Automatic power factor correction

correction of power factor by using micro controller

1. PROJECT PRESENTATION ON AUTOMATIC POWER FACTOR CORRECTION GUIDED BY:- LOPAMUDRA SAHU Presented By:- Pappu Kumar Dubey (1201214199) Vikas Kumar Manjhi (1201214203) Saurav Kumar (1201214205) Raushan Kumar (1201214218) Swayam Bikash Samal (1201214219) Ashish Ranjan Mahto (1201214457) DEPARTMENT OF ELECTRICAL ENGINEERING KIST BHUBANESWAR

2. CONTENTS: Introduction Block diagram Working principle Power supply circuit Power factor measurement circuit Micro Controller LCD Relay Capacitor Bank Advantage Disadvantage Applications C onclusion

3. INTRODUCTION: This project report represents one of the most effective automatic power factor improvements. Static capacitors which will be controlled by a Microcontroller with very low cost. P ower factor is set as standard value into the microcontroller IC . Resistors are used instead of potential transformer. Microcontroller IC ( AT89s52) reduce programming complexity that make it one of the most economical system than any other controlling system.

4. Source 230V AC POWER FACTOR MEASURMENT CIRCUIT LCD Display Micro controller Relay Capacitor Bank LOAD Power Supply 230V AC - 5V DC communication BLOCK DIAGRAM

5. Working Principle: Power supply is given to the circuit. Power factor is set as standard value into the microcontroller IC . In case of deviations , microcontroller activates relay . Relay senses and connects the capacitor. T he capacitor is connected parallel across the load by relay without any hazard. The APFC unit controls PF by activating/deactivating capacitors.

6. Power Supply Circuit Step-down Transformer Diode Rectifier Filtering Capacitor Voltage Regulator

7. POWER FACTOR MEARSURMENT CIRCUIT Potential Transformer Current Transformer Zero Crossing Detector

8. Circuit Diagram of ZCD

9. MICRO COTROLLER: A Microcontroller Contains: T he processor (The CPU ), Program memory, M emory for input and output(RAM ), A clock and an I/O control unit. Microcontroller it is an electronic clock driven reprogrammable device which can take some digital data , process the data and gives us to required output data.

10. Features of the AT89s52 • High-performance, Low-power Atmel ® AVR ® 8-bit Microcontroller • Advanced RISC Architecture – 131 Powerful Instructions – Most Single-clock Cycle Execution – 32 x 8 General Purpose Working Registers – Fully Static Operation – Up to 16 MIPS Throughput at 16 MHz – On-chip 2-cycle Multiplier • High Endurance Non-volatile Memory segments – 16 Kbytes of In-System Self-programmable Flash program memory – 512 Bytes EEPROM – 1 Kbyte Internal SRAM – Write/Erase Cycles: 10,000 Flash/100,000 EEPROM – Data retention: 20 years at 85°C/100 years at 25°C (1) – Optional Boot Code Section with Independent Lock Bits In-System Programming by On-chip Boot Program True Read-While-Write Operation – Programming Lock for Software Security

11. Program of Microcontroller # include<AT89x52.h> #include< lcd.h > Sbit Voltage=P1^0; Unsigned int powerfactor; Void factor(); Void main() { r1=1; Lcdlnit(); While(1) { Display(0*80”, power factor”,16); Display(65000); Delay(65000); Factor(); Deley(65000); If((powerfactor<=0.98) {r1=0;}}} Void factor() {Display(0*80”,Factor Val: “,16) While(Voltage); While(!Voltage); Powerfactor=((cosine(voltage))); hex(0*86,powerfactor);)

12. LCD: A liquid crystal display (LCD) is a flat panel display It uses the light modulating properties of liquid crystals (LCs). LCDs Applications: C omputer monitors,  T elevision, I nstrument panels,signage , etc. LCDs have replaced cathode ray tube (CRT) displays in most applications.

13. LCD PINOUT:

14. RELAY:

15. WORKING OF RELAY: A relay is an electrically operated switch . The coil current can be on or off so relays have two switch positions and they are double throw ( changeover ) switches. Relays allow one circuit to switch a second circuit which can be completely separate from the first. It is also known as a sensing device.

16. Capacitor Bank A capacitor bank is a group of several capacitors of the same rating that are connected in series or parallel with each other to store electrical energy . The resulting bank is then used to counteract(resist)  or correct a power factor lag or phase shift in an alternative current (AC) power supply. They can also be used in a direct current (DC) power supply to increase the ripple current capacity of the power supply or to increase the overall amount of stored energy. Capacitor banks are generally used in substations. Since most of the household and industrial appliances are either resistive( eg . incandescent light, heater, etc.) or inductive(e.g. refrigerator, air-conditioner, motor, etc ). The capacitive load of the capacitor bank will help to adjust the power factor as close to 1 as possible, in which case the voltage and current are in phase and deliver maximum usable power to the load.

17. Advantage • Reactive power decreases • Avoid poor voltage regulation • Overloading is avoided • Copper loss decreases • Transmission loss decreases • Improved voltage control • Efficiency of supply system and apparatus increases

18. Disadvantage They have short service life ranging from 8 to 10 years They are easily damaged if the voltage exceeds the rated value Once the capacitor is damaged, their repair is uneconomical.

19. Applications : Linear loads with low power factor (such as induction motors ). A high power factor is generally desirable in a transmission system to reduce transmission losses and improve voltage. Alarm signals for: failure to reach the target PF overcurrent in t he capacitor Defects at capacitor stages

20. CONCLUSION : This paper shows an efficient technique to improve the power factor of a power system by an economical way. Static capacitors are invariably used for power factor improvement in factories or distribution line. But this paper presents a system that uses capacitors only when power factor is low otherwise they are cut off from line. Thus it not only improves the power factor but also increases the life time of static capacitors. The power factor of any distribution line can also be improved easily by low cost small rating capacitor. This system with static capacitor can improve the power factor of any distribution line from load side. As, if this static capacitor will apply in the high voltage transmission line then it’s rating will be unexpectedly large which will be uneconomical & inefficient. So a variable speed synchronous condenser can be used in any high voltage transmission line to improve power factor & the speed of synchronous condenser can be controlled by microcontroller or any controlled device.