An intelligent thermal dual-frequency power supply heating device

Abstract

The present invention relates to the development and application of oil production technology, mainly for heating and tracing in the process of heavy oil lifting, and in particular to an intelligent thermal production dual-frequency power supply heating device, which is composed of a three-phase AC power supply, a three-phase isolation transformer, a rectifier circuit, a filter circuit, a DC absorption resistor, a control switch, an inverter circuit and a heating cable for heating the load. The present invention adopts dual-frequency technology, has a fast heating speed, and effectively solves the problem of DC heating electrolysis.

Description

Technical Field

[0001] The invention relates to the development and application of oil recovery technology, mainly for heating and tracing in the process of heavy oil lifting, and in particular to an intelligent thermal recovery dual-frequency power supply heating device. Background Art

[0002] At present, the heating of heavy oil during lifting during oil production is mostly based on the skin effect principle, using heating cables to heat the hollow rods in the oil wells. Its working principle is: the three-phase AC power supply is first rectified and then inverted before inputting into the medium-frequency transformer, and then the medium-frequency transformer isolates the output and connects it to the heating cable wrapped around the hollow rod, and the heating cable is used to heat the hollow rod. Referring to the article "Structure and Working Principle of Medium-Frequency Induction Heating Device", it can be learned that the heating principle is: the above-mentioned heating device is used to form a dual-frequency power supply to provide a variable-frequency current to the heating cable, and the heat used to heat the hollow rod is generated by the thermal effect of the induced current on the hollow rod, so the heating speed is fast, which is a very ideal heating method. The reason why a medium-frequency transformer is set between the AC output end of the inverter circuit and the heating cable is to obtain a larger heating current.

[0003] Although the above technical solution has solved the above technical problems to a certain extent, it still has many technical defects that need to be solved, as follows: Defect 1: The frequency of the medium frequency transformer cannot be adjusted arbitrarily; Defect 2: The noise pollution is too large; Defect 4: The operation is inconvenient; Defect 5: The workload is large during installation. Therefore, based on the above analysis, the dual-frequency power supply structure used in the prior art needs to be adjusted urgently. Summary of the invention

[0004] The present invention provides an intelligent thermal dual-frequency power supply heating device to solve the problems in the above-mentioned background technology.

[0005] In order to further solve the problems in the above-mentioned background technology, the present invention provides an intelligent thermal dual-frequency power supply heating device, which is composed of a three-phase AC power supply, a three-phase isolation transformer, a rectifier circuit, a filter circuit, a DC absorption resistor, a control switch, an inverter circuit and a heating cable for heating the load, wherein: the three-phase AC power supply is connected to the primary side coil of the three-phase isolation transformer, the outputs of the secondary side coils of the three-phase isolation transformer are respectively connected to the AC input ends of the rectifier circuit, the DC side output of the rectifier circuit is connected to the filter circuit, the other side of the filter circuit is connected to the DC side input of the inverter circuit, the AC side output of the inverter circuit is connected to the heating cable, a control switch is provided between the filter circuit and the inverter circuit, and DC absorption resistors are connected in parallel at both ends of the control switch, and the inverter circuit is controlled by a control device.

[0006] In the power heating device, a three-phase AC power supply is used as the initial input to provide basic electrical energy.

[0007] The three-phase isolation transformer is a key component. Since it is located between the three-phase AC power supply and the rectifier circuit, it can effectively isolate the pollution of the third harmonic of the rectifier equipment to the power grid; at the same time, compared with the prior art in which the AC output end of the inverter circuit is directly connected to the primary coil of the medium frequency transformer, the present invention installs the three-phase isolation transformer between the three-phase AC power supply and the rectifier circuit, and uses an industrial frequency of 50Hz input without the sound of audio current, so it can effectively eliminate the noise pollution caused by the AC power of the inverter circuit at the medium frequency.

