Total Harmonic Distortion Analysis Research Articles

Effects of a Static Synchronous Series Compensator (SSSC) Based on a Soft Switching 48-Pulse PWM Inverter on the Power Demand from the Grid

In this paper the effects of a Static Synchronous Series Compensator, which is constructed with a 48-pulse inverter, on the power demand from the grid are studied. Extensive simulation studies were carried out in the MATLAB simulation environment to observe the compensation achieved by the SSSC and its effects on the line voltage, line current, phase angle and real/reactive power. The designed device is simulated in a power system which is comprised of a three phase power source, a transmission line, line inductance and load. The system parameters such as line voltage, line current, reactive power Q and real power P transmissions are observed both when the SSSC is connected to and disconnected from the power system. The motivation for modeling a SSSC from a multi-pulse inverter is to enhance the voltage waveform of the device and this is observed in the total harmonic distortion (THD) analysis performed at the end of the paper. According to the results, the power flow and phase angle can be controlled successfully by the new device through voltage injection. Finally a THD analysis is performed to see the harmonics content. The effect on the quality of the line voltage and current is acceptable according to international standards.

New real-time algorithms for arbitrary, high precision function generation with applications to acoustic transducer excitation

A system is described for the design, downloading and execution of arbitrary functions, intended for use with acoustic and low-frequency ultrasonic transducers in condition monitoring and materials testing applications. The instrumentation comprises a software design tool and a powerful real-time digital signal processor unit, operating at 580 million multiplication-accumulations per second (MMACs). The embedded firmware employs both an established look-up table approach and a new function interpolation technique to generate the real-time signals with very high precision and flexibility. Using total harmonic distortion (THD) analysis, the purity of the waveforms have been compared with those generated using traditional analogue function generators; this analysis has confirmed that the new instrument has a consistently superior signal-to-noise ratio.

06/02642 Analysis of the current total harmonic distortion for different single-phase inverters for grid-connected pv-systemsSidrach-de-Cardona, M. and Carretero, J. Solar Energy Materials and Solar Cells, 2005, 87, (1–4), 529–540

06/02642 Analysis of the current total harmonic distortion for different single-phase inverters for grid-connected pv-systemsSidrach-de-Cardona, M. and Carretero, J. Solar Energy Materials and Solar Cells, 2005, 87, (1–4), 529–540

Online stack monitoring tool for dynamically and stationary operated fuel cell systems

The motivation for this development of a new fuel cell stack monitoring system is to establish a much simpler, low-cost stack diagnosis unit feasible for large production volumes. In comparison to conventional cell voltage monitoring (CVM) technology, where up to several hundreds of voltage channels have to be measured, Total Harmonic Distortion Analysis (AVL THDA) significantly reduces the required wiring, contacting and instrumentation. This new approach derives information about critical cell and stack status from only the stack sum voltage. A real-time output signal then indicates whether the stack – in fact every single cell – is operating under safe and reliable conditions. The new technique also detects critical stack operating conditions during load changes, where other monitoring systems usually have difficulty in distinguishing between a change in the voltage of a single cell as a result of load changes or resulting from the occurrence of a critical cell operating status.

Analysis of the current total harmonic distortion for different single-phase inverters for grid-connected pv-systems

A method to characterise the current total harmonic distortion for single-phase inverters is proposed. This method is based on the performance of the inverters along two different types of days: clear sky and partially cloudy sky days. An expression to estimate the average value of the current total harmonic distortion for each type of day is proposed. The values obtained from these expressions pick up the behaviour of the inverters for the two most usual climatic conditions. Moreover, the values obtained can be used to compare the electricity supply quality of different inverters.

Analysis and CAD implementation techniques of total harmonic distortion in analog VLSI circuits

This paper presents a new methodlogy to accurately evaluate the total harmonic distortion (THD) behavior of modern integrated circuits. The methodology is general, technology independent and is used to determine large-signal or reactive THD of signal processing circuits operating in the voltage or the current domain. It is based on Fourier series analysis and Parseval's theorem, where numerical integration may be needed to accurately compute THD. For low-frequency THD, the numerical integration can be simplified to a small number of summation without degrading the accuracy. The new methodology is incorporated in a computer-aided environment which accurately estimates THD, and the speed of calculation for many circuit is several orders of magnitude faster than SPICE or other commercial CAD tools. In addition, optimization of transistor sizes to reduce THD can be achieved by incorporating the methodology in an object-oriented CAD tool such as APLAC.