01变频电潜泵相似理论VSDTheoryAffinityLaws.课件

REDA Production System Variable Speed Drive 2/33State of the Art Technology,High Performance,Reliable,Variable Speed DriveSWD Flux Vector VSD3/33What does the VSD do for us Provides constant torque through the entire speed range Can be used manually to set the V/Hz ratio for specific applications(Base Speed)Provides reduced starting capabilities(Soft Start)Optimizes the output of the well(Avoids cycling of the well and equipment)4/33Why use a VSD in your application?Flexibility to the system:Provide lightning protection for the downhole equipment Eliminate the need for chokes in the system Provide inherent soft start no inrush currents.Protect the downhole equipment from pump off Enable remote operation/automation Enable smooth response to torque changes5/33 Slow acceleration ramp ultimately reduces pump wear,prevents sand infiltration,to increase run life Reduces downtime and maintenance AND!Speedstar 2000 can catch a back-spinning motor!(patent pending)Speedstar 2000 can provide Tracking underload.Why use a VSD in your application?6/33VSD Output to Motor The Speedstar 2000 controls the output and to the motor by:Changing the input AC signal to DC signal,Chopping the resulting DC signal,and finally,Varying the output voltage and frequency to the motor.By varying the voltage and frequency to the motor,we are changing what is called the V/Hertz ratio.7/33The increased speed causes the pump to put out more head and flow and,in an effort to obey the laws of physics,the brake horsepower required to do this task also increases.We can predict the change in pump performance with affinity laws.Sizing a VSD application is then a matter of matching the pump and motor at the speed of interest.Summary8/33V VS SD DD Di i s sc co on nn ne ec ct t S St te ep p-U Up pT Tr ra an ns sf fo or rm m e er rJ J B Bo ox x S St te ep p-D Do ow w n nT Tr ra an ns sf fo or rm m e er r B Ba an nk kVSD ApplicationFlowHZFlow6060HZHead60HeadHZHZ602BHP60BHPHZ60HZ3MHP60MHPHZ60HZIf we know the pump performance at 60 Hz,we can correct it toanother frequency by the affinity laws:(1)If we know the motor 60 Hz nameplate rating,we can calculate theoutput horsepower rating at any other frequency with:(1)Useful Equations(1)If we prefer to work with 50 Hz as a base,we can substitute in50 in place of 60 everywhere it appears in the equations.10/3360MHP60BHPHZ602HZ6060MHP60BHPUseful EquationsIf we know the pump BHP at 60 Hz and we know what is themaximum frequency we desire to run at,we can determinethe minimum permissible 60 Hz motor HP rating as:If we know the pump BHP at 60 Hz and we know what our motorsize is at 60 Hz,we can calculate the maximum allowablefrequency before overloading the motor as:11/33%Load=BHP60 MHP6060HZ2VoltsVoltsHz60Useful EquationsIf we know the voltage at 60 Hz,we can calculate it at anotherfrequency as:If we know the pump BHP at 60 Hz and the motor rated Hp at60 Hz,we can determine the motor load at any frequency as:6012/33Volts xKVAAmps x1.7321000Drive Output KVA=KVA x?V480VUseful EquationsAt any frequency,if we know the volts and amps,we can calculate the KVA as:480If we know the drive KVA rating at one input voltage,we canconvert it to another input voltage as:13/33Hp LimitHzHP LimitHz6060HZ6060SHP60BHPUseful EquationsIf we know the pump shaft HP rating at 60 Hz,we can convert itto another frequency as:If we know the pump shaft HP rating at 60 Hz and the pump BHPrequirement at 60 Hz,we can determine the maximum frequencyallowable before we exceed the shaft capability as:VSD APPLICATIONSAFFINITY LAWS15/33VSD ApplicationsThe VSD allows a great deal of flexibility in applying pumping equipment to a well.Look at a variable speed pump curve:16/33HeadFeetHPMotorLoad010002000Capacity-Barrels per Day300040005000600070006500500150025003500450055007500102030405060702.001.003.00Reda Single Stage Pump Performance CurveGN4000 540 Series Pump-Variable FrequencyHead CapacityPump Only Load70 Hz65 Hz60 Hz55 Hz50 Hz70 Hz65 Hz60 Hz55 Hz50 Hz17/33Remember that the SPS motor horsepower output rating will increase directly with the ratio of the frequency.What assumption is this based on?21HPHP21HZHZ1HP2HP21HZHZorVSD Applications18/33This assumes the VSD output maintains a constant volts-to-hertz ratio.21HPHP21HZHZ1HP2HP21HZHZorVSD