Dehydration high-voltage power supply and method capable of automatically switching waveforms according to load

Abstract

The invention relates to the technical field of crude oil dehydration data processing in the petroleum industry, and discloses a crude oil electric dehydration high-voltage power supply capable of automatically switching waveforms according to loads and a method. The crude oil electric dehydration high-voltage power supply comprises a temperature sensor arranged on a crude oil dehydration tank, and a voltage sensor and a current sensor which are arranged at the load end of the crude oil dehydration tank; the high-voltage power supply is provided with a digital control unit, the digital control unit is connected with a high-voltage switch, the high-voltage switch is connected with a direct-current generator and a high-voltage pulse generator, the high-voltage pulse generator is connected with a water chain of the crude oil dehydration tank, and the direct-current generator is connected with an electrode of the crude oil dehydration tank. The conductivity of the crude oil or the emulsified liquid is calculated and corrected by combining the collected current, voltage and temperature data, and the digital control unit performs multi-loop control through the conductivity data. According to the invention, the output of alternating current, direct current, pulse and composite electric field can be realized, and the working waveform can be intelligently switched according to the emulsion load characteristic, so that the electric dehydration efficiency and the system energy efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crude oil dehydration data processing in the petroleum industry, and particularly relates to a dehydration high-voltage power supply and method capable of automatically switching waveforms according to loads. BACKGROUND

[0002] Crude oil often contains a large amount of entrained water and salt impurities, and dehydration treatment is a key process for ensuring oil transportation safety and oil refining quality. Currently, the commonly used crude oil electric dehydration power supplies mainly include three types of high-voltage direct-current power supplies, high-voltage alternating-current power supplies and high-voltage pulse power supplies. In actual production, alternating-current dehydration or alternating-current and direct-current composite processes are often used, but there are problems such as high power consumption, low treatment efficiency and strong dependence on the properties of crude oil. In particular, for stable water-in-oil emulsions, the traditional 50Hz high-voltage alternating-current electric field is prone to cause inter-electrode dielectric breakdown and form a short circuit, and it is difficult to provide sufficient demulsification energy. In addition, a large number of experiments at home and abroad have shown that the use of high-frequency high-voltage pulse alternating-current electric field can shut down the pulse output before dielectric breakdown, apply a higher instantaneous electric field by using the pulse characteristics, avoid the breakdown phenomenon, and significantly improve the demulsification and dehydration effect. In addition, for difficult-to-treat crude oils containing heavy oil and polymer flooding, the "dual-frequency dual-voltage" electric dehydration technology has been proposed, which modifies the output mode of the power supply and the electrode structure to fundamentally solve the problem of heavy oil dehydration. In the prior art, although digital control units or single-chip microcomputers are used to realize digital control of the electric dehydration power supply, the output is fixed to a single waveform, and real-time sensing and adaptive adjustment of the load condition are lacking. For example, the existing composite dehydration power supply can switch between direct current and pulse, but only triggers the pulse mode when discharge is detected, and the switching strategy is relatively simple, and the synergistic effect of multiple waveforms cannot be fully utilized. In addition, the traditional power supply often uses a large-capacity step-up transformer and a single frequency, which is large in size, low in efficiency and high in noise, and is not conducive to flexible application and energy saving and consumption reduction. Therefore, there is an urgent need for a new type of dehydration high-voltage power supply system that can automatically adjust the output mode and parameters according to the load characteristics of the emulsion to improve the demulsification efficiency and reduce energy consumption and noise.

[0003] Therefore, in view of the above problems, a dehydration high-voltage power supply and method and system capable of automatically switching waveforms according to loads are needed. SUMMARY

[0004] The present application aims to provide a dehydration high-voltage power supply and method capable of automatically switching waveforms according to loads. The output of alternating current, direct current, pulse and composite electric fields can be realized, and the working waveform can be intelligently switched according to the load characteristics of the emulsion to improve the electric dehydration efficiency and system energy efficiency.

