CN108442912A - A kind of low-voltage alternating-current frequency conversion power drive system of fracturing unit truck - Google Patents

Abstract

The invention discloses a low-voltage AC variable-frequency electric drive system for a fracturing vehicle, which includes a fracturing vehicle. A frequency converter, a switch, a data acquisition module, an embedded PC, a variable-frequency motor and a fracturing pump are arranged on the chassis of the fracturing vehicle. There is a remote PC at a distance of 60 meters; the embedded PC, remote PC, and data acquisition module are connected to the switch using a star Ethernet structure. The remote PC is used as the main controller to remotely control the system, and the embedded PC is used as the local controller to connect with the circuit breaker and the frequency converter respectively, and communicate with the data acquisition module through the switch. The low-voltage AC variable-frequency electric drive system of the fracturing vehicle occupies a small space, and at the same time, it can also realize automatic pressure test and disc pump operation, which improves the efficiency of fracturing operations and reduces the labor intensity of maintenance personnel. In addition, it also has video monitoring for fracturing The function of the pump or working area is conducive to the diagnosis of the leaking part of the fracturing pump in the first time, which greatly improves the stability and safety of equipment operation.

Description

A low-voltage AC variable-frequency electric drive system for a fracturing vehicle

technical field

The invention belongs to the technical field of oil, coal bed methane and shale gas development equipment, in particular to a low-voltage AC variable-frequency electric drive system for a fracturing vehicle.

Background technique

The fracturing truck is an important equipment to improve oil and gas recovery, and it is also a necessary equipment for shale gas exploitation. The traditional fracturing truck uses a diesel engine to drive the fracturing pump through a transmission box. By changing the speed of the diesel engine and the gear position of the transmission box To adjust the speed of the fracturing pump, so as to finally control the displacement of the injected downhole fracturing fluid. In recent years, with the continuous expansion of the scale of shale gas exploitation, the power of diesel engines for fracturing vehicles has become larger and larger, resulting in increased fuel consumption and increased mining costs. The more serious consequences are excessive emissions and air pollution. Environmental problems. In order to solve these problems, the scheme of directly driving the fracturing pump with an electric motor instead of a diesel engine and a transmission box has been paid more and more attention, and has begun to be applied initially.

The complete set of electric-driven fracturing pumps uses a high-power AC frequency converter to drive the motor. When the frequency converter is connected to the power grid, it will inject harmonic current into the power grid and generate harmonic effects at the power grid access point. Affecting the normal operation of other electrical equipment connected to the public grid will also increase the loss of power generation, transmission and distribution, and interfere with the smooth operation of the grid. Therefore, there are strict control standards for "harmonic pollution" in the world. Electric drive fracturing equipment There must also be an anti-harmonic device, and most of the electric drive fracturing equipment that appears on the market currently use high-voltage frequency converters, which mostly use 18-pulse or even more multiple rectification methods, and their harmonic current is small, which is in line with harmonic The wave current does not exceed the international standard of 5%, but this kind of frequency converter is integrated with a phase-shifting rectifier transformer, and the volume and weight of a complete set of variable frequency drive devices are too large. It has certain advantages as a skid-mounted device, but it cannot be mounted on a fracturing vehicle In the limited space, considering that the road transportation environment of some remote fracturing well sites is harsh, the fracturing operation needs to be highly mobile, and the well site still needs a certain number of fracturing vehicles. If the electric drive adopts low-voltage variable-frequency drive As a whole, the scheme can reduce the volume and weight of the whole set of fracturing equipment, and can be placed on the fracturing truck. However, ordinary low-voltage high-power inverters mostly use 6-pulse rectification, and their harmonic currents exceed 30%, far exceeding the standard.

In addition, the seals in the hydraulic end of the fracturing pump are vulnerable parts. In order to replace the seals, maintenance personnel often need to open the valve box cover and use a sled to turn the pump shaft and manually adjust the position of the plunger to the other end of the valve box. After the plunger is moved out of the valve assembly, enough space is left to observe or replace the seal in the valve assembly. This operation process is called "disc pump". If the five-cylinder pump is used for fracturing, this operation process requires Continuous five times, the labor intensity of the disc pump is high, the time is long, and two people are required to cooperate to complete the maintenance of the fracturing pump; Liquid leakage, which cannot be observed when the operation is stopped or at low pressure, but personnel cannot observe closely during high-pressure operation, and it is impossible to know which plunger needs to be replaced.

