Essay: POWER SAVING FOR COMMERCIAL AREA BY AUTOMATIC POWERFACTOR IMPROVEMENT

ABSTRACT
The overall power factor of modern industries is very poor because of inductive loads absorbing reactive power. Especially, industrial plant with variable load conditions has large inductive loads and its power factor is very poor. These industries benefit most from automatic capacitor banks. This bank provides improved power factor, increased voltage level on the load and reduced electric utility bills. Besides, automatic capacitor banks may be able to eliminate KVAR energized at light-load periods and undesirable over-voltages. In most cases, the main reason why a customer installs a capacitor bank is to avoid penalization in the electricity bill. This inappropriate installation without enough study gives rise to a great variety of technical problems. Therefore, the fact that capacitor banks are designed for long-term use should be considered.
CHAPTER: 1 INTRODUCTION
In most industrial and commercial facilities, a majority of the electrical equipment is inductive loads such as AC induction motors, induction finances, transformers and ballast-type lighting. Problems of power quality in industrial plants are growing due to the increasing number of rectifier controlled motors and the overall increase of harmonics and inter harmonics. These loads cause poor power factor in industrial plants.
A poor power factor indicates ineffective utilization of electricity and affects total energy costs. These problems are aggravated by the proper selection, sizing and installation of capacitors
1.1 FUNDAMENTAL OF POWER FACTOR
Power factor is a measure of how effectively electrical power is being used by a system. To understand power factor, we first have to know that power has three components: working, reactive and apparent power. Working power is the current and voltage actually consumed. It performs the actual work, such as creating heat, light and motion. Working power is expressed in kilowatts (kW), which register as kilowatt-hour on electric meter.
Reactive is not useful work, but it is needed to sustain the electromagnetic field associated with many commercial/ industrial loads. It is measured in kilovolt-amperes-reactive, or kVAR.
The total required capacity, including working and reactive power, is known as apparent power. It is expressed in kilovolt-amperes or KVA.
Power factor is the ratio of working power to apparent power or kW/kVAR. Power factor values can carry from 0 to 1.00. Typically, values range from 0.80 to 0.98. A power factor below 0.80 is considered low.
1.2 INDUCTIVE LOADS CONTRIBUTING TO POOR POWER FACTOR
If the plant inductive loads, which require the use of a magnetizing current to create a magnetic field, Power factor corrections are required. Inductive characteristics are more pronounced in motors and transformers and are found more often in commercial and industrial facilities. One of the worst offenders is a lightly loaded induction motor, often found in “cycle processes” —for example, in the operation of saws, conveyors, and grinders- where the motor must be sized for the heaviest load. Other sources include: induction furnaces, standard stamping machines, weaving machines, single stroke presses, automated machine tools, welders and certain fluorescent lamp ballasts. Table 1 shows incorrect power factor of some industrial plants.
Industry
Uncorrected power
Factor
Saw Mills 45% – 60%
Plastic 55% – 70%
Machine Tools, Stamping 60% – 70%
Planting, Textile, Chemicals 65% – 75%
Hospitals, Foundries 70% – 80%
TABLE 1
TYPICAL LOW POWER FACTOR INDUSTRIES
1.3 POWER FACTOR CORRECTION
If the power factor of the plant is low, it uses more power than it needs to do the work. Poor power factor should be corrected as it substantially increases costs. Capacitors generally are the most economical means to improve power factors.
1.3.1 POWER FACTOR CORRECTION METHODS
Switch Capacitors
Synchronous Condenser
Static Synchronous Compensator(STATCOM)
Static Var Compensator(SVC)
Fixed Capacitors
SWITCHED CAPACITOR
It is suited for centralized power factor correction in applications where plant loading is constantly changing, resulting in the need for varying amounts of reactive power. An advanced microprocessor-based reactive power controller measures plant power factor via a single remote current transformer (included), and switches capacitor modules in and out of service to maintain a user-selected target power factor. Typically applied at service entrance or near fluctuating loads.
SYNCHRONOUS CONDENSER
Synchronous condenser is a salient pole synchronous generator without prime mover. Synchronous condenser stabilizes power system voltage by supplying reactive power to the power system and Use for power factor correction. It is more economical than capacitors.