[0005] The present application is implemented as follows:

[0006] The application provides a crude oil electric dehydration high-voltage power supply capable of automatically switching waveforms according to loads, comprising a crude oil dehydration tank, a temperature sensor arranged on the crude oil dehydration tank, and a voltage sensor and a current sensor arranged at a load end of the crude oil dehydration tank; the high-voltage power supply is provided with a digital control unit, the digital control unit adopts a digital control unit such as a TMS320F2812 type control processing unit, the digital control unit is connected with a high-voltage switch, the high-voltage switch is connected with a direct current generator and a high-voltage pulse generator, the high-voltage pulse generator is connected with a water chain of the crude oil dehydration tank, and the direct current generator is connected with electrodes of the crude oil dehydration tank. The direct current generator comprises a rectification filter circuit for rectifying and filtering an alternating current power supply to obtain direct current; the rectification filter circuit is connected with an adjustable direct current conversion circuit for outputting controllable direct current voltage; and the adjustable direct current conversion circuit is connected with a full-bridge inverter circuit for converting the direct current into alternating current with variable frequency.

[0007] The digital control unit is connected with the rectification filter circuit, the adjustable direct current conversion circuit, the full-bridge inverter circuit and the sensors on the crude oil dehydration tank, and is used for collecting load characteristic signals of emulsions, automatically switching output modes of the power supply according to the collected signals, and the output modes comprise at least one of high-voltage alternating current field, direct current field, high-voltage pulse electric field or a composite waveform thereof.

[0008] The digital control unit adopts a digital control unit or a single-chip microcomputer, and PWM control signals generated by the digital control unit are respectively used for driving power switch tubes of the adjustable direct current conversion circuit and the full-bridge inverter circuit through drivers, so that wide-range continuous adjustment data of output voltage amplitude, frequency and duty cycle are realized.

[0009] The high-voltage power supply comprises at least one high-voltage switch, the high-voltage switch is connected with input ends of the direct current generator and the high-voltage pulse generator, is driven by the digital control unit, and realizes switching between direct current mode and pulse mode. When it is detected that current of the dehydration tank load suddenly increases or breakdown discharge occurs, the digital control unit controls the high-voltage switch to switch to the pulse generator side, and triggers high-voltage pulses at a fixed time to open the water chain.

[0010] The digital control unit also collects load voltage division signal, current sensing signal and emulsion conductivity signal, and adjusts output waveform strategies based on multi-parameter feedback self-adaption; when the emulsion conductivity is low or the water content is high, a low-frequency or pulse-assisted alternating current field mode is preferably adopted; when the emulsion conductivity suddenly rises or a medium breakdown trend occurs, a high-voltage direct current superimposed pulse mode is preferably adopted.

[0011] The adjustable DC conversion circuit and full-bridge inverter circuit work in variable frequency PWM modulation state, and the output frequency is continuously adjusted in the range of hundreds of hertz to thousands of hertz. The output voltage amplitude and pulse width are changed as required; the step-up transformer is made of low-loss material, reducing operating loss and improving system efficiency. The output waveform includes AC rectangular pulse wave, DC voltage wave and its superimposed composite waveform, etc.; the digital control unit sets corresponding working parameters for different waveform modes to achieve the purposes of energy saving and noise reduction.

[0012] Further, the present application provides a method for automatically switching waveforms according to load, which is specifically executed in the following steps:

[0013] S1: Through the control circuit of the digital control unit, the voltage data at both ends of the crude oil dehydration tank load is collected through the voltage sensor, the current data is collected through the current sensor, and the temperature data of the crude oil dehydration tank is collected through the temperature sensor;

[0014] S2: The conductivity of the crude oil or emulsion is calculated and corrected in combination with the collected current, voltage and temperature data; the conductivity calculation formula of the crude oil or emulsion is as follows:

[0015]

[0016] Wherein, σ is the conductivity of the emulsion, unit is Siemens per meter (S / m), I is the current through the liquid (A), V is the voltage between electrodes (V), d is the distance between electrodes (m), A is the effective cross-sectional area of the electrode unit (m 2 );

[0017] S3: The conductivity is corrected according to the change of environmental temperature, and the corrected conductivity is as follows:

[0018] σ T = σ0·(1+α·(T-T0))

