Urban wind turbine monitoring and control board
This board was designed to monitor and control a small urban wind turbine capable of producing up to 5 kW, including in remote areas.
Consequently, it was designed not to rely on WiFi or Ethernet for internet access, but instead uses a SIM5360E module providing 3G connectivity to reach a dedicated server.
Among its features, it:
- measures the power generated by the three-phase generator of the wind turbine, as well as its period (hence rotation speed), and monitors the power injected into the mains
- ensures the MPPT does not receive more than 2 kW from the generator (otherwise it enters protection mode and shunts the wind turbine, inducing a strong instantaneous torque and stress on it) by dissipating the excess power
- measures the amount of vibrations on the wind turbine structure
- uploads data to the remote server
- periodically pulls configuration and instructions from the server
- embeds a hardware emergency switch
- offers additional connectivity for possible extensions
- provides a simple serial-console UI with a help menu, neatly framed MySQL-style tables, an ADC calibration interface, live readouts, system configuration, etc.
- stores configuration data (server URL, credentials, PID values, calibration parameters, etc.) in EEPROM
In addition to the board itself, a service was developed in Ruby and hosted in a Docker container. This service retrieves data from the board, serves configuration through a REST API, and provides a Web UI.
Illustrations
Development phase
Kicad plus a lot of documentation to read
First simple optocoupler test for load control
Testing the remote control of a simple resistive load using optocouplers where the gate is driven by the load’s voltage drop and the optocoupler. This was later replaced with active power delivery through isolation transformers to ensuring the load could be precisely controlled under all conditions.
First modular prototypes
Here the system is broken down into several modules:
- Braking board (black, upper left corner): replaces the previous module with an active version using a MOSFET and an insulated PWM gate control
- MCU (red board, center): interfaces all modules and manages system operation
- Isolation module (two white boards): operational amplifiers providing floating measurements on the 220V side, making them readable by the MCU’s grounded ADCs
- Sensing board (white board on the left): voltage dividers and shunt resistors for current and voltage measurement
- Accelerometer (bottom right corner): measures acceleration and raises an interrupt when vibrations exceed a given threshold
It glows at night!
Closed-loop electric load control with PID
Here, when the switch is closed, current flows to the desk lamp. The board monitors the drawn current and is instructed to dissipate energy on a second lamp using closed-loop control. Since this was just a feasibility test, the PID controller wasn’t finely tuned for fast response, and the derivative and integral contributions were set to zero, ensuring stability.
Final board
Assembling the board outside is quite nice during summer!
The white board handles braking by dissipating energy from the wind turbine through transistors mounted on a large heatsink. N.B. An external dump load can be added to the circuit to limit braking by introducing a minimum resistance in the circuit.
The system uses multiple linear transistors connected in parallel to handle the braking. Their load distribution occurs naturally via heat transfer in the heatsink: as a transistor warms up, its conductivity decreases, shifting more load to the cooler transistors.
This linear transistor-based board replaces the previous, smaller design that used a MOSFET with PWM control, which introduced resonant noise in the wind turbine structure during braking. N.B. Efficiency is not a concern here, since the purpose is to dissipate energy.
The small blue module on the right is the driver board, responsible for isolation and for controlling the base of the transistor array.
N.B. Although not visible here, fan outputs are available on the main board for extended heavy-duty braking.
The upper part of the board (current side) handles the measurement of voltage and current from the wind turbine generator to the external MPPT (upper left), as well as from the MPPT output to the mains (upper right). It is isolated from the lower part of the board using isolation amplifiers, transformers, and capacitors certified up to 1000 V RMS, with a minimum clearance of 10mm between tracks. Measurements are transferred as differential signals to the MCU (located in the lower center-right of the board) using the TI AMC1100, a fully differential isolation amplifier.
On the lower part of the board (logic side):
- Lower left: power supply units
- Lower right: interface connectors (emergency switch, braking control, external UART, accelerometer, SIM module, SPI port, USB)
