Electric submersible pump counter electromotive force monitor

Abstract

The utility model provides a counter electromotive force monitor for an electric submersible pump. The counter electromotive force monitor comprises a sampling voltage division circuit, a rectification filter circuit, a signal amplitude limiting circuit, a hysteresis comparator and an amplification output circuit which are connected in sequence, the output end of the amplification output circuit is connected with the controller; the input end of the sampling voltage division circuit is connected with any two lines of three drive lines of the electric submersible pump, and the sampling voltage division circuit divides collected high voltage signals into low voltage signals. The rectifying and filtering circuit rectifies and filters a low-voltage signal into a direct-current signal, and the signal amplitude limiting circuit limits the amplitude of the filtered direct-current signal; when the voltage is high, the amplification output circuit is used for outputting a control signal or giving an alarm, the counter electromotive force of the submersible motor is monitored in real time, and an electric shock accident caused by leakage of a protection cable on site or poor wiring of the protection cable is prevented.

Description

Technical Field

[0001] This utility model relates to the field of oil extraction technology, and in particular to a back EMF monitor for a submersible electric pump. Background Technology

[0002] The oil extraction industry employs various extraction methods depending on the formation, crude oil viscosity, underground pressure, and other different oil and gas environments. Electric Submersible Pumps (ESPs) are a type of artificial lift oil extraction method that uses a submersible motor to drive an electric submersible multistage centrifugal pump to lift crude oil from the well to the surface. An ESP system consists of three parts: the downhole unit, surface control, and power transmission. The downhole unit mainly comprises an electric submersible multistage centrifugal pump, a separator, a submersible motor, and a motor protector. Electricity from the surface is transmitted to the well via an ESP cable. The motor protector (to prevent well fluid from entering the motor) then transmits the power to the submersible motor, which drives the electric submersible multistage centrifugal pump.

[0003] The submersible pump motor is the core component of the submersible pump unit. Depending on the application environment, there are various types, such as oil-filled submersible motors, water-filled submersible motors, dry-type submersible motors, and shielded submersible motors. However, based on the rotor structure and excitation method, submersible pump motors can also be divided into three-phase asynchronous submersible motors, permanent magnet synchronous submersible motors, and excitation synchronous submersible motors. Permanent magnet synchronous submersible motors have permanent magnets installed on their rotors, relying on these magnets to provide the magnetic field. They have advantages such as high efficiency, high power factor, and good speed regulation performance. Excitation synchronous submersible motors have excitation windings on their rotors, generating a magnetic field by applying direct current. The magnetic field strength can be adjusted as needed, making them suitable for applications with high motor performance requirements.

[0004] Submersible motors operate at relatively high voltages, typically around 400V-2600V. For example, some small oil wells or submersible motors operating under normal conditions may operate at voltages between 400V and 1500V; while some large oil wells or scenarios requiring higher power may use operating voltages of 2000V and above.

[0005] When a submersible electric pump (ESP) is initially deployed or shut down, the presence of crude oil in the pipeline causes the pump and motor to rotate, putting the motor in a reverse generating state. Especially since high-voltage permanent magnet synchronous ESP motors can generate voltages as high as several hundred volts, this poses a risk of electric shock to personnel involved in pump deployment or maintenance. Current solutions involve short-circuiting the motor current and grounding it during deployment to prevent high-voltage electric shocks from the cable, but there is no monitoring for short-circuit grounding issues. This means that in the event of negligence during deployment, high voltage may remain on the cable, posing a risk to workers. Utility Model Content

[0006] The purpose of this invention is to at least solve one of the aforementioned technical defects.

[0007] Therefore, one objective of this utility model is to provide a back EMF monitor for a submersible electric pump, which monitors the back EMF of the submersible motor in real time to prevent electric shock accidents caused by missing or poorly connected protective cables.

[0008] To achieve the above objectives, one embodiment of this utility model provides a back EMF monitor for a submersible electric pump, comprising: a sampling voltage divider circuit, a rectifier filter circuit, a signal limiting circuit, a hysteresis comparator, and an amplification output circuit connected in sequence; the hysteresis comparator compares the voltages, and the output terminal of the amplification output circuit is connected to a controller; when the voltage is high, the amplification output circuit outputs a control signal or alarm to monitor the back EMF of the submersible motor in real time.

