Research On Intelligent Control Of PMSM Pumping Unit System

For oil companies,the profit maximization is of importance.On the one hand,the increase of profits lies in the improvement of production value,and on the other hand depanding on the reduction of production costs.Energy saving and consumption reduction in oilfield production is not only a need for the development of enterprises,but also making response to the policy of sustainable development policy.If considering the oil well as a system,it can be divided into well pumping unit and underground oil recovery part.In this paper,the energy saving research of pumping well system is carried out from two parts of variable frequency driving and vector control based on intelligent algorithm of high efficiency direct drive pumping unit system and appropriate parameters of the supply-recovery equilibrium of underground oil supply system.As the core equipment of oilfield production,pumping unit plays an important role in oilfield production.However,the question of energy consumption and low efficiency about pumping unit have been existed all the time.There are many reasons for these problems,one of which is to ensure that the oil pumping machine has the overload capacity enough and the motor with larger installed power is selected.The process of oil production,the load is not so high that resulting in the motor load rate is only about 30%.This phenomenon is usually called "big horse drives the little cart" and this phenomenon is more serious in the later period of oilfield development,which results in great waste of electric energy.In order to reduce the pumping energy consumption and improve the working efficiency of the pumping unit,this paper chooses the direct drive pumping unit which can replace the traditional walking beam pumping unit as the research object,and analyzes the principle of the compound permanent magnet synchronous motor(CPMSM)which is suitable for the direct drive pumping unit.By using the characteristics of low speed and large output torque of the CPMSM,the load of the pumping unit is directly driven,the system efficiency and power factor of the pumping unit are improved,and the ideal power saving effect is achieved.In order to effectively solve the energy saving problem of the pumping unit,the drive system of the CPMSM used in the direct drive pumping unit is studied in depth.For the purpose of improve the DC side voltage utilization of inverter,the space vector pulse width modulation technology is selected.Using space vector pulse width modulation technology to realize three-phase three level inverter function and reduce the harmonic content of output voltage.At the same time,in order to overcome the drawbacks of the existing three level SVPWM strategy without the dynamic balance of the neutral point potential of the divider capacitor,this paper further studies the virtual space vector pulse width modulation technology which can make use of virtual vector.But the technology can only achieve the balance of the neutral point voltage regulation in partial sector,so this paper proposes varied virtual SVPWM(V2SVPWM)strategy.V2SVPWM strategy uses positive and negative small vectors to rebuild dynamic virtual medium vector.V2SVPWM strategy has advantages on the realization of neutral point potential balance in the whole space and can solve the low frequency voltage oscillation caused by the SVPWM method.The stable working condition of motor is be of importance to the pumping unit energy consumption.Based on the mathematical model of the CPMSM,The intelligent control of quantum bacteria foraging optimization algorithm is introduced to achieve the MTPA control.Aiming at the uncertainty of bacterial location in quantum foraging optimization algorithm,Monte Carlo random sampling is adopted to achieve the location updating of individual bacterial.And in order to improve the diversity and convergence precision of the bacterial foraging optimization algorithm,the dynamic approximation strategy is proposed by this paper to increase the bacteria individual's search space and improve the convergence accuracy.Then four test function,such as Griewank funtion is tested by BFO algorithm,QBFO algorithm and DA-QBFO algorithm.And the results show that DA-QBFO algorithm has better performance on convergence speed and convergence precision,especially for multi peak and high dimensional function and has higher applicability.The CPMSM vector control with DA-QBFO algoriyhm has good dynamic response and steady state accuracy.Meanwhile,the field tests are carried out and the measured results reveal that this method can effectively suppress torque ripple and reduce energy consumption of pumping units.It is necessary to have performance test on the new CPMSM and the maintenance of old pumping unit motor is also important.The existing energy feedback load unit is composed of frequency converter and motor.Due to the mechanical connection between the tested motor and the load motor,the loading precision will be affected greatly.In this paper,the simplified model of the load unit is analyzed and the hierarchical method for learning rate adjustment of BP neutral network algorithm is proposed to establish the high precision loading closed-loop control system without internal parameters.Field tests show that the load test unit can save power significantly.The effective control of pumping unit motor can reduce the electrical energy consumption.And another starting point for pumping uni energy saving is the consumption reduction in the process of crude oil extraction.The changes in the underground oil layer environment of the pumping unit have an important influence on energy consumption and production efficiency.The dynamic model of pumping rod in the pumping unit and the dynamic model of the gas well pump are established.The utilization of these models can make analysis of the decrease of oil production efficiency and the increase of energy consumption caused by the mismatching between the oil supply capacity and production parameters.To solve this problem,a prediction method of pump fullness based on pump load is put forward to make the pump fullness be stable in the ideal interval.And The adjustment strategy of variable stroke is put forward with the limit of pump full level of sucker rod pump,which can reduce the stroke automatically when the full level is high,and improve the efficiency of the oil well system effectively.The effectiveness on pumping unit energy saving is provided by field test in Daqing oil field.