Shutdown delay protection system for frequency conversion cabinet of oil pumping unit

Abstract

The invention relates to a pumping unit frequency conversion cabinet shutdown time-delay protection system, which comprises a shutdown time-delay protection device for performing shutdown time-delay protection on a frequency converter, and is characterized in that the shutdown time-delay protection device of the frequency converter comprises a power supply circuit for converting 220V alternating-current phase voltage into 12V direct-current voltage and providing the 12V direct-current voltage for a time-base integrated circuit NE555; a low trigger end THR port of the time-base integrated circuit NE555 receives a shutdown signal of the frequency converter, and a discharge end DIS port of the time-base integrated circuit NE555 is connected with a base electrode of the triode Q1 through a resistor R2; an emitting electrode of the triode Q1 is grounded, and a coil of a relay RLY1 is connected in series between a collector electrode of the triode Q1 and + 12V direct-current voltage; and a normally open contact of the relay RLY1 is connected in series in a coil loop of an alternating current contactor of an output loop of the frequency converter. The device not only realizes shutdown instant trigger delay protection, but also can be immediately started to run after a period of time delay.

Description

Technical Field

[0001] The invention relates to energy-saving control of oil field ground pumping units, in particular to a pumping unit frequency conversion cabinet shutdown delay protection system, belonging to the technical field of pumping unit control. Background Art

[0002] The walking beam pumping unit is like a balance. The middle part of the walking beam is hinged to the top of the bracket through the middle bearing. With the middle bearing as the fulcrum, the walking beam swings back and forth at a certain angle. The head end of the walking beam is connected to a donkey head, which bears the pumping load; the tail shaft bearing seat is fixed below the tail end of the walking beam, and a crossbeam is fixed below the tail shaft bearing seat. The axis of the crossbeam is perpendicular to the axis of the walking beam. Connecting rods are hinged at the front and rear ends of the crossbeam, and connecting rod flanges are provided at the lower ends of the two connecting rods. The two connecting rod flanges are connected to the crank mechanism through crank pins and are provided with a balancing counterweight load.

[0003] When working, the power machine transmits high-speed rotational motion to the crankshaft through the belt and the reduction box, driving the crankshaft to do low-speed rotational motion. The crank mechanism drives the tail end of the walking beam to swing back and forth up and down through two connecting rods and the crossbeam, and the donkey head at the head end of the walking beam also swings up and down. The rope hanger hung on the donkey head drives the bare rod and the sucker rod to move up and down through the rope braid. The lower end of the sucker rod drives the plunger of the downhole deep well pump to move up and down, thereby continuously pumping the crude oil in the well out of the wellbore.

[0004] At present, most of the oil field walking beam pumping units are driven by permanent magnet synchronous motors, which are hereinafter referred to as pumping motors and are controlled by frequency converters. During operation, the load on them changes periodically. When the donkey head moves upward to pump crude oil out of the wellbore, the load on the donkey head is very large, and the tail end of the walking beam is balanced by the counterweight to balance the load on the head end. When the frequency converter cuts off the power of the pumping motor, the donkey head will swing for a distance before stopping in most cases. During the few seconds of the donkey head swinging, it will drag the pumping motor to generate negative electricity. Frequent start and stop of the pumping unit can easily cause damage to the inverter, especially the capacitor of the inverter.

[0005] Therefore, it is necessary to add a delay protection device to the frequency converter cabinet to ensure that the pumping motor cannot be started immediately after the pumping unit is shut down for a period of time. The commonly used delay device is the call delay, which requires a delay and wait for a period of time before running each time it is started, and it is impossible to start the machine immediately after a period of shutdown delay.

[0006] The Chinese utility model patent with publication number CN217135150U discloses a time-delay protection control circuit, which is applied to a switching power supply. The switching power supply circuit associated with the time-delay protection control circuit includes an output control circuit, a power output circuit and a feedback circuit. The time-delay protection control circuit includes a current sensing circuit, a voltage-stabilizing power supply circuit and a time-delay control circuit. The output control circuit is electrically connected to the feedback circuit and the power output circuit. The load and the current sensing circuit are electrically connected to the output end of the power output circuit. The voltage-stabilizing circuit is electrically connected to the feedback circuit and the time-delay control circuit respectively. The time-delay control circuit is electrically connected to the feedback circuit and the current sensing circuit respectively. When the output end of the current sensing circuit is overcurrent, the time-delay control circuit outputs a control signal to the feedback circuit by obtaining the current delay at the output end of the current sensing circuit. The feedback circuit feeds back a signal to the output control circuit according to the control signal. The output control circuit disconnects the output of the power output circuit according to the feedback signal to achieve a time-delay protection effect.

