https://github.com/kulia/voltage-current-logger
Realtime logger of voltage and current made for CST in Bhutan
https://github.com/kulia/voltage-current-logger
Last synced: about 1 year ago
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Realtime logger of voltage and current made for CST in Bhutan
- Host: GitHub
- URL: https://github.com/kulia/voltage-current-logger
- Owner: kulia
- Created: 2015-09-25T08:14:03.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2015-11-17T06:22:12.000Z (over 10 years ago)
- Last Synced: 2025-02-15T09:37:03.187Z (over 1 year ago)
- Language: Python
- Size: 318 KB
- Stars: 0
- Watchers: 4
- Forks: 1
- Open Issues: 1
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Metadata Files:
- Readme: README.md
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README
It is possible to use the chrome plugin [markdown Preview](https://chrome.google.com/webstore/detail/markdown-preview/jmchmkecamhbiokiopfpnfgbidieafmd?hl=en) to read .md files offline.
The text here is mostly based on the paper ``Understanding the requirements for acquisition of
real-time data under distorted conditions in a Microgrid''.
# Voltage and Current Logger
An description of a simple voltage and current logger that is deployed at CST - Royal University of Bhutan.
# Hardware
This chapter will describe the hardware necessary for the realtime voltage and current logger to work properly.
## Current measurements
To measure the current we used a current transformer as described in the figure below (thanks to Isabelle Florent for the figure). By using a magnetic core with with a coil, it was possible to measure the output voltage.
To make the output voltage from the current transformer match the input voltage range of the ADC better, it is possible to use an amplifier. A simple [inverting amplifier](https://en.wikipedia.org/wiki/Operational_amplifier_applications#Inverting_amplifier) was used. Remeber that the amplifier inverts the signal, so that the signal needs to be multiplied by -1. The figure below describe the setup of the amplifier.
If you measure AC current it is important to change the scope of the input voltage, as described in the section "Change Input Scope" below.
## Measure voltage
We used a transformer to lineary decrease the AC voltage on the grid to a value applicable for measurments. After the transformer, the voltage ranged between -6 and 6 volts. After the transformer we used a voltage devidor to decrease the maximum voltage down to 5 V. The circuit is described in the figure below.
The circuit in the next chapter was used to change the scope from [-5 V, 5 V] to [0, 5 V].
## Change Input Scope
The Arduino's [ADC](https://en.wikipedia.org/wiki/Analog-to-digital_converter) can only read positive values, from 0 to 5 V. As the AC voltage and current has both positive and negative values it is necasarry to change the refrence. The circuit below can be used.
To find the new output voltage we can use the node voltage method. With an input voltage between -5 V to 5 V the corresponding output voltage would be 0 to 4.5 V.
# Software
## Dependencies
__Python 2.7__
Download [python 2.7](https://www.python.org/downloads/).
__Pip__
[Install pip](https://pip.pypa.io/en/latest/installing/).
__Pyserial__
To automate the communication between the arduino and the computer you need to install pyserial. Most system can install it by writing the following command in either the terminal or the command prompt:
> pip install pyserial
Another alternativ can be found [here](https://learn.adafruit.com/arduino-lesson-17-email-sending-movement-detector/installing-python-and-pyserial).
__Arduino IDE__
Install [Arduino IDE](https://www.arduino.cc/en/Main/Software).
## logger
The logger.py program takes the port as an input and starts to log.
__Windows__
Go to the _Device Manager_ to find the right port. If the port is, as an example, 6, you can start the program by typing the following command to the command prompt
> python logger.py COM6
__Linux__
Find the port connected to the arduino. Then type
$ python logger.py /dev/ttyACM__N__
__Where is the data stored__
The data is stored in _raw-data/_ as a .txt document. The number indicates microsenconds after Epoch, as a time refrence.