Current Harmonic Aggregation Cases for Contemporary Loads

Power electronic circuits in modern power supplies have improved the conversion efficiency on the one hand but have also increased harmonic emissions. Harmonic currents from the operation of these units affect the voltage waveforms of the network and could compromise the reliability of the network. Load and source non-linearity can, therefore, limit the renewable source’s hosting capacity in the grid, as a large number of inverter units may increase the harmonic distortions. As a result, voltage and current distortions could reach unbearable levels in devices connected to the network. Harmonic estimation modelling often relies on measurement data, and differences may appear in mathematical simulations as the harmonic aggregation or cancellation may generate different results due to the inaccuracies and limitations of the measurement device. In this paper, the effect of harmonic currents cancellation on the aggregation of different load currents is evaluated to show its impact in the network by presenting a comparison between the measurement and mathematical aggregation of harmonics. Furthermore, the harmonic cancellation phenomenon is also qualified for multiple loads connected to the power supply.

Method for Evaluation of the Utility’s and Consumers’ Contribution to the Current and Voltage Distortions at the PCC

In this article, a method that allows sharing responsibilities for the generation of harmonic currents between the utility and consumers powered by one point of common coupling (PCC) is addressed. For these purposes, mathematical modeling of the power supply system (PSS) with two consumers is carried out in order to introduce new indices using the simplest PSS structure as an example. Two indices are introduced that quantify the consumers’ contribution to the distortion of current and voltage at the PCC and that evaluate harmonic emission from the utility side. Experimental tests are carried out where both linear and nonlinear loads are considered, capacitive loads are taken into account, and harmonic distortions from the utility side are modeled to show the applicability of the indices in a wide range of load types. The experiments confirmed the theoretical results and illustrated that the quantitative assessment of the contributions is unambiguous. It suggests that the proposed criterion could be a reasonable basis for further tax policy on harmonic pollution for each consumer at the PCC and for the utility.

Design and Implementation of Periodic Control for a Matrix Converter-Based Interior Permanent Magnet Synchronous Motor Drive System

The matrix converter-based IPMSM drive has 360 Hz virtual DC-bus voltage variations which produce severe stator harmonic currents. To solve this problem, a speed-loop classical periodic controller and two current-loop periodic controllers, including a classical periodic controller and a selective harmonic controller, are proposed in this paper. By using the proposed methods, the harmonic currents are obviously reduced and the speed responses of the IPMSM are clearly improved. A detailed analysis is discussed. A digital signal processor, type SH7237, manufactured by Renesas Electronics Corporation is used for the control algorithms. Experimental results show that those proposed periodic controllers reduce up to nearly 32% of the total harmonic distortion at the stator currents, and also apparently improve the transient, tracking, and repetitive load disturbance speed responses.

Experimental Determination of Parameters of Nonlinear Electrical Load

The paper deals with issues of modeling nonlinear electrical loads of various types, such an uncontrolled rectifier, thyristor rectifier, thyristor power regulator and mixed equivalent nonlinear load. For these load types, existing analytical expressions were identified to determine the magnitudes of harmonic currents, and waveforms of currents were obtained during measurements in laboratory conditions with variable parameters of the grid impedance and load. The obtained results were compared, and it was found that the error in determining the magnitudes of harmonic currents can reach 60% for an individual load and 54% for an equivalent load. A more accurate method for determining the parameters of nonlinear electrical load is also proposed, which is based on the application of shunt harmonic filters. In laboratory conditions, it was found that when using the developed method, the error did not exceed 10% for an individual load and 14% for an equivalent load.

Electrochemical Frequency Modulation: New Approach and Revision of Previous Model

A careful evaluation of the earlier model (1-2) for electrochemical frequency modulation (EFM) involving two sinusoidal applied potentials for the determination of corrosion parameters shows an algebraic error. Although the missing term in the original derivation appears to be insignificant, it is found that errors involved in corrosion current determination, and especially in evaluation of the Tafel slopes can be very significant, which is of consequence because of the rising popularity of this technique. The magnitude of error is found to be a function of the inherent corrosion characteristics (anodic and cathodic Tafel slopes) of the corroding material as well as the applied peak potential of the modulation. A corrected model with detailed steps showing the appropriate math is presented. In addition, using the experimental data available in the literature, the errors involved in estimating the corrosion parameters by the earlier EFM model of Bosch et al (1-2) are evaluated. The corrected corrosion current and the Tafel slopes can be recovered from the incorrect model without the benefit of the harmonic currents, as shown in this paper.The analysis is also presented for the case of only one applied sinusoidal frequency modulation, which offers several advantages over the multiple frequency modulation.