[0019] Wherein, σ T is the conductivity at temperature T, σ0 is the conductivity at reference temperature T0, and α is the conductivity temperature coefficient;

[0020] S4: The digital control unit performs multi-loop control through the conductivity data, which specifically includes voltage loop control output stable voltage, current loop monitoring load stable flow, and frequency / duty cycle loop adjusting output stable waveform;

[0021] The voltage loop control output stable voltage is specifically executed in the following steps:

[0022] S4.1: Sampling output voltage V out ;

[0023] S4.2: Obtaining target set value Vref ;

[0024] S4.3: Calculate voltage error e v = V ref - V out ;

[0025] S4.4: Input PI controller to calculate output u v as the reference value of the current loop; where the controller formula is as follows: u v [n] = u v [n-1] + K pv · (e v [n] - e v [n-1]) + K iv · e v [n]

[0026] Where u v [n] is the voltage loop control output, e v [n] is the voltage error this time, K pv is the voltage loop proportional coefficient, K iv is the voltage loop integral coefficient, and n is the current sampling period;

[0027] The current loop monitors the load steady flow, the purpose is to quickly respond to load changes, limit the maximum output current, and protect power devices;

[0028] Further, the current loop monitors the load steady flow: specifically, the following steps are performed:

[0029] S4.5: Sample load current I load ;

[0030] S4.6: Set the current reference value I ref = u v ;

[0031] S4.7: Calculate error e i = I ref - I load ;

[0032] S4.8: Use PI controller to calculate PWM control amount u i , sent to the modulator; the formula is as follows:

[0033] u i [n] = u i [n-1] + K pi · (e i [n] - e i [n-1]) + K ii · e i [n]

[0034] where u i [n] is the current error, K i [n] is the current error, K pi K ii is a proportional and integral parameter;

[0035] Further, the frequency / duty cycle loop adjusts the PWM duty cycle according to the controller to achieve voltage control, as follows:

[0036] S4.9: receiving the current loop control output u i ;

[0037] S4.10: generating a reference waveform;

[0038] S4.11: comparing the reference value with the triangular wave carrier to form a PWM waveform; the duty cycle is as follows:

[0039]

[0040] where D[n] is the current cycle duty cycle, u i [n] is the current loop output, V dc is the voltage obtained by sampling.

[0041] S5: the digital control unit switches between the two high-voltage generators through software logic; in the start-up or standby phase, the digital control unit first uses the DC generator to slowly pre-electric field process the emulsion; during the dehydration process, if abnormal drop of the load voltage amplitude or sudden surge of the current is detected, indicating that breakdown or water chain formation occurs, the digital control unit controls the high-voltage switch to jump to the pulse power side, and periodically triggers the high-voltage pulse generator to open the water chain.

[0042] Further, the present application provides an automatic switching waveform adjustment system according to the load, which comprises a data acquisition module for acquiring temperature data on the crude oil dehydration tank, voltage data and current data at the load end;

[0043] The data analysis module acquires current, voltage, and temperature parameter data, completes the conductivity calculation and correction of the crude oil or emulsion, and according to the conductivity data of the emulsion, if the conductivity is within the set threshold and there is no discharge phenomenon, the AC high-voltage output is maintained; when a significant rise in conductivity or a sudden drop in voltage is detected, it is judged that rapid demulsification is needed, and the automatic switching to pulse mode is triggered; a series of high-voltage pulses are output through high-frequency PWM control, and corona discharge is used to break the water droplet aggregation chain; after the dehydration effect is monitored to restore the conductivity or the inter-electrode voltage rises, the digital control processing unit switches back to the AC mode and ends the current pulse wave segment, and the whole process uses multiple waveforms alternately, corresponding to different emulsion states, and outputs different regulation and control data;

[0044] Data execution module, the digital control processing unit judges and outputs the regulation and control data of different modes, and sends to the direct current generator and the high voltage pulse generator for execution;

[0045] Data storage module, the historical regulation and control data are stored for data query of the staff;

[0046] Man-machine interaction module, the real-time monitoring data and the execution data of the high-voltage power supply are displayed through the establishment of the man-machine interaction display module.

