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23 pages, 6655 KiB

Open AccessArticle

Optimal Design of C-Type Filter in Harmonics Polluted Distribution Systems

by Rohollah Tamaskani, Masume Khodsuz and Mohammad Yazdani-Asrami

Energies 2022, 15(4), 1587; https://0-doi-org.brum.beds.ac.uk/10.3390/en15041587 - 21 Feb 2022

Cited by 6 | Viewed by 2086

This paper aims to find the optimal size of parameters of a C-type filter in a non-sinusoidal system using a new optimization method called the Archimedes optimization algorithm (AOA). The inductance and capacitance values of the filter are acquired in which the power [...] Read more.

This paper aims to find the optimal size of parameters of a C-type filter in a non-sinusoidal system using a new optimization method called the Archimedes optimization algorithm (AOA). The inductance and capacitance values of the filter are acquired in which the power loss in the Thevenin resistor and the power loss characteristics of the load bus are minimized based on a new proposed objective function. Subject to technical and practical limitations of the IEEE 519 standard, an optimization problem is defined to achieve an optimal filter design that can increase the system power quality. The effectiveness of the proposed method is proved by comparison with the recent previously published methods. The results show the effectiveness of the proposed approach using the AOA in finding the minimum power losses and the harmonic content of frequency-dependent components. Eventually, the current study confirmed that the suggested objective function minimizes power losses of fundamental and harmonic order harmonics in non-sinusoidal systems. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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19 pages, 9366 KiB

Open AccessArticle

Enhanced TVI for Grid Forming VSC under Unbalanced Faults

by Markel Zubiaga, Carmen Cardozo, Thibault Prevost, Alain Sanchez-Ruiz, Eneko Olea, Pedro Izurza, Siam Hasan Khan and Joseba Arza

Energies 2021, 14(19), 6168; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196168 - 27 Sep 2021

Cited by 7 | Viewed by 2549

Abstract

With an increasing capacity of inverter-based generation and with a 100% renewable energy power system on the horizon, grid forming converters have the potential to become the prevalent control mode in the grid. Thus, the correct performance of these devices is going to [...] Read more.

With an increasing capacity of inverter-based generation and with a 100% renewable energy power system on the horizon, grid forming converters have the potential to become the prevalent control mode in the grid. Thus, the correct performance of these devices is going to be crucial for system stability and security of supply. Most research related to the grid-forming control is focused on normal operating conditions, although significant effort has been devoted to current limitation strategies to ensure Low Voltage Ride Through (LVRT) capability. However, most contributions usually consider only balanced faults. This paper, proposes a new current limiting method based on the well-known threshold virtual impedance (TVI) that keeps the voltage source behaviour associated to the grid forming (GFM) capability, even when the current limit is reached, while reducing the voltage unbalance according to user-defined settings. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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24 pages, 8620 KiB

Open AccessArticle

Phasor Estimation of Transient Electrical Signals Composed of Harmonics and Interharmonics

by Jon Vazquez, Jose Felix Miñambres, Miguel Angel Zorrozua and Jorge Lázaro

Energies 2021, 14(16), 5166; https://0-doi-org.brum.beds.ac.uk/10.3390/en14165166 - 20 Aug 2021

Cited by 2 | Viewed by 1607

Abstract

Numerical relays have become essential tools for carrying out the protection and surveillance tasks of electrical power systems. These relays implement their functions from the phasors of the electrical network signals, estimated by digital processing using digital filters. Digital filters must meet certain [...] Read more.

Numerical relays have become essential tools for carrying out the protection and surveillance tasks of electrical power systems. These relays implement their functions from the phasors of the electrical network signals, estimated by digital processing using digital filters. Digital filters must meet certain requirements, such as providing a fast and effective response to increasingly complex transient signals made up of components that make the estimation process difficult. In addition to the decreasing exponential (decaying dc offset), harmonics, and signal noise, it must be added that the interharmonic components that in recent years have acquired great relevance, mainly because of the increase in non-linear loads and the extensive use of power electronic systems. The presence of these interharmonic components causes a poor response in most of the filters implemented today. This article presents the design of a new digital filter, C-CharmDF (Cleaned Characteristic Harmonic Digital Filter) for phasor estimation on noisy transient signals with decreasing exponential components, harmonics, and interharmonics. A detailed study was carried out for severe transient situations and stationary signals. It was found that the method can be suitable for relays that implement both fault location functions and system protection functions. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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14 pages, 2565 KiB