[0007] The delayed protection control circuit has the following shortcomings: the protection control output is the power output circuit, the trigger source is the overcurrent signal at the output end of the power output circuit, and when the overcurrent at the output end of the power output circuit is sensed, the protection action is implemented after a delay period; when the overcurrent phenomenon at the output end disappears, the protection action is canceled, and there is repeated oscillating protection. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the call trigger delay in the prior art and to provide a pumping unit frequency conversion cabinet shutdown delay protection system, which adopts the pulse rising edge trigger delay to realize the shutdown instant trigger delay protection. After a delay period, the system can start running immediately without having to wait for a period of time each time it is started.

[0009] In order to solve the above technical problems, a shutdown delay protection system for a pumping unit frequency conversion cabinet of the present invention includes a shutdown delay protection device for performing shutdown delay protection on a frequency converter, and the shutdown delay protection device includes: The power supply circuit converts the 220V AC phase voltage into a 12V DC voltage and supplies it to the time base integrated circuit NE555; The time base integrated circuit NE555, its low trigger terminal THR port receives the shutdown signal of the inverter, and the discharge terminal DIS port of NE555 is connected to the base of the transistor Q1 through the resistor R2; In the transistor amplifier circuit, the emitter of the transistor Q1 is grounded, and the coil of the relay RLY1 is connected in series between the collector of the transistor Q1 and the +12V DC voltage; the normally open contact of the relay RLY1 is connected in series in the coil loop of the AC contactor KM3 of the inverter output loop.

[0010] As an improvement of the present invention, the 12V DC voltage is connected to the low trigger end THR port of the timing integrated circuit NE555 through the normally closed auxiliary contact of the inverter output circuit AC contactor KM3; the main contact of the inverter output circuit AC contactor KM3 is connected in series in the power circuit connected to the inverter output end and the oil pumping motor.

[0011] As a further improvement of the present invention, the power supply circuit includes: Step-down transformer, the primary winding is connected to the single-phase 220V AC phase voltage in the frequency converter cabinet, and the secondary winding is connected to the AC side of the rectifier B1; The rectifier rectifies the 220V AC voltage into a 21V DC voltage, and the DC side is connected to the input end of the three-terminal voltage regulator block U1 through a pre-stabilization filter circuit; The three-terminal voltage regulator steps down the 21V DC voltage and stabilizes it to 12V DC voltage for output.

[0012] As a further improvement of the present invention, the output end of the three-terminal voltage stabilizing block U1 is provided with a post-voltage stabilizing filtering circuit, and the post-voltage stabilizing filtering circuit includes a capacitor C1 and a capacitor C4 connected in parallel with each other, one end of the capacitor C1 and the capacitor C4 is connected to the output end of the three-terminal voltage stabilizing block U1, and the other end is grounded.

[0013] As a further improvement of the present invention, the pre-stabilization filter circuit includes a capacitor C2 and a capacitor C7 connected in parallel with each other, one end of the capacitor C2 and the capacitor C7 is connected to the input end of the three-terminal voltage stabilization block U1, and the other end is grounded.

[0014] As a further improvement of the present invention, a trigger filter discharge circuit is provided between the normally closed auxiliary contact of the AC contactor KM3 of the inverter output circuit and the low trigger terminal THR port of NE555.

[0015] As a further improvement of the present invention, the trigger filter discharge circuit includes a pull-down resistor R6, a discharge resistor R7, a charging resistor R8, a coupling capacitor C5 and a filter capacitor C6. The charging resistor R8 and the coupling capacitor C5 are connected in series between the normally closed auxiliary contact of the inverter output circuit AC contactor KM3 and the low trigger end THR port of NE555. The node between the charging resistor R8 and the coupling capacitor C5 is grounded through the filter capacitor C6, and the two sides of the coupling capacitor C5 are grounded through the pull-down resistor R6 and the discharge resistor R7 respectively.