Contents of the invention

The purpose of the present invention is to provide a low-voltage AC variable-frequency electric drive system for fracturing trucks, which solves the problem that the complete set of electric drive system devices is difficult to arrange on the fracturing truck due to too large and heavy, and can realize automatic pressure test and disk Pump operation improves the efficiency of fracturing operations and reduces the labor intensity of maintenance personnel. It also has the function of video monitoring the fracturing pump or operating area, and can diagnose the leaking part of the fracturing pump in the first time, improving the stability and stability of equipment operation. safety.

In order to achieve the above object, the technical solution adopted in the present invention is a low-voltage AC variable-frequency electric drive system for a fracturing vehicle, including a fracturing vehicle, and a frequency converter, a switch, and a data acquisition module are arranged on the chassis of the fracturing vehicle , embedded PC, remote PC, variable frequency motor and fracturing pump; the frequency converter consists of a rectifier bridge and an inverter bridge, wherein the rectifier bridge is connected to the well site power grid through a circuit breaker, and the power supply of the inverter bridge and the variable frequency motor The rotating shaft of the variable frequency motor is connected to the crankshaft of the fracturing pump; the signal output end of the switch is respectively connected to the signal input end of the embedded PC and the signal input end of the remote PC, and the control end of the remote PC is connected to the embedded PC. The signal input end of the type PC is connected, the control end of the embedded PC is connected with the circuit breaker and the frequency converter respectively, and the signal input end of the switch is connected with the data acquisition module; the rotating shaft of the frequency conversion motor is provided with a speed sensor, and the The hydraulic end of the fracturing pump is provided with a pressure sensor, the multiple plunger shafts of the fracturing pump are provided with collars, and the inner side of the power end of the fracturing pump is provided with multiple mounting seats, and the surface of each mounting seat is uniform. Displacement sensors are provided, and each displacement sensor is used to detect the position of the corresponding collar, and the rotational speed sensor, the pressure sensor, and the displacement sensor are respectively connected to the signal input terminals of the data acquisition module.

The technical scheme of the present invention also has the following characteristics:

It also includes a network camera, the signal output end of the network camera is connected with the signal input end of the switch.

An electric control room is also included, and a frequency conversion cabinet and a control cabinet are arranged in the electric control room, the frequency converter is arranged in the frequency conversion cabinet, and the switch is arranged in the control cabinet.

The electric control room is provided with an air conditioner and a temperature sensor, and the signal output end of the temperature sensor is connected with the signal input end of the data acquisition module.

The rectifier bridge is an IGBT rectifier bridge.

The mounting seat is a magnetic suction seat.

The beneficial effects of the present invention are:

(1) The overall number of power devices is small, light in weight and small in size, which makes it easy to arrange the entire set of frequency converters on the fracturing truck. After the assembly is completed, the fracturing truck does not have the problem of overweight and exceeding the limit, and can drive high-power fracturing pump motor;

(2) The circuit topology adopts fully-controlled power electronic devices, and the input adopts a controllable PWM rectifier circuit, which does not need to use multiple rectification methods of phase-shifting rectifier transformers, which saves space and does not need to use active power filters. It can reduce the grid current harmonics on the input side, the input current is similar to a sine wave, the input power factor is adjustable, and the harmonic distortion is low, which has little impact on the quality of the grid on the input side, and the system does not need to add additional anti-harmonic devices , saving costs;

(3) There is an automatic "disc pump" working mode, the electric drive system replaces the manual disc pump, the plunger is easy to adjust, saves labor and time, and is convenient for users to maintain and inspect the pump;

(4) The "pressure test" function of the fracturing vehicle is convenient and quick to operate. Just press the "automatic pressure test" button once, and the motor will rotate to the specified speed according to the specified acceleration or specified time. When the pressure of the fracturing pump reaches the set value, The motor stops automatically, and the whole process of pressure test does not need to be repeated many times, which saves working time;

(5) Intelligent monitoring. After the system is installed with video monitoring software, it can automatically monitor and record the operation site. It can be triggered by equipment status alarm events such as fracturing pumps, so that the operator's operation screen can be automatically switched to the video screen, making the operator the first Timely check the external conditions of the equipment, especially the leaking part of the plunger of the fracturing pump, and replace the plunger seal in a targeted manner when the pump is inspected after the operation is completed. At the same time, there is an early warning function that reminds personnel to enter the dangerous operation area to improve the fracturing performance. The safety and reliability of the vehicle.