[0009] The input terminal of the sampling voltage divider circuit is connected to any two of the three drive lines of the submersible pump, which divides the high voltage signal into a low voltage signal; the rectifier and filter circuit rectifies and filters the low voltage signal into a DC signal; and the signal limiting circuit limits the amplitude of the filtered DC signal.

[0010] The hysteresis comparator includes a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a capacitor; wherein the first resistor is connected to the non-inverting input terminal of the first operational amplifier, one end of the third resistor is connected to the inverting input terminal, and the other end is connected to the high level VCC; the second resistor is connected between the non-inverting input terminal and the output terminal; the capacitor is connected in parallel with the fourth resistor, with one end connected to the inverting input terminal and the other end grounded.

[0011] More preferably, the sampling voltage divider circuit includes two identical voltage divider branches and a total voltage divider resistor connected in series between the two voltage divider branches, wherein any one branch includes multiple voltage divider resistors connected in series to a drive line of the submersible pump.

[0012] More preferably, the rectifier-filter circuit includes a rectifier bridge and an LC filter network; wherein the two AC input terminals of the rectifier bridge are respectively connected to a voltage divider branch.

[0013] More preferably, the signal limiting circuit uses a Zener diode.

[0014] More preferably, a voltage follower is provided between the signal limiting circuit and the hysteresis comparator.

[0015] More preferably, the amplification output circuit includes a first transistor and a second transistor connected in an NPN Darlington configuration, a fifth resistor disposed between the base of the first transistor and the output terminal of the hysteresis comparator, and a sixth resistor connected in parallel therewith; the bases of the first transistor and the bases of the second transistor are respectively connected to a resistor grounded.

[0016] More preferably, the controller is a relay or a PLC.

[0017] More preferably, the amplified output circuit further includes a reverse voltage protection diode disposed between one of the output terminals and VCC, wherein the anode of the reverse voltage protection diode is connected to VCC; the cathode of the reverse voltage protection diode is connected to the cathode of the load freewheeling diode; the anode of the load freewheeling diode is connected to the collector of the first transistor; and a TVS diode disposed at the other output terminal, wherein the other end of the TVS diode is grounded.

[0018] A further preferred embodiment includes an indicator circuit, wherein the indicator circuit includes a first light-emitting diode and a second light-emitting diode; the first light-emitting diode is connected to a power supply, and the second light-emitting diode is connected to the output terminal of the amplification output circuit.

[0019] According to the embodiment of this utility model, the back EMF monitor for submersible electric pump can continuously monitor the back EMF of the motor compared to the prior art. When the back EMF of the motor is greater than the safe voltage for the human body, an alarm signal is issued to remind on-site workers that the motor is energized and to be careful to avoid electric shock.

[0020] This application uses a hysteresis comparator to convert the acquired signal into a fast-response pulse signal, which has strong anti-interference ability, eliminates poor output conversion, speeds up the response, improves stability, and effectively eliminates jitter.

[0021] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 A circuit connection block diagram of a back EMF monitor for a submersible electric pump provided by this utility model;

[0024] Figure 2 This is a schematic diagram of the sampling voltage divider circuit, rectifier filter circuit, and signal limiting circuit in this utility model.

[0025] Figure 3This is a circuit diagram of the hysteresis comparator and the amplified output circuit in this utility model.

[0026] In the picture:

[0027] 1. Sampling voltage divider circuit; 2. Rectifier and filter circuit; 3. Signal limiting circuit; 4. Hysteresis comparator; 5. Amplifier output circuit; 6. Controller; Detailed Implementation

[0028] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0029] like Figure 1 As shown in the figure, a back EMF monitor for a submersible electric pump according to an embodiment of the present invention includes: a sampling voltage divider circuit 1, a rectifier and filter circuit 2, a signal limiting circuit 3, a hysteresis comparator 4, and an amplifier output circuit 5 connected in sequence; the output terminal of the amplifier output circuit is connected to a controller 6.