[0008] In addition, in the prior art, the operator often needs to adjust the output voltage of the medium frequency transformer according to the well depth to increase the power, which is very inconvenient to operate. However, based on the above technical solution, in the process of using the heating cable to heat the load through the eddy current effect, if it is necessary to increase the heating power according to the well depth, the operator can achieve this by adjusting the frequency of the output end of the inverter circuit, because once the frequency of the AC end of the inverter circuit is changed, the inductive reactance between the heating cable and the load (usually a hollow rod) can be changed, thereby reducing the inductive heating and increasing the resistive heating. In addition, given that the thermal efficiency of resistive heating is close to 1, the operator does not need to adjust the gear, that is, there is no need to change the output voltage of the transformer, but to change the heating power by changing the frequency of the output end of the inverter circuit. Therefore, in this case, there will be no risk of insulation degradation of the heating cable due to the increase in voltage, the service life of the heating cable will be extended, and the probability of short circuit accidents will be greatly reduced, thereby greatly improving the stability of the entire system.

[0009] The function of the filter circuit is to suppress the fluctuation of the voltage and current output by the rectifier circuit, provide a stable voltage and current for the inverter circuit, and also suppress the interference of the inverter circuit to the rectifier circuit.

[0010] The inverter circuit converts DC power into AC power and transmits it to the load. The output frequency of the AC end of the inverter circuit can be adjusted by controlling the conduction and shutdown of each device (IGBT) in the inverter circuit through a control device. Considering that the output end of the inverter circuit in the present invention is directly connected to the heating cable, the medium frequency transformer is omitted.

[0011] Based on the improvement of the above technical solution, even if the medium frequency transformer is omitted, the operator can still increase the heating power according to the well depth by adjusting the frequency of the output end of the inverter circuit, and the heating efficiency can still meet the actual needs. In addition, based on this technical improvement, the actual heating frequency range of the inverter circuit can reach 5 to 6000 Hz, that is, a dual-frequency power supply with a frequency range of 5 to 6000 Hz is provided for the heating cable. Compared with the dual-frequency power supply limited by the medium frequency transformer in the prior art, the adaptability of the dual power supply provided by the present invention is greatly enhanced.

[0012] The control switch is a DC contactor, and a DC absorption resistor is connected in parallel at both ends of the contactor to absorb part of the DC power.

[0013] It should be noted that, because the medium frequency transformer is omitted between the AC output end of the inverter circuit and the heating cable, compared with the prior art, the present invention also reduces the actual number of accessories installed at the AC output end of the inverter circuit, which greatly saves electric energy on the one hand, and on the other hand greatly saves the operator from a series of problems such as winding the medium frequency transformer and adjusting the resonance of the non-polar capacitor.

[0014] Furthermore, the control device includes a single-chip microcomputer control unit, the single-chip microcomputer control unit is electrically connected to a keyboard display unit, a detection and protection unit, a parameter storage unit and a serial communication unit, and the single-chip microcomputer control unit, the detection and protection unit, the keyboard display unit, the drive unit, the parameter storage unit and the serial communication unit are powered by a power supply circuit;

[0015] The single-chip microcomputer control unit includes a single-chip microcomputer control system;

[0016] The detection and protection unit includes a voltage detection module, a current detection module, a temperature detection module and an isolation drive module. The voltage detection module detects the voltage value after filtering and voltage stabilization and transmits it to the single-chip control system. The current detection module detects the current value after filtering and voltage stabilization and transmits it to the single-chip control system. When the single-chip control system detects that the voltage value and the current value are abnormal, the isolation drive module is started to protect the circuit. The temperature detection module detects the temperature on the load and transmits it to the single-chip control system.

[0017] The keyboard display unit includes a keyboard operation module and an LED display module. The keyboard operation module can input numerical values ​​to the single-chip control system, and the LED display module displays the numerical values ​​detected by the voltage detection module, the current detection module and the temperature detection module.

[0018] Preferably, the three-phase isolation transformer is a triangular transformer, which can greatly reduce the actual occupied space of the present invention, thereby enhancing the applicability of the present invention.

[0019] Preferably, the three-phase isolation transformer is provided with a plurality of taps corresponding to standard voltages of different countries, so that the requirement on the input voltage range can be relaxed.

[0020] In addition to the technical problems solved by the present invention, the technical features that constitute the technical solution, and the advantages brought by the technical features of the technical solution described above, other technical problems that can be solved by the present invention, other technical features included in the technical solution, and the advantages brought by these technical features will be further described in detail in conjunction with the accompanying drawings.