[0016] As a further improvement of the present invention, the Q output port of the time base integrated circuit NE555 is grounded through the resistor R4 and the capacitor C3, and the TRIG port of the time base integrated circuit NE555 is connected to the positive electrode of the capacitor C3.

[0017] As a further improvement of the present invention, the Q output port of the time base integrated circuit NE555 is further connected to the positive electrode of the capacitor C3 through the diode D2 and the resistor R3.

[0018] As a further improvement of the present invention, the discharge terminal DIS of the time base integrated circuit NE555 is further connected to the emitter of the transistor Q1 through a light emitting diode L1.

[0019] As a further improvement of the present invention, one end of the resistor R2 is connected to a +12V DC voltage through a resistor R5, and the other end of the resistor R2 is connected to the base of the transistor Q1.

[0020] As a further improvement of the present invention, two ends of the coil of the relay RLY1 are connected with a freewheeling diode D1.

[0021] As a further improvement of the present invention, when the main contact of the AC contactor KM3 of the inverter output circuit connected in series in the main circuit of the inverter cabinet is disconnected to shut down the inverter cabinet, the normally closed auxiliary contact of the AC contactor KM3 of the inverter output circuit is closed, and the signal circuit of the low trigger end THR port of the time base integrated circuit NE555 is turned on, so that it is connected to the 12V DC voltage, and the low trigger end THR port rises from a low level to a high level. The discharge end DIS port of the time base integrated circuit NE555 is turned on to the ground in a low resistance state, the transistor Q1 is cut off, the coil of the relay RLY1 loses power, and the current in the coil is released through the freewheeling diode D1. The normally open contact of the relay RLY1 is disconnected, and the zero line circuit of the coil of the AC contactor KM3 of the inverter output circuit is cut off, so that the coil of the AC contactor KM3 of the inverter output circuit cannot be energized, and its main contact remains disconnected, so that the inverter cabinet cannot be started, thereby avoiding damage to the inverter when the donkey head swings and the oil pumping motor is negatively generated.

[0022] As a further improvement of the present invention, when the low trigger end THR port of the time base integrated circuit NE555 rises from a low level to a high level, the Q output port of the time base integrated circuit NE555 changes from a high level to a low level, and the TRIG port starts to discharge from a high level through the resistor R4, and the potential gradually becomes lower to realize the delay function.

[0023] As a further improvement of the present invention, when the potential of the TRIG port of the clock-based integrated circuit NE555 is lower than 4V, its Q output port changes from low level to high level, and the capacitor C3 is quickly charged through the diode D2 and the resistor R3, and the TRIG port of the second foot becomes high level to quickly restore the device to the trigger state.

[0024] As a further improvement of the present invention, the normally open contact of the relay RLY1 is connected in series between the A1 port of the shutdown delay protection device and the phase voltage neutral line; In the control circuit of the frequency converter, the start button SA1, the stop button SB1, the frequency conversion gear of the power frequency conversion switch SF1 and the coil of the AC contactor KM3 of the frequency converter output circuit are sequentially connected in series between the working end of the frequency converter switch and the A1 port of the shutdown delay protection device; The first auxiliary normally open contact KM3-1 of the AC contactor of the inverter output circuit is connected in parallel to both ends of the start button SA1, and the manual-automatic switch SF2 is connected in series with the delayed closed normally open contact of the delay relay SS and is also connected in parallel to both ends of the start button SA1; The second auxiliary normally open contact KM3-2 of the AC contactor of the inverter output circuit is connected to the starting end of the inverter.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. It adopts a new circuit, improves the operating experience, reduces the device cost, and realizes the long-term working reliability of the pumping unit frequency conversion cabinet; 2. The trigger delay circuit uses the time-base integrated circuit NE555, which has the advantages of low cost, easy use, wide adaptability, large driving current and certain load capacity; 3. When the frequency converter cabinet cuts off the power of the oil pumping motor, the donkey head will swing a certain distance before stopping in most cases. During the few seconds of the donkey head swinging, the oil pumping motor will be dragged to generate negative power. The present invention can prevent the frequency converter from being damaged when the oil pump is dragging the motor to generate negative power; 4. The frequency conversion cabinet not only realizes delayed protection, but also can start running immediately after a period of shutdown delay, avoiding redundant delay waiting every time it starts; 5. After the shutdown delay protection is executed, the device can quickly return to the initial waiting state. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The accompanying drawings are only provided for reference and explanation and are not intended to limit the present invention.

