Two situations arise when using powerfactorcorrection systems:
1. Installation of the powerfactorcorrection between the VSD and the motor, and 2. Installation of the powerfactorcorrection on the line side of the VSD
In the first case, powerfactorcorrection should not in any case be connected between the output of the VSD and the motor. In typical DOL situations, some installations will have a fixed KVAR value of capacitors sized to counteract the motors inductive reactance hence increase the powerfactor on the supply line. Be cautious when replacing DOL components with a VSD – if there are PF correction capacitors connected to the motor remove them as premature damage to the inverter and motor will occur due to the high frequency switching voltage occurring on the output of the inverter. Most capacitors are not designed to withstand the high switching currents produced by VSD’s.
Installation capacitor bank for powerfactorcorrection will obtain profitable both sides consumer and electric flow. Thesis also shows capacitor bank was used extensively by the high-power user as industry sector and commercial. Installation of capacitor bank can reduce reactive current consumption further minimize a losses. There were various types of connection and protection to optimize efficiency and life span of capacitor bank. Apart from that, capacitor bank operation for powerfactorcorrection will control with variety of techniques. However, this paper more focuses to the three phase system capacitor bank.
To put the cost of this process into perspective, a cost comparison can be made between the cost of powerfactorcorrection and the cost of photovoltaic solar, a technology that the government has deemed worthy of public subsidies. While solar “generates” KW and powerfactor reduces KW, both technologies will have the same net effect on fossil fuel generation. A power meter located at the utility substation would not be able to determine if the 3090 - KWH annual decrease in usage was due to the powerfactorcorrection system that we installed or a 2800 watt residential solar array at the same location (Annual KWH : Array Capacity x 1.1) . At the present day cost of $7.50 per watt for installed photovoltaic solar, the 2800 watt array would cost $21,000. The powerfactor system that we installed would cost approximately $4 , 000 for the 80 units, based on mass production costs of the devices. The net cost, when the value of offset generation is deducted, is $2,800. If we add a 20% cost overrun to the total and figure that the powerfactorcorrection system would have a net cost of $3,600, it would still cost 83% less than a solar array with the equivalent KW output. The public subsidy on that array would be approximately $8 , 000, or over double the cost of the powerfactor system if it were 100% subsidized.
Modern electronic equipment can create noise that will cause problems with other equipment on the same supply system. To reduce system disturbances it is therefore essential to correct for this, which requires an understanding of the problems poor power factors can cause, the requirements of correcting the powerfactor, and the methods of powerfactorcorrection.
Figure 9−2. Single Stage Conversion with NCP1652
In this single stage PFC converter, the most useful power circuit is the flyback topology or an equivalent buck-boost derivation. The flyback stage not only handles the output voltage regulation and input to output isolation functions, but can provide powerfactorcorrection as well. The circuit essentially functions as a conventional boost PFC converter with the output being derived from an isolated secondary winding on the boost choke rather than using a high voltage diode directly after the choke as in the conventional high voltage boost mode. The dc input to the converter following the ac bridge rectifier is a full-wave rectified sine wave, operating at twice the line frequency (100 or 120 Hz) instead of a pure dc voltage. The normal input “bulk” capacitor following the bridge rectifier must be reduced to a value of 1 mF or less so that the capacitive input filter does not have any significant effect on the powerfactor. The value of this capacitor should be sufficient to provide a low impedance at the converter’s switching frequency, but small enough to offer very high impedance at the ac line frequency.
Film Capacitors – PowerFactorCorrection B32305A4302B080 PFC DeltaCap X Black premium capacitors MKD480-D-30.0-X Preliminary data
These figures apply to the capacitor alone. Because the fixing and the terminals may influence the vibration properties, it is necessary to check stability when a capacitor is built in and exposed to vibration. Irrespective of this, you are advised not to locate capacitors where vibration amplitude reaches the maximum in strongly vibrating equipment.
Bharat Institute of Technology, Meerut, Uttar Pradesh ,India
Abstract-The main aim of this project is to enhance the power quality by constantly monitoring the load p.f. , when the load p.f.
drops below a definite value it results in the rise of line current resulting in more line loss and greater voltage drop. So a method is to be developed to improve powerfactor automatically. Inductive loads are main reasons for low powerfactor in power systems. Therefore we need to develop a method to improve powerfactor automatically. Automatic powerfactor controller project provides solution to this problem. Low powerfactor creates unnecessary loading on transmission lines. By inserting the capacitances of required magnitude p.f. can be improved therefore improving the efficiency of the system. . In this project, powerfactorcorrection unit is developed with microcontroller section, relays, p.t., c.t. and z.c.u.
Different problems associated accompanied by essentials and cautions for capacitor used for correction purpose were discussed in details.
Celtekligil (2008) discussed the application of a method for dynamic powerfactorcorrection and voltage regulation in light rail transportation system. Main reactors have been switched on through thyristors using automatic power controllers by sensing the powerfactor and constantly monitoring the current and voltage, calculating the powerfactor and switching inductance banks as required. The system proposed connects inductive loads in parallel with the capacitive system to improve the powerfactor.
In this paper, the Single Ended Primary Inductor converter (SEPIC) is used to achieve high powerfactor with reduced input current ripple. The conventional powerfactorcorrection suffers from high conduction losses due to the diode bridge at the input side. Thus bridgeless SEPIC converter is used to avoid conduction loss by using only two semiconductor switches in the current flowing path during each switching cycle. By implementing the improved topology in DCM it ensures almost unity powerfactor in a simple and effective manner.
