Permanent magnet synchronous motor to improve the power factor
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Abstract: Due to the way electricity for the conversion, local oil wells in oil fields on the grid point Measurement single well test, such as the power factor less than 0.9, to pay the tariff adjustment. Wells used for permanent magnet motor with low power factor, adjusted.
Key words: permanent magnet synchronous motor; power factor; raise
Key words: TM351 Document code: B
 
As the oil for electricity metering points changed from the original single-well (point) measurement, the single (point) can not power factor standards. In 2003, production set factory only temporary power factor adjustment on electricity to pay 1,500,000 yuan. To this end, has taken various measures to improve the power factor, energy consumption reached.
First, the impact of permanent magnet synchronous motor power factor of the reasons
On the unit used by the permanent magnet synchronous motor is an asynchronous start of the synchronous motor, the rotor into the lead after the exchange at the same pace, similar to the exchange of synchronous motor. Run by the stator coils in the air gap in the rotating magnetic field generated by the rotor and the mutual attraction between the magnet so that the air-gap stator and rotor synchronous rotating magnetic field and acting. The equivalent resistance for the rotor circuit, the high power factor. In the absence of excitation current, no-load its loss. The efficiency of electric motors up to 96% higher than the three-phase asynchronous motor.
The impact of permanent magnet synchronous motor power factor is due to the quality of voltage (voltage amplitude) and load rate. When the voltage is higher than the motor-EMF-point, permanent magnet motor was running inductive load; On the contrary, the motor was running capacitive load. As a result, voltage fluctuations can cause fluctuations in electric power factor compensation difficult. If the voltage amplitude and motor EMF close to the point, the deviation ± 2% voltage range, the electric power factor greater than or equal to 0.9, or low power factor; In addition, when the permanent magnet synchronous motor load rate of less than 25 %, The motor power factor is also low.
Second, permanent magnet motor to improve power factor method
Through the single point of the low power factor analysis, were taken the following methods to adjust.
1. Based on the measured rate appropriately to change the electrical load in order to ensure proper load rate.
2. Voltage stability of the system, especially the heavy end of the line, the voltage is generally low.
3. Voltage stability of the single well make it permanent magnet synchronous motor close to the no-load back-EMF.
4. When the voltage running higher than the permanent magnet motor EMF point, the sensitivity can be the size of reactive power, plus compensation capacitor, to enhance the power factor.
5. When the voltage lower than the permanent magnet motor to run the back-EMF points, adjustable transformer tap, the second to increase the appropriate voltage amplitude, so that the motor running in the back-EMF voltage near to improve power factor.
6. Workhorse for the long lines, transformer tap-conditioning, the transformer secondary voltage amplitude is still lower than the permanent magnet motor EMF point, they can replace the permanent magnet synchronous motor, using compensation capacitor counter.
Third, analysis of the effect of the adjustment and
The six oil wells part of the team to adjust the test so that the power factor does not target the basic standards of oil wells.
First of all, on the line and substation capacitor Adjustments have been made so that the end of the voltage increased.
Secondly, based on single well test results, to take corresponding countermeasures, and some increase in capacitance, and some transformer gear adjustment on the part of the well adjusted motor power. The results indicate that the use of permanent magnet synchronous motor of the wells in addition to a power factor, all other qualified, power factor adjustment of electricity dropped significantly.
The oil production in the six-team approach to be successful, the factory is now in use. At present, temporary set of plant oil power factor to adjust electricity tariffs by the early 2004's 500,000 yuan down to 50,000 yuan, achieved good results.