in which the output voltage has three possible values. This results in smaller harmonics, but on the other hand it has more components and is more complex to control. In this paper, study of different three level inverter topologies and SPWM technique is explain and SPWM technique has been applied to formulate the switching pattern for three level and five level H-Bridge inverter that minimize the harmonic distortion at the inverter output. This paper deals with comparison of simulation results of
contain certain amount of harmonics in the output. Inverters quality is expressed with the help of parameters of performance. Parameters like lower order harmonics (LOH), total harmonic distortion (THD) Distortion Factor basically plays a vital role on the performance of an inverter. Harmonics give undesirable effects the following undesirable effects [1]-[2. Ill effects of harmonics are A. Poor Quality Supply As all power electronic converters generate harmonic currents, which will
1. INTRODUCTION – HARMONIC LAOD FLOW ANALYSIS SOFTWARE 3 2. POWER SYSTEM HARMONICS 4 2.1 Concept of Power System Harmonics 4 2.1.1Fourier Series and Harmonics 4 2.1.2 Distortion Indices 6 2.1.3 Characteristics of Harmonics in Power Systems 7 2.2 HARMONIC SOURCES 8 2.3 EFFECT OF HARMONICS 9 2.3.1 Thermal losses in harmonic environment 10 2.3.2 Effects on power system equipment 10 2.3.3 Capacitor banks 10 2.3.4 Transformers 11 2.3.5 Rotating machines 11 3. HARMONIC LOAD FLOW ANALYSIS
Alexander B. Nassif and Jing Yong [7] have proposed a method to identify the consumers generating inter harmonic frequencies. The inter-harmonics can be measured by means of Impedance based approach applied at the metering point. The main idea is that, the inter-harmonic impedance of the system is much smaller than that of an inter-harmonic generating load. This method can identify the source of each inter-harmonic component without having to rely solely on the active power measurement and requires
motor. Harmonics generated by unit of speed control are filtered by an input filter circuit. Experimental results would be in 230V and speed control of single-phase motor shows that PWM AC Chopper is simple and cost effective control method compared to better control method to other methods in terms of simplicity and input harmonic content. In this harmonics reduction techniques for designing a Pulse Width Modulation (PWM) AC voltage controller is required. So that Total current Harmonics Distortion
frequency in medium voltage industrial drive presents various challenges. Multilevel inverter topologies are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference
ripple within a pre-defined range. To study the impact of VSFPWM on switching loss reduction over the entire modulation index range, the simulations were carried out different speeds (modulation indices) for a constant load torque. Table II and Table III compares the current ripple, and the percentage change in the current distortion and the switching losses for CSFSVPWM-VSFSVPWM and CSFDPWM2-VSFDPWM2 techniques respectively. Similar to the analytical results at section II, there is higher switching
containing harmonics from the supply which in turn causes voltage harmonics. Current harmonic causes increased power system losses, excessive heating in rotating machinery, interference with nearby communication circuits and control circuits, etc. It has become a vital importance to maintain the sinusoidal nature of voltage and currents in the power system. Various international agencies like IEEE and IEC have issued standards, which put limits on various current and voltage harmonics. The limits
span several buildings, with terminals, or dial in terminals. The internet, and TCP/IP were developed by the Department of Defense so as to be able to link together several LANs around the country. Each individual system was built sometimes by different vendors, and were sometimes
uses high switching frequency pulse width modulation (PWM). The attractive features of a multilevel converter can be explained as follows. Staircase waveform quality: Multilevel converters not only can generate the output voltages with very low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced. Common-mode (CM) voltage: Multilevel converters produce smaller CM voltage; therefore, the stress in the bearings of a motor connected