STATIC SYNCHRONOUS COMPENSTOR (STATCOM)
The Static Synchronous Compensator (STATCOM) is a shunt device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow and improve transient stability on power grids [1]. The STATCOM regulates voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system.
When system voltage is low, the STATCOM generates reactive power (STATCOM capacitive).When system voltage is high, it absorbs reactive power (STATCOM inductive).
Similarly to the SVC the STATCOM can provide instantaneous and continuously variable reactive power in response to grid voltage transients enhancing the grid voltage stability installing a STATCOM at one or more suitable points in the network will increase the grid transfer capability through enhanced voltage stability, while maintaining a smooth voltage profile under different network conditions.
The STATCOM provides additional versatility in terms of power quality improvement capabilities.Power factor correction is the term given to a technology that has been used since the turn of the 20th century to restore This is normally achieved by the addition of capacitors to the electrical network which compensate for the reactive power demand of the inductive load and thus reduce the burden on the supply. There should be no effect on the operation of the equipment.
A sample analogy for power factor is to relate it to a garden hose. Circumstances, if you need 10 litres of water per minute to come out at the end of the hose, the tap should be turned on to deliver that amount of water. But if your hose leaks, is squashed between rocks, or is kinked because it is cheap, you will experience a drop in pressure. To achieve your target of 10 litters per minute, therefore, you need to turn up the tap and force more water through the hose. That is Power Factor Correction.
STATICVARCOMPENSATOR (SVC)
The Static Var Compensator (SVC) is a shunt device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow and improve transient stability on power grids [1]. The SVC regulates voltage at its terminals by controlling the amount of reactive power injected into or absorbed from the power system. When system voltage is low, the SVC generates reactive power (SVC capacitive). When system voltage is high, it absorbs reactive power (SVC inductive the variation of reactive power is performed by switching three-phase capacitor banks and inductor banks connected on the secondary side of a coupling transformer. Each capacitor bank is switched on and off by three thyristor switches (Thyristor Switched Capacitor or TSC). Reactors are either switched on-off (Thyristor Switched Reactor or TSR) or phase-controlled (Thyristor Controlled Reactor or TCR).
A rapidly operating Static Var Compensator (SVC) can continuously provide the reactive power required to control dynamic voltage swings under various system conditions and thereby improve the power system transmission and distribution performance.
Installing an SVC at one or more suitable points in the network will increase transfer capability through enhanced voltage stability, while maintaining a smooth voltage profile under different network conditions. In addition, an SVC can mitigate active power oscillations through voltage amplitude modulation.
FIXED CAPACITOR
Where the load does not change or where the capacitor is switched with the load, such as the load side of a Ideally suited for power factor correction in applications motor contactor. It is suitable for locations using induction motors, like food processing plants, or where small multiple loads require reactive power compensation Each Fixed Capacitor Bank is designed for high reliability and long life. These products are designed for applications that do not contain harmonic generating.
1.4 ADVANTAGES OF POWER FACTOR CORRECTION
Eliminate Power Factor Penalties
Increase System Capacity
Reduce Line Losses in distribution systems
Conserve Energy
Improve voltage stability
Less total plant KVA for the same KW working power
Improved voltage regulation due to reduced line voltage drop
Reduction in size of transformers, cables and switchgear in new installations
Increase equipment life
Save on utility cost
Enhance equipment operation by improving voltage
Improve energy efficiency.
Reduction in size of transformers, cables and switchgear in new installations.
Delay costly upgrades.
Less total plant KVA for the same KW working power.
Improved voltage regulation due to reduced line voltage drop.
Environmental benefit-reduction of power consumption due to improved energy efficiency. Reduced power consumption means less greenhouse gas emissions and fossil fuel depletion by power stations.
Reduction of electricity bills.
Extra kVA available from the existing supply.
Reduction of I2R losses in transformers and distribution equipment
Reduction of voltage drops in long cables.
Extended equipment life- reduced electrical burden on cables and electrical components
DISADVANTAGES OF LOW POWER FACTOR
Increases heating losses in the transformers and distribution equipments.
Reduce plant life.
Unstable voltage levels.
Increase power losses.
Upgrade costly equipments.
Decrease energy efficiency.
Increase electricity costs by paying power factor surcharges
 
CHAPTER: 2 LITERATURE SURVEY
2.1 BOOKS RESEARCH
1. A book of “principal of power system” which is written by Mr. V.k. mehta &Rohit mehta is giving us the fulfilled basic knowledge about the power factor.
