core to be switched to be charged within the second predetermined time, preventing surge voltage from occurring when both ends of the core are connected simultaneously, which could damage the inverter. This allows the inverter to smoothly receive the current in the switched circuit.

[0055] During the next switch, if the circuit needs to be switched to conductors B and C, the first microcontroller sends the positive voltage information of conductor B and the negative voltage information of conductor C to the second microcontroller. After a second predetermined time, the second microcontroller controls Y4 to open and Y1 to close, thus forming a circuit with conductors B and C. If there are more than three conductors, more switching elements need to be set up accordingly to achieve circuit switching.

[0056] In implementation, this invention allows the rectifier section (rectifier module) of the original pumping well inverter drive to be moved to the transformer end, while the inverter section remains in the original distribution box. The DC section in the middle of the inverter is lengthened, and the cable core is connected to the DC bus of the inverter's DC line through a switching element. After the DC power from the cable core is transmitted to the inverter, it is converted into AC power by the inverter module inside the inverter and then transmitted to the pumping well motor, thus achieving DC input and saving operating costs.

[0057] In this invention, the step of connecting the cores containing the positive and negative voltages in the switched cable to the corresponding positive and negative DC busbars of the frequency converter includes: when the second microcontroller receives the core information, it controls the connection of the cores containing the positive and negative voltages in the cable to the corresponding positive and negative DC busbars of the frequency converter through the second switch group; after a third predetermined time, the original connected cores before the switch are disconnected from the positive or negative DC busbars of the frequency converter.

[0058] In this embodiment of the invention, before the current circuit switching is performed, the wire core connected to the inverter is the original circuit core. For example, Y1 and Y2 are in the open state, and Y3 and Y4 are in the closed state. The original connection circuit is that wire core A is connected to the positive voltage DC bus of the inverter, and wire core C is connected to the negative voltage DC bus of the inverter. When the circuit switching is performed, the second microcontroller receives the wire core information, and after a second predetermined time, if the circuit is to be switched to wire cores A and B, the second microcontroller first controls Y2 to be closed, that is, to connect the negative voltage DC bus of the inverter to the unenergized wire core B in the cable core. After a third predetermined time, the second microcontroller controls Y3 to be opened, that is, to disconnect the connection between the negative voltage DC bus of the inverter and the original connection (circuit) wire core.

[0059] During circuit switching, the circuit to be switched is connected first to ensure current in the conductor, and then the original connecting conductor is disconnected after a delay. This allows the inverter to smoothly receive the current transmitted by the positive and negative conductors through the DC inverter decryption module, preventing instantaneous voltage fluctuations when switching between positive and negative voltages simultaneously, which would affect the continuous operation of the pumping unit motor.

[0060] By setting the DC sequence conversion module and DC inverter decryption module to connect the core to be switched first when switching the circuit, the positive or negative voltage output terminal of the rectifier module and the positive or negative voltage DC bus of the frequency converter are connected to the two cores at the same time. After a 10-second delay, the core that was connected before the switch is disconnected from the two cores connected at the same time, thereby improving the current stability.

[0061] In this invention, before switching the circuit, it is checked whether the core to be switched is grounded or short-circuited. If so, the circuit is not switched to that core.

[0062] In this embodiment of the invention, the method for checking whether the conductor to be switched has a grounding or short circuit includes: a first microcontroller connected to a resistance tester, the resistance tester being connected to each conductor in the cable; before switching, the first microcontroller uses the resistance tester to detect whether the insulation resistance of the conductor to be switched to is greater than 0.5Ω; if so, it indicates that the conductor has a grounding phenomenon; the first microcontroller uses the resistance tester to detect whether the DC resistance of the conductor to be switched to is greater than 1Ω; if so, it indicates that the conductor has a short circuit. For example, if the conductors forming the return circuit before switching are A and C, and the switching is to switch conductors A and C to A and B, then before switching, it is necessary to use the resistance tester to detect whether conductor B has a grounding or short circuit. If so, the circuit cannot be switched to conductor B.