Research of operating modes of conductors in power supply systems of cranes with induction feed, taking into account the influence of higher harmonics of the current

Purpose. Investigation of the influence of higher harmonics of current on current distribution, voltage and power losses in the supply systems of crane trolleys and development of a calculation method for practical use. Methodology. The analytical method and the results of the modeling method were used for research. Results. Analytical relationships have been obtained that make it possible to determine the current distribution, voltage and power losses in the systems of induction feeding of crane trolleys, taking into account the composition and amplitude of the higher harmonics of the current. Originality. For the first time, analytical dependences are obtained that take into account the effect of changing the trolley parameters on the frequency in the feed systems. Numerical values have been determined for the most commonly used induction feed systems for cranes. It is shown that with an increase in the cross-section of the feed bar there is a decrease in the main, and especially additional, losses. Practical value. Theoretical relationships have been obtained that can be used to calculate the optimization of induction feed systems in the presence of higher harmonic currents arising in power systems during operation of crane semiconductor controlled electric drives.

Reducing of total harmonic distortion by simulating passive filters to suppress harmonic currents with the case: Faculty of Engineering Building, Universitas Kristen Indonesia Jakarta

Today’s electrical appliances use power electronics to save electricity. However, this equipment generates non-sinusoidal current, causing wave defect, expressed as total harmonic distortion (THD). As the %THD increases, the greater risk of equipment damage. For this reason, the research was carried out in the Faculty of Engineering Building, Universitas Kristen Indonesia Jakarta (FT UKI Jakarta) where there are many load combinations such as computers, various types of lights, laboratory equipment such as transformers, electric motors and so on. The research was conducted using quantitative method. Data collection is carried out directly in the main panel. Based on the measurement results, the calculation of the maximum load current (IL) and short circuit (ISC) is carried out. Through these values, it can be seen that whether the odd dominant harmonic values and orders meets the IEEE 519-2014 standards or not. Calculations and analysis of the measurement results have shown that the %THDI in the FT UKI building has not meet the standard. Therefore, it is necessary to simulate the filter design to reduce the %THDI, so that the results can meets the IEEE 519-2014 standard, which is below 5%.

Reducing of total harmonic distortion using passive filter simulation to suppress harmonic currents with the case: General Hospital, Universitas Kristen Indonesia Jakarta

With the increasing need for and use of electrical energy amid increasingly rapid technological advances, especially in the use of electronic equipment in hospitals, it is necessary to pay attention to the problem of harmonics due to the use of non-linear electrical equipment. Therefore, it is necessary to measure the current and voltage THD for each non-linear equipment user. If the current and voltage THD values do not meet the standards, then a filter design is carried out so that the THD values meet the standards. Based on the results of THD measurements on the Main Distribution Panel (MDP) of RSU UKI, it was found that the THD of the voltage varied between 0.7877% - 2.4363% and the current THD varied between 5.3073% - 9.2363%. The measured THD value refers to the IEEE 519-2014 standard. If the THD value of the measurement results exceeds the IEEE 519-2014 standard, a harmonic filter is needed. With the simulated single tuned filter design, the current THD decreases within the standard value. The THD value of the current after installing the filter at the three MDP’s of the RSU UKI, namely MDP A of 1.72%, MDP B of 0.64% and MDP C of 1.30%.

Complex Design Method of Filtration Station Considering Harmonic Components

The paper deals with a new methodology for calculating the filter parameters. The basis is respect for the fact that the real filter current consists of other harmonic components, which filter is tuned. The proposed methodology was used to design filters for traction substation 25 kV/50 Hz. The operation of the locomotives in the AC supply systems of 25 kV/50 Hz leads to a rising of higher order harmonic currents. Due to the 1-phase supply system, these are mainly the 3rd and 5th harmonics. By simulation and subsequent measurement of the proposed traction power station filters the proposed methodology was verified. Thus, the filter design can also be used for filter compensating stations of the standard 3-phase distribution network. The described method presents an optimal filter design without unnecessary oversizing. This fact reduces the size and cost of the filter. It is shown that it is possible to design a filter that meets the requirements for power quality under extreme load and to minimise distortion of line voltage.