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Wind and Hydro Power Technologies Spring 2011

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http://www.youtube.com/watch?v=IpaEGhjpZgc

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CONCEPTS OF ELECTRICITY Electricity is a form of energy that is caused be the flow of electrons through the atoms of a conductor. Flow rate of electrons or the number passing a given point in a circuit per unit time is called current measured in electrons per second

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Alternating Current (AC) The type of electricity where the charge flows in one direction then the other direction. EX: Homes, Wind Turbines, Microhydro Turbines, Alternators. Direct Current (DC) - electrons flow in one direction. Example: Batteries, PV modules, Generators http://www.youtube.com/watch?v=JZjMuIHoBeg&feature=related

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CURRENT Flow rate of electrons or the number passing a given point in a circuit per unit time is called current. Measured in Amps Count um passing here!

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Time Delay? Does it take time for electrons to flow from a switch to a bulb? Light Bulb --- -- - - - - - - -- 10 miles

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Time Delay? Does it take time for electrons to flow from a switch to a bulb? NO!! Wire is already full of electrons! Light Bulb --- --------------- ------------- --- -- - - - - - - -- 10 miles ------------- ------------------ - - - - - - - - ------

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VOLTAGE voltage (Volts, V). Electro-motive force (EMF) or electrical pressure 12v, 24v, & 48v common for DC systems 120v and much higher are common for AC

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Resistance Measure of energy used up Depends on the material (and temperature) Resistance: opposition to electron movement Unit: Ohm ( ); Wires: very low resistance (often neglected) Insulators: very high resistance (often assumed to be infinite) As resistance increases, it takes more push (voltage) to cause a current Ohms Law I = V / R

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Power Power is the rate at which energy is being delivered or consumed Power = (Current)(Voltage) P = IV Units: Watt (W) So if 2 A of current is flowing through a load at 120 V, the Power used by the load is P = IV = (2A)(120V) = 240 W

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Another Example: A microhydro system is rated at 1000 watts @ 48VAC What is the amperage that is deliver to the battery? 1kW @ 48volts AC

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Another Example: A microhydro system is rated at 1000 watts @ 48VAC What is the amperage that is deliver to the battery? Power = Amps X Volts 1000 W = ?amps x 48V 1000 W = amps 48V Amps = 20.8 1kW @ 48volts AC

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Power Power: Rate at which energy is delivered Power = Energy Time Measured in Watts (W), kilowatts (kW), or horsepower Power is an instantaneous quantity Power does not accumulate Think gallons per minute

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Energy Energy: Ability to do something Measured in kilowatt Hours (kWhrs) Why? Since Power = Energy/Time, then Power Time = Energy Energy does accumulates over time Think gallons Gallons = (gallons/min) minutes

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How does this relate to microhydro? Turbines are linked to generators/alternators Which produce either AC or DC Power. Used to power a load directly or, Charge batteries for later use or, Sell back to the grid for a profit Power has to be transferred from the turbine to the load. We call this thewire run More on this later!

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Balance Of System

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What is the BOS? DC only system (small cabin) Charge controller Batteries Conventional AC system (house) Charge controller Batteries Inverter

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Typical Off-Grid Battery Charging System

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Off-Grid Batteryless System

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Grid-Tie Batteryless System

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ModelList Price ($US) C35$119.00 C40$159.00 C60$199.00 ie. Xantrex C Series Charge Controller 12, 24, 48 VDC automatically directs extra power to a dedicated load such as an electric water heater and ensures batteries are never over-charged. Model # is rated DC current www.xantrex.com

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Diversion Load, aka Dump Load Usually a resistive load like a heater At least as large as the full turbine output and within the current limit of the charge controller Head lights as dump load for wind turbine

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Dump Loads All dump loads place a load on the turbine and transfer the energy to a form of a heater. You have 2 options: Air heating element Water heating element

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Outback Inverters

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Xantrex Inverters

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Batteryless Grid-Tie Options Systems available for PV and wind Still a special system for Microhydro Contact Hydro Induction Power www.hipowerhydro.com

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Balance of System Design Outline Wire run and its importance Wire run sizing System circuits Battery bank sizing System specs.

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Wire Run Need to know the distance from the turbine to the load to: Determine system voltage and design Calculate what type of wire/cable to use How much it will cost.