Description of drawings

Fig. 1 is a schematic structural diagram of a low-voltage AC variable-frequency electric drive system of a fracturing vehicle of the present invention;

Fig. 2 is a structural schematic diagram of a frequency converter in a low-voltage AC variable-frequency electric drive system of a fracturing vehicle of the present invention;

Fig. 3 is a control schematic diagram of the fracturing pump in the low-voltage AC variable-frequency electric drive system of the present invention when the fracturing pump performs the disc pump;

Fig. 4 is a control schematic diagram of the fracturing pump in the low-voltage AC variable-frequency electric drive system of a fracturing vehicle according to the present invention.

In the figure, 1. Power end, 2. Crankshaft, 3. Mounting seat, 4. Displacement sensor, 5. Coupling, 6. Fluid end, 7. Plunger shaft.

Detailed ways

The technical solution of the present invention will be further described in detail below in conjunction with the description of the drawings and specific embodiments.

As shown in Figure 1, a low-voltage AC variable-frequency electric drive system for a fracturing vehicle of the present invention is provided with a frequency converter, a switch, a data acquisition module, an embedded PC, a variable-frequency motor, and a fracturing pump on the chassis vehicle. There is a remote PC for remote operation at a distance of 60 meters; referring to Figure 2, the frequency converter is composed of a rectifier bridge and an inverter bridge, wherein the rectifier bridge is connected to the power grid of the well site through a circuit breaker, and the inverter bridge is connected to the power supply end of the variable frequency motor ; As shown in Figure 3, the rotating shaft of variable frequency motor is connected with crankshaft 2 in the power end 1 of fracturing pump; In conjunction with Figure 4, described embedded PC, remote PC, data acquisition module adopt star Ethernet structure to connect in on the switch. The remote PC is used as the main controller to remotely control the system, and the embedded PC is used as the local controller to connect with the circuit breaker and the frequency converter respectively, and communicate with the data acquisition module through the switch; The hydraulic end 6 of the fracturing pump is provided with a pressure sensor, the multiple plunger shafts 7 of the fracturing pump are provided with collars 5, and the inner side of the power end 1 of the fracturing pump is provided with a plurality of mounting seats 3, and each Displacement sensors 5 are arranged on the surface of the seat 3, each displacement sensor 5 is used to detect the position of the corresponding collar 5, and the rotational speed sensor, pressure sensor and displacement sensor 5 are respectively connected to the signal input terminals of the data acquisition module.

As shown in FIG. 1 , a network camera is also included, and the network camera is connected to a port of the switch through a network cable.

As shown in Fig. 1, it also includes an electric control room, in which a frequency conversion cabinet and a control cabinet are arranged, the frequency converter is arranged in the frequency conversion cabinet, and the switch is arranged in the control cabinet.

As shown in Figure 1, an air conditioner and a temperature sensor are installed in the electric control room, and the signal output end of the temperature sensor is connected to the signal input end of the data acquisition module.

As shown in FIG. 3 , the mounting base 3 is a magnetic suction base.

The chassis of the fracturing vehicle is mainly equipped with an electric control room, a frequency conversion motor, a fracturing pump, a data collector, and a network camera. The information is connected to the electric control room through the signal cable through the data collector, and the camera is connected to the electric control room through an Ethernet cable. The remote PC is arranged in the operation room. Before the operation starts, the grid power is introduced to the power input socket of the electric control room of the fracturing vehicle through the circuit breaker cable, and the communication port of the electric control room of the fracturing vehicle is connected to the remote PC in the operation room with an industrial Ethernet cable. After confirming safety on site, operators use remote PCs for centralized control, specifically including remote closing of circuit breakers, pressure testing, fracturing displacement adjustment, equipment status monitoring, video monitoring of suspicious targets, automatic disc pumps and other fracturing operations In the whole process, there are frequency conversion cabinets and control cabinets in the electric control room. In order to ensure the heat dissipation of the frequency conversion cabinet, the electric control room is also equipped with air conditioners.

The main circuit of the low-voltage AC variable-frequency electric drive system of a fracturing vehicle of the present invention adopts an AC-DC-AC current source topology structure, and the three-phase AC power on the grid side is converted into an adjustable voltage by a rectifier bridge after being filtered by LC The direct current is output by the inverter bridge to output adjustable three-phase alternating current and then transmitted to the variable frequency motor, which drives the fracturing pump. The rectifier devices in the rectifier bridge are all fully controllable rectifier devices.