2.2 RESEARCH ARTICLE
(i) Mr.Anant Kumar Tiwari, Mrs. Durga Sharma, Mr.Vijay Kumar Sharma Dr. C.V. Raman Institute of Science and Technology Bilaspur. Assistant professor Dr.C.V. Raman Institute of Science and Technology, Bilaspur. Assistant professor Lkct Indore (M.P.)
By observing all aspects of the power factor it is clear that power factor is the most significant part for the utility company as well as for the consumer. Utility companies get rid from the power losses while the consumers are free from low power factor penalty charges.
(ii) SWITCHING POWER SUPPLY WITH AUTOMATIC POWER FACTOR CORRECTION
Inventor: James D. Bucher, II, St. Paul, Minn.
Assignee: Zytec Corporation, Eden Prairie, Minn.
Appl. No.: 929,603
An off-line switching power supply is described which controls the switching transistor of a fly-back circuit in such a fashion as to achieve better than 0.99 power factor control. The technique used for power factor control allows the switching power supply to operate either from AC or DC sources. The power supply operating from an AC source will accept all international voltages and line frequencies as input to produce a well regulated DC output.
The inductor of the fly-back circuit is maintained at the verge of continuous/discontinuous operation by the power factor control circuit to achieve a high efficiency operation and to minimize switching losses. The power factor correction circuit uses pulse width modulation and frequency modulation to control the switching transistor and maintain a high power factor under varying line and load conditions. The power supply also includes integral current limiting protection and RFI filtering for safe and quiet operation.
3. AUTOMATIC POWER FACTOR CORRECTION SYSTEM
Inventors: William D. Gail A. McDaniel, Timothy J. McDaniel
APPL NO; 10/162,406
An automatic power factor correction system, for an electrical power installation drawing varying levels of reactive power, measures an electrical parameter of the power drawn by a load of a power installation which is capable of indicating a level of reactive power drawn by the load and Couples a Combination of Capacitors to the power line to compensate for the level of reactive power indicated by the electrical parameter measured’ In particular, the System measures the phase angle of the power drawn and calculates a combination of capacitors to connect to ‘the power line to compensate for a measured level of reactive power.
CHAPTER: 3 CANVAS REPORT
3.1 OBSERVATION SHEETS
3.1.1 ACTIVITIE
GENERAL IMPRESSIONS /OBSERVATIONS
Observe in collage, substation, and home.
At that area the voltage level will be unstable.
The efficiency of equipment wills not 100%.
The billing will be high at fewer loads.
ELEMENTS, FEATURES AND SPECIAL NOTES
Fan
Lamps
Panels and P.F meter.
Heater
Refrigerator
Induction motor
3.1.2 ENVIRONMENT
A. GENERAL IMPRESSION /OBSERVATION
Noisy environment at industry.
Clean atmosphere.
Cold environment due to fans and A.C.
B. ELEMENT, FEATURES & SPECIAL NOTES
an
Lamps
Heater
Refrigerator
A.C and coolers.
3.1.3 INTERACTIONS
A.GENERAL IMPRESSION / OBSERVATION
Family members
Student & staff
Worker
Supervisor
B.ELEMENTS, FEATURES, SPECIAL NOTES
Fan
Lamps.
Heater
Refrigerator
Induction motor
3.1.4 OBJECTS
A.GENERAL IMPRESSION / OBSERVATIONS
Meter
Transformer
Display
Capacitor
Fan, heater lamps
B.ELEMENTS, FEATURES AND SPECIAL NOTES
Meter: use for measuring various electrical quantity.
Transformer: use for voltage up-down.
Display: use for shoes reading.
Capacitor: use for power factor improvement.
Fan, heater lamps: use as a inductive load
C.INVENTORY OF KEY OBJECTS
Fan
Lamps.
Meter
Fan, heater lamps
A.C and coolers.
3.1.5 USERS
A.GENERAL IMPRESSION / OBSERVATION
Students and teacher
Family members.
Supervisor and observer.
Official staff.