[0027] Figure 1 The electrical schematic diagram of the frequency conversion control cabinet of the oil pumping unit involved in the present invention; Figure 2 The electrical schematic diagram of the shutdown delay protection device in the present invention. Implementation

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] like Figure 1 As shown, the oil pumping unit frequency conversion cabinet shutdown delay protection system of the present invention includes a shutdown delay protection device for performing shutdown delay protection on the frequency converter, the A4 port of the shutdown delay protection device is connected to the AC 220V phase line, the A2 port is connected to the neutral line, and the A1 port is connected to the coil circuit of the AC contactor KM3 of the frequency converter output circuit. The shutdown delay protection device is installed in the oil pumping unit frequency conversion control cabinet, and the oil pumping motor M1 driving the oil pumping unit to operate is provided with a power frequency circuit and a frequency conversion circuit, and the total power supply is controlled by the air switch QF.

[0031] In the power frequency circuit, the main contact of the power frequency circuit AC contactor KM1 and the thermal relay FR are connected in series in the power circuit for controlling the oil pumping motor M1.

[0032] When industrial frequency operation is selected, the industrial frequency conversion switch SF1 is turned to the industrial frequency gear, the industrial frequency indicator light LP1 lights up, and after the start button SA1 is pressed, the coil of the industrial frequency circuit AC contactor KM1 is energized, and the normally open auxiliary contact KM1-1 of the industrial frequency circuit AC contactor KM1 closes for self-protection. At the same time, its main contact closes, and the oil pumping motor M1 starts to run.

[0033] When the stop button SB1 is pressed, the coil of the power frequency circuit AC contactor KM1 loses power, its main contact and normally open auxiliary contact KM1-1 are disconnected, and the oil pumping motor M1 stops.

[0034] In the frequency conversion main circuit, the lower terminal of the air switch QF is connected to the input end of the 80A filter through the main contact of the AC contactor KM2 in the frequency converter power supply circuit. The output end of the 80A filter provides power to the frequency converter. The main contact of the AC contactor KM3 in the frequency converter output circuit is connected in series in the power circuit between the frequency converter and the oil pumping motor M1.

[0035] In the control circuit of the frequency converter, the start button SA1, the stop button SB1, the frequency gear of the industrial frequency conversion switch SF1 and the coil of the frequency converter output circuit AC contactor KM3 are connected in series between the working end R1B of the frequency converter switch and the A1 port of the shutdown delay protection device. The first auxiliary normally open contact KM3-1 of the frequency converter output circuit AC contactor is connected in parallel at both ends of the start button SA1, and the second auxiliary normally open contact KM3-2 of the frequency converter output circuit AC contactor is connected to the starting end of the frequency converter.

[0036] When variable frequency operation is selected, the industrial frequency variable frequency switching switch SF1 is turned to the variable frequency gear, the coil of the inverter power supply circuit AC contactor KM2 is energized, its main contact is closed, and the frequency conversion indicator light LP2 lights up, and at the same time, 220V AC voltage is provided to the shutdown delay protection device.

[0037] After pressing the start button SA1, the coil of the AC contactor KM3 in the inverter output circuit is energized, its first auxiliary normally open contact KM3-1 is closed for self-protection, and the second auxiliary normally open contact KM3-2 is closed, starting the inverter; at the same time, the main contact of the AC contactor KM3 in the inverter output circuit is closed, and the inverter is able to control the operation of the oil pumping motor M1.

[0038] The starting end of the inverter is also connected to a manual switch SA2 for easy manual starting.

[0039] The fault terminal R1A of the inverter switching switch is connected in series with the fault indicator light LP3. When the inverter fails, it automatically switches to the fault terminal R1A, disconnects the working terminal R1B, and the fault indicator light LP3 lights up.

[0040] The manual-automatic transfer switch SF2 is connected in series with the delayed closing normally open contact of the delay relay SS and is also connected in parallel to the two ends of the start button SA1.

