Power quality analysis based on a novel nonlinear dependence between parameters of nonsinusoidal regime

The performance of a grid-interactive roof-mounted 100 kWp solar photovoltaic power plant at National Institute of Technology, Trichy (NITT) has been analysed. The plant has been operational since June 2013. The climatic, irradiation conditions at the location are accounted, while the system performance is analysed. The output power of the PV array, power quality is assessed after the power conditioning and AC power supplied to the grid, consistency of the system and efficiency of the system have been utilised in the performance analysis attempted. The power quality parameters are Power Factor (PF), RMS Voltage, Total Voltage Harmonic Distortion (THD), Total Current Harmonic distortion has been measured and analysed. In addition, the cost benefits to NIT Trichy for installing the plant have also been analysed.

With an increase of non-linear load in today’s electrical power systems, the rate of power quality drops and the voltage source and frequency deteriorate if not properly compensated with an appropriate device. Filters are most common techniques that employed to overcome this problem and improving power quality. In this paper an improved optimization technique of filter applies to the power system is based on a particle swarm optimization with using artificial neural network technique applied to the unified power flow quality conditioner (PSO-ANN UPQC). Design particle swarm optimization and artificial neural network together result in a very high performance of flexible AC transmission lines (FACTs) controller and it implements to the system to compensate all types of power quality disturbances. This technique is very powerful for minimization of total harmonic distortion of source voltages and currents as a limit permitted by IEEE-519. The work creates a power system model in MATLAB/Simulink program to investigate our proposed optimization technique for improving control circuit of filters. The work also has measured all power quality disturbances of the electrical arc furnace of steel factory and suggests this technique of filter to improve the power quality.

Harmonic analysis currently plays an important role for the power quality analysis because the non-linear loads, as source of the harmonic distortion, have significantly increased. The harmonic distortion influences power quality in power systems such as overheating of electrical equipment and aging of electrical equipment. Therefore, non-linear loads should be monitored in real time. This research proposes the design and implementation of the prototype current harmonic analysis that can be applied in real time based on S-transform Method. The equipment of this prototype can be explained as follows: CT-235, TZ2L9 and CT for KWH meters as current sensor, microcontroller AT mega 8535 as data acquisition, and Visual Basic software as displaying current waveform, current spectrum, rms current value, and total harmonic distortion (THD) for current. S-transform method is used to obtain the THD for current. The experimental result is validated by FLUKE 43B and the THD for current is accurately measured.

This paper exhibits performance enhancement of PWM AC chopper fed capacitor run induction motor by using optimization algorithm. The PWM AC chopper utilizes enhanced asymmetrical pulse width modulation technique by incorporating four pulses in quarter cycle. The switching instants are obtained optimally by bacteria foraging optimization, particle swarm optimization and cuckoo search optimization algorithm. The power quality parameters considered in this paper are total harmonic distortion of current, total harmonic distortion of voltage, power factor and efficiency. The simulation result shows that proposed algorithm shows better performance compared to other optimization techniques.

Harmonics are one of the key power quality issues on the front burner in the power system. Advancements in solid-state technology in recent times have resulted in the proliferation of non-linear loads which are the main sources of harmonics. Harmonics penetration in power system networks is detrimental to effective system operation and can result in frequent failures and damage to electrical equipment. This, therefore, creates the need for harmonic mitigation in power system networks for power quality enhancement. This work examined the impact of a shunt passive filter (SPF) in minimizing harmonic distortion on an electrical distribution network considering the power network layout of 7-Up Industry Plc as a case study. The indices for quantifying the level of harmonic distortion and shunt passive filter design for harmonic mitigation in power networks were respectively analysed and presented. The considered 7-Up Industry Plc power network was modelled and simulated with and without SPF in MATLAB/Simulink software environment R2020a. The voltage and current total harmonic distortion, VTHD and ITHD, from the two system states, were evaluated. The observed voltage and current waveforms from the simulation of the test network without any filter applied were distorted, signifying the harmonics’ presence. The estimated VTHD and ITHD values with no filter used were 6.084 and 19.79 % respectively. SPF application on the test network mitigated the VTHD and ITHD to 0.7802 and 2.448 %, giving an improvement of 5.304 and 17.342 % respectively in the minimization of voltage and current total harmonic distortion compared to the no filter case. This study established that a shunt passive filter is suitable for power quality enhancement in an electrical distribution network. Keywords: Electrical distribution network, harmonics, non-linear load, power quality, shunt passive filter, total harmonic distortion