B.ELEMENTS, FEATURES AND SPECIAL NOTES
(List of identified people involved)
Student
Teacher
Observer and supervisor
Workers
3.2 Ideation Canvas
A. PEOPLE
Worker
Supervisor
Junior engineer
Staff and student
B. ACTIVITIES
Supervisor take a reading
Staff and student study and teaching
Worker operate machine
C. LOCATIONS/ SITUATIONS/ CONTEXT
Industry high intensity discharge lightning inductive furnace
Power plant non sinusoidal component induction generator
D. PROPS/ POSSIBLE SOLUTIONS
Micro controller
Capacitor bank
High power factor motor
Induction motor with phase advancer
Static capacitor
Synchronous condenser
Standard motor
Static VAR compensator
3.3 Product Development Canvas
A. PURPOSE
Reduce cost of bill
Improve power factor
Power saving
B.PRODUCT EXPIRIENCE
Satisfaction after use
Less cost for users
Easy implement
C.PRODUCT FUNCTIONS
Saving billing cost
Power saving
Improve power factor
D.PRODUCT FEATURES
Automatic power factor improvement
Reading of power factor show on LCD
E.COMPONENTS
Capacitive bank
LCD
Micro controller
Relay
F.CUSTOMER RAVALIDATION
Easy to installation
Reliable
G.REJECT, REDESIGN, AND RETAIN
Fault in capacitor
Programming defect
.
3.4 EMPATHY CANVAS
A.USER
Worker
Student
Staff
Supervisor
B. STAKEHOLDERS
Industries
Commercial area
Substation
C. ACTIVITIES
Student and staff :-Staff are teach and student are learn
Supervisor:-Take a reading from panel
D.STORY BOARDING:
(I) HAPPY:
At time going for visit we have enjoy travelling and also enjoy the rain.
After visiting substation we have to take lunch with supervisor and J.E of substation and after lunch have to play game with theme.
(II) SAD:
After visiting we have argument with each other for selecting fault and deciding the project title.
Due to rain cloths are dirty.
CHAPTER: 4 SYSTEM DESIGN
4.1 Basic block diagram of automatic power factor improvement
Fig: 4.1 Basic block diagram of automatic power factor improvement
4.1.1 LOAD BANKS
A load bank is a device which develops an electric load, applies the load to an electrical power source and converts or dissipates the resultant power output of the source.
The purpose of a load bank is to accurately mimic the operational or “real” load that a power source will see in actual application. However, unlike the “real” load, which is likely to be dispersed, unpredictable and random in value, a load bank provides a contained, organized and fully controllable load.
Consequently, a load bank can be further defined as a self-contained, unitized, systematic device that includes load elements with control and accessory devices required for operation.
Whereas the “real” load is served by the power source and uses the energy output of the source for some productive purpose, the load bank serves the power source, using its energy output to test, support or protect the power source.
Types of load bank
The three most common types of load banks are resistive load banks, reactive load banks, and capacitive load banks.
A) Resistive load bank
A resistive load bank, the most common type, provides equivalent loading of both generator and prime mover. That is, for each kilowatt load applied to the generator by the load bank, an equal amount of load is applied to the prime mover by the generator. A resistive load bank, therefore, removes energy from the complete system: load bank from generator—generator from prime mover—prime mover from fuel. Additional energy is removed as a consequence of resistive load bank operation: waste heat from coolant, exhaust and generator losses and energy consumed by accessory devices. A resistive load bank impacts upon all aspects of a generating system.
The “load” of a resistive load bank is created by the conversion of electrical energy to heat via high-current resistors such as grid resistors. This heat must be dissipated from the load bank, either by air or by water, by forced means or convection.
In a testing system, a resistive load simulates real-life resistive loads, such as incandescent and heating loads as well as the resistive or unity power factor component of magnetic (motors, transformers) loads.
B) Reactive load bank:
A “reactive” load includes inductive (lagging power factor) and/or capacitive (leading power factor) loads.
Inductive loads, the more common type, consist of iron-core reactive elements which, when used in conjunction with a resistive load bank, create a lagging power factor load. Typically, the inductive load will be rated at a numeric value 75% that of the corresponding resistive load such that when applied together a resultant 0.8 power factor load is provided. That is to say, for each 100 kW of resistive load, 75 KVAR of inductive load is provided.
Other ratios are possible to obtain other power factor ratings. Inductive loads are used to simulate real-life mixed commercial loads consisting of lighting, heating, motors, transformers, etc. With a resistive/inductive load bank, full power system testing is possible, given the impact of reactive currents on generator/voltage regulator performance as well as effects on conductors and switchgear.
