Distortion In Power Systems Research Articles

Novel Frequency Estimator for Distorted Power System Signals Using Two-Point Iterative Windowed DFT

Novel Frequency Estimator for Distorted Power System Signals Using Two-Point Iterative Windowed DFT

Astrophysics-based transit search optimization heuristics for parameter estimation of multi-frequency sinusoidal signals

This study investigates an astrophysics-based Transit search optimization algorithm (TSOA) for solving a challenging engineering problem. This innovative strategy uses the fundamentals of physics to improve the accuracy and efficacy of problem solving techniques. Harmonic distortions in power systems have become a massive challenge because of the nonlinear loads associated with the electrical power distribution system. Overheating of the equipment, motor failure, capacitor failure, and improper power metering are all issues caused by harmonic distortion. A new examination of the causes and consequences of these issues, as well as the status of hardware and software available for harmonic evaluation, is necessary in light of the unprecedented advancements in power electronic devices and their integration at all levels in the power and energy system. In order to estimate phase and amplitude simultaneously with a specified frequency, an objective function of power system harmonics is created. Keeping in mind the adverse effects of harmonics, parameter estimation is carried out under various conditions by taking different particle sizes and signal-to-noise ratios. TSOA proved its efficacy for both phase and amplitude parameters under different situations and precisely estimated the harmonics signal up to an accuracy of 1.1648E–15. Two harmonic signals were taken in this research work, and the best MSE values achieved are 9.748E–4, 8.287E–07, 6.157E–10, and 1.165E–15 for 30, 60, 90, and 150 dB noise, respectively, under case study 1 while varying the particle size from 50 to 450. The results for case study 2 proved to be best up to 7.373E–16, and no significant change occurred by increasing the generations above 500. The proposed study would be a step further in developing a more accurate and robust computing platform for robust estimation of harmonics arising in power and energy systems.

Assessment of unbalance and distortion in power systems that include active power line conditioners.

This paper presents a decomposition of the apparent power of a system that allows to separate the contribution to the unbalance of the whole set of harmonics of voltages and currents. From this set of power terms, the unbalanced fundamental, balanced harmonics and unbalanced harmonic indices are derived, that allow to evaluate separately the distortion and the unbalance. This procedure gives a more appropriate way to characterize the mitigation obtained using modern equipments with active compensation. These new indicators of the electric power quality have been applied here to a system with unbalance and distortion in the supply and the load, before and after the connection of a parallel active compensator, and with the connection of a series-parallel active compensator. The results obtained with a dedicated experimental platform have allowed to verify the validity of the new proposed indices.

Minimization of Harmonic Distortion in Power Systems at Fault Occurrence

Minimization of Harmonic Distortion in Power Systems at Fault Occurrence

Design and Development of Three Phase Detuned Filter Reactor for Reduction of Harmonic Distortion in Power Systems

Harmonics refers to a form of electrical distortion that can adversely impact power systems, electrical equipment, and the overall quality of power supply. The presence of non-linear loads, such as electronic devices, can cause the current waveform to deviate from the ideal sine wave, resulting in higher frequency currents that are multiples of the fundamental frequency. These distortions can lead to several negative effects, such as reduced power factor, increased energy losses, equipment overheating, and electromagnetic interference. These, in turn, can lower system efficiency, increase energy consumption, and escalate equipment maintenance costs. Several approaches have been developed to address the adverse effects of harmonics, such as the use of filters, capacitors, and other reactive components. These techniques aim to minimize harmonic distortion and improve power supply quality. This paper examines the effectiveness of a 1kVAr detuned reactor in mitigating harmonic distortion in power systems and electrical components. The detuned filter reactor reduces the harmonic distortion actively. It does so by monitoring the harmonic content of the power and injecting a counteracting current to cancel out the harmonic frequencies, creating a subtle "detuning" effect that reduces harmonic distortion. Detuned filter reactors find extensive application in radio and audio equipment, among other fields.

