Untitled record

full description

invention background

This application is a partial application from the application number 1110111011, which was filed in the Kingdom of Saudi Arabia on 01/0/1301 AH corresponding to 01/01/0111 CE.

5 The present invention relates generally to the performance control of an induction motor and, more specifically, to methods for controlling the performance of an induction motor used in a pumping system.

In the oil and gas industry, a (for example, diesel, gasoline, natural gas, or propane engine) is sometimes used to power a three-phase generator. The generator, in turn, supplies power to a three-phase induction motor used to drive a mechanical pump. The operation of the induction motor in the said system at variable speeds, the capacity of the pumping system is greatly expanded.However, the methods were not

11 The precedent for supplying variable speed operation of the pump in these pumping systems is quite satisfactory. In one of the methods previously used to drive a variable speed pump in a motor-driven pump system, the variable frequency and voltage capacity is transmitted to a three-phase motor that drives the pump. Typically, in a system that uses a generator as a power source, an electronic variable speed drive (also known as a variable frequency drive (VFD) is mediated by an electronic variable speed drive)

15th drive between the alternator and the induction motor to provide the variable voltage values ​​and frequencies to the motor. There are many potential faults with the use of a variable speed drive motor, including voltage harmonics generated on the motor's conductors that could damage the motor, and current harmonics generated at the input of a variable frequency motor (VFD) which could cause problems. For the generator, the complexity of the VFD design and/or the need for an expensive output transformer when higher voltages are used (often when the motor connections are very long).

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To eliminate the need for a variable speed motor, some of the earlier methods use a variable frequency power system that varies the speed and excitation of a three-phase generator to produce a frequency with the desired output and voltage in an attempt to achieve the required operation of the three-phase motor in the pump. US Patent No. 2121010, Pettigrew, discloses a variable speed drive system of this type,

5 The operation of the aforementioned system compared to the previous systems of the type that uses a variable speed drive as described in the current application above is discussed.

Unfortunately, variable frequency power systems, of the kind represented by Pettigrew, have significant drawbacks. For example, when trying to simply control the output of a three-phase generator may not produce the required operation of the pump. The output speed of the induction motor that drives the pump varies based on 11 factors such as the pump load. When this occurs, the user of said variable frequency power system will not be able to precisely control the pump speed and may encounter a variety of undesirable situations. For example, the pump may be operating at a lower speed than expected, resulting in less than ideal production, or the pump may be operating at a higher than desired speed and experience a “pump dry” or “pump stop” condition that causes the pump to operate without fluid. 15 To cool and lubricate it, or the pump stops running to allow fluid to be refilled into the packaging, including

It causes sediment to settle in the pump.

These conditions result in damage to the pump and a shortening of its service life.

The present invention is directed at overcoming the defects described and, in addition, improving the state of the art in the oil and gas industry.

01 General description of the invention

In one embodiment, a system and method for controlling the rotor speed of a motor that drives a pump is presented. By controlling the speed of the motor rotor rather than the frequency of the generator, the operation of the pump is more precise and precisely controlled.

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A system is provided to control the speed of the motor operating the load. The motor is electrically connected to a generator which is driven by a motor. The generator has a controllable field. The system includes a first control feedback loop configured to reduce the difference between the magnetic flux in the motor rotor and the magnetic flux command level where the magnetic flux in the member is estimated

5 The rotor is based on measuring the electrical input values ​​to the motor cables. A control feedback loop has been configured again to limit the difference between the motor's rotor speed and the desired speed as the motor speed is estimated based on measured electrical input values ​​to the motor's cables.

A method is provided for controlling the speed of a motor running a load. The motor is electrically connected to a generator which is driven by a motor. The generator has a controllable field and the motor has

11 throttle throttle; The method includes performing the steps of periodically measuring the input voltage and current to the motor cables. Based on the measurements of the input voltage and current to the motor cables, a signal is generated representing the rating of the motor's rotor flux. The motor rotor flow rating is compared to the rotor flow command signal and is used to generate a signal representing the rotor flow error. The method also includes the generation of a stream excitation command signal based on the signal representing the rotor flow error with a signal

15th Stream excitation command that controls generator field excitation.

A signal is generated representing an estimate of the motor's speed based on measurements of the voltage and current inputs to the motor. A comparison of the signal of the speed command with the signal representing an estimate of the engine speed is used to generate a signal representing the engine speed error. The throttle position command signal is generated based on the signal representing

Engine speed error. A throttle command signal is generated based on the signal representing a speed error

01 engine so that the throttle position command signal controls the engine throttle position.