[0047] Further, the application provides a computer storage medium, the storage medium stores a computer program, when the computer program in the storage medium runs, executes the above-mentioned, any one of the crude oil electric dehydration methods according to load automatic switching waveform.

[0048] Compared with the prior art, the beneficial effects of the application are:

[0049] 1, the present application realizes the self-adaptive switching of the dehydration power supply working state through the digital and intelligent control method, the high-voltage frequency conversion and PWM modulation: the front-stage variable voltage circuit adopts IGBT device, the output frequency, voltage and pulse width can be continuously adjusted in a wide range, fully meeting the working condition requirements of different water content crude oils;

[0050] Multi-mode waveform output: the power supply can output multiple waveforms such as power frequency / high-frequency alternating current, direct current, adjustable pulse and composite waveform, can automatically switch modes according to the change of emulsion resistance and conductivity, respectively uses the optimal electric field in the demulsification initial stage and stable stage, avoids breakdown failure;

[0051] Multi-parameter monitoring feedback: the system monitors the load voltage, current and calculates the conductivity, adopts multi-loop closed-loop control, realizes real-time adjustment of output, energy utilization is more efficient, output is more stable, and the change of parameters such as conductivity can be used as a quantitative index of demulsification progress;

[0052] Energy saving and noise reduction: based on the load demand, the output voltage and frequency are adjusted to avoid excessive energy consumption; high-frequency voltage boosting and electronic switching technology are used to replace the bulky transformer, the volume is reduced, the iron loss and mechanical resonance noise are reduced, the reliability and maintenance convenience are improved;

[0053] Improve demulsification efficiency: through the synergistic effect of alternating current, direct current and pulse multi-mode, the mechanism of electric field induced water droplet coalescence can be more comprehensively utilized, which can significantly improve the crude oil dehydration efficiency, especially for stable emulsion and heavy crude oil. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as a limitation to the scope. For those skilled in the art, other related drawings can also be obtained from these drawings without any creative effort.

[0055] Figure 1 is a flow chart of the method of the present application;

[0056] Figure 2 is a system structure diagram of the present application;

[0057] Figure 3 is a power supply device structure connection diagram of the present application;

[0058] Figure 4 is a circuit connection diagram of the power supply of the present application. DETAILED DESCRIPTION

[0059] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only for selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of the present application.

[0060] Please refer to Figures 1-4 The present application provides a crude oil electric dehydration high-voltage power supply and method capable of automatically switching waveforms according to load.

[0061] In the present embodiment, as Figure 4The high-voltage power supply control system of the application comprises VD1-VD6 rectifier diodes, VD7-VD8 freewheeling diodes, V1 IGBT-V4 IGBT power switch tubes, R current-limiting resistor, T high-frequency transformer and dehydration electrode. The specific embodiment is that three-phase alternating current power supplies are connected to the rectification unit through input terminals A, B and C. The rectification unit is composed of six rectifier diodes VD1, VD2, VD3, VD4, VD5 and VD6, forming a three-phase full-wave rectifier bridge circuit. VD1 and VD4 are connected to the positive and negative half cycles of the A-phase input respectively, VD2 and VD5 are connected to the positive and negative half cycles of the B-phase input respectively, and VD3 and VD6 are connected to the positive and negative half cycles of the C-phase input respectively. The anode and cathode of each diode are connected according to the bridge topology structure. The positive electrode of the three-phase rectification output is output through the current-limiting resistor R, and the negative electrode is directly grounded. The rectified direct current voltage is input to the inverter unit through the current-limiting resistor R. The inverter unit is composed of four IGBT tubes, namely V1 IGBT, V2 IGBT, V3 IGBT and V4 IGBT, forming an H-bridge structure. The pin connection relationship is that V1 IGBT and V3 IGBT are used as bridge upper arm devices, and their collector electrodes are connected to the positive electrode of the rectification output. V2 IGBT and V4 IGBT are used as bridge lower arm devices, and their emitter electrodes are connected to the common ground terminal. The emitter electrode of V1 IGBT and the collector electrode of V2 IGBT are connected to one side winding of the high-frequency transformer T. Similarly, the emitter electrode of V3 IGBT and the collector electrode of V4 IGBT are connected to the other side winding of the high-frequency transformer T. The gates of the four IGBTs are connected to the control drive circuit, which is used to send on / off signals according to the load state to realize automatic switching of the output waveform. The primary winding of the high-frequency transformer T is driven by the inverter bridge output. The transformer is used to realize high-frequency voltage transformation and electrical isolation. The secondary winding is connected to the output rectification unit, which is composed of two freewheeling diodes VD7 and VD8. The specific connection of the output rectification part is that one end of the transformer secondary winding is connected to the anode of VD7, and the other end is connected to the anode of VD8. The cathodes of VD7 and VD8 are combined to form the positive electrode of the rectification output, which is directly connected to the electrode of the crude oil dehydrator. The negative electrode of the rectification output is grounded to form a stable high-voltage direct current power supply. Through the above circuit structure, when the control module needs to switch the power supply waveform according to the load state, the control IGBT conduction logic is changed to change the output voltage waveform, realizing efficient and stable crude oil electric dehydration treatment.