[0041] When the manual-automatic switch SF2 is in the automatic position, it is energized and the coil of the delay relay SS is energized. The start-up of the frequency converter cabinet is completed by the delayed closing of the normally open contact of the delay relay SS. If the power grid fails, the frequency converter cabinet loses power. After the power grid is restored, the delay relay SS is energized for 8-15 seconds to automatically start the frequency converter cabinet, which can avoid all the pumping units starting at the same time and causing impact on the power grid.

[0042] like Figure 2 As shown, the shutdown delay protection device includes: The power supply circuit, the time-base integrated circuit NE555 and the transistor amplifier circuit are installed inside the frequency conversion cabinet of the oil pump to control the on-off of the control circuit of the AC contactor KM3 coil of the frequency converter output circuit.

[0043] The power supply circuit includes a rectifier B1, a step-down transformer B2 and a three-terminal voltage regulator block U1. It is powered by a single-phase AC 220V in the frequency converter cabinet, converts the 220V AC phase voltage into a 12V DC voltage and provides it to the time-base integrated circuit NE555, triggering the delay circuit control relay to achieve delay protection.

[0044] Specifically, the primary winding of the step-down transformer B2 is connected to the single-phase 220V AC phase voltage in the frequency converter cabinet through the fuse F1, and the secondary winding is connected to the AC side of the rectifier B1. After passing through the fuse F1 and the step-down transformer B2, a 15V AC voltage is obtained. The rectifier B1 rectifies the 220V AC voltage into a 21V DC voltage, and the DC side is connected to the input end of the three-terminal voltage regulator block U1 through the pre-stabilization filter circuit.

[0045] The pre-stabilization filter circuit is composed of resistor R1, capacitor C2 and capacitor C7. Capacitor C2 and capacitor C7 are connected in parallel with each other and connected to the positive electrode of the DC side of rectifier B1 through resistor R1. The negative electrode of the DC side of rectifier B1 is grounded. Capacitor C7 is an electrolytic capacitor. One end of capacitor C2 and the positive electrode of capacitor C7 are connected to the Vin input end of the three-terminal voltage stabilization block U1, and the other end of capacitor C2 and the negative electrode of capacitor C7 are grounded.

[0046] The 21V DC voltage output by the rectifier B1 is filtered by the resistor R1 and the capacitors C2 and C7, and then sent to the input end of the three-terminal voltage regulator U1. The three-terminal voltage regulator U1 steps down the 21V DC voltage and stabilizes it to 12V DC voltage before outputting it. The second pin of the three-terminal voltage regulator U1 is grounded.

[0047] The post-stabilization filter circuit is composed of capacitors C1 and C4 connected in parallel. Capacitor C1 is an electrolytic capacitor. The positive electrode of capacitor C1 and one end of capacitor C4 are connected to the output end of the three-terminal voltage regulator block U1, and the negative electrode of capacitor C1 and the other end of capacitor C4 are grounded. After further filtering by capacitors C1 and C4, a more stable 12V DC voltage is output.

[0048] The trigger delay circuit is realized by the time base integrated circuit NE555. The time base integrated circuit NE555 is a digital integrated circuit. It is a timer composed of 21 crystal triodes, 4 crystal diodes and 16 resistors. It has the functions of voltage divider, comparator, trigger and discharger. It has the characteristics of low cost, easy use, wide adaptability, large driving current and certain load capacity.

[0049] The time base integrated circuit NE555 has a total of 8 pins. The GND port on the 1st pin is grounded, the VCC port on the 8th pin is connected to a +12V DC voltage, the RESET port on the 4th pin is also connected to a +12V DC voltage, and the CVolt port on the 5th pin is grounded through a capacitor C8 to filter and eliminate interference.

[0050] The main contact of the AC contactor KM3 in the inverter output circuit is connected in series in the power circuit connected to the oil pumping motor at the inverter output end. The connector CN1 is externally connected to the normally closed auxiliary contact KM3-3 of the AC contactor KM3 in the inverter output circuit. The 12V DC voltage output by the three-terminal voltage regulator block U1 is connected to the 6th pin low trigger terminal THR port of the time base integrated circuit NE555 through the normally closed auxiliary contact KM3-3 of the AC contactor KM3 in the inverter output circuit. A trigger filter discharge circuit is provided between the normally closed auxiliary contact KM3-3 of the AC contactor KM3 in the inverter output circuit and the low trigger terminal THR port of NE555.