[0063] Meanwhile, the first microcontroller will start timing after each circuit switch. If the next circuit switch is not performed after a predetermined time, such as more than 3 hours, the alarm unit will be activated.

[0064] In this invention, a current comparison module is also included; the current comparison module is connected to the transformer and the frequency converter respectively, and the current comparison module is used to count the total current output by the transformer and the total current received by the frequency converter, and calculate the difference between the two; if the difference is greater than a predetermined percentage of the total current output by the transformer, the alarm module is controlled to sound an alarm.

[0065] In this embodiment of the invention, the predetermined percentage is 10%. Under normal power supply conditions, the difference between the current output by the inverter and the current received by the inverter should not be less than 10% of the total output current. If it exceeds 10%, it indicates that there may be electricity theft or a fault in the line, and the cable line needs to be inspected.

[0066] In this invention, the signal transmission distance of the wireless transmission module is less than or equal to 200 meters.

[0067] In this embodiment of the invention, the wireless transmission module can employ Zigbee communication technology. This technology is suitable for short-range and low-speed wireless communication, thus limiting the DC inverter decryption module to use only in close proximity with the DC sequence conversion module. Even if the DC inverter decryption module is stolen, it cannot obtain cable core circuit switching information over a long distance. Generally, the cable length between the transformer and the frequency converter at the power supply is around 100 meters. A wireless transmission module with a transmission distance of 200 meters can fully meet the requirements, and the data transmission speed is faster and more stable.

[0068] The invention also includes: an anti-theft box; the low-voltage side of the transformer and the DC sequence conversion module are located inside the anti-theft box; a wireless combination lock is provided at the door of the anti-theft box; and an alarm device connected to the wireless combination lock is provided inside the anti-theft box.

[0069] In this embodiment of the invention, the anti-theft enclosure seals the low-voltage side of the transformer inside. The enclosure is equipped with an alarm device. If the enclosure is forcibly opened without inputting an unlock command via the network, the alarm will be triggered.

[0070] It is understood that the various method embodiments mentioned above in this invention can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this invention will not elaborate further.

[0071] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0072] This invention addresses the shortcomings of existing anti-theft technologies by designing a DC disordered anti-theft device. It converts directly usable AC power for civilian use into DC power, which is inconvenient for civilian applications, using a rectifier. To further prevent electricity theft, an internal DC sequence-changing module randomly alters the current sequence in the cable, further preventing thieves from installing bypass circuits in the power circuit and using DC power. This fundamentally eliminates the possibility of electricity being used for civilian purposes while ensuring that production power is not affected, thus technically resolving the issue of electricity theft.

[0073] This invention converts alternating current into disordered direct current, preventing electricity thieves from using it unless they can decipher the DC phase sequence. This fundamentally ensures that the power is usable in oil fields but not for civilian use. The invention has already been tested and applied in actual production by injection and production teams in the work area, achieving significant results and demonstrating broad application and promotion value.

