Application of the hottest high voltage inverter i

Application of high-voltage inverter in oilfield water injection pump

1 purpose and significance of installing high-voltage inverter

water injection pump is the source equipment to meet oilfield water injection and ensure formation pressure. With the middle and late stage of oilfield exploitation, the amount of oilfield water injection will also increase year by year. The power consumption of water injection has accounted for 19% of production power, and the power charge of water injection accounts for 16% of the total power charge, showing a significant upward trend year by year. In the high-pressure water injection system, the phenomenon of a big horse pulling a small car in the high-pressure motor is relatively common. There is a large pressure difference between the pump pressure of the water injection pump and the dry pressure of the water injection pipeline, and the water injection pressure of the water injection pipe must be guaranteed by controlling the high-pressure return valve at the pump outlet, which not only causes a large amount of electric energy to be consumed in vain, but also is very unfavorable to the operation of the pump and the use of the pipeline due to the high pump pressure. After installing the high-voltage variable-frequency speed regulation device, the parameters are set according to the pressure required by the water injection pipe, and the water injection volume is automatically adjusted, which can not only save a lot of electric energy, but also reduce the loss of the machine and pump, which is of great positive significance to reduce the production cost

Liaohe xinsanlian water injection station has put into operation a water injection pump with the model of dfjax11, which is matched with a 6kv/1800kw asynchronous motor with the model of yb1800s. It is controlled by direct drive. The flow of the centrifugal pump is adjusted by controlling the opening of the outlet valve, resulting in a large amount of throttling loss. The centrifugal pump and motor operate in a low efficiency working area, resulting in serious energy waste. At present, the monthly water injection flow is 183210m3, and the water injection volume decreases correspondingly in summer and autumn. The actual pump pressure of the centrifugal pump in operation is 16.5mpa, and the actual operating pressure of the water injection pipe is 12.5mpa. Due to the implementation and operation of multi pump water injection, when the pressure of the water injection pipe rises above the current actual water injection pressure of the water injection pipe, the high-pressure water injection volume will be reduced, which cannot meet the water injection demand of the oil well. At the same time, if the sewage volume is greater than the water injection volume, the sewage will be discharged. Therefore, when the water injection motor is running, the pressure of the water injection pipe must be controlled by adjusting the high-pressure return valve at the outlet of the centrifugal pump to maintain the balance of combined water injection. In this way, the average pressure difference between pump pressure and pipe dry pressure reaches more than 4MPa, resulting in a large amount of waste of electric energy

through comprehensive investigation and consideration, we selected jd-bpf high-voltage inverter of Shandong xinfengguang electronic company. Through application, the inverter has good safety performance, high reliability, reasonable design, long service life of vulnerable parts, good starting performance, obvious consumption reduction effect, and convenient installation, maintenance and maintenance

2. Principle of high voltage inverter

Figure 1 Structure of variable frequency speed regulation system

jd-bp37 series high voltage variable frequency speed regulation system is shown in Figure 1, which is composed of phase-shifting transformer, power unit and controller. 6kv/1800kw frequency converter has 24 power units in total, and every 8 power units are connected in series to form a phase

2.1 power unit circuit

Figure 2 unit structure

each power unit structure is completely consistent and interchangeable. Its circuit structure is shown in Figure 3.2. It is a basic AC DC AC single-phase inverter circuit, and six diodes are on the rectifier side to realize three-phase full bridge rectification. Through sinusoidal PWM control of IGBT inverter bridge, each power unit is exactly the same and interchangeable, which is not only convenient for debugging and maintenance, but also very economical for backup, If a unit fails, the output end of the unit can be automatically short circuited, and the whole machine can be temporarily derated until it stops running slowly