[0062] In the embodiment, the control system takes the TMS320F2812 digital control unit as an example. The digital control unit generates multiple PWM drive signals, which drive all power switches through corresponding drivers. The control circuit collects the voltage (through a high-voltage voltage divider) and current of the dehydrator load.

[0063] In this embodiment, the application collects current, voltage, and temperature parameters, and combines the following formula to complete the calculation and correction of the conductivity of crude oil or emulsion. The specific formula is:

[0064] The conductivity basic calculation model of the emulsion of crude oil is:

[0065]

[0066] Wherein σ is the conductivity of the emulsion, the unit is Siemens per meter (S / m), I is the current through the liquid (unit: A), V is the voltage between the electrodes (unit: V), d is the distance between the electrodes (unit: m) A is the effective cross-sectional area of the electrode (unit: m 2 ), if necessary, the conductivity is directly calculated by the resistance R as follows:

[0067]

[0068] Wherein R is the resistance (unit: Ω), L is the length of the sample between the electrodes (unit: m), A is the electrode area (unit: m 2 ).

[0069] The conductivity is corrected considering the influence of the change of the environmental temperature on the measurement result, and the corrected conductivity formula is as follows:

[0070] σ T = σ0·(1+α·(T-T0))

[0071] Wherein σ T is the conductivity at temperature T, σ0 is the conductivity at reference temperature T0, and α is the conductivity temperature coefficient. The digital control unit is built-in with multiple algorithms to realize multi-loop control: the voltage loop ensures the stability of the output voltage, the frequency / duty cycle loop adjusts the output waveform, and the current loop monitors the load flow.

[0072] In this embodiment, the core control strategy of the application contains three control closed loops: voltage loop, current loop, and modulation loop (duty cycle / frequency loop). The voltage loop control algorithm stabilizes the output voltage, and the data processing steps are:

[0073] Sampling the output voltage V out ;

[0074] Obtaining the target set value V ref ;

[0075] Calculating the voltage error e v = V ref -V out .

[0076] Inputting the PI controller to calculate the output u v , as the reference value of the current loop.

[0077] The controller is as follows:

[0078] u v [n] = u v [n-1] + K pv · (e v [n] - e v [n-1]) + K iv · e v [n]

[0079] wherein u v [n] is the output of the voltage loop control, e v [n] is the voltage error, K pv is the proportional coefficient of the voltage loop, and K iv is the integral coefficient of the voltage loop, and n is the current sampling period. In the embodiment, the current loop control algorithm is used to quickly respond to load changes, limit the maximum output current, and protect the power device. The data processing steps are as follows:

[0080] Sampling the load current I load ;

[0081] Setting the current reference value I ref = u v ;

[0082] Calculating the error e i = I ref - I load , using a PI controller to calculate the PWM control amount u i , and sending it to the modulator, as follows:

[0083] u i [n] = u i [n-1] + K pi · (e i [n] - e i [n-1]) + K ii · e i [n]

[0084] wherein u i [n] is the current output of the current loop control, e i [n] is the current error, K pi K ii are proportional and integral parameters.