[0051] The trigger filter discharge circuit includes a pull-down resistor R6, a discharge resistor R7, a charging resistor R8, a coupling capacitor C5 and a filter capacitor C6. The charging resistor R8 and the coupling capacitor C5 are connected in series between the normally closed auxiliary contact KM3-3 of the AC contactor KM3 in the inverter output circuit and the low trigger end THR port of the time base integrated circuit NE555. The node between the charging resistor R8 and the coupling capacitor C5 is grounded through the filter capacitor C6, and the two sides of the coupling capacitor C5 are grounded through the pull-down resistor R6 and the discharge resistor R7 respectively.

[0052] The 7th foot discharge terminal DIS of the time base integrated circuit NE555 is connected to a resistor R2, one end of the resistor R2 is connected to a +12V DC voltage through a resistor R5, the other end of the resistor R2 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is grounded, the coil of the relay RLY1 is connected in series between the collector of the transistor Q1 and the +12V DC voltage, and the two ends of the coil of the relay RLY1 are connected to a freewheeling diode D1. The normally open contact of the relay RLY1 is connected in series between the A1 port and the neutral line of the shutdown delay protection device, and is connected in series in the control circuit of the AC contactor KM3 coil of the inverter output circuit to control whether the coil of the AC contactor KM3 of the inverter output circuit can be energized.

[0053] The Q output port of the third pin of the time base integrated circuit NE555 is connected to the positive electrode of the capacitor C3 through the resistor R4, the negative electrode of the capacitor C3 is grounded, and the TRIG port of the time base integrated circuit NE555 is connected to the positive electrode of the capacitor C3.

[0054] The 3rd pin Q output port of the time base integrated circuit NE555 is also connected to the positive electrode of the capacitor C3 through the diode D2 and the resistor R3.

[0055] The discharge terminal DIS of the time base integrated circuit NE555 is also connected to the emitter of the transistor Q1 through the light emitting diode L1 and is grounded together.

[0056] When the power is initially turned on, the TRIG port at the 2nd pin of the timing integrated circuit NE555 is at a low level, the THR port at the 6th pin is at a low level, the Q output port at the 3rd pin is at a high level, and the Q output port at the 3rd pin quickly charges the capacitor C3 through the diode D2 and the resistor R3, and the pin 2 of the timing integrated circuit NE555 becomes a high level to realize the rapid recovery of the device to the trigger state.

[0057] The 7th foot discharge terminal DIS of the time base integrated circuit NE555 is cut off to the ground in a high impedance state. When the current flows through the resistor R2, the light-emitting diode L1, the resistor R5 and the transistor Q1, the light-emitting diode L1 emits light to show that the transistor Q1 is in the on state. When the transistor Q1 is turned on, the coil of the relay RLY1 is energized, and its normally open contact is attracted, connecting the zero line circuit of the coil of the AC contactor KM3 of the inverter output circuit, so that the coil of the AC contactor KM3 of the inverter output circuit is energized, and its main contact is closed, connecting the power supply circuit of the inverter to the oil pumping motor, and the oil pumping motor can be started at any time, and the normally closed auxiliary contact KM3-3 of the AC contactor KM3 of the inverter output circuit is disconnected.

[0058] When the inverter is shut down, the coil of the AC contactor KM3 in the inverter output circuit loses power, its main contact is disconnected, and its normally closed auxiliary contact KM3-3 is turned on. At this time, the 12V DC voltage is charged to the filter capacitor C6 through the connector CN1 and the charging resistor R8, and the upper end of the filter capacitor C6 changes from a low level to a high level. The filter capacitor C6 is used to eliminate interference from the connector CN1. When the connector CN1 is disconnected, the charge of the filter capacitor C6 is released through the discharge resistor R7. When the upper end of the filter capacitor C6 changes from a low level to a high level, through the coupling capacitor C5, the low trigger end THR port of the 6th pin of the time base integrated circuit NE555 changes from a low level to a high level, showing a high level rising edge. Then, the high level of the low trigger end THR port of the 6th pin of the time base integrated circuit NE555 quickly changes back to a low level through the pull-down resistor R6, and the coupling capacitor C5 completes the charging process, and thereafter, regardless of whether the connector CN1 is disconnected or not, the potential of the low trigger end THR port of the 6th pin of the time base integrated circuit NE555 remains at a low level.