[0074] 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. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A device for preventing theft of electricity in oil pumping wells, characterized in that, include: Rectifier module, DC sequence conversion module, and DC inverter decryption module; The rectifier module is connected to the pumping unit well transformer, the DC sequence conversion module is connected to the rectifier module for converting the AC output of the transformer into DC, and is connected to the DC inverter decryption module via a cable; The DC sequence conversion module is used to transmit the positive and negative voltages of the DC power output from the rectifier module to two cores of the cable, and randomly switch the circuit among all cores. Simultaneously, it sends the core information corresponding to the positive and negative voltages after the switch to the DC inverter decryption module. The random circuit switching among all cores includes: during circuit switching, first randomly connecting the positive or negative voltage output terminal of the transformer to any unenergized core in the cable; after a first predetermined time, disconnecting the previously connected core from the positive or negative voltage output terminal of the transformer; the DC sequence conversion module switches circuits at predetermined intervals or random intervals; the first predetermined time is 10~20 seconds. The DC inverter decryption module is connected to the pumping unit motor via a frequency converter. The DC inverter decryption module is used to connect the cores with positive and negative voltages in the switched cable to the corresponding positive and negative voltage DC bus of the frequency converter according to the received core information. The inverter module inside the frequency converter converts the DC power into AC power and transmits it to the pumping unit motor. The step of connecting the cores containing the positive and negative voltages in the switched cable to the corresponding positive and negative DC bus of the frequency converter includes: when the DC inverter decryption module receives the core information, and after a second predetermined time, controlling the cores containing the positive and negative voltages in the cable to connect to the corresponding positive and negative DC bus of the frequency converter, and after a third predetermined time, disconnecting the original connected cores before the switch from the positive or negative DC bus of the frequency converter.

2. The anti-theft electrical device for oil pumping wells according to claim 1, characterized in that: The rectifier module is also used to boost the voltage output by the transformer to a predetermined voltage and then transmit it to the DC sequence conversion module; The frequency converter is used to convert the DC power transmitted through the cable into AC power, and then step it down to a predetermined pressure range before transmitting it to the pumping unit motor.

3. The anti-theft electrical device for oil pumping wells according to claim 1, characterized in that, The DC sequence conversion module includes: a first microcontroller, a first control switch group, and a wireless transmission module; The first microcontroller is connected to the first control switch group, which is connected to the positive and negative voltage output terminals of the transformer and to each wire core in the cable. The first microcontroller is used to control the connection or disconnection of the circuit between the positive voltage output terminal and / or negative voltage output terminal of the transformer and each wire core through the first control switch group. The first microcontroller is connected to the DC inverter decryption module via a wireless transmission module. The first microcontroller is used to send the information of the wire cores connected to the first control switch group to the DC inverter decryption module via the wireless transmission module each time a circuit switch is performed.

4. The anti-theft electrical device for oil pumping wells according to claim 1, characterized in that, The DC inverter decryption module includes: a second microcontroller and a second control switch group; The second microcontroller is connected to the second control switch group, and the second control switch group is connected to each wire core in the cable and the positive and negative DC bus of the frequency converter respectively; The second microcontroller is connected to the DC sequence conversion module. When the second microcontroller receives the core information and after a second predetermined time, it controls the cores containing the positive and negative voltages in the cable to connect to the corresponding positive and negative voltage DC bus of the frequency converter through the second control switch group.

5. The anti-theft electrical device for oil pumping wells according to claim 4, characterized in that: The second predetermined time is 10 seconds.

6. The anti-theft electrical device for oil pumping wells according to claim 1, characterized in that: Before switching the circuit, check whether the core to be switched is grounded or short-circuited. If so, do not switch the circuit to that core. The timer starts after each circuit switch. If no next circuit switch is performed within 3 hours, the alarm unit will sound an alarm.

7. The anti-theft electrical device for oil pumping wells according to claim 1, characterized in that, It also includes a current comparison module; The current comparison module is connected to the transformer and the frequency converter respectively. The current comparison module is used to count the total current output by the transformer and the total current received by the frequency converter, and calculate the difference between the two. If the difference is greater than a predetermined percentage of the total output current of the transformer, the alarm module is controlled to sound an alarm.

8. The anti-theft electrical device for oil pumping wells according to claim 3, characterized in that: The signal transmission distance of the wireless transmission module is less than or equal to 200 meters.

9. The anti-theft electrical device for oil pumping wells according to any one of claims 1-8, characterized in that, Also includes: Anti-theft box; The low-voltage side of the transformer and the DC sequence conversion module are located inside the anti-theft box. The door of the anti-theft box is equipped with a wireless combination lock, and an alarm device connected to the wireless combination lock is installed inside the anti-theft box.

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