Wednesday, August 7, 2013

Proposed Algorithm for development of microcontroler based ELC

Proposed System must contain:
1: Sense the voltage and frequency of the generator output.
2: If load increase the voltage and frequency of the generator decrease.
3: If load decrease the voltage and frequency of the generator increase.
4: If demand decrease the power will be diverted to dump load.
5: If demand increase the power will be diverted to main load.
6: If demand increase than that of actual power production then system will be off (i.e. automatic power will cut down to the main load and send to dump load).

System Description:
Ø  Voltage sensor that senses the voltage across the load, and gives output.
Ø A microcontroller which interprets the readings corresponding to a sequence finds the error in the voltage and generates a pulse width modulated wave as per the error in voltage at any instant.
Ø A thyristor based uncontrolled rectifier circuit which is connected to a series resistive dump load and is switched by the PWM wave generated by the microcontroller.

Algorithm of system:
Step1: Set a reference voltage and frequency which is fixed (for programming based it is 5 V)
Step2: Sense the voltage and frequency
Step3: Both signals will compared and error output is fed to microcontroller as input
Step4: The error is compared with a very high frequency triangular wave and the corresponding output is fed to the PI Controller section of the code in microcontroller
Step5: The PI controller is turned on only after an initial voltage of around 230V has been achieved after the start so that the initial errors when the voltage is rising do not interfere with the integral part of the controller
Step6: The output of the PI controller section is the required PWM signal for switching the IGBT to regulate the dump load
Step7: The PWM output is then given to the thyristor through an opto-isolation and pulse driver circuit