[0085] The modulation loop control algorithm generates a PWM duty cycle according to the controller to achieve voltage control. The data processing steps are as follows: receiving the current loop control output u i ;

[0086] Generating a reference waveform.

[0087] The reference value is compared with the triangular wave carrier to form a PWM waveform. The duty cycle formula is

[0088]

[0089] where D[n] is the duty cycle of the current cycle, u i [n] is the output of the current loop, V dc is the voltage obtained by sampling.

[0090] In addition, the present application switches between the two high-voltage generators through software logic: in the starting or standby phase, the system can first use the stabilized DC generator to slowly pre-electric field process the emulsion; during the dehydration process, if abnormal drop of the load voltage amplitude or sudden surge of the current is detected, indicating that breakdown or water chain formation occurs, the digital control unit will control the high-voltage switch to jump to the pulse power side, and periodically trigger high-energy pulses to open the water chain. The entire switching process is automatically completed by the digital control unit program logic without manual intervention.

[0091] In this embodiment, the digital control unit continuously monitors the AC impedance and DC conductivity of the emulsion, and calculates the demulsification efficiency index. As mentioned above, high-frequency pulses of 1-2 kHz can significantly improve the demulsification efficiency. Therefore, when the emulsion is a stable water-in-oil emulsion, the digital control unit can prefer the high-frequency pulse mode; when the emulsion conductivity is low and the water content is high, low-frequency or low-frequency AC field can be applied to promote large drop coalescence; when the conductivity suddenly rises and breakdown tendency occurs, switch to the DC superimposed pulse mode or pure pulse mode to eliminate the water droplet "bridge" phenomenon. In addition, the system has an automatic optimization function: during the electric field action process, the digital control unit compares the demulsification effect under different frequencies and duty cycles, and dynamically adjusts the output parameters to the optimal range, which can use the PID algorithm built-in the digital control unit. Real-time current is set to 20mA, when the real-time current rises more than 20%, trigger the waveform adjustment program, as shown in the following table;

[0092] Table 1 Trigger waveform adjustment data table

[0093]

[0094] The current rate of change is calculated as follows:

[0095]

[0096] In this embodiment, the optimal control parameters are automatically found by optimizing the score function under different frequency and duty cycle combinations. The score function formula is as follows:

[0097] J(f,D) = a · R(f,D) + b · (f,D)

[0098] Wherein, R(f, D) is the residual water rate, T(f, D) is the demulsification time, E(f, D) is the energy consumption, and a, b, g are weight factors respectively assigned as 0.5, 0.3, 0.2. The automatic optimization step is to first set the search range of frequency as 1000Hz-2500Hz, and the duty cycle as 20%-80%. Then, experiments are conducted on each combination of frequency and duty cycle, and the residual water rate, demulsification time and energy consumption are recorded. Then, the score function is calculated.

[0099] Finally, the parameter combination with the minimum score function is selected as the optimal frequency and duty cycle. The control system sets the optimal parameters, and outputs control signals according to the optimal parameters to adjust the actual working state. In the actual working process, the frequency and duty cycle are adjusted in real time according to the current change and working condition; as shown in Table 2.

[0100] Table 2 Adjustment of frequency and duty cycle data table

[0101]

[0102]

[0103] In this embodiment, the minimum score function is 2.07, the corresponding frequency is 2000Hz and the duty cycle is 50%, and this combination is the optimal parameter. Through the monitoring of the current change rate, the system waveform can be adjusted in real time and the control parameters can be optimized by using the automatic optimization function. The present application can significantly improve the stability and efficiency of the dehydration process and avoid the breakdown phenomenon.

[0104] In this embodiment, the circuit module of the present application is integrated: high reliability and easy maintenance are achieved, and the embodiment adopts modular design. The rectification + DC / DC can be composed into a unit module, and multiple groups can be connected in parallel to improve the power capacity; the inverter bridge and the step-up transformer are located in the high-voltage cavity for isolation. The entire power cabinet adopts a digital control unit digital control structure, and the system can be seamlessly connected with the DCS control system of the oilfield site to realize monitoring data transmission and remote parameter delivery. The human-computer interaction module control software provides a parameter setting interface, which can display the electrode voltage, current waveform and emulsion conductivity change curve of the dehydration tank in real time for the operator to monitor and analyze.