[0059] When the low trigger terminal THR of the 6th pin of the time-base integrated circuit NE555 rises from a low level to a high level, the output port Q of the 3rd pin changes from a high level to a low level, and the discharge terminal DIS of the 7th pin is connected to the ground in a low resistance state, then the node between the resistors R2 and R5 is a low level, the light-emitting diode L1 is off, the transistor Q1 is cut off, the coil of the relay RLY1 loses power, and its normally open contact is disconnected, disconnecting the neutral line circuit of the coil of the AC contactor KM3 in the inverter output circuit, so that the coil of the AC contactor KM3 in the inverter output circuit cannot be energized, and its main contact remains disconnected, cutting off the main circuit of the inverter cabinet, and the inverter cannot be started, thereby avoiding the inverter being damaged in the state of the pumping unit shaking its head.

[0060] When the transistor Q1 changes from on to off, the current in the coil of the relay RLY1 is released through the freewheeling diode D1.

[0061] When the Q output port of the 3rd pin of the time base integrated circuit NE555 changes from high level to low level, the TRIG port of the 2nd pin starts to discharge from high level through the resistor R4, and the potential gradually becomes lower to realize the delay function. The delay time is determined by the resistor R4 and the capacitor C3, usually 10 seconds. The donkey head can stop completely within 10 seconds.

[0062] When the potential of the TRIG port at the second pin of the time base integrated circuit NE555 is lower than 4V, the Q output port at the third pin changes from a low level to a high level, and the capacitor C3 is quickly charged through the diode D2 and the resistor R3, and the TRIG port at the second pin becomes a high level to enable the device to quickly return to the triggering state.

[0063] The above is only a preferred embodiment of the present invention, which shows and describes the basic principles and main features of the present invention and the advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation modes without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. The technical features not described in the present invention can be realized by or using existing technologies, which will not be repeated here.

Claims

1. A shutdown delay protection system for a pumping unit frequency conversion cabinet, comprising a shutdown delay protection device for performing shutdown delay protection on a frequency converter, characterized in that: The shutdown delay protection device comprises: The power supply circuit converts the 220V AC phase voltage into a 12V DC voltage and supplies it to the time base integrated circuit NE555; The time base integrated circuit NE555, its low trigger terminal THR port receives the shutdown signal of the inverter, and the discharge terminal DIS port of NE555 is connected to the base of the transistor Q1 through the resistor R2; In the transistor amplifier circuit, the emitter of the transistor Q1 is grounded, and the coil of the relay RLY1 is connected in series between the collector of the transistor Q1 and the +12V DC voltage; the normally open contact of the relay RLY1 is connected in series in the coil loop of the AC contactor KM3 of the inverter output loop.

2. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 1 is characterized in that: The 12V DC voltage is connected to the low trigger end THR port of the time base integrated circuit NE555 through the normally closed auxiliary contact of the inverter output circuit AC contactor KM3; the main contact of the inverter output circuit AC contactor KM3 is connected in series in the power circuit connected to the inverter output end and the oil pumping motor.

3. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 1 is characterized in that: The power supply circuit comprises: Step-down transformer, the primary winding is connected to the single-phase 220V AC phase voltage in the frequency converter cabinet, and the secondary winding is connected to the AC side of the rectifier B1; The rectifier rectifies the 220V AC voltage into a 21V DC voltage, and the DC side is connected to the input end of the three-terminal voltage regulator block U1 through a pre-stabilization filter circuit; The three-terminal voltage regulator steps down the 21V DC voltage and stabilizes it to 12V DC voltage for output.

4. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 3 is characterized in that: The output end of the three-terminal voltage stabilizing block U1 is provided with a post-stabilizing filter circuit, which includes a capacitor C1 and a capacitor C4 connected in parallel. One end of the capacitor C1 and the capacitor C4 are connected to the output end of the three-terminal voltage stabilizing block U1, and the other end is grounded.

5. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 3 is characterized in that: The pre-stabilization filter circuit comprises a capacitor C2 and a capacitor C7 connected in parallel with each other. One end of the capacitor C2 and the capacitor C7 is connected to the input end of the three-terminal voltage stabilization block U1, and the other end is grounded.

6. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 3 is characterized in that: A trigger filter discharge circuit is provided between the normally closed auxiliary contact of the AC contactor KM3 of the inverter output circuit and the low trigger terminal THR port of NE555.

7. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 6 is characterized in that: The trigger filter discharge circuit includes a pull-down resistor R6, a discharge resistor R7, a charging resistor R8, a coupling capacitor C5 and a filter capacitor C6. The charging resistor R8 and the coupling capacitor C5 are connected in series between the normally closed auxiliary contact of the inverter output circuit AC contactor KM3 and the low trigger end THR port of NE555. The node between the charging resistor R8 and the coupling capacitor C5 is grounded through the filter capacitor C6, and the two sides of the coupling capacitor C5 are grounded through the pull-down resistor R6 and the discharge resistor R7 respectively.

8. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 1 is characterized in that: The Q output port of the time base integrated circuit NE555 is grounded through the resistor R4 and the capacitor C3, and the TRIG port of the time base integrated circuit NE555 is connected to the positive electrode of the capacitor C3.

9. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 8 is characterized in that: The Q output port of the time base integrated circuit NE555 is also connected to the positive electrode of the capacitor C3 through the diode D2 and the resistor R3.

10. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 1 is characterized in that: The discharge terminal DIS of the time base integrated circuit NE555 is also connected to the emitter of the transistor Q1 through the light emitting diode L1.

11. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 1 is characterized in that: One end of the resistor R2 is connected to a +12V DC voltage through a resistor R5, and the other end of the resistor R2 is connected to the base of the transistor Q1.

12. The shutdown delay protection system for the oil pumping unit frequency conversion cabinet according to claim 1 is characterized in that: Two ends of the coil of the relay RLY1 are connected with a freewheeling diode D1 .

13. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 9 is characterized in that: When the main contact of the AC contactor KM3 of the inverter output circuit connected in series in the main circuit of the inverter cabinet is disconnected to shut down the inverter cabinet, the normally closed auxiliary contact of the AC contactor KM3 of the inverter output circuit is closed, and the signal circuit of the low trigger end THR of the time base integrated circuit NE555 is turned on, so that it is connected to the 12V DC voltage, and the low trigger end THR rises from a low level to a high level. The discharge end DIS of the time base integrated circuit NE555 is turned on to the ground in a low resistance state, the transistor Q1 is cut off, the coil of the relay RLY1 loses power, and the current in the coil is released through the freewheeling diode D1. The normally open contact of the relay RLY1 is disconnected, cutting off the neutral line circuit of the coil of the AC contactor KM3 of the inverter output circuit, so that the coil of the AC contactor KM3 of the inverter output circuit cannot be energized, and its main contact remains disconnected, so that the inverter cabinet cannot be started, avoiding damage to the inverter when the donkey head swings and the oil pumping motor is negatively generated.

14. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 13 is characterized in that: When the low trigger terminal THR of the time base integrated circuit NE555 rises from a low level to a high level, the Q output port of the time base integrated circuit NE555 changes from a high level to a low level, and the TRIG port starts to discharge from a high level through the resistor R4, and the potential gradually decreases to realize the delay function.

15. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to claim 14 is characterized in that: When the potential of the TRIG port of the time-base integrated circuit NE555 is lower than 4V, its Q output port changes from low level to high level, and quickly charges the capacitor C3 through the diode D2 and the resistor R3. The TRIG port of the second foot becomes high level to quickly restore the device to the trigger state.

16. The shutdown delay protection system for the pumping unit frequency conversion cabinet according to any one of claims 1 to 15, characterized in that: The normally open contact of the relay RLY1 is connected in series between the A1 port of the shutdown delay protection device and the phase voltage neutral line; In the control circuit of the frequency converter, the start button SA1, the stop button SB1, the frequency conversion gear of the power frequency conversion switch SF1 and the coil of the AC contactor KM3 of the frequency converter output circuit are sequentially connected in series between the working end of the frequency converter switch and the A1 port of the shutdown delay protection device; The first auxiliary normally open contact KM3-1 of the AC contactor of the inverter output circuit is connected in parallel to both ends of the start button SA1, and the manual-automatic switch SF2 is connected in series with the delayed closed normally open contact of the delay relay SS and is also connected in parallel to both ends of the start button SA1; The second auxiliary normally open contact KM3-2 of the AC contactor of the inverter output circuit is connected to the starting end of the inverter.

Images