Abstract: The electrical energy is almost exclusively generated,transmitted and distributed in the form of alternating current. Therefore, the question of powerfactor immediately comes into picture. Most of the loads(e.g. induction motors, arc lamps) are inductive in nature and hence have low lagging powerfactor. The low powerfactor is highly undesirable as it causes an increase in current, resulting in additional losses of active power in all elements of power system from power station generator down to the utilisation devices[1-3]. In order to ensure most favourable conditions for a supply system from engineering and economical standpoint, it is important to have powerfactor as close to unity as possible. In this paper various powerfactorimprovement techniques will be discussed.
rectifiers, switched mode power supply (SMPS), adjustable speed drives, ferromagnetic devices, arcing equipment’s, induction heating systems etc. As is well known, the current is proportional to the voltage in case of a linear load whereas the current is not proportional to the voltage in case of non-linear load. A linear load draws active power from the grid with only fundamental component being present in the current and absorbs/injects reactive power from/to the grid. However, a non-linear load draws active power from the grid, where the current has fundamental and harmonics. These harmonics do not provide extra power but unnecessarily, yet unavoidably, increase the system volt-ampere (VA). This shows up as an increase in the RMS current in the lines and leads to an extra heating of the transmission conductors and system elements. The injection of harmonics thus has a number of disadvantages, as reported in . Hence, the compensation of reactive power is necessary for both linear and non-linear loads. Harmonic compensation up to standard values , and powerfactorimprovement are main issues for such loads The powerfactor PF is defined as the ratio of the active powerP to the apparent power S. Thus
Quantum of Energy generation is one of the metric for the measurement of a Nation’s development. The requirement of energy is much more than the amount of power getting generated in developing countries like India. Under these circumstances Demand side management (DSM) is one of the methods to improve the utilization of energy. Most of the industrial and domestic loads are inductive in nature and hence the powerfactor of the loads are very poor. An improvement in the powerfactor results in availability of more active power for the same generated power. Powerfactorimprovement is most commonly used in industrial units. Automatic powerfactor controllers (APFC) are equipped with semiconductor devices, switching of capacitor banks for the improvement of powerfactor. In present days, solid state electronics control for electric motors are frequently used for drive control (speed and torque). This can introduce harmonics in current and voltages. The general opinion among technologists is that improvement in powerfactor reduces losses in an electrical system. Although this is true in a general way, it is not so in systems which use switched electronic devices that can introduce large amount of harmonics.
ABSTRACT: AC/DC converters possess no harm for pure resistive loads as Output Voltage Ripple can be compromised. In almost all practical applications of the Converter, the Power quality issues like Input Current Distortion and poor PowerFactor comes into picture. These make the Converter Operation inefficient. Optimal Filter Design and Topological approach for addressing this issue are the possible ways for improving the efficiency of the Converter. This paper investigates the harmonic content and other power quality issues like displacement factor, distortion factor for various Single Phase Converter topologies. The Total Harmonic Distortion is seen to be minimum and PowerFactor nearly unity for closed loop PowerFactorImprovement. The Converters are simulated in MATLAB/Simulink and the results are obtained.
lamps) are inductive in nature and hence have low lagging powerfactor. The low powerfactor is highly undesirable as it causes an increase in current, resulting in additional losses of active power in all the elements of power sys-tem from power station generator down to the utilisation devices. A static VAR compensator consisting of capacitor bank in four binary sequential steps with a thyristor (SCR) controlled reactor of smallest step size is employed in the investigative work. This work deals with the performance evaluation through analytical studies and practical implementation on an existing system consisting of a distribution transformer of 1phase, 50Hz, 1KV/230V capacity. The PIC controller determines firing pulse of SCR to compensate excessive reactive power component for PF improvement. In order to ensure most favourable conditions for a supply system from engineering and economical standpoint, it is im-portant to have powerfactor as close to unity as possible. In this paper, we shall discuss the methods of powerfactorimprovement using PIC .
In this paper, the powerfactorimprovement and harmonics compensation for active load is acquired by the Shunt Hybrid filter (SHF). Dominant harmonic current are infused by the passive filter and the hysteresis controlled shunt active filter infuses the fundamental reactive current and other than dominant harmonic currents. Supply current detection method for controlling the active filter using Artificial Neural Network (ANN), updates the weight by least mean square (LMS) algorithm which determines the reference signal for the hysteresis controller. By trial and error, the learning rate is fixed. The dynamic response of the shunt active filter for active load is studied using MATLABSimulink and the results are verified.