2.2 input side structure

each unit is powered by a phase-shifting transformer on the input side, and each power unit bears motor current, 1/8 phase voltage and 1/24 output power. Each of the 24 units has its own independent three-phase input winding on the transformer. The power units and the secondary windings of the transformer are insulated from each other. The secondary winding adopts extended delta connection method, which aims to realize multiplicity and reduce the harmonic component of input current. The 24 secondary windings are divided into three phase groups, with a mutual difference of 20 °, forming an 18 pulse rectification mode; This multi-stage phase-shifting superposition rectification method can greatly improve the current waveform at the side, make the side power factor close to 1 under load, and the harmonic component of input current is low. The total harmonic component of the measured input current is less than 5%. Due to the independence of the secondary winding of the transformer, the main circuit of each power unit is relatively independent, similar to the conventional low-voltage frequency converter, which is convenient to adopt the existing mature technology

2.3 controller

the core of the controller is realized by the cooperative operation of high-speed 16 bit MCU and industrial PC. The carefully designed algorithm can ensure the optimal operation performance of the motor. The industrial control PC provides a friendly all Chinese windows monitoring and operation interface, and can realize remote monitoring and networking control at the same time. The controller is used for logic processing of switch signals in the cabinet and coordination with various on-site operation signals and status signals, which enhances the flexibility of the system

large scale integrated circuits such as 8-bit single chip microcomputer and surface welding technology are used in the controller and each control unit board, and the system has high reliability. In addition, there is a CPU, which is also an 8-bit MCU, responsible for managing the LED display and keyboard

in addition, multi-channel optical fiber communication technology is adopted between the controller and the power unit. The low-voltage part and the high-voltage part are completely and reliably isolated. The system has high safety and good anti electromagnetic interference performance. In addition, the control power supply of each power unit adopts a unified controller independent of the high-voltage system, which is convenient for debugging, maintenance, on-site training, and enhances the reliability of the system

2.4 control power supply

the controller has a set of power supply system independent of high-voltage power supply. Without high-voltage, the waveform of each point of the equipment is basically similar to that of high-voltage, which brings great convenience to the reliability, debugging and training of the whole machine

Figure 3 independent control power supply system

3. Site conditions and energy-saving effect statistics

in view of the problems existing on site, the optimization and transformation of the system mainly need to solve two problems: first, on the basis of meeting the water distribution of the system, reduce the displacement loss as much as possible; Second, on the premise of meeting the water injection pressure, reduce the pump pipe differential pressure as much as possible, that is, reduce the pressure loss. The system optimization is planned to start with kinetic energy and potential energy at the same time, so as to reduce energy consumption and improve system efficiency as much as possible

3.1 site system composition

Figure 4 site system composition

the closed-loop control process of the system is as follows: the intelligent sensor monitors and processes the real-time data of each operating water injection pump, that is, collects and transmits the operating parameters of the water injection pump and the station, such as: pump displacement Q single, motor current I, pump inlet and outlet pressure P pump, water injection station outlet dry pressure P dry, total displacement Q total, average unit consumption, etc, These control parameters (Q single, I, P pump, P dry, Q total) are compared and optimized with their expected values and the characteristic curve of the pump itself. Among them, the dry pressure and total flow of the water injection station are the two main parameters that the system needs to monitor and control. In this system, on the one hand, a high reliability pressure sensor is installed on the pump outlet pipeline to compare the measured pressure signal with the injection pressure (expected value) of the system. 5. Detection performance:, and send the difference value to the process parameter regulator (PID) for proportional and integral calculation, and finally send the output result to the programmable controller (PLC); On the other hand, a flowmeter is installed on the pump inlet pipeline to monitor the actual total flow of the system, and the difference between this value and the system injection volume is PID adjusted again, and finally the output result is sent to PLC. According to the two PID setting signals received, PLC uses the method of fuzzy reasoning. On the premise of meeting the dry pressure of the system, the system automatically adjusts the output frequency of the high-voltage converter in time to control the speed of the variable-frequency pump. According to the centrifugal pump, the change of pump speed can cause the corresponding displacement change, and the desired displacement value can be achieved through the change of frequency. Through the above closed-loop control, the actual pressure and displacement of the system are close to the injection pressure and injection volume of the system. The system is designed as a closed-loop control system, and the flow and pressure are the two main parameters of the system. The measured flow and pressure signals of the system and the flow and pressure (expected value) required by geology are adjusted by double PID; Through the fuzzy reasoning method, the system automatically optimizes the control. According to the reasoning results, the system automatically adjusts the output of the high-voltage converter in time, and automatically calculates the best operating frequency of the converter