Open AccessArticle

A Systematic Study on the Harmonic Overlap Effects for DC/AC Converters under Low Switching Frequency Modulation

by Ze Wang, Zhen He and Chao Gao

Energies 2021, 14(10), 2811; https://0-doi-org.brum.beds.ac.uk/10.3390/en14102811 - 13 May 2021

Cited by 2 | Viewed by 1787

Abstract

In most high power industrial applications, the low switching frequency modulations (LSFM) are usually implemented to reduce power loss and heat dissipation pressure. However, there are some unexpected influences caused by the low order harmonic sinusoidal pulse width modulation (SPWM), such as the [...] Read more.

In most high power industrial applications, the low switching frequency modulations (LSFM) are usually implemented to reduce power loss and heat dissipation pressure. However, there are some unexpected influences caused by the low order harmonic sinusoidal pulse width modulation (SPWM), such as the imbalanced submodule power in cascaded half-bridge inverter (CHB) and limited output power capability in H-bridge neutral-point-clamped (HNPC) converter. This paper starts by generalizing the basic characteristic of two-level SPWM, then deeply investigates the influences of low-frequency modulation on the operation of the circuits. They are classified into three mechanisms and generally named as harmonic overlap effect (HOE). The corresponding solutions to copy with the mechanisms are proposed and verified in some topologies through high-power simulations in simulations. In addition, a comprehensive summary of the influences and solutions of these effects on typical high power converters is drawn. The design rules of the modulation schemes for multilevel voltage source converters (VSCs) at low switching frequency are also proposed. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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11 pages, 1139 KiB

Open AccessArticle

New Time-Frequency Transient Features for Nonintrusive Load Monitoring

by Mahfoud Drouaz, Bruno Colicchio, Ali Moukadem, Alain Dieterlen and Djafar Ould-Abdeslam

Energies 2021, 14(5), 1437; https://0-doi-org.brum.beds.ac.uk/10.3390/en14051437 - 05 Mar 2021

Cited by 14 | Viewed by 1922

Abstract

A crucial step in nonintrusive load monitoring (NILM) is feature extraction, which consists of signal processing techniques to extract features from voltage and current signals. This paper presents a new time-frequency feature based on Stockwell transform. The extracted features aim to describe the [...] Read more.

A crucial step in nonintrusive load monitoring (NILM) is feature extraction, which consists of signal processing techniques to extract features from voltage and current signals. This paper presents a new time-frequency feature based on Stockwell transform. The extracted features aim to describe the shape of the current transient signal by applying an energy measure on the fundamental and the harmonic frequency voices. In order to validate the proposed methodology, classical machine learning tools are applied (k-NN and decision tree classifiers) on two existing datasets (Controlled On/Off Loads Library (COOLL) and Home Equipment Laboratory Dataset (HELD1)). The classification rates achieved are clearly higher than that for other related studies in the literature, with 99.52% and 96.92% classification rates for the COOLL and HELD1 datasets, respectively. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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14 pages, 1470 KiB

Open AccessArticle

Adaptive Online State of Charge Estimation of EVs Lithium-Ion Batteries with Deep Recurrent Neural Networks

by Gelareh Javid, Djaffar Ould Abdeslam and Michel Basset

Energies 2021, 14(3), 758; https://0-doi-org.brum.beds.ac.uk/10.3390/en14030758 - 01 Feb 2021

Cited by 23 | Viewed by 2572

Abstract

The State of Charge (SOC) estimation is a significant issue for safe performance and the lifespan of Lithium-ion (Li-ion) batteries. In this paper, a Robust Adaptive Online Long Short-Term Memory (RoLSTM) method is proposed to extract SOC estimation for Li-ion Batteries in Electric [...] Read more.