Research on harmonics liability division considering the influence of user harmonics on economic loss

With the rapid development of power electronics technology, a large number of nonlinear devices are widely used in power network, industry and home, and the harmonic problem has attracted more attention. In the distorted power system, it is the premise of harmonic pollution control to clarify the shared harmonic responsibility of the system side and each user at the common connection point. The existing liability division methods mainly focus on a certain harmonic, and the results are difficult to reflect the actual harmonic influence of users. The direct effect of harmonic problem can be measured by economic loss, which is the main basis for the division of harmonic responsibility is beneficial to the implementation of reward and punishment measures. This paper presents a harmonic liability division method considering the effect of user harmonic on economic loss. Firstly, the harmonic compatibility level of users is graded considering different proportions and different types of equipment. Secondly, reference to the national standard to develop economic indicators to measure the impact of harmonics on users at all levels; Finally, each harmonic responsibility of the system side and the user side is calculated, and the final comprehensive harmonic responsibility index is obtained by combining the economic index of each user harmonic influence. The reasonableness of this method is verified by the measured harmonic data of users connected to a substation.

Harmonics Signal Feature Extraction Techniques: A Review

Harmonic estimation is essential for mitigating or suppressing harmonic distortions in power systems. The most important idea is that spectrum analysis, waveform estimation, harmonic source classification, source location, the determination of harmonic source contributions, data clustering, and filter-based harmonic elimination capacity are also considered. The feature extraction method is a fundamental component of the optimization that improves the effectiveness of the Harmonic Mitigation method. In this study, techniques to extract fundamental frequencies and harmonics in the frequency domain, the time domain, and the spatial domain include 67 literature reviews and an overall assessment. The combinations of signal processing with artificial intelligence (AI) techniques are also reviewed and evaluated in this study. The benefit of the feature extraction methods is that the analysis extracts the powerful basic information of the feedback signals from the sensors with the most redundancy, ensuring the highest efficiency for the next sampling process of algorithms. This study provides an overview of the fundamental frequency and harmonic extraction methods of recent years, an analysis, and a presentation of their advantages and limitations.

A Comprehensive Review of Harmonic Issues and Estimation Techniques in Power System Networks Based on Traditional and Artificial Intelligence/Machine Learning

Modern industrial and commercial devices that are fed by power electronics circuits and behave non-linearly tend to produce power quality issues in power systems including harmonics and interharmonics, swell, flicker, spikes, notches, and transient instabilities. Among them, harmonic emission is the most significant challenge to be overcome by the distribution networks. Unwanted current, overheating motors and transformers, equipment failure, and circuit breaker misoperation are some of the harmonic consequences. While it is important to employ the best methods to mitigate or suppress the harmonic distortions in power systems, it is even more essential to estimate these harmonics at the outset by developing smart, efficient, and accurate techniques. Due to their capability for learning, predicting, and identifying, researchers have turned to Artificial Intelligence technologies for harmonic estimation in distribution networks. Although the power system parameters (impedance/admittance model) and many harmonic monitors are prerequisites for traditional harmonic estimation methods, by utilizing Artificial Intelligence, these requirements are minimized. In this paper, a comprehensive review of traditional and modern (smart) harmonic estimation techniques are discussed.

A Survey on the Investigation and Analysis for a Power System (Micro-Grid) with Stochastic Harmonic Distortion of Multiple Converters

The current study is based on a survey on the exploration and analysis of stochastic harmonic distortion in power systems using multiple converters (Micro-Grid). When Renewable Energy Systems are integrated into EPS, they may create clean energy, fulfill consumer energy needs, and help to protect fossil fuel supplies, which are rapidly dwindling. These renewable energy sources (RES) are frequently connected to the grid via power converters (Voltage Source Converters) to provide the necessary energy regulation and conversion. However, Voltage Source Converter (VSCs) generates both current and voltage harmonics, has a negative impact on the Power Quality (PQ) of a small grid and has the potential to cause damage or equipment failure. In the face of uncertainties, such as those resulting from design parameter selection or system parameter changes, the amount of harmonic distortion of many VSCs may be greatly influenced and difficult to forecast. When dealing with VSC harmonic distortion levels in the face of uncertainty, it is necessary to use statistical methodologies.

