Power Factor Correction

[tallgirl]

I'm looking at a contract where we will need to develop our own power factor correction setup, vis a vis, utility capacitor bank switching.

What is the best of the rip-off power factor correction gadgets? The idea is to set up a number of inductive loads, measure the power factor in real time, then have the gear enable and disable the previously mentioned rip-off power factor correction gadgets to get back to unity on the power factor. Whenever the angle changes from lagging to leading, turn the power factor correction thingy off. All the while, increasing and decreasing locally produced power.

For bonus points, if any of y'all have a favorite Modbus enabled revenue grade meter you'd like to recommend, that would helpful. I've looked at this one in the past -- http://www.gepower.com/prod_serv/products/metering/en/utility_revenue_meters/kv2_multifunc_elec.htm -- but it's more than I want in an electric meter, which prolly means it is going to cost more than I want to spend.

(And for the terminally curious, PV systems are notorious for making utility power factor worse since PV inverters produce near-unity output and don't produce KVArs on their own. Thus, the PoCo is providing fewer KVA while still providing all the KVArs ...)

 

[wirenut1980]

Why does it have to be a rip-off gadget? Sounds like you are describing a regular switched capacitor bank. Why not just market it as such? I really don't like these gadgets that claim to do all this stuff...Maybe it is just because all these customers come to me asking if this thing or that is legit...most of the time it is just snake oil, or something cleverly disguised power factor correction.

 

[tallgirl]

Because I don't want to build a test system with a real capacitor bank. My client is going to do that -- I just have to make sure that the control software responds correctly when it sees the power factor change. Also, it has to be small enough as to be useless, except for software development purposes.

I set up and tear down solar power systems on a regular basis and if I had to have "real" equipment I'd go broke. Not that, you know, I'm getting rich as it is!

 

[masterinbama]

What type of signal input does your power factor metering accept?

I installed some metering that used scaled 4-20MA inputs for some of the signals (can't remember which ones) Seems to me that you could actually design your software using ghost inputs and then tweak it after it's operational. I do this all the time for rate of flow and operating pressure loops. Engineer I worked for used to say "Getting the players in the ballpark is the hard part. once they are there, finding their playing position is easy"

 

[PowerQualityDoctor]

Power Factor Correction and Metering

Power Factor Correction and Metering

Why don't you use off-the-shelf PF controller? You can get one is reasonably low cost and save a lot of work.

You can use a power meter with relay outputs and set a set-point to each relay, but this is just more work. In addition, PF controller has added features like unti-resonance protection, testing the capacitor capacity and providing notifications etc.

You are welcome to visit my site to see list of power analyzers/meters that I recommend and the pros and cons of each one.