[0030] The input terminal of the sampling voltage divider circuit 1 is connected to any two of the three drive lines of the submersible pump, which divides the high voltage signal into a low voltage signal; the rectifier and filter circuit 2 rectifies and filters the low voltage signal into a DC signal; and the signal limiting circuit 3 limits the amplitude of the filtered DC signal.

[0031] like Figure 2 The sampling voltage divider circuit 1 includes two identical voltage divider branches and a total voltage divider resistor connected in series between the two branches. Each branch includes multiple voltage divider resistors connected in series to a drive line of the submersible pump. The sampling voltage divider circuit includes resistors R6, R7, R34, R35, and R36 connected in series in the first voltage divider branch; and resistors R8, R9, R10, R37, and R38 connected in series in the second branch. Resistor R11 connects the first and second voltage divider branches, dividing the high-voltage signal into a low-voltage signal while reducing signal energy.

[0032] More preferably, the rectifier-filter circuit 2 includes a rectifier bridge and an LC filter network; wherein the two AC input terminals of the rectifier bridge are respectively connected to a voltage divider branch. The rectifier bridge DB1, resistor R14, capacitor C2, capacitor E2, and diode D4 constitute a rectifier-filter and signal limiting circuit, and the signal limiting circuit 3 uses a Zener diode D4; the high-voltage AC signal is sampled and divided before entering DB1 for full-bridge rectification. After rectification, the signal becomes a DC pulsating signal. This DC pulsating signal is filtered by C2 and E2 and then becomes a DC signal, which is then limited by D4.

[0033] The hysteresis comparator 4 includes a first operational amplifier chip U1A, a first resistor R17, a second resistor R18, a third resistor R15, a fourth resistor R16, and a capacitor C3; wherein the first resistor R17 is connected to the non-inverting input terminal of the first operational amplifier U1A, one end of the third resistor R15 is connected to the inverting input terminal, and the other end is connected to the high level VCC; the second resistor R18 is connected between the non-inverting input terminal and the output terminal; the capacitor C3 is connected in parallel with the fourth resistor R16, with one end connected to the inverting input terminal and the other end grounded.

[0034] Furthermore, a voltage follower is provided between the signal limiting circuit 3 and the hysteresis comparator 4. Chip U1B is a voltage follower, providing a high-impedance load to the preceding circuit to reduce its impact, while simultaneously providing a low-impedance signal source to the following circuit, achieving isolation between the preceding and following stages. After limiting, the signal passes through U1B and enters the hysteresis comparator composed of U1A, R17, R18, R15, R16, and C3. This comparator determines whether to activate based on the input voltage level. The hysteresis comparator, also known as a Schmitt trigger comparator, is a special type of comparator with strong anti-interference capabilities, elimination of poor output conversion, faster response speed, and improved stability. Here, the hysteresis comparator is set to operate at 36V and recover at 25V, effectively eliminating jitter.

[0035] More preferably, the amplification output circuit 5 includes a first transistor Q1 and a second transistor Q2 connected in an NPN Darlington configuration, a fifth resistor R22 and a sixth resistor R23 connected in parallel between the base of the first transistor Q1 and the output terminal of the hysteresis comparator 4; the base of the first transistor Q1 and the base of the second transistor Q2 are respectively connected to a resistor grounded.

[0036] More preferably, the amplified output circuit 5 further includes a reverse voltage protection diode disposed between one of the output terminals and VCC, wherein the anode of the reverse voltage protection diode is connected to VCC; the cathode of the reverse voltage protection diode is connected to the cathode of the load freewheeling diode; the anode of the load freewheeling diode is connected to the collector of the first transistor; and a TVS diode disposed at the other output terminal, wherein the other end of the TVS diode is grounded.

[0037] A further preferred embodiment includes an indicator circuit, comprising a first LED and a second LED; the first LED is connected to a power supply, and the second LED is connected to the output terminal of the amplification output circuit. The controller 6 is a relay or a PLC. The output signal can directly control the relay to perform opening and closing actions, or it can be input into the PLC to display the acquired signal.

