There are two types of conversion techniques , one is uncontrolled in which diodes are implemented and other is controlled in which thyristors are implemented respectively .The performance improvement is achieved for total harmonics distortion (THD) in input current, DC voltage ripples and form factor. Three-phase controlled rectifiers have a wide range of applications, to large high voltage direct current (HVDC) transmission systems from small rectifiers. They are used for electrochemical processes, wide range of motor drives, controlled power supplies, traction equipment and other applications.
B)Non-Linear load with Device – The device Same setup are used in this system with only one difference is that the compensation are provided in the system to maintain the voltage profile, increase transient stability of transmission line and the main objective of system is to concern with the total harmonics distortion. Obviously this system after providing compensation reduces the total harmonics distortion as the STATCOM provide compensation it is shunt connected FACTS controller power electronic based or IGBT basesd device which injects the current into the system to overcome the power quality problem. This system modal with devices reduce the harmonic distortion and it is 189.17%.If we have to seen comparison point of view two machine system without STATCOM device contain more harmonics as compare to two machine system with STATCOM device therefore without FACTS devices 519.47% and with FACTS device the harmonics are 189.17% and hence we can conclude that two machine system with STATCOM device reduces total harmonic distortion as small as possible and enhances the system stability, transit stability, maintain voltage profile of transmission line, power oscillation damping etc.
Abstract: This paper deals with renewable energy systems in modern smart grids have growth in many countries, and with that increase the quality of power becomes a major concern for power system operators, especially at the load side. Among the most important power quality challenges, the harmonics comes on top, as they affect the voltage and current quality at the point of common coupling (PCC), and negatively affects the loads. One of the most used renewable generators is the solar photovoltaic (PV) systems, where it is connected into the low voltage distribution grid using power electronics inverters, and with the increased penetration level, massive harmonic current is injected into the network. There is a need to reduced the resulting harmonics distortion and highlight its possible constraints. The simulation is performed with increasing the connected PV modules, and the results are analyzed showing high level of THD with the increased PV penetration at the PCC considering a higher loading level of the distribution transformer.
For analysis of fault condition typical methodology of quick Fourier transform area unit initial use and take a look at for various winding fault conditions. Then fuzzy logic controller supported fuzzy rule base style for analysis of stator coil winding faults. From each the conditions it clear that the FFT analysis solely calibrate total harmonics distortion (THD) of faulted voltage and current signal of 3 section induction motor input facet (stator side). Whereas fuzzy logic controller directly analyzed the sort of the fault on induction motor stator coil winding.
Inverter play important role in power system especially with it capability on reducing system size and increase efficient. Recent research trend of power electronics system are focusing on multilevel inverter topic in optimization on voltage output, reduce total harmonics distortion, modulation technique and switching configuration. Standalone application multilevel inverter is high focused due to the rise of renewable energy policy all around the world. Hence, this research emphasis on identify best topology of multilevel inverter and optimize it among the diode-clamped, capacitor clamped and cascaded H-bridge multilevel inverter to be used for standalone application in term of total harmonics distortion and voltage boosting capability. The first part of research that is identify best topology multilevel inverter is applying sinusoidal pulse width modulation technique. The result shown cascade H-bridge give the best output in both total harmonics distortion (9.27%) and fundamental component voltage (240 V rms ).
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In this paper, the recently introduced C-type passive filter is presented for reducing harmonics distortion and improving the load true power factor based on minimization of the total investment cost of the proposed filter under non- sinusoidal conditions. In this paper, optimal sizing of C-type passive filter parameters is presented based on minimization of its total investment cost under non-sinusoidal conditions, while taking into consideration the following constraints : Maintaining the load power factor (PF) at an adequate range, i.e. 90%≤ PF ≤ 95%. Maintaining the voltage total harmonic distortion (THD V ) at an acceptable range according to the system voltage level, i.e. THD V ≤ 5%.
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Power factor has a high impact on power system industries. A load with low power factor draws more current than a load with high power factor 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 power factor. 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 power factor (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 power factor 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 power factor and reduction of total harmonics distortion. The boost converter can perform this type of active power factor 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.
