CN211377908U - Novel underground oil pumping pipeline heating unblocking power circuit - Google Patents

Abstract

The utility model discloses a novel stifled power supply circuit is separated in heating of underground oil pumping pipeline. The novel circuit inversion part has great promotion as the traditional part, S₁～S₅Is a power switch tube; l is₁、L₂、L₃、L₄The switch tube is connected with the bridge tube; l is_A、L_BIs an output filter inductor; r is a load; d₁And D₂Is a self-contained high performance diode; net side sampling L_A、L_BThe double-inductance filtering can eliminate the differential mode voltage of the inverter and the rest L₁、L₂、L₃、L₄The four independent inductors adopt a decoupling integration technology and are implemented by detecting the working current of the circuitThe problem that the pipeline is blocked is solved by researching a blockage removing power supply of an oil and gas pipeline, and the oil pipe is equivalent to be a resistor by using an equivalent principle.

Description

Novel underground oil pumping pipeline heating unblocking power circuit

Technical Field

The utility model relates to an oil gas pipeline removes stifled power supply circuit, especially relates to a novel oil gas pipeline of voltage, frequency adjustable removes stifled power supply circuit.

Background

Oil is a very important resource for a country, and in many wars and military conflicts, oil occupancy is a very important cause. Therefore, each oil country pays great attention to oil exploitation, but in the process of oil and natural gas exploitation, the oil and natural gas exploitation is largeThe problems of high wax content, high solidifying point and the like in the exploitation of the asphalt containing the colloid in the oil field^[1]And the pipeline is easy to block in the mining process, so that the mining cost is increased. Meanwhile, in an oil and gas transportation pipeline, due to the nature of crude oil and the environment, the transportation pipeline can be blocked, certain troubles are brought to transportation, and the yield of actual production is reduced. The yield reduction brings huge economic loss to national society, and once the transportation of petroleum has problems, the problem of insufficient raw materials is brought to the downstream of the petroleum. The oil gas pipeline heating technology adopts a special heating mode, compared with the traditional heating mode, the oil gas pipeline is used as a heating device to convert electric energy into heat energy and act on crude oil solidified bodies in the pipeline, the solidified bodies are melted by heating the pipeline so as to achieve the effect of dredging the pipeline, and the pipeline is prevented from being blocked^[2]. The main working principle is as follows: the electric energy is exported by separating stifled power supply unit, after distribution transformer steps up the processing, carries the frequency conversion heating switch board through the cable in, keeps apart the adjustment after carrying the electric energy oil gas pipeline through the switch board at last, and pipeline and ground form a passageway that has the electric current to flow through, according to joule one lenz law, when the electric current passes through the oil gas pipeline, the pipeline is because of having certain resistance and generating heat, and the heat Q of production is directly proportional with electric current I's square. The heat is directly transmitted to the crude oil or solidified body in the pipeline through the pipeline, so that the crude oil in the pipeline keeps a certain temperature and is not condensed into solid^[3]。

Specifically, as shown in fig. 1, U, V, W is connected with a 380V three-phase alternating current power supply; k₁、K₂、K₃Is an alternating current contactor; r is resistance; l is an isolation reactor; c_l-Cn is an electrolytic capacitor (n-6 or 8); VT1-VT4 is an insulated gate transistor (IGBT); t is an amorphous transformer; u shape₀For frequency-conversion inverting output voltage, U_dAnd outputting voltage to the secondary side of the transformer.

(1) The left part of fig. 1 is a three-phase diode bridge rectifier circuit, which utilizes the single-phase conductivity of the diodes, i.e. the current can only flow from the positive pole to the negative pole, but not from the negative pole to the positive pole. The diode can be conducted only when the forward voltage of the diode is larger than a certain value, and the resistance of the diode after conduction is very small, which is equivalent to a wire. When reverse voltage is applied, reverse current is very small and can be ignored due to the structure of the diode, which is equivalent to disconnection and is called an off state.

The rectifying circuit is connected by three diodes in common anode and three diodes in common cathode, and the output voltage is U1.

The input voltage is:

wherein U is the effective value of the input alternating current.

(2) The middle part of the circuit in fig. 1 is an inductance-capacitance filter circuit, which mainly utilizes the characteristics of direct resistance and alternating current of an inductor and high resistance and low resistance of a filter capacitor to filter high-frequency harmonic waves in a rectification output circuit and ensure the stability and the persistence of direct current output.

(3) The right side of fig. 1 is an inverter circuit part which mainly functions to invert the input direct current into alternating current with adjustable frequency and voltage amplitude. The insulated gate transistor (IGBT) is a full-control power electronic device, and the conduction angle of the IGBT is controlled by a control circuit, so that the effect of controlling voltage output and output frequency is achieved. When the traditional H-bridge inverter works in a freewheeling stage, a body diode with poor performance needs to pass through, and leakage current exists when the traditional H-bridge inverter is incorporated into a power grid. Therefore, the conventional power supply circuit cannot achieve a good effect^[4]。

Among these, the references are as follows:

[1] li Wenjiang, Quchangjiu, Yan, Tianliyong, design research on variable frequency heating power supply of oil extraction tube [ J ] Instrument and Meter user, 2007(03): 130-.

