Saturday, March 29, 2014

BMH Documentation (Draft)

BMH Power Plant Engineers Operating Manual.

Summary


A micro hydro turbine driving an induction generator is like a finely tuned instrument. It runs most efficiently when water flow and head pressure resonate mechanically with the turbine geometry and the rotational speed. The rotational speed generates a precise pitch of 60 cycles per second which in turn is tuned to resonate (electrically) with the load and a bank of capacitors to keep currents oscillating through the copper windings of the generator and create magnetic fields in synchrony which in turn produce the current that we can use to light up our lives.

Since there are significant energy flows to be controlled and contained, it is important to understand how to control the energy smoothly, avoiding sudden surges or stepwise impacts in both the electrical as well as the hydraulic circuits.  The operator, typically an engineer or highly trained technician, must understand, and be able to predict the result of turning On or Off any circuit breaker, switch or valve before actually touching a breaker, valve or controlling device. (In many localities grid-connected power plants are required to be operated under the supervision of an engineer.) Always check the readouts first to find out what loads are being powered when making any changes, and try to anticipate the result of the adjustment and the effects on the connected load. This manual will explain each switch, breaker, valve and controller and the function each serves.


This manual will give the procedures for startup of the plant, planned shutdown, unplanned shutdown and subsequent startup procedure. Monitoring and metering will also be explained. It may be useful for the more experienced operator to refer to the diagrams for further insight to the operation of this plant.

Conventions / Definitions as they apply to the Buttermilk Micro Hydro plant:
(Starting from the top.)

Storm Water Diversion = currently a pair of logs placed at an angle ~12 feet
upstream from the water intake. Their function is to protect the down stream
structures during extreme weather events. (Maintenance or future
enhancement / automation project.)
Water flow measuring weir = located immediately upstream from the water
intake. Functions to get an approximate measure of total water flow reaching the
intake. (Maintenance or future enhancement / automation project.)
Slide gate = at the entry to the flume, function is to shut off water at the water
intake during severe weather events or flume repairs.
Water intake = the 8” x 48” rectangular opening in the upstream end of the
flume.
Warm water feed = the warm Honderosa spring water fed via (blue)
underground pipe that keeps the water intake from freezing closed during most
subzero winter nights.
Flume = the structure that currently carries the water from the water intake to the
gravel baffle (and screening) box. (Maintenance or future enhancement /
automation project.)
Minimum flow bypass = the circular opening in the flume bottom that insures
the escape of a minimum of 200 Gallons / minute to keep the waterfall hydrated.
(Maintenance or future enhancement / automation project.)
Gravel baffle box = the 4ʼ x 4ʼ x 5ʼ high (wood) box (Maintenance and / or future
enhancement / automation project.) with the integral second gravel chamber
and attached first gravel chamber, ball and chain flush valves, moving screen,
screen drive mechanism, head valve, head valve drive / operator, and attached
to the flume upstream.
(see: http://energyindependence-rob.blogspot.com/2010/07/dealing-with-sandgravel-
ice-leaves.html for diagrams/drawings)
Gravel Chamber = the first gravel chamber removes most negative buoyancy
material that did not fall out of the minimum flow bypass. The second gravel
chamber mostly collects fine sand and mud. (Maintenance or future
enhancement / automation project.)
Moving screen = the HDPE conveyor belt screen that functions to keep floating
or neutral debris from going down the penstock and clogging the turbines. The
screen duty cycle can be adjusted so it does not clog itself with heavy debris
loads or frazzle ice formation. (Maintenance and / or future enhancement /
automation project.)
Frazzle ice = the slushy watery ice that forms in the shallower upstream rapids
as water is supercooled during sub zero nights. The frazzle ice solidifies
immediately when it meets any cold or metal surface and blocks water flow.
Once ice covers the stream no further frazzle ice will form and the water will run
unimpeded underneath the ice cover, more so if snow also covers the ice. Even
water falling vertically will be covered with ice.
Head valve = the butterfly valve and operator (motor and drive circuitry) at the
bottom outlet of the gravel baffle box where the penstock connects.
Penstock = the 8” insulated or buried steel pipe that keeps the water contained
as the pressure increases going down to the powerhouse.

Green LED = indicates normal, OK, valve open, valve opening, green condition.
Red LED = indicates fault, valve closed, valve closing, red condition.
NO = Normally Open contacts / circuit
NC = Normally Closed contacts / circuit
GEN1 = Smaller 10kW turbine / generator
GEN2 = Larger 15kW turbine / generator
Rotork1 = Valve and valve controller on GEN1
Rotork2 = Valve and valve controller on GEN2

I. Start-up of water flow at intake.

During warm weather months the flow of water to the turbine may be started
(acquire ʻgreenʼ condition) by following these steps:
The initial conditions are:
a. All power house valves closed, No water flow.
b. GEN(1 and 2) Rotork in manual / local mode and run to CLOSED
position.
c. Utility power present and fed through to homes, transfer switches in
Normal mode, not Utility / Emergency.