[0105] In this embodiment, the working process is exemplified as follows: after the system is started, the direct current output is preheated and the emulsion conductivity is detected; if the conductivity is within the set threshold value and there is no discharge phenomenon, the alternating current high voltage output is maintained; when the conductivity is detected to be significantly increased or the voltage is suddenly dropped, the digital control unit determines that rapid demulsification is needed, and triggers automatic switching to the pulse mode; a series of high-voltage pulses are output through high-frequency PWM control, and the water droplet aggregation chain is broken by corona discharge; after the dehydration effect is monitored to recover the conductivity or the voltage between the electrodes rises, the digital control unit can switch back to the alternating current mode and end the current pulse band. The entire process uses multiple waveforms alternately, which corresponds to different emulsion states, effectively improves the total dehydration rate and the system efficiency.

[0106] In summary, the application provides a clear structure, a strong crude oil electric dehydration high-voltage power supply, through the dynamic perception and intelligent control of the load characteristics, seamless switching of multiple waveforms and multiple working modes is realized, thereby improving the dehydration efficiency, reducing the energy consumption, reducing the operation noise, and meeting the needs of modern oilfields for efficient dehydration equipment.

[0107] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high-voltage power supply for crude oil electro-dehydration that automatically switches waveforms according to load, comprising a crude oil dehydration tank, characterized in that: It includes a temperature sensor installed on the crude oil dehydration tank, and a voltage sensor and a current sensor installed at the load end of the crude oil dehydration tank; the high-voltage power supply is equipped with a digital control unit, which is connected to a high-voltage switch, which is connected to a DC generator and a high-voltage pulse generator, the high-voltage pulse generator is connected to the water chain of the crude oil dehydration tank, and the DC generator is connected to the electrodes of the crude oil dehydration tank.

2. The high-voltage power supply for crude oil electro-dehydration that automatically switches waveforms according to the load as described in claim 1, characterized in that: The DC generator includes a rectifier and filter circuit for rectifying and filtering AC power to obtain DC power; an adjustable DC-DC converter circuit connected to the rectifier and filter circuit for outputting a controllable DC voltage; and a full-bridge inverter circuit connected to the adjustable DC-DC converter circuit for converting DC power into AC power with a variable frequency.

3. The high-voltage power supply for crude oil electro-dehydration that automatically switches waveforms according to the load as described in claim 1, characterized in that: The digital control unit is a digital control unit or a microcontroller. The PWM control signal generated by the control unit drives the power switching transistors of the adjustable DC-DC converter circuit and the full-bridge inverter circuit through the driver, so as to realize the wide-range continuous adjustment of the output voltage amplitude, frequency and duty cycle.

4. A high-voltage power supply for crude oil electro-dehydration that automatically switches waveforms according to the load, as described in any one of claims 1-2, characterized in that: The high-voltage power supply includes at least one high-voltage switch, which is connected to the input terminals of the DC generator and the high-voltage pulse generator and is driven by the digital control unit to achieve switching between DC mode and pulse mode.

5. A method for automatically switching waveforms based on load, characterized in that: Follow these steps: S1: Through the control circuit of the digital control unit, voltage data at both ends of the crude oil dehydration tank is collected by a voltage sensor, current data is collected by a current sensor, and temperature data of the crude oil dehydration tank is collected by a temperature sensor. S2: Based on the collected current, voltage, and temperature data, the conductivity of crude oil or emulsion is calculated and corrected; the formula for calculating the conductivity of crude oil or emulsion is as follows: Where σ is the conductivity of the emulsion, I is the current flowing through the liquid, V is the voltage between the electrodes, d is the distance between the electrodes, and A is the effective cross-sectional area of ​​the electrode (unit). S3: The conductivity is corrected according to the change in ambient temperature. The corrected conductivity is as follows: s T =σ0·(1+α·(T-T0)) Where, σ T Let σ0 be the conductivity at temperature T, σ0 be the conductivity at reference temperature T0, and α be the temperature coefficient of conductivity. S4: The digital control unit performs multi-loop control based on conductivity data, specifically including voltage loop control to stabilize the output voltage, current loop monitoring to stabilize the load flow, and frequency / duty cycle loop adjusting the output waveform. S5: The digital control unit switches between two high-voltage generators through software logic. During startup or standby, the digital control unit first uses a regulated DC generator to slowly pre-electrically treat the emulsion. During dehydration, if an abnormal drop in load voltage amplitude or a surge in current is detected, indicating a breakdown or the formation of a water chain, the digital control unit controls the high-voltage switch to switch to the pulse power supply side and periodically triggers high-energy pulses to open the water chain.