It includes one or more series elements with a set of tuned elements. The series elements increase the input circuit effective impedance to reduce overall harmonic and to de-tune the shunt element relative to supply and load ends. It has gained popularity due to ability to attenuate all harmonic frequencies and achieve low level of residual harmonic distortion.
In recent years the world has witnessed an increase in the use of non-linear loads. These loads draw harmonic non-sinusoidal currents and voltages in the connection point with the utility and distribute them through it. A shunt active power filters (SAPF) has been proposed as an effective tool for improving power quality and reactive power compensation. The simulated system is a three phase balanced voltage system with nonlinear load. A particle swarm optimization (PSO) is implemented to optimize the gains of a proportional-integral (PI) algorithm to control the SAPF. The control of the DC voltage of the APF is of great importance. The DC voltage passes by a transient after load variation. This transient is a function of the controller parameters and the load variation. The aim of this work is to determine if the control schemes will be able to adapt to the changing conditions. Different studied for SAPF are implemented in MATLAB\Simulink and results are tabulated and discussed. Results show that the proposed filter can effectively reduce harmonics while keeping its DC-link balanced.
Pulse width modulation (PWM) is a powerful technique for controlling analogue with a processor’s digital outputs. It is also known as pulse duration modulation (PDM). The leading edge of the carrier pulse remains fixed and the occurrence of the trailing of the pulses varies. PWM signals find a wide application in modern electronics. Some of these reasons are: We can obtain the output voltage control foregoing any other additional element, lower order harmonic can be eliminated or compact beside its output voltage control with this method and as we know higher order harmonics can be filtered easily, easy to Generate – PWM signals are quite easy to generate. Many modern microcontrollers include PWM hardware within the chip; using this hardware often takes very little attention from the microprocessor and it can run in the background without interfering with executing code.
The term power quality applies to a vast extension of electromagnetic phenomena and voltage variations caused by disturbances in an electric system. The IEC (International Electrotechnical Commission) classifies the electromagnetic phenomena in conducted low-frequency phenomena (harmonics, interharmonics and others), radiated low-frequency phenomena, conducted high- frequency phenomena, radiated high frequency phenomena, Electrostatic discharge phenomena and Nuclear electromagnetic pulse (Dugan and Macgrhanagan, 2004).
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The current harmonics on the ac side of a 6-pulseconverter will be of orders n= 5, 7, 11, 13, …, which called characteristic harmonics. These current harmonics flow through the plant and utility power system and cause voltage distortion and power losses in the system. They also interact with power factor correction capacitor banks leading to equipment failures. Besides, the non-ideal conditions may lead to the generation of another harmonics with different orders, but these non-characteristic harmonics cannot significantly affect the power quality .
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nonlinear loads on harmonic cancellation are also quantified in . Harmonic cancellation due to different single-phase nonlinear loads is illustrated in . It is also proven by simulation in [8, 14, 17] that background voltage distortion affects current harmonics. In , voltage, impedance and frequency variations effects on the harmonics generated from a single PC are discussed. Attempts to quantify the effect of linear loads on the generated harmonics are given in .
highly non-linear loads. The use of non linear loads is increasing day by day. This increasing use of non linear loads has created more distortions in current and voltage waveforms. Controlling and reducing such harmonics have been a major concern of power engineers for many years. This increased power quality disturbances has lead to various optimizations techniques and filter designs. Harmonic distortions are the major cause for power quality problems. For this analyzing the harmonics present in non linear loads is significant. Here a survey is made to show details of harmonics present in various non linear loads. This paper discusses the problem of harmonic pollution in electrical networks and it proposes how the waveforms of voltage/current is distorted and harmonics are injected in to the system due to nonlinear loads such as Variable Speed Drive, Arcing Devices, UPS, Personal Computer, Printers, Fluorescent Lamp, Cell Phone battery charger.