In the low-voltage AC variable frequency electric drive system of the fracturing vehicle of the present invention, when the fracturing pump needs to be overhauled after the fracturing operation, the adjustment of the plunger position of the fracturing pump can be automatically completed. device, data acquisition module, embedded PC and remote PC; the displacement sensor 4 is attached to the surface of the power end 1 through a strong magnetic suction seat, and the displacement sensor 4 can be fixed and installed without secondary processing on the surface of the power end. Attention should be paid to aligning the center line of the displacement sensor 4 with the protruding part of the collar 5 on the plunger shaft 7, the variable frequency motor is connected to the power end 1, the data acquisition module is connected to the displacement sensor 4 through a signal cable, the data acquisition module, embedded The PC is connected with an Ethernet cable, and the remote PC and the embedded PC also use Ethernet communication to realize remote operation. When the frequency conversion motor rotates, the crankshaft 2 in the power end 1 rotates to drive the plunger shaft 7 to move in a straight line, and the plunger shaft 7. The mechanically connected coupling 5 then reciprocates close to or away from the displacement sensor 4 at the power end 1. The data acquisition module converts the displacement signal of the displacement sensor 4 into a digital signal and transmits it to the embedded PC for analysis and processing to determine the plunger shaft. 7 Whether it moves to the position where the plunger head can completely withdraw from the valve cavity of fluid end 6, and the seal in fluid end 6 can be checked or replaced after the plunger head is withdrawn in place. The remote PC can realize remote control operation, embedded PC The machine realizes the local control operation.

The flow of the disc pump control software of the present invention is as follows: after pressing the “disc pump” key on the remote PC operation panel to start, the parameters are initialized first, and then each key is scanned to see if each key is pressed. When the plunger shaft A key is pressed, the plunger shaft The A position is set as the flag position, and the variable frequency motor speed value is set, and the position of the coupling displacement sensor 4 of the plunger shaft A is cyclically detected. When the plunger position of the plunger shaft A is not in place, the variable frequency motor rotates at the specified speed. When the plug shaft A plunger position is in place, the displacement sensor 4 sends a signal, and the frequency conversion motor stops rotating.

The pressure test control software process of the present invention is: press the pressure test key to start, after the parameters are initialized, set the overpressure value and the motor speed, the pressure sensor cyclically detects the pressure value, and when the pressure value does not reach the overpressure value, the frequency conversion motor will press the specified The speed rotates, and the motor stops automatically when the overvoltage value is reached. The pressure test process is automated, which changes the previous process of manually pressing the pressure test button multiple times to repeat the pressure test, saving operating time.

The control system of the present invention is mainly composed of a remote PC, a switch, a network camera, a position sensor 4, a rotational speed sensor, a temperature sensor, a pressure sensor, a data acquisition module, an embedded PC, a frequency converter and a circuit breaker. The remote PC and embedded PC, network camera, frequency converter, data acquisition module, etc. all use Ethernet communication through the switch, and Ethernet not only transmits control signals but also transmits on-site monitoring video signals. The operation can be remotely controlled by a remote PC 60 meters away, or locally through an embedded PC, and the controlled object is mainly a frequency converter.

The working principle of the low-voltage AC variable-frequency electric drive system of a kind of fracturing vehicle of the present invention is:

First of all, in terms of the main circuit structure, the three-phase AC power of the power grid is converted into DC after input rectification, and the DC is filtered by the inductor and then enters the inverter bridge to be inverted to become the required three-phase AC power. Since the input side uses an IGBT controllable rectifier bridge, through Controlling the conduction angle of the IGBTs of each bridge arm controls the DC input voltage and power factor of the inverter bridge, so that the power supply current waveform on the input side is close to sinusoidal, greatly reducing the harmonic current and harmonic voltage distortion on the grid side Rate. By changing the conduction angle of the inverter bridge, that is, the frequency value of the frequency converter, a three-phase AC power with controllable current and voltage is obtained, and the speed of the frequency conversion motor also changes accordingly, and the displacement of the corresponding fracturing pump also changes accordingly. Smooth speed regulation can get the displacement required by the frac pump.

If the remote PC can remotely control all fracturing operations, before the fracturing operation, after checking the safety of the line, the remote PC remote closes the circuit breaker and connects to the power grid. After the fracturing operation officially starts, the remote PC is set up Overpressure value, when performing pressure test operation, after pressing the pressure test button, the frequency converter will drive the frequency conversion motor to rotate the fracturing pump after receiving the specified speed signal, and the frequency conversion motor will automatically stop when the pressure reaches the overpressure value, and the fracturing truck will The pump pressure is kept at the set value of overpressure, and when the displacement of the fracturing pump needs to be adjusted for official operations, the remote PC controls the speed reference signal of the frequency converter, and the frequency conversion motor rotates at a given speed. After the speed sensor detects the speed, the remote PC The computer calculates the corresponding displacement of the fracturing pump. When the operation is over and the pump is checked, press the remote PC’s “disc pump” button to perform automatic disc pump operation. At this time, if the position of the plunger axis A is adjusted, press the axis A. key, the axis A displacement sensor detects whether the plunger has completely withdrawn from the valve cavity of the hydraulic end. If it is completely withdrawn in place, the remote PC will issue a stop command to stop the frequency conversion motor. If it is not in place, the frequency conversion motor will always drive fracturing at the set speed The pump plunger shaft 7 moves back and forth until the position sensor 4 sends a signal in place. The embedded PC can realize the local operation of the fracturing vehicle, but the closing of the circuit breaker can only be operated by the remote PC close to the power distribution room to ensure the safety of on-site power consumption.