The State of Charge (SOC) estimation is a significant issue for safe performance and the lifespan of Lithium-ion (Li-ion) batteries. In this paper, a Robust Adaptive Online Long Short-Term Memory (RoLSTM) method is proposed to extract SOC estimation for Li-ion Batteries in Electric Vehicles (EVs). This real-time, as its name suggests, method is based on a Recurrent Neural Network (RNN) containing Long Short-Term Memory (LSTM) units and using the Robust and Adaptive online gradient learning method (RoAdam) for optimization. In the proposed architecture, one sequential model is defined for each of the three inputs: voltage, current, and temperature of the battery. Therefore, the three networks work in parallel. With this approach, the number of LSTM units are reduced. Using this suggested method, one is not dependent on precise battery models and can avoid complicated mathematical methods. In addition, unlike the traditional recursive neural network where content is re-written at any time, the LSTM network can decide on preserving the current memory through the proposed gateways. In that case, it can easily transfer this information over long paths to receive and maintain long-term dependencies. Using real databases, the experiment results illustrate the better performance of RoLSTM applied to SOC estimation of Li-Ion batteries in comparison with a neural network modeling and unscented Kalman filter method that have been used thus far. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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15 pages, 2350 KiB

Open AccessArticle

Multiobjective Reactive Power Optimization of Renewable Energy Power Plants Based on Time-and-Space Grouping Method

by Linan Qu, Shujie Zhang, Hsiung-Cheng Lin, Ning Chen and Lingling Li

Energies 2020, 13(14), 3556; https://0-doi-org.brum.beds.ac.uk/10.3390/en13143556 - 10 Jul 2020

Cited by 4 | Viewed by 1562

Abstract

The large-scale renewable energy power plants connected to a weak grid may cause bus voltage fluctuations in the renewable energy power plant and even power grid. Therefore, reactive power compensation is demanded to stabilize the bus voltage and reduce network loss. For this [...] Read more.

The large-scale renewable energy power plants connected to a weak grid may cause bus voltage fluctuations in the renewable energy power plant and even power grid. Therefore, reactive power compensation is demanded to stabilize the bus voltage and reduce network loss. For this purpose, time-series characteristics of renewable energy power plants are firstly reflected using K-means++ clustering method. The time group behaviors of renewable energy power plants, spatial behaviors of renewable energy generation units, and a time-and-space grouping model of renewable energy power plants are thus established. Then, a mixed-integer optimization method for reactive power compensation in renewable energy power plants is developed based on the second-order cone programming (SOCP). Accordingly, power flow constraints can be simplified to achieve reactive power optimization more efficiently and quickly. Finally, the feasibility and economy for the proposed method are verified by actual renewable energy power plants. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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Review

Jump to: Research

18 pages, 2653 KiB

Open AccessReview

High-Impedance Fault Diagnosis: A Review

by Abdulaziz Aljohani and Ibrahim Habiballah

Energies 2020, 13(23), 6447; https://0-doi-org.brum.beds.ac.uk/10.3390/en13236447 - 05 Dec 2020

Cited by 31 | Viewed by 5448

Abstract

High-impedance faults (HIFs) represent one of the biggest challenges in power distribution networks. An HIF occurs when an electrical conductor unintentionally comes into contact with a highly resistive medium, resulting in a fault current lower than 75 amperes in medium-voltage circuits. Under such [...] Read more.

High-impedance faults (HIFs) represent one of the biggest challenges in power distribution networks. An HIF occurs when an electrical conductor unintentionally comes into contact with a highly resistive medium, resulting in a fault current lower than 75 amperes in medium-voltage circuits. Under such condition, the fault current is relatively close in value to the normal drawn ampere from the load, resulting in a condition of blindness towards HIFs by conventional overcurrent relays. This paper intends to review the literature related to the HIF phenomenon including models and characteristics. In this work, detection, classification, and location methodologies are reviewed. In addition, diagnosis techniques are categorized, evaluated, and compared with one another. Finally, disadvantages of current approaches and a look ahead to the future of fault diagnosis are discussed. Full article

(This article belongs to the Special Issue Advanced Techniques for Power Quality Improvement)

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