[2] The application of the frequency conversion heating technology of the alternating current oil pipe in oilfield production [ J ]. the electrical application, 2008(18):32-34.

[3] Application of frequency-conversion temp-regulating electric heater in electric heating system of oil field pipeline [ J ] science and technology and enterprise, 2013(12):352

[4] Design and control of LCL filter single-phase H6 bridge grid-connected inverter [ J ] electronic technology application, 2018,44(11): 145-.

Disclosure of Invention

The utility model aims to overcome body diode's poor performance, leak current problem and improve the frequency range of output high frequency alternating current to compare in the tradition and solve stifled power supply circuit, neotype circuit contravariant part has had great promotion with the tradition type.

The purpose of the utility model is realized through the following technical scheme: s₁～S₅Is a power switch tube; l is₁、 L₂、L₃、L₄The switch tube is connected with the bridge tube; l is_A、L_BIs an output filter inductor; r is a load; d₁And D₂Is a self-contained high performance diode; A. b, C, D are respectively the middle points of the upper and lower bridge arms, and the point G is the R grounding point; points P, N are DC power supply U_dcA positive terminal and a negative terminal. C_PVIs the parasitic capacitance between the N point and the G point. Net side sampling L_A、L_BThe dual inductive filtering may eliminate differential mode voltages of the inverter. In which 6 inductors are used, where L₁、L₂、L₃、L₄The four independent inductors adopt a decoupling integration technology, real-time control is implemented through detection of circuit working current, and output voltage and frequency are controlled by changing the given value of input reference voltage and controlling the size of a load, so that the purpose of control is achieved, and stable output and adjustable voltage and frequency are realized.

The utility model has the advantages that:

(1) compared with a power frequency electric heating device, the variable-frequency electric heating device for the oil production pipe has the advantages that a double-step-down structure is used for not isolating a grid-connected inverter, a diode with high withstand voltage performance is additionally arranged, current in a follow current stage does not pass through a body diode with poor performance, and voltage and current which can be borne by the inverter are larger, so that the reliability of the inverter is improved, the maintenance and replacement period is prolonged, the output voltage is larger, and the variable-frequency electric heating device has the characteristics of high power, high heating temperature, easiness in realizing automatic control, convenience in operation and use and the like.

(2) Compared with an H-bridge inverter circuit (PGCI), the double-buck type structure non-isolated grid-connected inverter solves the current leakage problem of the H-bridge inverter under the condition that the system does not contain a transformer, reduces the reverse phase loss, improves the efficiency of the oil pipe variable frequency electric heating system circuit, and enables the pipeline blockage removing distance to be longer.

Drawings

FIG. 1 is a schematic diagram of a conventional power supply circuit

FIG. 2 is a topological diagram of a novel dual buck rectification inverter circuit

FIG. 3 is a schematic diagram of an equivalent circuit of a novel rectifying inverter circuit working mode 1

FIG. 4 is a schematic diagram of an equivalent circuit of a novel rectifying inverter circuit working mode2

FIG. 5 is a schematic diagram of an equivalent circuit of a novel rectifying inverter circuit working mode3

FIG. 6 is a schematic diagram of an equivalent circuit of a novel rectification inverter circuit working mode4

FIG. 7 is a driving logic diagram

FIG. 8 is a graph of the rectified and filtered waveform output

FIG. 9 is a graph of the positive half cycle common mode voltage waveform

FIG. 10 is a graph of the negative half cycle common mode voltage waveform

FIG. 11 is a voltage waveform diagram of the transformer output frequency 2kHz

FIG. 12 is a voltage waveform diagram of 1kHz output frequency of a transformer

Detailed Description

The technical scheme of the invention is further described in detail by combining the attached drawings:

the operating principle of the circuit will be analyzed below in connection with the conduction of the switching device in various operating states of the circuit. And simultaneously, the output voltage and the output waveform of the bridge arm are obtained by combining the conduction of the switching devices of the circuit under different working states. It can be known from analysis that the novel circuit has four working states, the conduction conditions of the devices in different working states are different, and the conduction conditions of the devices in different states are explained by the following combined graphs.

1) Working state 1, working mode. As shown in FIG. 3, i_gd>0，S₁、S₄、S₅Opening, S₂、S₃U at the moment of turn-off_dc、S₅、S₁、L₁、L_A、R、L_B、L₄And S₄Form a forward charging closed loop i_gdThe output voltage of the bridge arm at the moment of positive increase is as follows:

u_AB＝+U_dc(4)

u_AN＝u_AB＝+u_dc(5)

u_BN＝0 (6)

by combining the formula (5) and the formula (6), the common mode voltage of the working mode 1 is u_cm：

2) Operating state 2, freewheel mode. As shown in FIG. 4, i_gd>0，S₁Conduction, S₂、S₃、S₄、S₅When the circuit is turned off, the circuit is equivalent to the Mode 2. At this time S₁、L₁、L_A、R、L_B、L₄And D₂Form a forward discharge follow current loop i_gdThe positive direction decreases. The follow current path does not pass through the body diode with poor performance, the reverse recovery loss is reduced, the isolation of the output circuit of the inverter and the direct-current voltage in the follow current stage is realized, and the efficiency and the reliability of the inverter can be improved^[5-6]