SAPF Parameter Optimization with the Application of Taguchi SNR Method

Non-linear devices draw non-sinusoidal currents from the source; hence, they cause harmonic distortions in power systems. The shunt active power filter (SAPF) is a well-known method for alleviating current harmonics, compensating the reactive power and improving the power factor; however, the effective design of an SAPF is quite challenging and a thrust area of research. The current controlling technique, switching pulse generation technique and parameter selection are cumbersome tasks in SAPF design. SAPF performance depends on the proper selection of many parameters, such as filter interfacing impedance, DC-link capacitor and PI-controller gains. The effect of these parameters on the performance of SAPF has been studied and optimum values have been obtained by using the Taguchi method. This paper also indicates the benefits of using the Taguchi method compared with existing genetic algorithm (GA) for optimizing the parameters of the SAPF. An instantaneous reactive power theory (IRPT)-based SAPF has been modeled and simulated in MATLAB/Simulink. The SAPF’s parameters have been optimized by using the both proposed Taguchi SNR and the existing GA method. With optimized values of parameters results have been obtained, analyzed and the superiority of the proposed Taguchi method over the existing GA method is discussed. The simulation results were also validated with experimental results.

Multi-Objective Bee Swarm Optimization Algorithm with Minimum Manhattan Distance for Passive Power Filter Optimization Problems

Harmonic distortion in power systems is a significant problem, and it is thus necessary to mitigate critical harmonics. This study proposes an optimal method for designing passive power filters (PPFs) to suppress these harmonics. The design of a PPF involves multi-objective optimization. A multi-objective bee swarm optimization (MOBSO) with Pareto optimality is implemented, and an external archive is used to store the non-dominated solutions obtained. The minimum Manhattan distance strategy was used to select the most balanced solution in the Pareto solution set. A series of case studies are presented to demonstrate the efficiency and superiority of the proposed method. Therefore, the proposed method has a very promising future not only in filter design but also in solving other multi-objective optimization problems.

Inverter Two-Level PWM Harmonic Enhancement Based on Phase Shift Tuning Technique

Frequency harmonic reduction and elimination is a vital field of research due to its importance in minimizing the percentage of total harmonic distortion in power systems. The two-level Pulse Width Modulation (PWM) method of AC generation is with less sophisticated control circuitry requirement compared to higher level PWM techniques. This paper is proposing a new control methodology with a reduced harmonic spectrum. The new trend here is to manipulate the PWM two-level reference waveform by duplicating the generation process with a tuned phase shifting added to the reference waveform. The new technique results in a harmonic reduction of the unfiltered output with about 50% compared to that of the conventional Bipolar SPWM.

Enhancing the Performance of DFIG Wind Turbines Considering Excitation Parameters of the Insulated Gate Bipolar Transistors and a New PLL Scheme

The major aim for achieving the successful synchronization of a wind turbine system to the grid is to mitigate electrical and mechanical stresses on the wind generator. During transient state, the gearbox, shaft, and rotor of the wind generator could be damaged due to mechanical stress. The rotor and stator windings of the wind generator, including its insulation, could be affected. This paper undertakes an extensive analysis of the effects of the excitation parameters of the power converter Insulated Gate Bipolar Transistors (IGBTs), on the transient state performance of the Doubly Fed Induction Generator (DFIG), considering different scenarios. The optimal excitation parameters of IGBTs were used for further analysis of the wind generator, considering a new Phase-Locked-Loop (PLL) scheme. The PLL computes the phase displacement of the grid required to achieve orientation and synchronization control. Consequently, it helps in preventing power system distortion due to stator-grid interphase. This paper proposes a new approach that integrates PLL control strategy and a Series Dynamic Braking Resistor (SDBR) to augment the fault ride through capability of a variable speed wind turbine that is DFIG-based. The SDBR helps the post fault recovery of the wind generator. Simulations were run in Power System Computer Aided Design and Electromagnetic Transient state Including DC (PSCAD/EMTDC) to examine severe fault conditions, and to test the robustness of the controllers employed. The results show that the proposed hybrid control strategy aids the fast recovery of the DFIG wind generator variables during fault conditions.