Abstract: This paper presents brushless dc (BLDC) motor drive with boost powerfactor correction to overcome power quality problem at AC mains. Boost PFC converter is applied to achieve unity powerfactor at AC mains. A reduction in harmonics is also observed. Here we are analyzing a conventional BLDC motor drive and comparing with Boost PFC based BLDC motor drive and expected improvement in overall powerfactor is seen. In this paper we simulate two cases of BLDC motor drive with and without PFC converter using Matlab/Simulink. The unity powerfactorimprovement achieved was verified by hardware implementation and testing.
From the literature, it is observed that most of the work concentrates on the PFC for BLDC motor drive with the rectifier bridge. As the bridgeless buck converter  is not suitable for wide voltage control, here a canonical switching cell (CSC) converter is proposed. The proposed converter has exceptional performance as a powerfactor pre-regulator, better load regulation and minimal number of components. A CSC converter comprises of a combination of switch, inductor and diode known as canonical switching cell in combination with a dc link capacitor and an inductor. The project aims at configuring the PowerFactorImprovement – Canonical switching Cell (PFI-CSC) converter fed BLDC motor drive in order to develop a
ABSTRACT: This Paper Describe the powerfactorImprovement of a induction motor using condenser operated through PLC, by improving the powerfactor of induction motor the energy saving measures are automatically achieved. Powerfactor is the value of a system that reflects how much power is being borrowed from Power Company for the system. If powerfactor becomes poor than unity, then organization or industry requires more current for supplying same amount of power.as the current increases line losses also increases because of voltage drop=I2R.Induction motor is widely used in industries due to their features like low cost, reliability, robustness. At no load induction motor has very low powerfactor of about 0.33 as the load goes on increasing the powerfactor also get improved as we go towards full load. Powerfactor correction serves to correct low powerfactor by reducing phase difference between voltage and current phasors.it is difficult to control the powerfactor of continuously varying load. This work is to make the system that wills correct the powerfactor by switching condenser bank through the PLC.
Abstract—Various inductive loads used in all industries deals with the problem of powerfactorimprovement. Capacitor bank connected in shunt helps in maintaining the powerfactor closer to unity. They improve the electrical supply quality and increase the efficiency of the system. Also the line losses are also reduced. Shunt capacitor banks are less costly and can be installed anywhere. This paper deals with shunt capacitor bank designing for powerfactorimprovement considering overvoltages for substation installation.
S indicates the capacity of the source required to supply the load. The apparent power specifications of source and load equipment can be more important than the average power specifications. This is because any electrical equipment requires appropriate design of conductor size, amount of dielectric (insulation) and magnetic material to handle both current and voltage magnitudes. Thus S has a direct bearing on size and cost of any electrical equipment. Since average power represents the useful output of the load equipment (essentially energy converting devices like motors, heaters, lighting), operating such equipment close to unity powerfactor is desirable (i.e, P should be as close to S as possible, or Q should be minimized).
This paper deals with the powerfactor of Electrode- less Fluorescent Lamp (EFLs) by using fuzzy logic controller. The output voltage of the cuk converter contains voltage ripples and steady state error. To overcome the voltage ripples and steady state error, the closed loop system of Fuzzy Logic Controller (FLC) and Single Ended Primary Inductor Converter (SEPIC) are used. By using FLC, the powerfactor and the efficiency are slightly get increased when compared to Proportional Integral (PI). The SEPIC is used to reduce the voltage ripples. PI controllers are not much efficient and require more time to implement due to their robustness. These controllers are suitable for single input value only not suitable for changing values. The FLC is proposed to improve the efficiency and more number of inputs can be used. Finally, a step-by-step design methodology is proposed and stimulated through MATLAB/SIMULINK for improving the powerfactor and efficiency by reducing the voltage ripples.
Abstract—In this paper the current harmonic can be compensated by using the Hybrid Power Filter, the Passive Power Filter and the combination of both. The system has the function of voltage stability, and harmonic suppression. The reference current can be calculated by using a new control algorithm by using three phase hybrid shunt Active power. An improved Control algorithm is proposed to improve the Performance of Hybrid Power filter. This paper deals with Space Vector Pulse Width Modulation technique to generate the gating pulses to VSI(Here VSI is using as a filter) . The simulation results of the Non-linear systems have been carried out with MATLAB 7.6., MULTISIM.
In this paper, the circuit for the three phase ac voltage regulator employing modified sinusoidal pulse width modulation technique is used and the results are obtained by simulation. Comparing the modified sine wave with a high-frequency triangular signal, switching pulses for the conduction of semiconductor power elements (IGBT) can be achieved. A shift of these switching pulses acts so that the current waveform is near to the voltage waveform, which is verified from simulation results. This critical value of the shifting angle depends on the resistive and inductive load components as well as on the active output power. The operation of this ac voltage regulator gives the following advantages: Improved load powerfactor due to high frequency switching, Control range is wide in terms of firing angles regardless of load powerfactor. The investigation leads to the conclusion that there is a value of the shifting angle for which the PF can be improved.