1. Insure that there is at least enough flow in the stream to support turbine/
GEN1 operation. This can be judged by observing the flow into the flume.
Standing on the flume looking upstream, the water should cover ~80% of the
width of the sloping bedrock stone weir, or within ~20% of the right side of the
flume. (This measurement method should be refined when the temporary intake
structures are made permanent by having a constant slope and marks ground
or cemented into the trailing edge of the bedrock leading into the flume.)
2. Check that the moving screen (trash rack) is clear and operational. (see:
Moving Screen Maintenance) Flush the 1st and 2nd sand and gravel settling
chambers by pumping the ball valves (via stainless chains) up and down
several times or until the water flows clean from the flush opening. (This
procedure should be refined when the temporary intake structures are made
permanent.)

II. Start-up of co-generation.

The initial conditions are: all the above and:
1. Open Head Valve (press button once on ʻHead Valve and
Communication box), wait for valve to open as indicated by ONE green LED.
(the ʻgreenʼ condition)
After 15 minutes check that pressure is stable at 95 PSI. (It was
previously insured that a good volume of water is available in stream above and
no ice/sand/gravel is present in penstock water. ( See: “Winter Icing Conditions”
for cautions.)
2. Utility grid power ON. Beckwith 5 minute timer expired and ʻOutput 1ʼ
RED LED is ON and GREEN LED is blinking.
3. Top four load side breakers ON. We are using grid power as indicated on
the Net Grid meter lower right in Beckwith enclosure.
4. Bottom six Generator side breakers OFF. We are not making any power
yet.
5. Check for nominal meter readings of Honders ~1-3kW, Buyske ~ 1-3kW,
NET from Grid −3kW to −8kW on PM620 meter in lower right hand corner of
Beckwith enclosure. (The signs will change once the PM620ʼs are directionally
adjusted to conform to Utility practice.)
6. REV PWR RESET to OFF (down) (located under Beckwith 3410)
3. Open the GEN 1 or 2 (which ever one is being started) manual main
(RED WHEEL) valve to 50%.
4. Open GEN 1 or 2 Rotork in MANUAL mode to get RPM ~2000 using
manual mode with the lever and hand-wheel or local control with open / close
switch. Observe open / close LEDs in Rotork housing, after alternating red/
green both should be OFF indicating speed is within range.
5. Switch REV PWR RESET to ON (up) (located under Beckwith 3410)
6. GEN1or 2 breaker ON, never both.
7. C1 breaker ON for GEN1. C1 and C2 breaker ON for GEN2. (Do not run
both GENs simultaneously.)
8. Switch Rotork valve to remote (automatic enabled). The Rotork controller
should now open the valve slowly to maximum power.
9. Observe pressure gauge reading, (~90 PSI GEN 1, ~80PSI GEN 2),
holding steady, not dropping for lack of water at the top or too much power
input to GEN2. If too much power revert to manual control, 5/8 open 80 psi.
Check that the Reverse Power Relay ORANGE light is OFF.
Check PM620 Grid Power, Summary kW3Ø 5 to15 depending on house
loading.
Check that power factor, PF3Ø > .90 or as close to 1.000 as you can get
by switching breaker C2 and/or C3. Closer to 1.00 is better. If PF3Ø is -
(negative) then turn off C3 if you can get closer to +or- 1.00
Check that the pressure remains stable at ~90 PSI GEN 1, ~80PSI GEN2.
If it is raining/snowing be sure to set screen to continuous mode to
prevent clogging.
10. GEN1or2 set the Rotork valve controller to remote (automatic enabled).
11. Set house meters to read kW3Ø.
12. Switch REV PWR RESET to ON (down) (This will change with further
automation.)

III. Shut-down of water flow.
During warm weather months the flow of water to the turbine may be stopped
(ʻredʼ condition)by closing either the head valve, the manual valves, or the
Rotorks in the powerhouse.
and following this sequence:

The initial conditions are:
a. Head Valve open, normal water flow. ʻGreenʼ condition.
b. GEN(1 or 2) operating, Rotork in automatic control mode.
c. Utility power present and BMH power fed back to grid and through
to homes, transfer switches in Normal mode, not Utility / Emergency.

Sequence to follow:
1. Set the GEN(1 or 2) Rotork to Manual.
2. Switch REV PWR RESET to OFF (up) (located under Beckwith 3410)
3. While observing the Valve position indicator on the Rotork run the valve
to its fully closed position. All should be quiet now.
4. Turn off all (lower) Generator side breakers. Do not touch the upper 4
Load side breakers.
During cold weather months or anytime there is a danger that BMH may stop
generating power it is best to switch REV PWR RESET to OFF (up) (this will
change with further automation.)