[0021] The dual-frequency power supply studied based on the technical solution of the present invention has the following advantages and positive effects:

[0022] (1) The device can set the required output frequency according to the heating depth of the oil well, ranging from 5 to 6000 Hz, which can be adjusted arbitrarily according to the length of the cable; (2) The use of front-end three-phase transformer isolation transformation technology can ensure that the power grid is not polluted and the equipment is safe and reliable; (3) The input voltage range requirement is relaxed, three-phase 380~460V, which greatly reduces the noise pollution of the output end medium frequency transformer; (4) The device also solves the previous dangerous work of manually adjusting the gear according to the heating depth; (5) The device has reduced accessories and carried out integrated transformation. There is no need to wind the medium frequency transformer and adjust the resonance of the non-polar capacitor, which solves the trouble of tedious work and large workload in the previous equipment assembly and saves labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a circuit schematic diagram of the present invention;

[0024] Figure 2 It is a hardware block diagram of the control system of the present invention;

[0025] Figure 3 It is a system principle block diagram of the present invention.

[0026] In the figure: 1. three-phase isolation transformer; 2. rectifier circuit; 3. filter circuit; 4. DC absorption resistor; 5. control switch; 6. inverter circuit; 7. heating cable; 8. single-chip control unit; 9. keyboard display unit; 10. detection and protection unit; 11. parameter storage unit; 12. serial communication unit; 13. drive unit; 14. power supply circuit; 111. single-chip control system; 112. LED display module; 113. keyboard operation module; 114. parameter storage module; 115. voltage detection module; 116. current detection module; 117. isolation drive module; 118. temperature detection module; 119. communication unit module. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Embodiment 1:

[0029] like Figure 1As shown, an intelligent thermal dual-frequency power supply heating device is composed of a three-phase AC power supply, a three-phase isolation transformer 1, a rectifier circuit 2, a filter circuit 3, a DC absorption resistor 4, a control switch 5, an inverter circuit 6 and a heating cable 7 for heating the load.

[0030] Wherein: the three-phase AC power supply is connected to the primary side coil of the three-phase isolation transformer 1, the outputs of the secondary side coils of the three-phase isolation transformer 1 are respectively connected to the AC input ends of the rectifier circuit 2, the DC side output of the rectifier circuit 2 is connected to the filter circuit 3, the other side of the filter circuit 3 is connected to the DC side input of the inverter circuit 6, the AC side output of the inverter circuit 6 is connected to the heating cable 7, a control switch 5 is provided between the filter circuit 3 and the inverter circuit 6, and a DC absorption resistor 4 is connected in parallel at both ends of the control switch 5, and the inverter circuit 6 is controlled by a control device.

[0031] Preferably, the filter circuit 3 includes two capacitors connected in series.

[0032] like Figure 2 and Figure 3 As shown, the control device includes a single-chip microcomputer control unit 8, the single-chip microcomputer control unit 8 is electrically connected to a keyboard display unit 9, a detection and protection unit 10, a parameter storage unit 11 and a serial communication unit 12, and the single-chip microcomputer control unit 8, the detection and protection unit 10, the keyboard display unit 9, the drive unit 13, the parameter storage unit 11 and the serial communication unit 12 are powered by a power supply circuit 14; the single-chip microcomputer control unit 8 includes a single-chip microcomputer control system 111; the detection and protection unit 10 includes a voltage detection module 115, a current detection module 116, a temperature detection module 118 and an isolation drive module 117, and the keyboard display unit 9 includes a keyboard operation module 113 and an LED display module 112.

[0033] The three-phase electricity first passes through the three-phase isolation transformer 1 to convert it into the required voltage, and then passes through the rectifier circuit 2 to convert the AC power into DC power, and then passes through the filter circuit 3 to perform filtering and voltage stabilization processing. After the processing is completed, the voltage detection module 115 and the current detection module 116 detect the values ​​of the voltage and current, and send the values ​​to the single-chip control system 111. The single-chip control system 111 sends it to the LED display module 112 after processing, and displays its specific value. The current after rectification and filtering passes through the load through the PWM inversion process, so that the load temperature increases, and its temperature is detected by the temperature detection module 118, and the specific value is displayed. The value is transmitted to the single-chip control system 111, and then displayed through the LED display module 112. If the temperature cannot meet the requirement, the frequency to be changed is input through the keyboard operation module 113. The single-chip control system 111 calculates and transmits the calculation result to the communication unit module 119. The communication unit module 119 is electrically connected to the inverter circuit 6, and can control the conduction and disconnection of the IGBT in the inverter circuit 6 to achieve the required frequency. The change of frequency can change the inductive reactance between the heating cable 7 and the hollow rod, reduce the inductive heating, increase the resistive heating, and complete the conversion of the heating power without adjusting the gear to change the size of the transformer output voltage.