Matpower-Based Harmonic Power Flow Analysis for Power Systems With Passive Power Filters

As an open-source MATLAB-based power system simulation package, MATPOWER has been proven to have an adjustable feature that supports modifications to solve specific problems in power systems. Since it was first released, the MATPOWER framework has been widely used for solving steady-state electric power scheduling problems. However, a modification to solve a harmonic power flow (HPF) using MATPOWER has not been launched yet. This paper presents modification procedures to customize the network component models and problem formulations in MATPOWER for the HPF study. The modification procedures can be used to evaluate the bus admittance matrix, bus voltages, and current sources for any harmonic order. Moreover, the modified MATPOWER can evaluate the passive power filter (PPF) installation to improve the harmonic distortion in power systems. The simulation results were satisfactory, indicating that the modification enabled to solve problems in both fundamental and harmonic power flows.

A hybrid fuzzy with feedback integral phase locked loop-based control strategy for unified power quality conditioner

This paper proposes a hybrid fuzzy control strategy comprising both Takagi-Sugeno fuzzy and Mamdani fuzzy along with novel feedback integral phase-locked loop based modified synchronous reference frame for unified power quality conditioner for power quality enhancement in power distribution network. The hybrid fuzzy controller can vary the gain nonlinearly for controlling dc-bus capacitor voltage of unified power quality conditioner, which limits the dc-bus voltage deviations during the load and supply voltage turbulences. Moreover, the proposed novel feedback integral phase-locked loop system is employed to improve the grid synchronization performance of unified power quality conditioner by considering the feedback integral loop and nonlinear adaptive-filter type phase detector approach. As a consequence, the proposed feedback integral phase-locked loop system can extract the positive sequence signal perfectly during power system disturbances. Additionally, the novelty of modified synchronous reference frame control technique relies upon nonintervention with low pass filter as well as high pass filter. Hence, the proposed control technique quickly and accurately extracts the reference signal from the distorted power system. The efficacy of the proposed control technique is justified through a real-time Opal-RT Hardware underneath different states of power system and compared with both conventional modified phase locked loop system and Takagi-Sugeno fuzzy with synchronous reference frame-based control system.

Power System Distortion Mitigation by Using Series Active Power Filter

The power quality improvement faces different significant problems due to the wide use of power electronics and voltage instability. To overcome these different power quality problems, an active power filter is used. The active power filter in general has four main categories, shunt, series, unified power quality conditioner and hybrid active power filter. The shunt active power filter is usually used to mitigate source current harmonics and compensate reactive power for power factor improvement. The series active power filter is usually used to mitigate voltage problems (sags, swells, transients, dips, distortions….). The unified power quality conditioner is used for all voltage and current problems. In this paper, the three phase three-wire series active power filter is utilized alone to mitigate all power system problems (voltages and currents) for this case study, such as voltage sag, voltage swell, voltage harmonics, and source current harmonics to comply with the harmonics limits given in IEEE 519-1992, and IEC 61000-4-7 standards. The source current harmonic problem mainly exists due to, 1) distorted voltage source, and 2) non-linear loads. The series active power filter can effectively eliminate the source current harmonics in case of distorted voltage source. Consequently, the series active power filter can be used alone as a power quality improvement for all voltage and current problems as mentioned in this case study.

A Novel Method for Assessing the Contribution of Harmonic Sources to Voltage Distortion in Power Systems

This paper presents a method for evaluating the harmonic contributions of multiple harmonic sources to voltage distortion at the point of common coupling (PCC). The proposed method quantitatively represents harmonic contributions based on the equivalent voltage models of harmonic sources. The equivalent voltage models can be estimated using the recursive least square (RLS) algorithm and measured voltage and current at the PCC. The assessment of harmonic contribution heavily depends on the accuracy of equivalent model estimation. Many existing studies have assumed that the equivalent model parameters of harmonic sources are not changed. However, because harmonic source parameters and system operating conditions are not constant in real power systems, this assumption can lead large errors in harmonic contribution assessment. In this paper, we propose a new assessment method based on variable forgetting factor RLS and parameter change detection to solve the problem. The proposed method is also effective for evaluating comprehensive harmonic contributions as well as individual harmonic contributions. The case studies show that the proposed method is superior to the previous one even under parameter changing conditions.