Given the adverse impact and unnecessary costs associated with harmonic pollution in electrical power systems, such as increasing losses and decreasing life expectancy of equipment, development of new filtering techniques with higher quality of power, higher efficiency of transmission and distribution, and lower cost of filters is urgently required. This has become all the more important as society increasingly moves towards an environment filled with sophisticated electronic equipment and power-sensitive electrical machinery. The present work was conceived to provide a way forward towards the goal of improving Power Quality (PQ) by designing a new passive shunt filter based on minimizing the responsibility of the consumer for harmonic pollution, while simultaneously taking into account other relevant objective functions and related techno-economic considerations. Shunt passive filters are commonly found in power industries, where quality of power is paramount, in view of their simplicity of design, lower cost and their having possibly different range of frequency response characteristics that can satisfy a specific harmonic filtering needs. In addition, passive filters, in general, have two primary favourable features, they support reactive power to correct the load power factor and they mitigate harmonic distortion. This study favours passive filters while conceptualizing the research problem and formulating a proposed design. This thesis presents an optimal design of single-tuned passive filters that mm1m1zes consumer's responsibility for harmonic pollution. A solution for the allocation ofresponsibility between supplier and consumer has proved complex and elusive and it remains, therefore, absent. When, whoever takes whatever steps to contain the harmonic distortion, involves costs and expenditure, the situation inevitably leads to conflict between consumer and utility. In order to avoid this unwholesome state of affairs and introduce a degree of rationality and clarity, this study focuses on quantifying harmonic pollution responsibility by substantiating a new "NonLinearity Current Index" (NLCI) and presenting the mathematical modelling of the filter accordingly. The task of designing the filter, then, is posed as a quadratic optimization problem with nonlinear constraints, whose objective function includes the newly proposed NLCI, which will be minimized, as well as five other conventional objective functions that are most frequently used in the design of passive filters. The five objective functions are: i. maximization ofload power factor; ii. Minimization of the voltage total harmonic distortion; iii. minimization of the current total harmonic distortion; iv. minimization of transmission loss; and v. minimization of the filter investment cost. A suitable analytic framework is established, in which circuit analysis is made and relevant auxiliary mathematical expressions are derived for the system under study, followed by the filter design problem posed as an optimization question with the required objective functions and constraints. This thesis uses FORTRAN Feasible Sequential Quadratic Programming (FFSQP) to obtain the optimal values for the single-tuned shunt passive filter elements. The performance of the proposed index and the other five conventional objective functions is evaluated using six numerical 'benchmark' case studies to demonstrate the applicability, viability, validity and usefulness of the proposed harmonic passive filters. A rigorous and thorough comparison of the results of the design with and without compensation is included. As resonance is a critical design issue of passive filters, special care was taken, during the problem formulation, to avoid any risk of it in the compensated system. Care was also taken to meet capacitor loading specifications as given in IEEE Standard 18-2012 and practical constraints for the voltage total and individual harmonic distortion limits were followed in accordance with IEEE 519-2014 guidelines. The results of this study demonstrate the validity and effectiveness of the optimization method, for the given objective functions, since improvements were seen in both power factor and displacement power factor in all the case studies as well as notable reductions in rms values of the line current which led to reduced transmission losses, voltage drop and increased transmission efficiency, to various degrees and in a variety of combinations. Incorporation of the newly designed passive filter resulted in a considerable reduction in NLCI, indicating increased linearity because of minimization of the difference between supply current rms and linear current m1s at the point of common coupling. Critical impedance values also improved, because of the greatly reduced m1s line current. The NLCI minimised passive filter design differentiates the contributions of the supplier and consumer to harmonic pollution in a given system, and, therefore, provides a valuable solution where currently there is none in the literature, reflected in the absence of recognised standards and methodologies in this area. The small size of the proposed filter, in comparison to many other published designs, entails considerably lower financial investment costs, which, combined with its effectiveness at reducing harmonic pollution makes it a very valuable contribution to power system design and installation.