A pump control system is also provided to control the mechanical input to the pump. The pump is coupled to an electric motor and the electric motor is coupled to a generator which is driven by a motor. The pump control system and the fault control unit contain a set of plurality of interface devices. The drive vector model is coupled in at least two of

05 means of intercommunication. The rotor stream collector is initialized to provide an associated stream error estimation in

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The engine vector model and one of the means of interconnection. The motor speed aggregation method is coupled in the motor vector model and the motor speed error control in the motor speed aggregation method and one of the intercommunication methods. The pump control system also includes a supervisory control device coupled to the motor speed-collecting device, the motor vector model, and the member flow-collecting device.

5 The rotor where the pump coupled motor speed is controlled by a first control feedback loop configured to provide excitation current command to the generator and a second control feedback loop configured to provide throttle position command to the motor. In another embodiment, the pump control system includes a motor torque rectifier which is configured to correct the motor's torque command. The rectifier is coupled in at least one of the interconnects, the motor speed control and the motor vector model, where the increase of

11 The system to put the throttle close to the fixed. During system startup, the supervisory control system is configured to adjust the magnetic flux level to reduce the load on the motor. In one embodiment, the supervisory control device sets the magnetic flux at zero degrees during system startup.

The other models corresponding to the invention will be clarified by the following detailed description accompanied by the attached figures.

15th Brief explanation of the drawings

The attached figures incorporated into and forming part of this specification illustrate several aspects of the present invention and, in addition to a description, represent an explanation of the principles corresponding to the invention. In the figures:

Figure 1 is a representative model of an induction motor control system comprising a control unit

by mistake

According to the directions of the present invention;

01 Figure 0 is a template diagram from a Simulink simulation running on a system similar to the one from Figure 1; And

Figures 0a-0d is a graphic representation of the results obtained from the simulation that was conducted on the system from Figure 0.

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While the invention is described under specific preferred embodiments, there is no intention to limit it to such embodiments. On the contrary, the objective is to cover all alternatives, modifications and equivalents included within the scope and corresponding scope of the invention as defined by the accompanying claims.

Detailed description:

5 Referring now to Figure 1, a pump control system 11 is illustrated. As explained in full below, the fault control system 01 from a pump control system 11 monitors one or more electrical input characteristics to the cables and the motor 11 and, depending on what Observed, the mechanical input values ​​to the pump 11 and adjusts the operation of the engine 10 and the generator 13. By controlling the mechanical input values ​​to the pump 11, the operation of the pump is more specific, accurate and reliable than that provided by the system which only controls the electrical output values ​​from the generator 11.

Engine 10 absorbs air and fuel by combusting the mixture, generating a rotary mechanical engine output 00. The output of the mechanical rotor 00 depends on the position of the Txc throttle, the fuel used, the air temperature and density, etc. The engine 10 can be run on diesel, gasoline, liquid propane, natural gas or other fuels 15. Engine 10 is operationally coupled and running, alternator 13. In this regard, the output of the rotary mechanical actuator 00 is modular and directly coupled to the mechanical input from the generator 13. Even then, other types of connections such as gearboxes, belts, hydraulic power coupling and the like may be used depending on the specific application. Generator 13 is a synchronous three-phase generator, having a field that is controllable.

01 The alternator 13 is electrically coupled by electric cables to the motor, which is collectively expressed as 11. In the system shown, the pump is a centrifugal pump of the type known as an electrical submersible pump (ESP), in which each of the motor is placed 11 The pump 11 is in a well casing well below ground level and the cables are of reasonable length 11. In a typical oil well, for example, it can be up to

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The length of the cables is 11,000 km. Through the cables 11, the alternator 13 supplies the engine 11 with electrical power. In the embodiment shown in Figure 1, motor 11 is a three-phase induction motor. The electrical input to the motor 11 can be characterized by voltage values ​​(Vm .).

current inputs (Im. The motor generates 11 rotating mechanical outputs, which has a pump speed (Up) and pump torque (Tp).

The actuator 11 is mechanically coupled, and drives, the pump 11, which is located at or near the bottom of the well casing and is submerged or partially immersed in the fluid (for example, oil and/or water) being pumped. The pump 11 generates a fluid output that can feature, Among other variables, pump head (Hp) and pump flow (Qp.