3.2 analysis of power saving effect

3.2.1 proportional to the cube of power and speed:

p1/p2 μ (n1/n2) 3 (where n is the pump speed and P is the output power)

it can be seen that the power change of the pump is directly proportional to the third power of the speed, that is, when the pump speed decreases by 1 unit, the pump power will decrease by the third power of the unit. The frequency conversion speed regulation officially controls the pump speed by changing the frequency of the power supply through the frequency converter, which fully shows that the frequency conversion speed regulation is the best way to save energy

3.2.2 the system efficiency is improved and the unit consumption is reduced

after the transformation of the system through the high-voltage frequency converter, each pump can meet the water injection volume of the system under the premise of operating in the high-efficiency area, which effectively improves the system efficiency of the handheld spectrometer before and after use and reduces the unit consumption of the system. According to the analysis and calculation, the average unit consumption of water injection can be reduced by 0.2~0.4kw/h after the transformation of the system. Taking the average value of 0.3kw/h, the average daily water injection volume is 4100m3/d. If the electricity is calculated at 0.5 yuan per kilowatt hour, the electricity cost can be saved for one year:

4100 ′ 365 ′ 0.3 ′ 0.5=224000 yuan (RMB)

3.2.3 adjust the excess water volume and save electric energy

the average daily water injection volume is 4100m3/d, The required water injection volume fluctuates greatly (sometimes 2600m3/d, sometimes 5500m3/d) and changes frequently (once a week or several days). The high-voltage frequency conversion transformation of the station can flexibly adjust the operation of the pump in the station according to the water volume required outside the station, so that it can be consistent with the required water injection volume as far as possible on the premise of meeting the system pressure requirements, so as to significantly reduce the waste of electric energy and water sources

when 3600m3/d water injection is required, the pump capacity is greater than the required water volume, and an additional 1500m3/D will be injected; When it is required to inject 5500m3/d, it will be difficult to start one pump without paying attention to demoulding. Opening two pumps will inject 2220m3/d more water, which will cause a waste of water and electric energy. According to the above data and the operation situation in the station, in order to meet the injection allocation, the average additional water injection is 1600m3/d every day, and the unit consumption of the system is 7.1kw/h. Based on the electricity charge of 0.5 yuan per kilowatt hour, the water volume is mismatched for about 150 days a year before the transformation, Then the annual electricity saving fee after adjustment by high-voltage frequency conversion is:

1600 ′ 150 ′ 7.1 ′ 0.5=852000 yuan (RMB)

3.3 actual electricity saving effect

the frequency converter was installed and officially operated in the new triple 2 # water injection motor in August 2004. The statistics of power consumption before and after using the frequency converter are shown in the following table:

Table 1: power consumption before using the frequency converter in May 2004

from table 1 and table 2, 2 # the unit consumption of water injection before and after the installation of frequency converter of water injection pump motor decreases from 6.79 to 5.38, regardless of other aspects:

power saving rate = (power consumption before installation - power consumption after installation)/power consumption before installation *100%

= ()/*100%

=43.88%

considering the influence of various noodle parts of water injection volume, the actual power saving rate is different from the calculated value, but there will not be much difference according to the on-site operation, The overall power saving effect will not change

4 conclusion

to sum up, jd-bp37 series high-voltage inverter runs smoothly, has reliable performance, is simple and practical, and has obvious power-saving effect, which improves the working environment of staff. There is no impulse current and large