UPFC, UNIFIED POWER FACTOR CONTROL Project Title UPFC, UNIFIED POWER FACTOR CONTROL Under the Guidance of Submitted by

ABSTARCT The time lag between the zero voltage pulse and zero current pulse duly generated by suitable operational amplifier circuits are fed to two interrupt pins of the microcontroller where the program takes over to calculate the time difference between the voltage and current both for inductive load and capacitive load. The time difference is calculated to display the leading power factor or the lagging power factor based on which appropriate number of opto-isolators triggers the back to back SCRs to switch either capacitor or inductor depending on the requirement. This is achieved by using a set of capacitors and inductor forming as load whose current is sensed by a CT for further processing against the voltage to display the power factor. The microcontroller used in the project is of 8051 family which is of 8 bit.

PROJECT BLOCK DIAGRAM

HARDWARE COMPONENTS MICROCONTROLLER (AT89S52/AT89C51) SCR OPTO-ISOLATOR LCD CURRENT TRANSFORMER INDUCTIVE CHOKE SHUNT CAPACITOR PUSH BUTTONS LED 1N4007 / 1N4148 RESISTOR CAPACITOR

POWER SUPPLY Bridge rectifier 5v Regulator 230 V AC 50 Hz 5V DC Filter(470µf) 12V step down transformer

It is a smaller computer Has on-chip RAM, ROM, I/O ports... MICROCONTROLLER It is a smaller computer Has on-chip RAM, ROM, I/O ports... RAM ROM I/O Port Timer Serial COM Port Microcontroller CPU A single chip

INTERNAL STRUCTURE OF A MICRO CONTROLLER-AT89S52/51 CPU On-chip RAM On-chip ROM for program code 4 I/O Ports Timer 0 Serial Port OSC Interrupt Control External interrupts Timer 1 Timer/Counter Bus Control TxD RxD P0 P1 P2 P3 Address/Data Counter Inputs

Features of AT89S51/52 Compatible with MCS®-51 Products 8K Bytes of In-System Programmable (ISP) Flash Memory Endurance: 10,000 Write/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel Interrupt Recovery from Power-down Mode Watchdog Timer Dual Data Pointer

Pin Description

SCR A Silicon Controlled Rectifier (or Semiconductor Controlled Rectifier) is a four layer solid state device that controls current flow An SCR can be seen as a conventional rectifier controlled by a gate signal It is a 4-layered 3-terminal device When the gate to cathode voltage exceeds a certain threshold, the device turns 'on' and conducts current

Contd.. The operation of a SCR can be understood in terms of a pair of tightly coupled Bipolar Junction Transistors SCR has three states: Reverse blocking mode, forward blocking mode, and forward conducting mode

Optocoupler Opto coupler is a 6 pin IC. It is a combination of 1 LED and a traic. Pin 5 is not generally used and when light falls on the triac then it switches ON the triac.

Contd.. When logic zero is given as input to the LED then the light doesn’t fall on triac so the triac is off means the current does not flow through the triac. When logic 1 is given as input to the LED then light emitted by LED falls on triac so it starts conducting i.e., now there will be current flowing through the triac.

QUAD VOLTAGE COMPARATOR LM339 FEATURES ● Wide single supply voltage range 2.0VDC TO 36VDC or dual supplies ±1.0VDC to ±18VDC ● Very low supply current drain (0.8㎃) independent of supply voltage (1.0㎽/comparator at 5.0VDC) ● Low input biasing current 25㎁ ● Low input offset current ±5㎁ and offset voltage ● Input common-mode voltage range includes ground ● Differential input voltage range equal to the power supply voltage ● Low output 250㎷ at 4㎃ saturation voltage ● Output voltage compatible with TTL, DTL, ECL, MOS and CMOS logic system ● Moisture Sensitivity Level 3

LIQUID CRYSTAL DISPLAY (LCD) Most common LCDs connected to the microcontrollers are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD.

If an 8-bit data bus is used the LCD will require 11 data lines LCD BACKGROUND If an 8-bit data bus is used the LCD will require 11 data lines (3 control lines plus the 8 lines for the data bus) The three control lines are referred to as EN, RS, and RW EN=Enable (used to tell the LCD that you are sending it data) RS=Register Select (When RS is low (0), data is treated as a command) (When RS is High(1), data being sent is text data ) R/W=Read/Write (When RW is low (0), the data written to the LCD) (When RW is low (0), the data reading to the LCD)

Soft ware Requirements Keil an ARM Company makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families. Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors.

i.e the programs written in one of the HLL like ‘C’ will compile the code to run on the system for a particular processor like x86 (underlying microprocessor in the computer). For example compilers for Dos platform is different from the Compilers for Unix platform  So if one wants to define a compiler then compiler is a program that translates source code into object code.

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