At this time, the output voltage of the bridge arm is as follows:

u_AB＝0 (8)

when S is₄And S₅Of the same typeWhen switching the tube, S₄And S₅Voltage stress of [15-16 ]]I.e. by

In the formula (12), V_s4And V_s5Are respectively S₄And S₅The voltage across. From FIG. 4, it can be derived from Kirchhoff's VoltageLaw (KVL) voltage law:

u_AN＝u_BN(10)

simultaneous expressions (9) and (10) can be obtained:

substituting the formula (11) into the common mode leakage current formula to obtain u of the working mode2_cmComprises the following steps:

3) working state 3, working mode. As shown in FIG. 5, i_gd<0，S₂、S₃、S₅Conduction, S₁、S₄When the circuit is turned off, the circuit is equivalent to the Mode 3. At this time U_dc、S₅、S₃、L₃、L_B、R、L_A、L₂And S₂Form a reverse charging closed loop i_gdNegative increase

At this time, the output voltage of the bridge arm is as follows:

u_CD＝-U_dc(13)

u_CN＝0 (14)

u_DN＝-u_CD＝+u_dc(15)

the u of the operating mode3 can be obtained by substituting the formulas (14) and (15) into the common mode leakage current formula_cmComprises the following steps:

4) operating state 4, freewheel mode. As shown in FIG. 6, i_gd<0，S₃Conduction, S₁、S₂、S₄、S₅When the circuit is turned off, the circuit is equivalent to the Mode 4. At this point R, L_A、L₂、D₁、S₃、L₃And L_BForming a reverse discharge follow current loop i_gdNegative reduction is realized, and the isolation of an output circuit of the inverter from voltage in a negative follow current stage is realized

The output voltage of the bridge arm at this time is:

u_CD＝0 (17)

as can be seen from FIG. 6, when S is₅And S₂When the switching tubes are of the same type, S₅And S₂Is the same as the voltage stress, i.e.

In the above formula, Vs₅And Vs₂Are respectively a switch tube S₅And S₂The voltage across. From FIG. 6, from KVL:

simultaneous expressions (18) and (19) can be obtained:

substituting the formula (20) into the common mode leakage current formula can obtain u of the working mode4_cmComprises the following steps:

the parameters used in the simulation are shown in the table.

The following conclusions can be drawn through the research on the novel oil pipe electrical heating blockage removal power supply circuit structure, the working mode, the common-mode leakage current sum, which is provided by the invention:

(1) the switching tube of the inverter circuit is in a half-cycle operation mode, so that the switching loss is reduced; and the freewheeling loop current does not pass through the poorly performing body diode. The efficiency and reliability of the circuit are improved.

(2) The common mode voltage remains stable throughout the duty cycle. Therefore, the inverter circuit eliminates the leakage current problem of the conventional circuit.

(3) The output voltage of the power supply circuit is adjustable within a certain range, and alternating voltage and current with different frequencies and amplitudes can be output, so that the heating temperature of the oil pipe can be controlled within a certain range, and the application range of the power supply circuit is expanded.

Among these, the references are as follows:

[5] yaoshitong, Xiaolan, Weixing, double-buck full-bridge grid-connected inverter [ J ]. Chinese Motor engineering newspaper 2011,31(12):29-33.

[6] The problems of oscillation and suppression measures of the power electronic power system are researched [ J ] high voltage technology, 2017,43(04): 1057-.

Claims (3)

1. The utility model provides a novel stifled power supply circuit is separated in heating of underground oil pumping pipeline which characterized in that: includes 6 rectifier diodes, rectifier filter resistor inductor and freewheeling diode D₁、D₂Switching tube S₁、S₂、S₃、S₄、S₅Switch inductor L₁、L₂、L₃、L₄Output filterWave inductor L_A、L_BA load resistance R;

positive terminal and S of rectified and filtered output DC voltage U1₅Connection, S₅The other end of (a) is respectively connected with D_1\、D₂、S₁、S₃Connection, D₁Respectively with L₂、S₂Connection, D₂Respectively with L₄、S₄Connection, S₁And one end of (A) and L₁Connection, L₁And one end of (A) and L₂、L_AConnection, L_AConnected to one end of a load R, S₃And one end of (A) and L₃Connection, L₃And one end of (A) and L₄、L_BConnection, L_BConnected to the other end of the load R and grounded, S₂、S₄Are connected to the negative terminal of the rectified and filtered voltage U1.

2. The novel underground oil pumping pipeline heating plug removal power supply circuit according to claim 1, characterized in that: switch tube S₁、S₂、S₃、S₄、S₅The gate of which receives the modulation signal output by the hysteresis control.

3. The novel underground oil pumping pipeline heating plug removal power supply circuit according to claim 2, characterized in that: the modulation signal is a high-frequency pulse width modulation signal.

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