[0034] In this embodiment, the three-phase isolation transformer 1 is provided with a plurality of taps corresponding to standard voltages of different countries.

[0035] In this embodiment, the three-phase isolation transformer 1 is a triangle transformer.

[0036] After more than one year of practical application, the present invention has achieved the expected experimental effect. The stability of the entire system has been improved to more than 20%, the failure rate has been reduced, the service life of the heating cable has been extended, there is no electrical breakdown phenomenon, noise pollution has disappeared, and the pollution of power grid harmonics has disappeared, so that the application of DC transmission in the heating system is reflected. Compared with the heating depth of less than 1200m in the prior art, it has been increased to less than 2500m, and the heating speed is fast, saving electricity, which can save 30% of the investment in the heavy oil electric heating market.

[0037] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and deformations of these embodiments without departing from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. An intelligent thermal dual-frequency power supply heating device, characterized in that: It consists of a three-phase AC power supply, a three-phase isolation transformer, a rectifier circuit, a filter circuit, a DC absorption resistor, a control switch, an inverter circuit and a heating cable for heating a load, wherein: the three-phase AC power supply is connected to the primary coil of the three-phase isolation transformer, the outputs of the secondary coils of the three-phase isolation transformer are respectively connected to the AC input ends of the rectifier circuit, the DC side output of the rectifier circuit is connected to the filter circuit, the other side of the filter circuit is connected to the DC side input of the inverter circuit, the AC side output of the inverter circuit is connected to the heating cable, a control switch is provided between the filter circuit and the inverter circuit, and DC absorption resistors are connected in parallel at both ends of the control switch to absorb part of the DC power; the inverter circuit is controlled by a control device; the heating efficiency is increased according to the well depth by adjusting the frequency of the output end of the inverter circuit; the actual heating frequency range of the inverter circuit reaches 5~6000HZ, that is, a dual-frequency power supply with a frequency range of 5~6000HZ is provided for the heating cable; The communication unit module is electrically connected to the inverter circuit, and can control the on and off of the IGBT in the inverter circuit to achieve the required frequency. The change of frequency can change the inductive reactance between the heating cable and the hollow rod; A three-phase isolation transformer is installed between the three-phase AC power supply and the rectifier circuit, and a 50Hz industrial frequency input is used to generate sound without audio current.

2. According to claim 1, the intelligent thermal dual-frequency power supply heating device is characterized in that: The control device comprises a single-chip microcomputer control unit, the single-chip microcomputer control unit is electrically connected to a keyboard display unit, a detection and protection unit, a parameter storage unit and a serial communication unit, and the single-chip microcomputer control unit, the detection and protection unit, the keyboard display unit, the drive unit, the parameter storage unit and the serial communication unit are powered by a power supply circuit; The single-chip microcomputer control unit includes a single-chip microcomputer control system; The detection and protection unit includes a voltage detection module, a current detection module, a temperature detection module and an isolation drive module. The voltage detection module detects the voltage value after filtering and voltage stabilization and transmits it to the single-chip control system. The current detection module detects the current value after filtering and voltage stabilization and transmits it to the single-chip control system. When the single-chip control system detects that the voltage value and the current value are abnormal, the isolation drive module is started to protect the circuit. The temperature detection module detects the temperature on the load and transmits it to the single-chip control system. The keyboard display unit includes a keyboard operation module and an LED display module. The keyboard operation module can input numerical values ​​to the single-chip control system, and the LED display module displays the numerical values ​​detected by the voltage detection module, the current detection module and the temperature detection module.

3. The intelligent thermal dual-frequency power supply heating device according to claim 1 is characterized in that: The three-phase isolation transformer is provided with a plurality of taps corresponding to standard voltages of different countries.

4. An intelligent thermal dual-frequency power supply heating device according to claim 1 or 3, characterized in that: The three-phase isolation transformer is a triangle transformer.

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