11 The fault controller 01 is, in general, in electrical contact with the motor 10 and the generator 13. The fault controller 01 is also configured to monitor input voltage (Vm) and input current (Im) values ​​to the cables and the motor 11. The fault controller 01 includes Interface devices 03, motor vector model 01, rotary flow collector 01, rotary flow error control 01, velocity collecting device

motor 00, and motor speed error control 03. The error control unit 01 also optionally includes 15 motor torque rectifier 01.

Interfaces 03 are generally used to control or convert signals and data sent or received by the Fault Control Unit 01. In this regard, Interfaces 03 can include many electrical components such as, for example, input/output devices on Parallelism, analog to digital A/D converters, D/A digital to analog converters, current and voltage sensors=, flow estimators,

Filters, complements and the like.

In the embodiment shown, the 03 interfaces here have two outputs. The first output is the throttle position command (Txc , which is converted from the Tec(torque error command) from the engine speed error control 03 or, on systems where the

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Using torque rectifier 01, linearized torque Tlc (command output) from torque rectifier 01. The second output is an Eic (excitation current command) which is converted from error λec (estimate) Generated by Rotary Flow Fault Control 01.

<p>5 For the input values, the interstellar 03 generates three motor voltage . measurement signals</p>

represent the voltages for voltage values ​​(Vmm) measurement signals

<p>(Vm) on each phase of the cables and the motor 11 and two motor current measurement signals two motor</p>

two (Im) currents to express (Imm) current measurement signals

of the three phases. The three-phase current can be easily calculated, since the three-phase currents 11 must add up to zero, but they can also be measured.

The motor vector model 01 is in electrical contact with interface devices 03, the rotary flow collecting device 01, the supervisory control device 01, and the motor speed-collecting device 00, and when used, it is a motor torque rectifying device 01. The motor vector model 01 performs Many mathematical functions using motor voltage (Vmm) and current measurement signals

15th Engine (Imm) to provide estimates as described in US Patent No. 2112101 Beck et al. (Patent 101'), which are included in the present application for reference. For example, the Engine Vector Model 01 calculates and outputs an estimate The performance of an induction motor 11 including motor speed at the motor shaft (Ume, λre) magnetic flux of the rotor, and mechanical torque

01 Tme (mechanical torque of the motor shaft).

The rotor flux summation device 01 depicted in Figure 1 receives two input values, namely a rotor flux estimate from the motor vector model 01 and a rotor flux command rotor λrc from the Supervisory control 01. During normal operation, the organ flow command is maintained

05 The rotor (λrc) is generally at a constant value to maintain the correct torque

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Tp) torque) for the motor. However, while starting the 10 motor, the flow order can be reduced

The rotor (λrc) is greatly reduced or even set at zero to reduce the load on the motor 10. Based on the input values ​​received, the rotor flow collector 01 generates an output, a λee error estimate.

5 The estimate for the flow error (λee) is received by the rotor flow error control 01. In general, the rotor flow error control 01 is a control circuit architecture designed to adjust its output to drive the fault duration to zero. In the embodiment of Figure 1, the rotor flow error control 01 is a proportional (integral-derivative) (PID) control method. However, other types of control architectures can be used, such as

11 Proportional-integral (PI), random logical controllers, and the like, as is known in the art. The rotor flux error control 01 provides an output in the form of a flux excitation command (λec) to Interface devices 03 interface devices.

The 00 motor speed aggregator shown in Figure 1 receives two input values, defining an estimate

15th The motor speed (Ume) from the motor vector model 01 and the motor speed command (Umc) from the supervisory control device 01. Based on the input values ​​received, the motor speed aggregator 00 generates an output, specifically the estimation of speed error (Uee).

The speed error rating (Uee) is received by the motor speed error control 03. In general, the motor speed error control 03 is a control loop architecture that is designed to adjust its output

01 To push the error duration to zero. In the embodiment shown in Figure 1, the motor speed error control 03 is a proportional-integrated-derived (PID) control device. However, other types of control architectures may be used, such as proportional-integrated (PI) controllers, approximate logic controllers, and the like, as is known in the art. As shown in Figure 1, the motor speed error control device 03 generates and transmits the torque command.

05 . engine command (Tec) to the optional engine torque regulating device 01. If . is cancelled

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Motor torque rectifier tool 01 From the error controller 01, the motor torque (Tec) command is provided directly to the interface devices 03.

