Saturday, August 15, 2015

Approaching two years of grid storage operation.

To date we have accumulated about 40,000 kWh stored excess in the grid after almost 2 years of grid connected operation while powering 3 homes. Our local utility has taken about 12,000 kWh of this total to pay for our use of their wires to SEND them the power. They assess DEMAND / DELIVERY charges regardless of which way the power flows. At least they finally stopped taking our $ and are now just taking our stored kWh's to pay the commercial demand / delivery charges.

All the data logger can hold shows the seasonal water availability.

The data logged the last whole month shows the daily use patterns and the waning water as summer drought set in.

Monday, February 9, 2015

Turbine RPM / Valve Control with Programmable Logic (Arduino)

A small niobium magnet attached (tape works) to the turbine/generator shaft creates a narrow pulse at pin 2 of the Arduino for each revolution. The Arduino program checks the time between pulses, calculates the RPM, and makes the AC motor that operates the butterfly valve run in a direction so as to keep the RPM constant. There are some fancy PID (Proportional Integral Differential) loops programmed in to keep things stable. Here is the diagram.
I could not upload a more readable PDF here but I can email it to you if you drop me a line.
I think I posted the Arduino program elsewhere on this blog. This link will get you to a simplified schematic of the hall sensor / Arduino hookup.   I'm still trying to use their schematic editor on a Mac but it is frustratingly windows centric, not intuitive -- yet, but I'll keep at it, so expect more clarity.