Hydro-Power Generator

At reduced speed It will produce lower voltage at lesser frequency, The best option I see is connecting it to a cyclo-inverter.

What load is being imposed on the generators when they turn at 120 prm? If you simply disconnect or otherwise restrict some of the the loads, does the speed increase? (At 60 Hz, rpm = 7200/(number of poles) = 7200/64 = 112.5 rpm. Something isn't quite matching up here.)

The stator construction (number of canals) restricts feasible pole number options. Possibly your next winding choice is 128 (!) poles that will give wanted frequency at about 62 RPM. But then power will be about half. Would suggest consulting with water flow control system manufacturer and applier (smells amature) chances are something's wrong there or you're out of water level specs. Plenty can be done in both

We can de grade the generators to synch with underpowered turbines. However, to produce the most power we can, the turbines will have to be upgraded. Do you have experience with custom runners designed to local conditions with the intent to enhance turbine performance or horsepower ? What do you think that would cost in the US ?

Kaplin runners have adjustable blades to compensate for available flow conditions. They were made by Allis but I think they are now out of that business.

Your prime mover needs to be replaced to take advantage of the available water HP (if there is any) There is an old saying (don't know if it is true) that a ton of water must fall a quarter of a mile to generate 1 KWH (remember that the ton of H2O is total, over an hour period)

A machine that gives 3,600,000 Joules out of 3,946,916 is pretty efficient don't you think? (n=0,912104502) Wish my old AUDI was that efficient

Sir. The numbers that you are giving us do not compute for the speeds and frequency. I assume that you cannot get the generators up to speed to sync on the line, so even if you could rewind the machine for the lower speed, you would not have enough excess energy to make any power since all the available turbine energy is being consumed in just keeping it up to speed.

I just cant imagine Westinghouse mating these units to these turbines unless the head was higher at the time of installation. As I suggested before, are you sure that the flow of water is not restricted. Making some simple Cu ft flow measurements can provide available HP numbers. What are the name plate ratings on the Francis wheels? (HP and Head)

Are the Wicket gates and head gates opening fully?

Again, what are the tail water conditions? can the water get away in the tail race?

We had Westinghouse rewind two 20 MW machines for us to give us 12 % more output. These were Francis runners made by Crocker Wheeler in New Port News. We also had a 30 Mw Allis Chalmers machine that saved our tail during the NE Blackout by providing cold start cranking power for the Steam Plants.

Snakers

My numbers could very well confuse you. This area is obviously not my expertise. In looking at this issue, a broad range of solutions are at hand, which confuses me.

Neither I or anyone alive has seen the generators operate. I bought a closed Mill and the dormant power plant was part of the acquisition. I believe current technology can be applied to bring the seldom used equipment to production.

In 1921, turbines with lower rating than engineer spec were installed. The builders may have anticipated raising the head/dam, but that was not accomplished. The existing head is approximately 7 feet. The plant is "run of the river" with fairly good flow ranging from 300 to 4000 cfs. Normal flow is around 500 cfs. The generators are rated 312.5 kv when rotated at 150 rpm. Leffel, the turbine manufacturer, tells me the Francis z 36 turbines will rotate the generators at approx. 120 rpm at operating load under current conditions. The flow of water into and out of the power plant will be unrestricted. Some of the gates are frozen (open) but they will be operational. Water flow and control are important, but will not overcome the limitation of undersized turbines.

De rating the generator to match under sized turbines may produce usable energy, but does not benefit in the dam, plant and assets that would be impossible to install today.

I would like to maximize output, if that is feasible. The best of all worlds solution would be to rewind the generators to produce more power than 312.5 kv and bring turbine performance in line with the requirements of the rewound generators. Is that possible ? What engineering steps are involved ? What is a very general estimate of cost and time line be for such a project ?

Thank you for your input

The best way to help you is to provide me with the following specifications of the hydro-electricity generating plant:

1. Specify the type of turbine used i.e. Pelton Wheel 1 jet or 2 jet, Propeller, Kaplan Runner, Turgo, Cross-flow or Francis Turbine.

2. Diameter and sizes of the type of turbine and performance curves (Or kindly provide me the designed specifications of the turbine model/s and the system)...

3. Ensure that you include the actual and design head of water in m (provide proper layout sketches and dimensions). Also the fluctation in feed water head m.

4. Designed Water flow rate and turbine inlet pressure (if not included in the above information).

5. Specifications on the turbine inlet flow control system.

6. Sketch or layout of the Turbine feed outlet arrangement that include all the sizes i.e. diameters, length and pipe / tunnel routing when water exiting the turbine.

7. Sketch of the Turbine feed inlet arrangement that include all the sizes i.e. diameters, length and route of the penstock to the turbine.