Powerfactor correction (PFC) converters are widely used for improving the power quality at ac mains. Various configurations of nonisolated and isolated PFC converter have been reported in the literature for improving the power quality at ac mains. The cost of these PFC converters is primarily decided by the sensing requirements which in turn depend upon the mode of operation of the PFC converter. Continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are two modes of operation of a PFC converter. PFC converter operating in CCM offers low stress on PFC converter switches but requires sensing of supply voltage, dc link voltage, and supply current, which is a costly option in terms of cost of sensors. However, PFC converter operating in DCM requires single voltage sensor for dc link voltage control, and inherent PFC is achieved at ac mains but at the cost of high stress on PFC converter switches.
A Brushless DC motor drives have gained importance in the last decade due to power quality improvements that have also resulted in exceptional performance compared with other conventional drives. The advantages of including high torque to weight ratio, more torque per watt (increased efficiency), increased reliability, reduced noise, longer lifetime, elimination of ionizing sparks from the commutator, and overall reduction of electromagnetic interference (EMI). The applications of BLDC motor are many low and medium power applications ranging from household appliance, medical equipment, heating, ventilation and air conditioning. Two key performance parameters of brushless DC motors are the motor constants Kv and Km. Environments and requirements in which manufacturers use brushless type DC motors include maintenance free operation, high speeds, and operation where sparking is hazardous or could affect electronically sensitive equipment. However there are three main problems are considered in BLDC motor: they are 1) providing fast speed response, 2) improving the powerfactor near to unity in ac mains and 3) the reduction of torque repulsion.
ABSTRACT: A new single phase bridgeless converter topology with a powerfactor correction (PFC) is proposed. Less number of components is the main highlight of bridgeless resonant pseudoboost powerfactor correction rectifier compared to other topologies . In this the input diode bridge is absent and there is only one diode in the current path during each stage of the switching cycle .The rectifier is designed to work in resonant mode to achieve powerfactor close to unity in a very simple manner. Fuzzy logic control strategy for pseudoboost PFC is presented in this paper. Here the controlling action was established through a fuzzy Logic controller. It gives a faster output voltage response as compared to openloop.
Capacitors are commonly used within a lot of power system, especially electronic constructed circuitry. In three phase power system, capacitors normally installed within an isolating non-conductor metal box, which is called capacitor bank, they are fixed and switched. Fixed banks are connected permanently to the primary conductors through fused switches. Switch capacitors banks are tied to primary system through automated switch, allowing them to be put on line and taken off line as needed. Distribution power system usually connects capacitor in parallel rather connecting in series. The function of shunt power capacitor is to provide leading KVAR to an electrical system when and where needed. The actual capacitor in farads of a capacitor bank can be calculated using the following Equation (2).
Powerfactor has a high impact on power system industries. A load with low powerfactor draws more current than a load with high powerfactor for the same amount of useful power transferred. The high current increases the energy lost in the distribution system and requires large equipment to dissipate wasted energy. Electrical utilities usually charge high cost to industrial/commercial consumers where there is a low powerfactor. With the development of technology in power semiconductors devices, the rate of using power electronics system has expanded to new and wide applications that include residential, commercial, aerospace and other systems. In the non- linear systems, loads are the main sources of harmonics and it affects efficiency. The current dawn by the power electronics interface from the line is distorted resulting in a high total harmonic distortion (THD) and low powerfactor (PF).This creates adverse effects on the power system that include increased magnitude of neutral current in a three phase system, over heating of transformers and induction motor. Hence, there is a continuous need for both the improvement of powerfactor and reduction of line current harmonics. This work is to implement a boost converter with average current mode control technique for the improvement of the powerfactor and reduction of total harmonics distortion. The boost converter can perform this type of active powerfactor correction in many discontinuous or continuous modes. Average current measurement provides the input current with high degree of accuracy. Average current mode control technique works wells even when the mode boundary is crossed into the discontinuous mode at low current levels. Open and closed loop boost converter using average current mode control has been simulated by power simulation (PSIM) software. Hence the waveforms of the input current shows the improvement of PF and reduction of THD.
rectifier diodes with advantage of improving low powerfactor and eliminating high input line harmonics (Current Source Rectifier). Phase winding energizing is done by machine side converter as second stage [6, 7]. The CSR in modified SRM drive have six bidirectional self-commutated switches. No short circuit must be applied to the mains filtering capacitors and No open circuit must be applied to the output current.