This paper is devoted to the design and implementation of a multipurpose platform (MPP) for power system monitoring and analysis. This MPP is a novel device, which combines the abilities of a power quality (PQ) analyzer, an event logger, a synchronized phasor measurement unit, and an interarea oscillation identifier, all in one device. The multiple functions of the proposed MPP can serve the needs of the power system operators (SOs) as a wide-area monitoring system to observe the states and stability of the power system, and as a PQ analyzer to monitor the PQ events and parameters, permanently. Furthermore, the algorithms of flicker and harmonic current contributions at a point of common coupling can be embedded on this MPP, to determine the individual contributions of different loads supplied from the same bus. The operational features of the developed MPP have been tested on the Turkish electricity transmission system and its interfaces with the distribution system by installing 450 MPPs and integrating them with a monitoring and control center. The proposed all-in-one MPP can therefore meet the multiple requirements of the power SOs to serve the needs of modern electricity markets and convert an ordinary electricity system to a smart grid.

To mitigate environmental impact, specifically the CO2 emissions associated with conventional thermal and nuclear facilities, renewable energy sources are increasingly being adopted as primary alternatives. However, integrating these renewable sources into the utility grid poses a significant challenge, primarily due to the stochastic and nonlinear nature of weather. Consequently, it is imperative that power systems operate under an intelligent control model to ensure energy output meets strict power quality standards. In this context, accurate forecasting is a cornerstone of smart power management, particularly in off-grid architectures, where predicting Power Quality Parameters (PQPs) is fundamental for system optimization and error correction. This study conducts a comprehensive comparative evaluation of nine different predictive architectures for estimating PQPs. The algorithms analyzed include LSTM, GRU, DNN, CNN1D-LSTM, BiLSTM, attention mechanisms, DT, SVM, and XGBoost. The central objective is to develop a reliable basis for the automated regulation and enhancement of electrical quality in isolated systems. The specific parameters investigated are power voltage (U), Voltage Total Harmonic Distortion (THDu), Current Total Harmonic Distortion (THDi), and short-term flicker severity (Pst). Data for this investigation were acquired from an experimental off-grid setup at VSB-Technical University of Ostrava (VSB-TUO), Czech Republic. To assess model performance, we utilized root mean square error (RMSE) as the primary accuracy metric, while simultaneously evaluating computational efficiency in terms of processing speed and memory consumption during testing.

Problem. Electrical distribution networks are plagued by power quality problems, which have a negative impact on sensitive electrical loads. These problems include reactive current, low power factor on the load side, and voltage harmonics, voltage sags and voltage swells on the grid voltage side. To address these issues, a unified power quality conditioner (UPQC) that combines shunt and series compensators is suggested. The goal of the work is to implement a UPQC integrated with a photovoltaic (PV) system to mitigate power quality problems in the power system, and boosting the grid supply through power injection from the PV system. Methodology. One of the less complex and effective ways to improve the grid’s voltage quality is by using the unit vector template generation (UVTG) strategy as the composition technique (UPQC-P) through the UPQC series compensator. The synchronous reference frame (SRF) strategy through the UPQC shunt compensator to improve the current quality on the load side is used. To further optimize the SRF strategy, it is used the snake optimization (SO) to find the optimal values for the PI controller’s parameters. Results. The UPQC-PV is used to mitigation the power quality issues in the grid and loads by UVTG and SRF techniques in series and shunt compensators, respectively. Scientific novelty. The composition technique (UPQC-P) through a series compensator and uses the SO for tuning the PI controller in the shunt compensator. Practical value. This study reduces the total harmonic distortion (THD) in the load voltage to 0.57 %, while the THD in the grid voltage remains at 10 %. It restores the load voltage to its reference value of 230 V during voltage sags (down to 161 V) and swells (up to 300 V) in the grid. Additionally, it mitigates the low power factor on the load side (0.707 lagging) to achieve a unity power factor in grid current, balances the unbalanced load current to a balanced grid current, and enhances grid stability by injecting power from the PV system into the grid. References 33, table 3, figures 7.