6. The method for automatically switching waveforms according to load as described in claim 5, characterized in that: In step S4, the voltage loop control outputs a stable voltage, which is specifically executed according to the following steps: S4.1: Sampled output voltage V out ; S4.2: Obtain the target setpoint V ref ; S4.3: Calculate voltage error e v =V ref -V out ; S4.4: Input PI controller calculates output u v , serving as a reference value for the current loop; where the controller formula is as follows: u v [n] = u v [n-1]+K pv ·(e v [n]-e v [n-1])+K iv ·e v [n]where u v [n] represents the voltage loop control output, e v [n] represents the voltage error in this operation, K pv K is the voltage loop proportionality coefficient. iv is the voltage loop integral coefficient, and n is the current sampling period.

7. The method for automatically switching waveforms according to load as described in claim 5, characterized in that: In step S4, the current loop monitors the stable flow of the load: specifically, it is performed according to the following steps: S4.5: Sample load current I load ; S4.6: Set current reference value I ref =u v ; S4.7: Calculation error e i =I ref -I load ; S4.8: Calculate the PWM control quantity u using a PI controller. i The signal is fed into the modulator; the formula is as follows: u i [n]=u i [n-1]+K pi ·(e i [n]-e i [n-1])+K ii ·e i [n] Where u i [n] represents the current current loop control output, e i [n] represents the current error, K pi K ii These are the proportional and integral parameters.

8. The method for automatically switching waveforms according to load as described in claim 5, characterized in that: Frequency / duty cycle loop adjustment achieves voltage control based on the PWM duty cycle generated by the controller, as detailed in the following steps: S4.9: Receive current loop control output u i ; S4.10: Generate a reference waveform; S4.11: Compare the reference value with the triangular wave carrier to form a PWM waveform; the duty cycle is as follows: Where D[n] is the current cycle duty cycle, u i [n] represents the current loop output, V dc This is the voltage obtained through sampling.

9. A regulating system that automatically switches waveforms according to load, characterized in that: It includes a data acquisition module for collecting temperature data, voltage data, and current data from the crude oil dehydration tank and the load. The data analysis module collects current, voltage, and temperature parameter data to calculate and correct the conductivity of crude oil or emulsion. Based on the conductivity data of the emulsion, if the conductivity is within a set threshold and there is no discharge phenomenon, it maintains AC high-voltage output. When a significant increase in conductivity or a sudden drop in voltage is detected, it determines that rapid demulsification is required and triggers automatic switching to pulse mode. A series of high-voltage pulses are output through high-frequency PWM control to break the water droplet aggregation chain using corona discharge. Once the dehydration effect is monitored and the conductivity recovers or the inter-electrode voltage rises, the digital control processing unit switches back to AC mode and ends the current pulse band. Throughout the process, multiple waveforms are used alternately to correspond to different emulsification states and output different control data. The data execution module and the digital control processing unit judge and output the control data for different modes, and then send them to the DC generator and the high-voltage pulse generator for execution. The data storage module stores historical control data, making it convenient for staff to query the data. The human-computer interaction module displays real-time monitoring data and processing execution data of the high-voltage power supply through a human-computer interaction display module.

10. A computer-storable medium, characterized in that: The storage medium stores a computer program. When the computer program in the storage medium runs, it executes the high-voltage power supply for crude oil electro-dehydration that automatically switches waveforms according to the load, as described in any one of claims 5-8.

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