[0038] Transistors Q1 and Q2, resistors R22, R23, R20, and R21, and diodes D1, D2, and D3 constitute the output amplifier stage circuit of the device. Q1 and Q2 are connected in an NPN Darlington configuration. The Darlington connection features high current gain, high input impedance, and low output impedance. If the current gains of individual transistors are β1 and β2, then the equivalent current gain after the Darlington connection is βDarlington ≈ β1·β2, typically reaching several hundred to several thousand times. This high current gain characteristic allows the Darlington connection to control a large output current with a small base current, which is very useful in applications requiring amplification of weak current signals. The reason for using a Darlington output in this amplifier stage is to reduce the output current requirements of the preceding operational amplifier, enabling the driving of large current loads with a small current. Diode D1 is a reverse voltage protection diode to prevent damage to the device from external high-voltage pulses at the interface. Diode D2 is a freewheeling diode for inductive loads, preventing overvoltage during disconnection. Diode D3 is a TVS diode, which can absorb surge current and protect the interface.

[0039] Capacitors C1 and E1, resistors R24 and R25, and LEDs LED1 and LED2 form a power supply filtering and indicator circuit. Capacitors C1 and E1 are power supply filter capacitors. Resistor R24 ​​and LED1 are the power indicator light, which illuminates when power is available. Resistor R25 and LED2 are the operation indicator circuit; the indicator light illuminates when an overvoltage fault is detected and remains off when no fault is detected.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A back EMF monitor for a submersible electric pump, characterized in that, include: The circuit consists of a sampling voltage divider circuit, a rectifier and filter circuit, a signal limiting circuit, a hysteresis comparator, and an amplifier output circuit, connected in sequence. The hysteresis comparator compares the voltages, and the output of the amplifier output circuit is connected to a controller. The input terminal of the sampling voltage divider circuit is connected to any two of the three drive lines of the submersible pump, which divides the high voltage signal into a low voltage signal; the rectifier and filter circuit rectifies and filters the low voltage signal into a DC signal; and the signal limiting circuit limits the amplitude of the filtered DC signal. The hysteresis comparator includes a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a capacitor; The first resistor is connected to the non-inverting input of the first operational amplifier; one end of the third resistor is connected to the inverting input, and the other end is connected to the high level VCC; the second resistor is connected between the non-inverting input and the output; the capacitor is connected in parallel with the fourth resistor, with one end connected to the inverting input and the other end grounded.

2. The submersible electric pump back EMF monitor according to claim 1, characterized in that, The sampling voltage divider circuit includes two identical voltage divider branches and a total voltage divider resistor connected in series between the two voltage divider branches, wherein any one branch includes multiple voltage divider resistors connected in series to a drive line of the submersible pump.

3. The submersible electric pump back EMF monitor according to claim 2, characterized in that, The rectifier and filter circuit includes a rectifier bridge and an LC filter network; wherein the two AC input terminals of the rectifier bridge are each connected to a voltage divider branch.

4. The back EMF monitor for a submersible electric pump according to claim 1, characterized in that, The signal limiting circuit uses a Zener diode.

5. The back EMF monitor for a submersible electric pump according to claim 1, characterized in that, A voltage follower is provided between the signal limiting circuit and the hysteresis comparator.

6. The back EMF monitor for a submersible electric pump according to claim 1, characterized in that, The amplification output circuit includes a first transistor and a second transistor connected in an NPN Darlington configuration, a fifth resistor and a sixth resistor connected in parallel between the base of the first transistor and the output of the hysteresis comparator; the bases of the first transistor and the second transistor are respectively connected to a resistor grounded.

7. The submersible electric pump back EMF monitor according to claim 1, characterized in that, The controller is a relay or a PLC.

8. The submersible electric pump back EMF monitor according to claim 1, characterized in that, The amplified output circuit also includes a reverse voltage protection diode disposed between one of the output terminals and VCC, wherein the anode of the reverse voltage protection diode is connected to VCC; the cathode of the reverse voltage protection diode is connected to the cathode of the load freewheeling diode; the anode of the load freewheeling diode is connected to the collector of the first transistor; and a TVS diode disposed at the other output terminal, wherein the other end of the TVS diode is grounded.

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