Applications19/33Graphically it would look like this for a 200 HP,60 Hz motor:Motor HorsepowerFrequency(hertz)020406080100050100150200250300350VSD Applications20/33What about the pump-what happens as we change the frequency?Remember that the affinity laws will apply to the pump performance:21RPMBHPBHPRPMRPM2RPM13HeadHeadRPM 2RPM 1RPM212RPMFlowFlowRPMRPM1221RPMRPMVSD Applications21/33Since the ratio of the RPM is the same as the ratio of the frequency,we can relate the affinity laws directly to the power frequency in Hertz.21RPMRPM21HZHZVSD Applications22/33So if we know the pump performance at 60 Hz(i.e.we have a pump curve),we can easily calculate it at any other frequency.BHP60BHPHZ60HZ3Head60HeadHZHZ602FlowHZFlow6060HZVSD Applications23/33The BHP required by the pump increases with the cube of the hertz ratio.Graphically it would look like:0204060800100200300400500Pump BHPFrequency(hertz)VSD Applications24/33We can see that the pump requires less HP than the motor is capable of delivering up to some frequency and then it exceeds it.0204060800100200300400500Pump BHPFrequency(hertz)VSD Applications25/33In this particular case the pump BHP and motor HP match at 75 Hz and 250 Hp.What does this mean?0204060800100200300400500Pump BHPFrequency(hertz)VSD Applications26/33It means that the motor is capable of meeting the pumps needs up to 75 Hz.Above 75 Hz the pump will overload the motor and cause it to overheat and possibly burn.Maximum Frequency Allowed=75 Hz.VSD Applications27/33What would happen if we used a smaller motor?VSD Applications28/33Wed have a lower limit for our maximum frequency.0204060800100200300400500Pump BHPFrequency(hertz)Smaller MotorVSD Applications29/33If we were to use a smaller pump,we could go to a higher frequency.0204060800100200300400500Pump BHPFrequency(hertz)Smaller PumpVSD Applications30/33In general:Size a pump based on flow conditionsDecide what frequency range you need to operateSelect a motor large enough to meet BHP requirement up to maximum frequency.VSD Applications31/33How do you select a motor for operation other than 50 or 60Hz?Recall that:andBHP60BHPHZ60HZ3MHP60MHPHZ60HZVSD Applications32/33We know that at our desired maximum frequency the motor HP and pump BHP will be equal.Which means:HzMHPHzBHP60MHPHZ6060BHPHZ603VSD Applications33/33Solving for Motor HP at 60Hz,we obtain:60MHP60BHPHZ602VSD Applications34/33ExampleSelect a motor for the following conditions:Pump=GN4000/175Max Frequency=80 HzFluid Gravity=1.05VSD Applications35/33The first thing we need to know is the 60 Hz BHP of the pump.We can get this from the pump curve.VSD Applications36/33Reda Single Stage Pump Performance CurveGN4000 540 Series Pump-3500 RPMCapacity-Barrels per DayPump Only EfficiencyPump Only Load1025Head Capacity20301.000500 50 754010001500502.00200025003000400035004500550050003.0060006500HPMotor LoadPump OnlyEFFHeadFeet1.4537/33From the curve,the single stage BHP is about 1.45Next,calculate the total BHP.And plugging this result into our equation,we obtain:60BHP1.451751.05267 HP60MHP2678060260MHP60BHPHZ602VSD Applications38/33474 Hp60MHPThis tells us we will need at least a 474 Hp 60 Hz motor to do the job.We can do these same types of calculations even if 50 Hz is our base frequency.VSD Applications39/33Consider the followingInstalled Pump=GN4000/175Installed Motor=400 HP(60 Hz)What is the maximum frequency at which we can operate this pump without overloading the motor?VSD Applications40/33Lets go back to the basic relationship.Once again we are interested in knowing exactly where:So,once again,we can use the relationship:HzMHPHzBHP60MHP60BHPHZ602VSD Applications41/33We know:MHP60=400 HPBHP60=267 HPSolve for Hz60MHP60BHPHZ602VSD Applications42/33Rearranging gives:HZ6060MHP60BHPVSD Applications43/33And solving for the maximum allowable frequency:This is the maximum frequency this size motor will allow.Any higher frequency will overload the motor.HZ6040026773 HzVSD Applications44/33We have developed an equation to determine the frequency for 100%load on the motor;however we are also interested in knowing the load on the motor at other frequencies:%Load=BHP60 MHP6060HZ2VSD Applications45/33If we were operating at 53 Hz,for example,the load would be:%Load =267 40060532=52%VSD Applications