C) Capacitive load bank
A capacitive load bank is similar to a reactive load bank in rating and purpose, except leading power factor loads are created. These loads simulate certain electronic or non-linear loads typical of telecommunications, computer or UPS industries
4.1.2 AT89C51 MICROCONTROLLER: –
A microcontroller is a small on chip computer on a single integrated circuit contains a processor core, memory elements, and programmable I/O (Input/output) peripherals. (Short names μC or MCU). The AT89C51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of Flash programmable (ROM) and erasable read only memory (PEROM).
The device is manufactured by Atmel’s high-density non-volatile memory technology and is compatible with the student’s final year project and also in industry-standard MCS-51 instruction set and pin out. The on-chip Flash can be reprogrammed in system or by a programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications. Below figure shows the AT89C51 microcontroller.
AT89C51 MICROCONTROLLER PIN DIAGRAM: –
EA (Enable Access): – This is the pin number — 31 which is used for the, if the program code is stored in on chip ROM (4K bytes) then this pin is connected to the +Vcc if the program code is stored in the external ROM then this pin must be GND (Ground).
PSEN (Program Store Enable): – This pin is used to access the external program code in the ROM to do so this pin is connected to the OE pin of the ROM which contains the program code. At the same time the EA pin must be grounded. Pin – 29
ALE (Address Latch Enable): – This is the output active high pin; AT89C51 contains the combined address/data bus AD0-AD7 to De-multiplex this High to low pulse is send at that time when the pulse is high the address is latched and then data is fetched. Pin — 30.
Table 2 Pin Description of AT89C51
4.1.3 LCD (Liquid Crystal Display)
LCD (Liquid Crystal Display) screen is an electronic module which is used in a wide range of applications like display of the data like train incoming and outgoing from the railways stations and in data monitoring applications. A 16×2 LCD is a very basic module and is very simple and common in various circuits and different devices. They are preferred instead of the seven segment displays which is not compatible. There is so many advantages compared to seven segment displays. LCDs can display characters like A, B, C $, @ etc. and so on, numbers and even different graphics. Refreshing controllers already present inside the LCDs so AT89C51 not need to refresh the displays. It is cheap and the current dissipation is low.
TABEL 3: PIN FUNCTION OF LCD
4.1.4 CONTRAST CONTROL:
To have a clear view of the characters on the LCD, contrast should be adjusted. To adjust the contrast, the voltage should be varied. For this, a preset is used which can behave like a variable voltage device. As the voltage of this preset is varied, the contrast of the LCD can be adjusted.
Potentiometer:
Variable resistors used as potentiometers have all three terminals connected. This arrangement is normally used to vary voltage, for example to set the switching point of a circuit with a sensor, or control the volume (loudness) in an amplifier circuit. If the terminals at the ends of the track are connected across the power supply, then the wiper terminal will provide a voltage which can be varied from zero up to the maximum of the supply.
Presets
These are miniature versions of the standard variable resistor. They are designed to be mounted directly onto the circuit board and adjusted only when the circuit is built. For example, to set the frequency of an alarm tone or the sensitivity of a light-sensitive circuit. A small screwdriver or similar tool is required to adjust presets.
Presets are much cheaper than standard variable resistors so they are sometimes used in projects where a standard variable resistor would normally be used.
Multi turn presets are used where very precise adjustments must be made. The screw must be turned many times (10+) to move the slider from one end of the track to the other, giving very fine control.
CHAPTER: 5 FUTURE PLAN OF THE WORK
In this semester we have to find the project title and made observation and canvas sheets
Also design a block diagram of automatic power factor improvement
In future we have to design circuit diagram and layout of the power factor improvement. Design capacitive load bank connection diagram.
Programming the Microcontroller IC (AT89C51).
REFRENCE
“Principles of Power system by “V.K.MEHTA &ROHIT MEHTA”.
http://www.pscpower.com
http://www.onsemi.com
http://electrical-engineering-portal.com
http://www.engineersgarage.com/electronic-components/at89c51-microcontroller-
datasheet
Muhammad All Mazidi, the 8051 Microcontroller & Embedded Systems, Kenneth J
Ayala, the 8051 Microcontroller Architecture