Most of the two-stage converters for electric bike battery charging comprise of a boost converter for power factor correction (PFC) followed by a dc–dc converter with universal input voltage. These two-stage conversions suffer from poor efficiency and increased component count. In this paper, a single-stage switched inductor Cuk converter based PFC converter is proposed, which offers high step-down gain, low current stress, high efficiency, and reduced component count. The operational analysis and design equations for various components of the proposed converter are carried out in continuous current mode. This paper presents mathematical modeling, analysis, simulation, and experimentation on the proposed converter rated for 500 W, 48 V/10.4 A. The performance investigation of the proposed converter with respect to power quality indices like voltage total harmonic distortion (THD), current THD, and total power factor is carried out with various types of loads such as resistive load and battery load in both constant voltage (CV) and constant current (CC) mode. Furthermore, the dynamic performance of the proposed converter with battery charging is investigated in CV mode and CC mode with respect to the wide range of supply variations.

In modern time, LED (Light Emitting Diode) bulbs are being most preferred over incandescent bulbs, compact fluorescent lamps (CFL) and other lighting equipments because of their high luminous efficacy, long life, robustness, small size and so on. This paper covers the study, design and simulation of 30 Watt LED bulb driver circuit in MATLAB-Simulink environment. SEPIC (Single Ended Primary Inductor Converter) converter has been used as PFC (Power Factor Corrected) converter for shaping of input ac current and operates in CCM (Continuous Conduction Mode). For the study of LED bulb driver circuit the simulation results have been shown. The power quality parameters like power factor (PF), total harmonic distortion of input ac current (THD i ), crest factor (CF) have been shown in the table for a wide range of in input ac voltage 85– 265V with frequency of 50 Hz.

Multi-level inverter used in applications that require high power. The important factor in multi-level inverter is Total Harmonic Distortion (THD). This study discuss nine level cascaded H-bridge multilevel inverter. Also, proposed the effects of using filter on waveform and Total Harmonic Distortion (THD) of output voltage and current. Discussed LC low pass filter and sinusoidal pulse width modulation as control technique of switches. Comparison THD of nine level cascaded H-bridge multilevel inverter with and without filter. The proposed level and filter are design and simulate by MATLAB 2010 Version 7.11.0. The simulation results show the effects of using filter on THD and waveform of output voltage and current. Different methods for choosing filter value are used to illustrate the filter effect.

The use of capacitors for correcting power factor is a very well known approach in industry. However, the increase of harmonic sources in power systems is heightening the risk of resonance and, consequently, a drastic decrease in electric power quality. In order to keep the rating voltage, the power factor and the voltage and current harmonic distortions within acceptable limits, a fuzzy control approach was implemented. Based on this approach, a software program that is able to decide on the optimal distribution of the capacitor banks has also been developed. The program decision is based of the rating voltage, the power factor and the whole voltage and current harmonic distortions. When necessary, the computer program derides on the use of filters for harmonic compensation, indicating the best filter and the corresponding tuning frequency. Furthermore, the approach is able to deal with some aspects concerning the electric losses, both on the rating frequency and on the harmonic components.

Conventional current transformers (CTs) suffer from nonlinearities due to their ferromagnetic cores. On one hand, it is well-known that severe core saturation may occur because of large overcurrents or unidirectional transient components: this may substantially impact the operation of relays. On the other hand, weaker nonlinear effects are also present during regular working conditions. In particular, the spectral content of typical current waveforms is characterized by a strong fundamental term responsible for harmonic distortion affecting the frequency components at the secondary side. In turn, this has a significant impact on the accuracy that can be reached as long as current harmonics must be monitored. The target of this work is implementing a simple signal processing technique that allows compensating for this effect. The method, characterized by extremely low computational complexity, is first introduced and validated using numerical simulations. After this, it was tested experimentally to improve the harmonic measurement capability of inductive CTs. The achieved results highlight a noticeable reduction of errors at low-order harmonics over a wide range of primary current amplitudes. It is worth noting that the black-box approach makes the technique suitable also for compensating nonlinearities introduced by current transducers based on different operating principles. Thanks to this peculiarity and to the low computational complexity, the proposed method is suitable to be employed in power quality analyzers and merging units. In this way, high-accuracy monitoring of current harmonics in power systems can be achieved, opening the way to advanced power quality management and to the location of disturbing users.

In the given work has been analysed work single-phase three-zone AC-DC voltage converter. It is shown, that application multizone converters essentially improves quality of output voltage, and also an input current of the converter. Analytical expressions for total harmonic distortion of output voltage, input current, adjusting and external characteristics, and also a power factor are presented. Systems of pulse-phase regulation of new converters are created. The graphics illustrating results of computer modelling which visually show comparability of theoretical results and the spent experiments are resulted.