Unit pompa balok umumnya digunakan sebagai peralatan pompa utama di berbagai ladang minyak di Tiongkok, yang memiliki masalah seperti produksi rendah, konsumsi energi tinggi, dan kuda besar yang menarik mobil kecil. Dalam beberapa tahun terakhir, seiring perkembangan teknologi elektronika daya, teknologi konversi frekuensi telah banyak digunakan di ladang minyak karena keunggulannya seperti penghematan energi dan kemudahan pengaturan frekuensi. Selama pengoperasian unit pompa, motor listrik seringkali beroperasi dalam kondisi pembangkit.
In order to solve the problem of energy backflow, there are currently two main solutions for pumping units in various oil fields in China:
·Variable frequency braking unit and variable frequency feedback unit. Adding a braking unit and a braking resistor to the busbar directly consumes energy on the braking resistor, which is not only detrimental to energy conservation, but also difficult to solve the problems of heat dissipation and lifespan of the braking resistor;
·Parallel feedback units are connected to the busbar to feed back the energy generated by the motor during power generation to the grid, achieving reverse flow between the inverter and the grid. However, this does not solve the problem of low power factor and high harmonic current when energy flows from the grid to the inverter.
In response to the above situation, the four quadrant technology solution can overcome the shortcomings of the two solutions mentioned above. The four quadrant frequency conversion technology solves the problem of regenerative energy processing of pumping units when the system is unbalanced, with four quadrant operation function, while improving energy-saving efficiency, reducing harmonic pollution of the power supply, and improving power factor. The four quadrant frequency converter adopts IGBT rectification technology controlled by PWM, with bidirectional control of rectification and energy feedback. True four quadrant operation can perfectly solve the problem of energy backflow in pumping units.
Introduction to Four Quadrant Frequency Conversion Technology
1、 Principle of Four Quadrant Frequency Converter
The topology of the four quadrant frequency converter circuit, which uses three-phase pulse width modulation (PWM) rectification instead of uncontrolled rectification, is shown in Figure 1. It can convert the mechanical energy of the load into electrical energy and return it to the grid.
Four quadrant frequency converter - energy-saving solution for oilfield pumping units
Figure 1 Topology structure of four quadrant frequency converter circuit
2、 Advantages of Four Quadrant Frequency Converter
Using a high-speed and high computing power rectifier control unit DSP, six high-frequency PWM pulses are generated to control the turn-on and turn off of the IGBT on the rectifier side. The turn-on and turn off of the IGBT work together with the input reactor to produce a sine current waveform that is in phase with the input voltage. This eliminates the harmonics generated by diode rectification and analysis, and the power factor is close to 1, thereby eliminating harmonic pollution to the power grid;
The rectifier side of the four quadrant frequency conversion technology adopts IGBT power modules, which can achieve bidirectional flow of energy between the input grid and the motor. When the system is unbalanced, the potential energy generated by the imbalance can be fed back to the grid, greatly reducing the requirement for system balance;
Ketika motor dalam keadaan pembangkit, energi yang dihasilkan motor diumpankan kembali ke bus DC melalui dioda di sisi inverter. Kontrol umpan balik sisi penyearah dimulai, membalikkan DC ke AC, dan menyalurkan kembali energi ke jaringan dengan mengendalikan fase dan amplitudo tegangan inverter, sehingga menghasilkan efek penghematan energi.