During the entire fracturing process, the network camera on the fracturing vehicle monitors the on-site operations, and the image signals within the monitoring range are transmitted to the remote PC through the Ethernet cable and switch. The remote PC has a built-in video monitoring application software to monitor the fracturing Real-time monitoring images on the job site are digitally processed, stored and controlled, and an alarm can be triggered by an event. When the remote PC receives an equipment status alarm event detected by the embedded PC on the fracturing vehicle, it automatically sends Switch the operation screen to the video screen, so that the operator can observe the equipment status in the first time, especially the leaking part of the fracturing pump can be diagnosed in the first time, and the plunger seal can be replaced in a targeted manner when the pump is inspected after the operation is completed; When the software detects a human face in the set area, the remote PC will automatically send out an alarm signal, which technically prevents personnel from entering the dangerous operation area and enhances the safety of the fracturing vehicle. The network camera adopts POE power supply mode, and uses the power supply Ethernet interface on the switch. The Ethernet between the network camera and the switch not only transmits video signals but also provides power for the network camera, thereby reducing wiring and improving video surveillance. Safety and reliability of use.

The low-voltage AC variable frequency electric drive system of this fracturing vehicle improves the automation level of fracturing operations, and also provides the necessary equipment foundation for future digital fracturing and intelligent fracturing.

Claims (6)

1. a kind of low-voltage alternating-current frequency conversion power drive system of fracturing unit truck, including chassis vehicle, which is characterized in that set on the chassis vehicle It is equipped with frequency converter, interchanger, data acquisition module, embedded PC, long-range PC machine, variable-frequency motor and fracturing pump；The frequency conversion Device is made of rectifier bridge and inverter bridge, and wherein rectifier bridge accesses well site power grid, the electricity of inverter bridge and variable-frequency motor by breaker Source connects, bent axle (2) connection in the shaft of variable-frequency motor and the power end (1) of fracturing pump；The signal of the interchanger is defeated Outlet is connect with the signal input part of the signal input part of embedded PC, long-range PC machine respectively, the control terminal of long-range PC machine with The signal input part of embedded PC connects, and the control terminal of embedded PC is connect with breaker, frequency converter respectively, interchanger Signal input part is connect with data acquisition module；Speed probe, the fracturing pump are provided in the shaft of the variable-frequency motor Fluid end (6) in be provided with pressure sensor, be both provided with box cupling (5) on multiple plunger axis (7) of fracturing pump, fracturing pump Multiple mounting bases (3) are provided on the inside of power end (1), the surface of each mounting base (3) is both provided with displacement sensor (5), often A displacement sensor (5) is used to detect the position of corresponding box cupling (5), the speed probe, the pressure sensor, institute's rheme Displacement sensor (5) is connect with the signal input part of the data acquisition module respectively.

2. the low-voltage alternating-current frequency conversion power drive system of fracturing unit truck according to claim 1, which is characterized in that further include network Camera, the signal output end of the IP Camera are connect with the signal input part of the interchanger.

3. the low-voltage alternating-current frequency conversion power drive system of fracturing unit truck according to claim 1, which is characterized in that further include automatically controlled Room is provided with frequency conversion tank and switch board in the electric-controlled house, and the frequency converter is arranged in the frequency conversion tank, and the interchanger is set It sets in the switch board.

4. the low-voltage alternating-current frequency conversion power drive system of fracturing unit truck according to claim 1, which is characterized in that the electric-controlled house It is inside provided with air-conditioning and temperature sensor, the signal output end of the temperature sensor and the signal of the data acquisition module are defeated Enter end connection.

5. the low-voltage alternating-current frequency conversion power drive system of fracturing unit truck according to claim 4, which is characterized in that the rectifier bridge For IGBT rectifier bridges.

6. the low-voltage alternating-current frequency conversion power drive system of fracturing unit truck according to claim 1, which is characterized in that the mounting base (3) it is magnetic force suction base.