When in use, a torque rectifier 01 is used to ensure that a given input is associated with an appropriate and required corrective action. For example, when a three percent (0%) change in engine torque is required, a change in throttle speed of up to

Ten percent (11%). In such circumstances, the motor torque rectifier 01 processes the motor torque command (Tec) received from the motor speed error control 03 so that a straight torque command (Tlc) is produced. A linear torque command conversion is ensured The system gain for throttle position control is close to steady state, and for this reason, it is easier to tune the optimum response.

11 Straight torque (Tlc) is output to the interface hardware 03 and fed to the actuator 10. Accordingly, the throttle position is changed as required to respond properly to the torque command (Tec). As shown in Figure 1, the motor torque rectifier 01 receives two input values, namely the motor torque command (Tec) from motor speed error control 03 and motor speed rating (Ume) from motor vector model 01.

15th Referring also to Figure 1, most of the components of the error control unit 01 are in electrical contact with the control device 01. In particular, the supervisor control device 01 transmits the Umc (motor speed command) to the motor speed collector device 00 and the rotor flow command (λrc) to the rotor flow collector device 01. The values ​​of these two commands may be derived by manual actuator inputs, derived according to methods described 01 in patent No. 101', or derived by some other automated means. The supervisory control device 01 receives the signals that represent estimates of the motor speed at the motor shaft (Ume) and the mechanical torque of the motor shaft (Tme). The supervisory controller 01 also sets the programmable operating variables (identified with the letter “P” in a circle), for interface devices 03, the motor vector model 01, the rotor flow error control 01, the motor speed error control 03 and, when

05 When used, the motor torque rectifier is 01. The programmable operating variables include values

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acquired, filter parameters, reading table values, driver variables, and the like. The supervisory control device can also receive 10 variants of other inputs from the fault control module, and the system generates 11 variants of other outputs to the system 11.

During operation, the motor 10 is started within the system 11 while the rotor (λrc) flow command 5 is kept at or close to zero. Some flux is generally necessary to produce sufficient motor voltage (Im) of the vector motor model 01 to be able to estimate the motor speed (Ume). The stator speed of the motor 11 is determined by the motor vector unit 01 using the motor voltage measurement signals

(Imm) representing the series Vm (volts) and Im (currents) 11 for the phases of the cable and the motor 11. Initially, the supervisory control 01 also limits the calculated value of the motor speed reduction 11 to zero so that the calculated rating of the motor speed is (Ume) is the same as the electrical rotating speed of the stator of motor 11 and, for this reason, is also proportional to the rotating speed of motor 10.

The motor vector model 01 provides the motor speed rating (Ume) to the supervisory control device 01. 15 Once the motor speed rating (Ume) reaches a predetermined or desired level, the control device escalates to a rotor flow command (λrc) at a desired rate. When a predetermined or desired level is specified, the control method may enter 01 or use a constant variable or one or more lookup tables. When the lookup table is used, the supervisory control method uses the motor speed estimate (Ume) to locate the appropriate rotor flow command (λrc) on the lookup table. At this time, the supervisory control device 01, at a controlled rate, increases the limit on the calculated value

for the reduction value of the motor 11 so that the calculated estimate of the motor speed (Ume) is the actual rotational speed of the motor 11 and the pump 11.

The rotor flow collector method 01 compares the rotor flow order (λrc) with the organ flow estimation

The rotor (λre) presented by the motor vector model 01.

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Based on this comparison, the rotary flow collector 01 generates an estimate of the flow error (λee). The flow error estimation (λee) is used to control the rotor flow error 01 where the flow excitation order (λec) is determined. The λec then passes through the devices of interface 03 and is received by generator 13 as an excitation current command 5 (Eic). An excitatory current (Eic) command is received by the field current and determined by the generator 13

It changes the values ​​of voltages (Vm) and currents (Im) of the phases of the cables and the motor 11. The process described above is repeated at a predetermined iteration. Accordingly, a feedback loop is triggered for the first control.

At all times during operation, the motor speed aggregate method compares 00 motor speed command 11 Umc (motor speed command) to the motor speed estimate (Ume) received from a vector model.

Engine 01 and generate rated velocity error (Uee).

Then, the uee estimation by the motor speed error control 03 is used to generate the torque linearizer command (Tec). The torque command (Tec) is converted into a linear command by the motor speed error control utility 01 (when using the straightening). Generates a torque linearized command (15 Tlc). The torque command (Tlc) is transmitted through the devices

Interface 03 The throttle position command Txc (throttle position command) is produced and connected to the actuator 10. The above described process is repeated at a predetermined iteration. Thus, the control feedback loop is triggered again

The motor 11 driving the pump 11 operates on the throttle position (Txc) command and the excitation current 01 (Eic) command. Thus, the Up (pump speed) and pump torque are controlled

Tp ( torque) precisely and the pump head (Hp (Hp) pump head) and Qp (Qp pump flow) are precisely controlled or fixed according to the need of the specific application using the first and second control feedback loop.