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Good location of turbine to load Turbine Powerhouse

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House / Load 2,000 foot wire run

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Why is wire size Important? Correctly sized wire: Saves on Installation costs & Conserves resources & Keeps the fire department away! Incorrect wire size

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System Voltage and Design System Voltage can be determined by the wire run distance. Short wire runs can use lower voltage Longer wire runs should user higher voltage System Design and Configuration Larger systems with long wire runs can be AC systems with transformers.

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Hydro Induction Power Good for long wire runs, 60' - 500' head, 10 - 600 gpm The units produce 3-Phase 120V, 240V, or 480V 'wild' (unregulated) AC, which is then stepped down to battery voltage. The heavy-duty brushless alternator is housed on the Harris Housing www.hipowerhydro.com HV 600 with 2 Nozzles $2500 HV 600 with 4 Nozzles $2600 HV 1200 with 4 Nozzles $3000 HV 1800 with 4 Nozzles $3500 HV 3600 with 4 Nozzles $5000 Turgo option $600

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Electrical Transmission on a large scale Microhydro systems can use this model!

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Low voltag AC microhydro diagram Low Voltage AC Hydro Generator Step-up Transformer Step-Down Transformer Designed Balance of System AC Wire Run

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Low voltag AC microhydro diagram High Voltage AC Hydro Generator Step-Down Transformer Designed Balance of System AC Wire Run

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What do Transformers Do? Transfers electrical energy from one circuit to another with a different voltage. Known as mutual induction How is this beneficial to a microhydro system? Answer: allows for longer wire runs from turbine to the load with lower line losses.

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Large Transformers (need cooling)

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Wire Run / Wire Sizing Needed information: Distance from turbine to load Voltage of the turbine Max output of the turbine Type of output? AC or DC, 3 phase or single phase. Important Considerations Diameter of wire (American Wire Gauge AWG) Length of wire Free Air or Conduit Type of insulation on wire Temperature of location where wire located Moisture where wire is located Will conductor be exposed to sunlight Color of insulation Voltage Drop

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The quantity of electrons or amperes that a conductor can safely carry Factors affecting ampacity Size (diameter) of wire Type of wire (copper or aluminum) Insulation Temperature Ampacity

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American Wire Gauge (AWG)

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Wire Sizing for DC Applications Voltage drop is caused by a conductors electrical resistance This voltage drop can be used to calculate power loss For DC systems efficiency is paramount! Voltage Drop (Volts) = Electrical Resistance (Ohms) X Current (Amps) Power Loss (Watts) = Ohms X Amps Power Loss (Watts) = Voltage Drop (volts) X Current (Amps)

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VDI Voltage drop Index Easier method for determining wire size What you need to know Amps (Watts/volts) Feet (one-way distance) Acceptable % volt drop Voltage

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How to Use Formula and Chart Example: 1 KW, 24 volt system, 50 feet, 3% drop Amps = 1000 watts/ 24 volts = 41.67 amps VDI = 41.67 amps * 50 feet = 28.9 3% * 24 volts

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VDI Chart 24V VDI = 28.9 2 AWG wire Thats pretty big wire What if we make it a 48 volt system?

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How to Use Formula and Chart Example: 1 KW, 48 volt system, 50 feet, 3% drop Amps = 1000 watts/ 48 volts = 20.8 amps VDI = 20.8 amps * 50 feet = 7.23 3% * 48 volts

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VDI Chart 48V VDI = 7.2 8 AWG wire Thats better (smaller, less $, same losses).

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Energy Storage - Batteries

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Battery Bank Sizing Battery storage for PV and Wind systems typically require 3 or more days of battery storage Hydro systems run all the time Batteries in a hydro system typically need to store energy for less than a day Often, the battery is sized to provide sufficient current to the inverter rather than an amount of storage

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Battery Capacity (Amp-Hours) Battery capacity is rated in amp-hours. 1 amp-hour is the equivalent of drawing 1 amp steadily for one hour, or 2 amps steadily for half an hour.

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Series Connections

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Parallel Connections

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Series & Parallel

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Battery Cables

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Life Expectancy and cost At least 5 years Often over 10 years or 1500 deep cycles Shipping is expensive Cost is about $200- $400 per 6V battery

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Battery Care Dont discharge beyond 80% Charge at recommended rate Keep batteries at room temperature Use distilled water Size batteries properly Equalize every few months Keep batteries and connections clean