automatic voltage regulator using labview

[marvel89]

i want to develop  a computer controlled Automatic Voltage Regulator to control the output voltage of a 440v, 3Φ ac generator. {i am using only single phase of the generator }

i am  stepping down the output voltage of the generator below the ratio of DAQ card {usb 4716} i.e. 10v using a step down transformer{230 v to 6 volts } .Using this voltage as an input to a close loop Lab VIEW program we are controlling an external Relay Circuit .The Relay Circuit controls a bank of resistors to vary the excitation voltage. The Lab VIEW program broadly has a filter block, a comparator block and a digital output block, but i am unable to control the output voltage , can you plz suggest any changes to program or any thing wrong in it 

[RavensFan]

You have a lot of odd constructions in your code.  Such as converting an array to a blue DDT wire back to a scalar.  (Or blue DDT, to array, back to blue DDT, to a scalar).  All of those conversions could be cleaned up, eliminated, or replaced by something like an Index Array function.

You have a lot of comparisons and AND functions going on.  It looks like you are testing for ranges.  You should use the In Range and Coerce function to determine if the value is in a particular range.

Are you working with anyone with a strong electrical background?  I'm worried if you are trying to control 440 VAC circuits with relays.  Also, using a step down transformer.  You are dealing with lethal voltages.  And trying to control that high of a voltage AC circuit with relays, you might be running into serious arc flash dangers if you are switching relays on and off at the wrong time.

Why are you taking on this project?  What is the purpose?  Are you an engineer working in the industry or is this some sort of school project?

[SteveD123]

Okay

1. You do not include the advantech VIs, so no one without your flavor of hardware will be able to help in any detail.

2. Where are your equations? You take the (presumed) peak-peak voltage, multiply by 25.7954, subtract from 228, followed by some integration , multiplication and a divide-by-one step. WHY?

3. What debugging steps have you taken? What have you tried?

4. The generator output could be very spiky, especially if there are any real loads on it. The peak-peak detector might be operating on those spikes.

5. Is the generator wired in Star or Delta?

6. You do know about regulation factor on unloaded transformers, don't you?

(If not, step away from the generator NOW. You obviously do not have the knowledge to be playing around with 440 V generators.)

7. How does your generator behave with an unbalanced load like this? What fault level will it have; what circuit protection is in place?

(In fact, the whole tone of the questions suggests inexperience, or a lab exercise. Please be very careful with this stuff unless you really know what you are doing.)

[marvel89]

i m a student , i have already fabricated the hardware part , i am using  variac as a power source(230 v single phase ) , going from voltages 230 v and below , which in turn is controlling the relays , as the voltages is brought down the relays are switched on one by one , relay is powered by 12V , having resistors in series with each other , thus they move out as the relays are switched on one by one , the problem that i am facing is control of the voltage as the labview program caters for various voltage ranges. but the problem i am facing is controlling the output voltage  . don't worry i am taking all precautions while handling the equipment 

[SteveD123]

As I see it, your project has 4 parts:

1. The foward path from excitation voltage to generator voltage.

2. The voltage sensing system.

3. The setting of the excitation voltage using digital outputs to drive a chain of relays & resistors.

4. The control algorithm required to convert the sensed voltage to an excitation setting and result in a stable generator voltage.

You need to do some basic fault-finding, and narrow your issue to one of these areas.