Figure 9 is voltage waveform monitored from DC bus of the energy storage interface and current waveform of the grid side. The left are voltage waveforms happened at the time of nonlinear group load normal operation, LVRT beginning, LVRT process and LVRT end respectively. The right are current waveforms that go through this process. It can be seen from the simulation results that the filter design can suppress actively the harmonics caused by the nonlinear load to the grid. With energy storage participating in grid fault control, DC bus voltage can be maintained constant when the grid LVRT occurs. Once the grid is restored, the load resumes normal grid power supply. Waveforms also show that the harmonic suppression and LVRT prevention designed can play a good role in the grid fault. Active demand management function can also be implemented.
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The increasing use of power electronic based loads (adjustable speed drives, switch modern power supplies, etc) to improve system efficiency and controllability is increasing concern for harmonic distortion levels in end use facilities and on overall power system. The Active Power Filter uses power electronic switching to generate harmonic currents that cancel harmonic content from non – linear loads. The basic principle of Shunt Active Power Filter is that it generates a current equal and opposite in phase to the harmonic current drawn by the load and injects it at point of common coupling there by forcing currents to be pure sinusoidal. The active filter configuration implemented in this paper is based on the pulse – width modulated (PWM) voltage source inverter (VSI) that interfaces to the system through filter. In this configuration the filter is connected is in parallel for harmonic current cancellation so that the current being supplied from the source is sinusoidal. The control scheme of this three phase shunt Active Power Filter is based on the instantaneous Id – Iq theory. The compensating current controlled is achieved is with the VSI in the current controlled mode, the desired by accurately controlling the switching of the IGBTs through hysteresis current controller.
Harmonics are v and i frequency components which are embedded on the crest level of the normal sine v & i. The symphonious distortion in waveform issues are for the most part because of the significant increment of non- straight loads because of innovative advances, for example, the utilization of force electronic circuits and gadgets, in air conditioning/dc transmission connections, or burdens in the control of force frameworks utilizing power electronic or microchip controllers. Harmonic sources are categorized into 3 types of loads, viz., - :
DOI: 10.4236/epe.2019.115015 243 Energy and Power Engineering with a THD of less than of 6% and is frequently declared or promoted at 5% or less . Higher heating due to iron and copper losses at the harmonic frequen- cies is a major effect of harmonic voltages and currents in rotating machines (induction and synchronous). Moreover, according to , THD can increase by an amount of 2% due to the effect of vibration. In order to properly evaluate the effect of the Genset-Synchro concept on the signal quality at the output of the alternator, we have referred to the IEEE-519-2014 standard (Recommended practice and requirements for harmonic control in electric power systems). A power analyzer PM800 from Schneider electric is used, Figure 8. On the other hand, it was important to know the current and voltage distortion limits for our system. Based on IEEE-519 standard, Table 8 and Table 9 show the current and voltage distortion limits for systems rated 120 V through 69 kV.
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This chapter presents a unique case study of harmonics impact and network resonance in the Bluewater Power distribution network which connects the largest solar farm in North America of 80 MW. IEEE 519 recommends a power quality analysis for the system as it has a large number of dispersed generators that inject harmonics to the network. Large scale PV solar farms use a substantial number of power electronic converters. Therefore, a detailed harmonic analysis is performed on the Bluewater Power network in order to study the impact of this large scale solar farm on its distribution system. In addition to this analysis, the impact of harmonics from a 10 kW PV solar system is also presented. This study is performed based on the detailed network data, central Geographical Information System (GIS) database, and Supervisory Control and Data Acquisition (SCADA) infrastructure made available by Bluewater Power Corporation. The network is modeled in detail using PSCAD/EMTDC, which is validated with load flow studies using the CYME software and SCADA measurements. The validated network model is used for the network resonance study and harmonic analysis in the presence of a large solar farm for different operating scenarios of the network. This study is conducted for the steady state operating conditions neglecting any presence of ambient harmonics in the network.
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appliances are kept on. The real time data like power factor, active and reactive power, fundamental frequency, current and voltage frequency, energy components, harmonics and distortion etc. is found by using the DAQ card and the energy management analytical software. This will give details of the power factor correction according to which related investment energy manager can suggest. The connection is made at the main power line near meter. The connection is shown in Fig. 5.