8. The static pressure in kPa (design and actual) at the turbine inlet (unit is not running) and the pressure at the turbine inlet when it is running. If the system has a flow measuring device, then the flow rate of water when the control system is fully open and under no load conditions and the RPM of the turbine under such no load condition.

9. Specific speed of the turbine (From the Suppliers).

Regards,

Anton Cordier (Mech & Elect Eng)

e-mail cordiera@mweb.co.za

Guest -

Appreciate your interest in helping us. I am travelling, taking time to address this interesting challenge and will forward your list to my New Braunfels office. You will receive your answers by e-mail from there.

Thanks again

For a frequency of 60 Hz, the generator designed to rotate at 150 rpm should have a total of 48 poles. (For 50 Hz at 150 rpm it should have 40 poles).

If you rotate the generator (assumed it has 48 poles) at 120 rpm, the output frequency is 120/150 * 60 = 48 Hz, for 50 Hz it should be 40 Hz.

Since the turbine cannot provide the required input power to drive the 2x312.5 = 625 kVA generators (assuming a power factor of 0.8) of about 550 kW at 150 rpm (sonsidering losses of 50 kW), but only at 0.8 of the rated speed, the output power could be only 400 kW ( 500 kVA assuming a power factor of 0.8), i.e. roughly 75% of the rated output power of the generators.

This is assuming that the turbine is capable of delivering a torque of 220 kN*m ( 162263 lbf*ft) at 120 rpm, respectively of 176 kN*m (129810 lbf*ft) at 150 rpm.

Otherwise, look at the turbine curves and determine the torque at 150 rpm. Make the ratio of determined torque with 220 (in kN*m) and see the percentage of power possible to be obtained from that turbine.

As indicated in a previous answer, simply disconnect some load and the speed will increase up to the required speed of 150 rpm.

Basically generators produce as much power as load connected to them.

To Tomad..

We have learned that this equipment was installed in the early 20s and there is no indication that it has been run in the past 80 years or so. The new owner is going on past history and trying to evaluate the machines potential for restoration to a become a financial asset.

I imagine that the lower Lignum Vitae runner bearing would have to be replaced and I understand that the head gates are non operational. I'm not sure that the State's water rightrs are still in effect. He is looking for counseling, mainly from a business standpoint.

Your calculations are correct and would be very germane if the machine was operateable.

Don J

Tomad and Snakers are correct. I have a civil engineering degree and build and develop properties as a profession. I have a general understanding of power generation and a growing interest in renewable energy. The dormant hydro plant is very intriguing and challenging. The dam, power building and civil assets are unobtainable today. We have the financial resources to re-build, within reason and with fiscal sensibility. In today's environment, we can not take a flyer on something that will not at least work and provide some return. This asset may remain dormant or become what it was intended to do - produce power. Most of the gates work and the lignum vitae blocks were removed for replacement. Those items are secondary and mechanical. The real challenges are :

1. How to upgrade turbine hp so the generators perform to specifications;

2. If so, is it worthwhile to look at rewinding the generators to increase their efficiency and output as long as the turbine can match performance. In that manner, we may be able to generate more power than original spec if the flow and head conditions permit;

3. What additional power generating equipment, technology or processes can we add ?

An earlier post indicates 7 feet of head at 500 cfs (avg.) For a thumbnail calculation,

7 ft x 500 cfs x 62.4 lb/cf x 60 sec/min / 33,000 = 397 HP = 296 KW. (Without yet applying an efficiency factor.) HP(KW) would be proportional to other flow rates. But this might constitute an upper limit to your possibilities.

Is the average 500 cfs the whole river (250 per turbine), or can each turbine receive this flow?

Can you raise the height of the dam, and hence the head? Rewinding the turbines would increase the frequency, but not necessarily gain more HP(KW), if head/flow is the real limitation.

This is an intriguing project, with some details seemingly buried in the sands of time. I have already learned a lot from Anton Cordier's and Snaker's input. Please keep us updated on this.

Anton Cordier, Snakers, Guest and Tornado -

Each one of you has significantly broadened my understanding and options at hand. I thank you very much for your help. My wife has kidnapped me. We are in Prague, in Paris next week and thankfully be back at my office in New Braunfels on the 5th. Although this city is absolutely charming, so is NB and I love to work. I am corresponding when I can sneak away and will fill in details upon my return - like the two generators were built to produce 60 cps; the plant is in the city so if we try to raise the dam, our upstream neighbors will burn us down (which is legal in Texas for flooding a neighbor) etc etc. if you want to know anything at all, please e-mail debbie@rivermilltexas.com. She can have photos of equipment or any other information run down for you. An aerial of the 40 acre property, along with the empty Mill and power facility, is on our "starter" website www.rivermilltexas.com. I look forward to solving this riddle and have even more vexing questions for you afterwards.

Thank you so much.