Optimization of harmonics with active power filter based on ADALINE neural network

Mostly the power quality issues in the distribution line system happen due to the presence of harmonics. Especially, the nonlinear loads such as power electronic converters, high-speed semi-conducting switches, and solid state drives were the major causes for harmonics in distorted power system signals. Moreover, the estimation of magnitude and the phase of this harmful harmonic interference are necessary. By taking in to consideration of all the above factors, this paper develops an efficient technique for harmonic estimation and detection of the renewable wind energy resources and elimination of these harmonics will also be done accordingly for getting desired output from wind energy. 8 bit inputs (4 + 4) are collected and used to generate the intended input set for ANN training. The proposed work develops an Adaptive Linear Neural Network (ADALINE) for the estimation of harmonics which is the novelty of this work. For making the harmonics content more negligible and to enhance the load power quality, an Active Power Filter (APF) is used. The novel control design is developed with a Pulse Width Modulation (PWM) control. In addition, feed forward networks (trained by back propagation algorithm) works like a hysteresis band comparator. An APF control design is developed with ADALINE network in which the load and current along with voltage will be analyzed and then the controller will be calculating the control signal by considering the reference compensation current. Afterwards, the power system is injected with compensating current. The simulation is carried out with Matlab-Simulink laboratory prototype is developed with Xilinux 3E Spartan FPGA board to verify the proposed control designs. The proposed work is compared with exiting method comprising Shunt Active Power Filters (SAPF) with ADALINE for the performance perspectives. This method was found to be effective in terms of many parameters such as load voltage, load current, voltage, reactive power, real power and especially THD value than those of the existing works which are considered.

Wavelet Packet Decomposition for IEC Compliant Assessment of Harmonics under Stationary and Fluctuating Conditions

This paper presents the validation and characterization of a wavelet based decomposition method for the assessment of harmonic distortion in power systems, under stationary and non-stationary conditions. It uses Wavelet Packet Decomposition with Butterworth Infinite Impulse Response filters and a decomposition structure, which allows the measurement of both odd and even harmonics, up to the 63rd order, fully compliant with the requirements of the IEC 61000-4-7 standard. The method is shown to fulfil the IEC accuracy requirements for stationary harmonics, obtaining the same accuracy even under fluctuating conditions. Then, it is validated using simulated signals with real harmonic content. The proposed method is proven to be fully equivalent to Fourier analysis under stationary conditions, being often more accurate. Under non-stationary conditions, instead, it provides significantly higher accuracy, while the IEC strategy produces large errors. Lastly, the method is tested with real current and voltage signals, measured in conditions of high harmonic distortion. The proposed strategy provides a method with superior performance for fluctuating harmonics, but at the same time IEC compliant under stationary conditions.

Proposal of a Desynchronized Processing Technique for Assessing High-Frequency Distortion in Power Systems

Assessing high-frequency (HF) distortion (HFD) in power systems is a new challenge in the framework of in situ power quality monitoring. The International Electrotechnical Commission (IEC) suggests the use of a high-pass filter in the measurement chain, which can be analog (with a dedicated channel for HF assessment) or integrated into its digital form into the signal processing (SP) stage, in order to reduce the measurement uncertainty. This paper proposes a desynchronized processing technique (DPT) as an effective alternative to the other digital filtering techniques presented in the literature, which also allows for a potential simplification of the measurement hardware. The DPT performance is analyzed by means of numerical experiments and laboratory measurements performed using two different test beds and both 16- and 24-bit analog-to-digital converters (ADCs). The test beds are used to evaluate the combined contribution of the ADC and the SP stage to the whole measurement chain uncertainty and identify achievable accuracy levels for different frequency ranges and magnitudes of HFD. The results highlight the strengths of the DPT compared to other techniques and demonstrate its potential to include HF in a comprehensive waveform distortion assessment in power systems.