During cold weather months the stream water flow must be kept from entering
the penstock by:
1. Lowering the slide at the entry to the flume. ( needs improvements with the
rebuild)
2. Pull up 10” and hook both gravel flush ball valves.
3. Check that warm water flows down penstock to keep it from freezing solid.
4. Turn off all (lower) Generator side breakers. Do not touch the upper 4 Load
side breakers.

Winter Icing Conditions - - CAUTION

Over the years I have made continual improvements to the ʻtemporaryʼ intake
structures to mitigate some of the problems with slush and ice in winter, leaves
in the fall, sand gravel, rocks, logs and debris washed down every time it rains
more than an inch or two overnight.
Most winter problems would be greatly reduced or eliminated if there was a
deeper reservoir to draw water below the surface ice layer, but not so low as to
suck up sand and gravel. ( An 8” high x 48” wide opening just above the low,
upstream, end of the moving screen could be opened to take water in through
the screen if the water level is raised just above this opening. )
The first fall excursions to single digit temperatures will probably not cause
slushy (frizzle ice) water. But after a day or two of sub-zero nights frizzle ice will
start to dam up flowing water especially any place where there is the slightest
restriction or shallow water flow. So the first problem occurs under the storm
water diversion logs which will definitely have to be repositioned or removed in
winter. This means that they probably will not be able to be repositioned before
the spring thaws to deflect the likely storm waters.
The second problem area is the 8”x48” primary intake at the upstream end of
the flume. The water arrives super cooled to below freezing, carrying slush.
Icicles form along the top edge of the 48” wide opening and grow rapidly
together to the bottom of the flume and, with the slush, completely block the inlet
in short order. Then the upstream water rises until it flows around the plugged
up intake opening, dropping the head pressure, and starving the turbine.
Shutting down the power plant under these conditions is both difficult and risky.
The valve stems and motor drivers tend to be frozen in place or are unable to
close completely because of the cold and icing. This allows a trickle of water to
continue down the pipe with increased likelihood of freezing inside the
penstock. All means should be employed to keep a flow of water going down
the penstock to keep that from freezing solid and potentially bursting or splitting
or having it frozen until spring thaws. To facilitate this I have installed piping that
carries warm water (45°F) from our hillside spring (and domestic water supply)
to the intake structures. This warm water is directed to the penstock in the trash
conveyor enclosure.

Exercise extreme caution when restarting the plant after a shutdown forced by
extreme cold. It is possible for ice to come loose from the penstock walls and
damage valves, pipes and turbines. If ice in the penstock is a possibility then the
dump valve should be opened sightly to allow a low flow (~60GPM) through for
8 to 12 hours to insure all the ice is melted before starting the turbine /
generator.

The most risky procedures in plant operation are shut down and startup. A
running plant is far less prone to be damaged by nature or human error.

Gravel baffle box, aka Trash rack / conveyor.

The Gravel baffle box is still the (2007) original temporary wood construction
and needs to be reconstructed of more durable materials. At the same time the
badly worn down concrete and stone dam needs to be restored to its original
height as planned in this earlier graphic:



The rebuilt trash conveyor box may be left in the current place and configuration
with just an 8” x 48” opening added to the upstream side just above the lower
end of the trash conveyor belt  to allow water to enter. The trash conveyor has been
very effective in minimizing fall leaf drop and debris problems. The higher water
level behind the dam will minimize freezing problems in winter.

The Gravel Baffle Box: Raising the water level behind the low stone dam will minimize winter icing problems.



Net metering
The debiting and crediting of kWh is done inside the NET meter in real time as
power flows back and forth as local demand fluctuates.

Beckwith M3410 Grid Intertie Protection Relay
The Beckwith relay monitors the grid side of the system. If the grid goes out of
normal bounds it will separate BMH from the grid. During normal BMH-grid
connected operation, if the grid goes out of bounds it will also pull BMH out of
bounds with it. When the programmed trip point is reached the Beckwith will
separate BMH from the defunct grid and the BMH valve controller will attempt to
match local generation to the new load conditions for OFF GRID operation,
sparing the line men working on the dead grid, while continuing autonomous
operation.

Reverse Power Relay
The Reverse Rower Relay will monitor the direction of energy flow in the
connection between the BMH generator and everything else. If the water flow
decreases or stops and the generator output starts to drop below a
programmable minimum, the Reverse Rower Relay will open the relay in the
generator connection, preventing grid power from flowing to the idled generator
and causing it to 'motor'. Refer to the One Line Diagram to see more detail, or
the Power House wiring diagram for even more detail.

Monitoring
All monitoring functions are provided via webserver at:
http://Powershack.Shacknet.nu:1300
After entering a username and password all real time data as well as accumulated
totals may be read remotely using a standard web browser. (Chrome / Mac seems
to work the best.)


The video overview.

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