Reactive Power generation advantages and disadvantages

Sir

The reactive power requirement for the grid is for the sake of maintaining a good voltage profile.

Reactive power is the wattless component and results in unproductive work,especially in terms of (over)heating of yr equipment.This shall derate yr equipment.

regards

ravipra

the balance of the inductive reactance and capacitive reactance that keeps the power factor at unity (1.0) is what grid operators want.

Since a large number of transformers, capacitors and motors on the line can cause the power factor to go lower than one there is generally a need for some reactive component to balance the line. This can be either inductive or capacitive.

Often power sellers penalize large industrial operations for bad power factor, this forces them to install comensating devices, capacitve reactors etc. If they do not correct, the utility has adjustable compensators to help with this.

http://en.wikipedia.org/wiki/Static_VAr_compensator

http://en.wikipedia.org/wiki/Electric_power_transmission

http://en.wikipedia.org/wiki/Transformer

it is often hard to visualize the problem of excess circulating currents, but it is real and causes excess voltage drops and heatingf and can cause peaks that brteak equpment.

You may produce more kVAr (or even MVAr) of the reactive power and ask the grid operator to compensate you. It requires a kVAr-hours meter to be installed (and calibrated) by grid owner. Ask them for a rate and contract ammendment / correction. If you have synchro-generators they must be set for higher exciting. It could be even econimically effective to install banks of capacitors, and controllers. Do econimic calculation after getting your rate for kVAr (monthly max?) & kVARh. Be aware of harmonics! Detailed disscusion is possible with your electric diagrams.

Power consultant- Joe Wojcicki

yes , you shall first fix up the terms with grid owner.

Reactive power generation can be designed and supplied by us to any size +ve or -ve. It can be also automated to grid reqirement but first you should decide the term with grid authority. Depending on you agreement a budgeting can be done for suitable design

Prof Waheed Raye

Dear Mr. Joe,

Thanks for your comments.

Actually we don't get paid for reactive power. We only get paid for active power. So,in this situation, we don't have any advantages for producing more KVar. Can u give me some idea how high can we produce kvar without affecting our equipment and without affecting active power

I believe you can generate more KW or use less fuel if you add your own capacitors for the VARS. I'd be happy to help, but first read the replies to my question of the membership about "Get more out of your generators?". Maybe you can save more than the KVAR charges from the utility company. I've had great success at lumber mills with diesel generators, but they weren't tied to the grid.

Two versions of "adding kVArs" to the grid are:

(a) Extra bank of capacitor - requires investment for installacion and other costs

(b) Over exiting existing generator(s). Almost no money to invest, but...

you need to do serious analitical job of Power in Time data. And of vourse the diagram to discuss.

or (c) do nothing and pay punitive rate for bad Power Factor

Depending, of the input - prinary energy used (and being transformed to electricity) you may not have any savings of "fuel". But... you may get some financial compensation from the grid owner - see previous Comments also from Professor Raye.

ROI (Return On Investment) for (a) solution - capacitor bank, maybe from two months (case mensioned by capacitorbob) to 15 years in other cases. Of course I think the only solution that gives you ROI less than five years should be consider.

I cannot see any new notes from Power Generation person. How he see or solved the problem. It would be nice to hear from him.

I think over-exitation needs on going investement. When you overexite the exiter, the exiter life expectancy shall be reduced as a motor does (depends on what kind of excitation you use of course rotating or static) and when you over-exite you are pushing more current to the exciter so you have to pay for the power usage. And also the main consideration should be given for the maximum over exitation limit of your exciter to produce VAR.

OK, here is my 2 cents worth. The reactive power component contributes to maintaining an acceptable grid voltage profile. The grid voltage profile is one component of grid stability. If your grid is not stable, you get cascading outages, that is where a trip of one unit or line on the grid causes overloads on other sections of the grid which in turn causes them to trip etc. There are several instances of this happening on massive scales look at the August blackout in Canada and the US mid west for one example. The utility is well within its rights (it is even a FERC requirement that it do so) to demand that any generation or loads hooked onto its equipment not place the system as a whole at risk. Your utility will help you establish the required kvar or mvar you will be required to contribute to the system.

Hi, it's Capacitor Bob. Sorry I mssed a few days as I was out working on easier low voltage jobs.

Overexcitation is a huge concern with generators if you are not connected to the Grid, because ... if the capacitors are making more KVAR than required downstream of the generator, the reactive amps cannot flow back onto the grid. The generator pays the price and it will break down. I don't advocate anyone going into a "leading" situation because the grid probably can't use the extra KVAR as it probably occurs at a low load situation for them and then they have to switch their capacitors off, which could send a "transient" through their system, which causes more headaches, blah, blah blah.

It's easy and cheap enough to "automate" capacitors. I switch 1800KVAR in one step at 13.8KV with no problems.

Still looking for real life testimonials. Can I get more KW, or use less fuel, out of a generator if I supply the KVAR with capacitors? Never nind the cost of the capacitors. Automated capacitors at medium voltage run between $10-20 per KVAR installed, depending on if they are pole racked or metal enclosed.

Thanks everyone for the input, but I am still looking for the answer. Be well.