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Those skilled in the art will realize that the invention overcomes defects in earlier art, such as Pettigrew, to provide variable motor speed control or reduce the possibility that generator control may not translate far into the desired operation of the motor and pump. Indeed, the representative model of System 11 of Figure 1, according to the invention, is based on the torque control of the motor rather than the often defective 5 assumption that the desired frequency output from the generator results in the desired operation.

For motor and pump as in previous systems.

As an added advantage, the invention presents, though limited control and rotary flux intensification, to lower the peak starting current drawn by the motor and, as such, the current to be supplied to the generator. In earlier systems where the generator was run at frequency and voltage and then the motor was run “across the line,” the motor current would rise at a value of as much as one thousand percent (1111%) of the motor’s operating current.

To handle these large starting currents, earlier systems used for this approach required many components in the system to be much larger and more precise than it would otherwise. The present invention reduces the peak current to less than one hundred and fifty percent (151%) of the normal operating current of the motor, thus greatly reducing the weight, complexity and cost of the components required to implement the invention.

15th In order to test and evaluate System 11 (or an equivalent equivalent), a computer simulation was performed using Simulink software developed by MathWorks. The setup and structure of the simulation are schematically depicted in the template diagram 31 of Figure 0.

The engine represented in the simulation was a Simulink four-cylinder engine. In addition, the motor speed error control was 03 and the rotor flow error control was 01

01 It is a proportional integrated (proportional-integral (PI) control in the simulation. The simulation resulted in the results shown in Figures 0a to 0d. As shown in Figure 0b, the peak current in the rotating generator and the generator constant during operation was approximately 01 amperes, while the peak currents in the stationary state were approximately 13 amperes. In Figure 0c the motor rotor flow (solid line) smoothly covers the rotor flow order (dashed line). Moreover, at

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Figure 0d, the motor speed converged (solid line) and continued at the command speed (dashed line).

All references, including publications, patent applications, and patents referred to in this application are included by reference as if they had been individually referred to as

5 Included for reference and provided in its entirety in this application.

For the purposes of this disclosure, “coupled” means the connection of two components (electrical or mechanical) directly or indirectly to each other. Such a connection may be inherently fixed or movable in nature. Such a connection may be achieved by using two components (electrical or mechanical) And any additional intermediate organs are integrally formed in the form of a single unified body with each other or are

11 Install the two components and any additional member into each other. Such a binding may be permanent in nature or alternatively it may be releasing or releasing in nature.

The use of the expressions "a", "an" and "the" in the context of the description of the invention (particularly in the context of the following claims) should be interpreted as including the singular and plural, unless otherwise indicated in this application or the context is to the contrary This is explicit. It should be explained

15th The conventions “includes,” “includes,” “contains,” and “contains” are non-ending conventions (i.e. “comprising,” but not exclusively) unless otherwise indicated. It is not intended to clarify value ranges in this order except to provide an abbreviated way to indicate individually for each discrete value that falls within the range, unless otherwise indicated in this request, and each discrete value is included in the specification as if it had been individually mentioned in this request.

01 The methods are described in this application in any appropriate order unless otherwise indicated in this application or the context is expressly to the contrary. The use of any and all examples and use of all examples, or representative language (eg, “like”) that is provided in this application, is intended to further illustrate the invention and does not represent any limitation to the scope of the invention unless otherwise protected. It should not be Interpret any of the language used in the specification as referring to any element that is not protected on

05 The method considered essential for the implementation of the invention.

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Preferred embodiments of the present invention are described in this application, including the best known pattern of the inventors for carrying out the invention. Ordinarily skilled in the field, they may recognize alternative images of these preferred models when reading the above description. Inventors expect those skilled in the art to use these alternative images appropriately, and inventors aim to

5 Implementation of the invention other than as specified in this application. Therefore, the present invention includes all modifications and equivalents of the material described in the accompanying claims as permitted by applicable law. Furthermore, the invention includes any combination of the elements described above in all its possible alternative forms unless otherwise indicated in this application or the context expressly contradicts this.

<p>11</p>

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