变频电潜泵相似理论课件.ppt

REDA Production System Variable Speed Drive,2/33,State of the Art Technology,High Performance,Reliable,Variable Speed Drive,SWD Flux Vector VSD,3/33,What does the VSD do for us,Provides constant torque through the entire speed rangeCan 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),4/33,Why 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 offEnable remote operation/automationEnable smooth response to torque changes,5/33,Slow acceleration ramp ultimately reduces pump wear,prevents sand infiltration,to increase run lifeReduces downtime and maintenanceAND!Speedstar 2000 can catch a back-spinning motor!(patent pending)Speedstar 2000 can provide Tracking underload.,Why use a VSD in your application?,6/33,VSD Output to Motor,The Speedstar 2000 controls the output Voltage and Frequency 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.,7/33,The 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.,Summary,8/33,VSD Application,Flow,HZ,If 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.,10/33,60,MHP,Useful Equations,If 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=,MHP,60,60,HZ,2,Volts,Volts,Hz,60,Useful Equations,If 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:,60,12/33,Drive Output KVA=KVA x,?V480V,Useful Equations,At any frequency,if we know the volts and amps,we can calculate the KVA as:,480,If we know the drive KVA rating at one input voltage,we canconvert it to another input voltage as:,13/33,Hp Limit,Hz,HP Limit,Hz,60,60,Useful Equations,If 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 LAWS,15/33,VSD Applications,The VSD allows a great deal of flexibility in applying pumping equipment to a well.Look at a variable speed pump curve:,16/33,Head,Feet,0,1000,2000,Capacity-Barrels per Day,3000,4000,5000,6000,7000,6500,500,1500,2500,3500,4500,5500,7500,10,20,30,40,50,60,70,2.00,1.00,3.00,Reda Single Stage Pump Performance Curve,GN4000 540 Series Pump-Variable Frequency,Head Capacity,Pump Only Load,70 Hz,65 Hz,60 Hz,55 Hz,50 Hz,70 Hz,65 Hz,60 Hz,55 Hz,50 Hz,17/33,Remember that the SPS motor horsepower output rating will increase directly with the ratio of the frequency.What assumption is this based on?,or,VSD Applications,18/33,This assumes the VSD output maintains a constant volts-to-hertz ratio.,HP,HP,or,VSD Applications,19/33,Graphically it would look like this for a 200 HP,60 Hz motor:,VSD Applications,20/33,What about the pump-what happens as we change the frequency?Remember that the affinity laws will apply to the pump performance:,VSD Applications,21/33,Since 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.,2,1,RPM,RPM,HZ,HZ,VSD Applications,22/33,So 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.,60,HZ,3,HZ,60,2,60,HZ,VSD Applications,23/33,The BHP required by the pump increases with the cube of the hertz ratio.Graphically it would look like:,VSD Applications,24/33,We can see that the pump requires less HP than the motor is capable of delivering up to some frequency and then it exceeds it.,VSD Applications,25/33,In this particular case the pump BHP and motor HP match at 75 Hz and 250 Hp.What does this mean?,VSD Applications,26/33,It 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 Applications,27/33,What would happen if we used a smaller motor?,VSD Applications,28/33,Wed have a lower limit for our maximum frequency.,Smaller Motor,VSD Applications,29/33,If we were to use a smaller pump,we could go to a higher frequency.,VSD Applications,30/33,In 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 Applications,31/33,How do you select a motor for operation other than 50 or 60Hz?Recall that:,VSD Applications,32/33,We know that at our desired maximum frequency the motor HP and pump BHP will be equal.Which means:,VSD Applications,33/33,Solving for Motor HP at 60Hz,we obtain:,VSD Applications,34/33,ExampleSelect a motor for the following conditions:Pump=GN4000/175Max Frequency=80 HzFluid Gravity=1.05,VSD Applications,35/33,The first thing we need to know is the 60 Hz BHP of the pump.We can get this from the pump curve.,VSD Applications,36/33,Reda Single Stage Pump Performance Curve,GN4000 540 Series Pump-3500 RPM,Capacity-Barrels per Day,Pump Only Efficiency,Pump Only Load,10,25,Head Capacity,20,30,1.00,0,500,50,75,40,1000,1500,50,2.00,2000,2500,3000,4000,3500,4500,5500,5000,3.00,6000,6500,1.45,37/33,From the curve,the single stage BHP is about 1.45Next,calculate the total BHP.And plugging this result into our equation,we obtain:,VSD Applications,38/33,This 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 Applications,39/33,Consider 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 Applications,40/33,Lets go back to the basic relationship.Once again we are interested in knowing exactly where:So,once again,we can use the relationship:,60,BHP,HZ,60,2,VSD Applications,41/33,We know:MHP60=400 HPBHP60=267 HPSolve for Hz,VSD Applications,42/33,Rearranging gives:,VSD Applications,43/33,And solving for the maximum allowable frequency:This is the maximum frequency this size motor will allow.Any higher frequency will overload the motor.,VSD Applications,44/33,We 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:,VSD Applications,45/33,If we were operating at 53 Hz,for example,the load would be:,VSD Applications,