Assistant Professor, Dept. of Electronics, Vivekanand Education Society’s Institute of Technology, Mumbai, India 5
ABSTRACT: Powerfactorcorrection has always been a challenging task. We may not realize that we are wasting electrical energy due to lagging powerfactor in inductive loads that we use. With increasing regulations and standards from electricity board, it becomes necessary for industrial and factory units to abide them without affecting their efficiency and other standards. This has increased competition among manufacturers to design different PFC stages for different applications. There are stages for loads that do not vary with power supply known a passive stage and for loads that vary with power supply known as an active stage.
Abstract : In the current scenario, powerfactor has become an important concern in all industries. Poor powerfactor gives rise to many problems which result in financial loss of industries and also for the commercial users. The main concern of this work is to improve the usage of real power with respect to reactive power hence improving the powerfactor. Here we have used the technique of relay switching method with a capacitor so that any drop in powerfactor can be sensed by the controller and switch the capacitor as required. This will not only help to improve powerfactor but also demand of electricity supply on utility side will be reduced. The Significance of this work is to build an APFC (Automatic PowerFactorCorrection) Unit. The APFC appliance calculates the reactive power (KVAR) expended by a system’s load and compensates the lagging PF (powerfactor) utilizing capacitances from capacitor banks.
The harmonics are caused by many non linear loads; the most common in the industrial market today, are the variable speed controllers and switch mode power supplies. Harmonic voltages can be reduced by the use of a harmonic compensator, which is essentially a large inverter that cancels out the harmonics. This is an expensive option. Passive harmonic filters comprising resistors, inductors and capacitors can also be used to reduce harmonic voltages. This is also an expensive exercise. In order to reduce the damage caused to the capacitors by the harmonic currents, it is becoming common today to install detuning reactors in series with the powerfactorcorrection capacitors. These reactors are designed to make the correction circuit inductive to the higher frequency harmonics. Typically, a reactor would be designed to create a resonant circuit with the capacitors above the third harmonic, but sometimes it is below.
This is to certify that the work on the thesis entitled Load balancing and powerfactorcorrection in distribution system by Pushanjeet Mishra and Abhisek Kumar Panda is a
record of original research work carried out under my supervision and guidance for the partial fulfillment of the requirements for the degree of Bachelor in Technology in the department of Electrical Engineering, National Institute of Technology, Rourkela. Neither this thesis nor any part of it has been submitted for the award of any degree elsewhere.
The reason for this is that inductive circuit cyclically absorbs energy from the system (during the build-up of the magnetic fields) and re-injects that energy into the system (during the collapse of the magnetic fields) twice in every power-frequency cycle.
An exactly similar phenomenon occurs with shunt capacitive elements in a power system, such as cable capacitance or banks of power capacitors, etc. In this case, energy is stored electrostatically. The cyclic charging and discharging of capacitive circuit reacts on the generators of the system in the same manner as that described above for inductive circuit, but the current flow to and from capacitive circuit in exact phase opposition to that of the inductive circuit. This feature is the basis on which powerfactorcorrection schemes depend.
------------------------------------------------------------------------------------------------------------------------------------- ABSTRACT: The powerfactorcorrection of electrical
loads is a problem common to all industries. Earlier the powerfactorcorrection was done by adjusting the capacitive banks manually. The automated powerfactor corrector using capacitive banks is helpful in providing the powerfactorcorrection. Proposed automated project involves measuring the powerfactor value and correcting using microcontroller and the load to be controlled by using GSM.The objective is to improve the power quality by continuously monitoring the load powerfactor. When the load powerfactor falls below a certain value it results in increase of line current resulting in more line loss and greater voltage drop. The aim is to build a simple compact and energy efficient system for automatic powerfactor monitoring and control. It incorporates PIC 16F877 microcontroller kit along with zero crossing detector circuit and relay driver circuit. The voltage and current parameters are detected and controlled by using GSM.
The continuous-conduction mode (CCM) conventional boost topology has been widely used as a PFC converter because of its simplicity and high power capability.
Recently, in order to improve the efficiency of the front- end PFC rectifiers, many power supply manufacturers have started considering bridgeless powerfactorcorrection circuit topologies. Usually, the bridgeless PFC topologies, also known as dual boost PFC rectifiers, reduce the conduction loss by reducing the number of semiconductor components in the line current path.
 Laszlo Huber, Member IEEE, Liu Gang, and Milan M. Jovanovic, Fellow, IEEE,
“Design Oriented Analysis and Performance Evaluation of Buck PFC Front End”, 0885-8993/$26.00, 2010, IEEE.
 Huai Wei, IEEE Member, and Issa Batarseh, IEEE Senior Member, University of Central Florida, Orlando, FL 32816, “ Comparison of Basic Converter Topologies for PowerFactorCorrection” , 0-7803-4391-3/98/$10.00 1998 IEEE.
The powerfactor of an electrical system gives the idea about the efficiency of the system to do useful work out of the supplied electric power. A low powerfactor leads to increase in losses and also draws penalty by the utility. Modern mining industry using mechanized methods suffers from low powerfactor due to the use of different electric equipment which requires more reactive power. Significant savings in utility power costs can be realized by keeping up an average monthly powerfactor close to unity. Utilizing shunt capacitor banks for PowerFactorCorrection (PFC) is an exceptionally established methodology. The recent trend is to automate the switching procedure of capacitors to get greatest advantage in real time basis. Embedded systems based on microcontrollers can be used to monitor and control the switching of correction devices because of its dependability and execution.
The total harmonic distortion, known as THD, should be taken into consideration when dealing with non-linear loads. Also, harmonics cannot be improved or cancelled by adding linear components, such as capacitors or inductors. In the case of non-linear loads, different, yet more complex, methods need to be considered to improve PF correction and minimize THD. In many cases, the method used is active powerfactorcorrection utilizing a dedicated Integrated Circuit, known as IC, which is much more complex than a passive powerfactorcorrection method.