Electric Power Quality Improvement Research Articles

Assessing the efficiency of measures to enhance electric power quality in variable-frequency drive for scraper conveyors

The intensive implementation of variable-frequency drive machines and installations in underground mining processes necessitates addressing several issues, with a primary focus on ensuring the quality of electric power. Elevating the energy resource of mining machines and enhancing the energy efficiency of mining operations requires maintaining the rated indicators of electric power quality in mine power distribution systems. Achieving this involves assessing the level and composition of higher harmonic components in voltage and current within power circuits equipped with variable-frequency drives (VFD). Key objectives encompass the development of a simulation model based on the equivalent diagram of the power distribution system substitution with a scraper conveyor VFD to scrutinize the spectral composition of higher harmonic components in the power circuits of the mine power distribution system (MPDS). Additionally, the study involves analyzing the impact of harmonic filters (HFs), reactors, and sine filters on the quality of electric power in the VFD system of a scraper conveyor. Further analysis extends to the spectral composition of higher harmonic components in circuits related to insulation leakage and metering circuits of the residual-current device. Practical recommendations for improving electric power quality in the VFD system of a scraper conveyor are then developed based on the research findings. The established model of a variable-frequency drive system for scraper conveyors facilitates the assessment of the effectiveness of electric power quality improvement measures. The harmonic composition of voltage and current in the mine power distribution system is determined under maximum distortion conditions and in the presence of HFs, reactors, and sine filters. Research methods are chosen to unveil the spectral composition of voltage and current in symmetrical and single-phase modes of insulation leakage, as well as in metering circuits of residual-current devices (RCDs). It is noted that the harmonic composition of leakage voltage and current is primarily influenced by the parameters of the output voltage modulated by the autonomous frequency converter inverter. Considering the high level of harmonic components in voltage and current, adjustments to RCD settings, capacitive current compensator, and the protective shunting unit are recommended for electrical safety. The study emphasizes the importance of scientifically substantiating the rated indicators of higher harmonic components for leakage circuits and further exploring the physiological effects of higher current harmonics on the human body. The feasibility of installing a harmonic filter (HF) directly on the low-voltage supply section of a scraper conveyor should be technically justified. Interestingly, the presence of HFs, reactors, and sine filters does not significantly impact the harmonic composition or the magnitudes of coefficients of the harmonic components in the phase voltage of the system concerning ground and leakage currents through insulation. However, higher harmonic components induced in leakage current circuits may pose a potential hazard, leading to a violation of magnetic compatibility and posing risks in case of contact with live parts of electrical equipment.

Analysis of energy losses reduction potential on the distribution line of campus building through electric power quality improvement

In public and commercial buildings, the reduction of electricity consumption activities can be conducted through 3 paths, including improving the quality level of electric power, increasing the efficiency of electrical equipment, and reducing the waste of electric energy use. In this paper, the energy losses reduction potential on the distribution line of Engineering Faculty, Andalas University buildings through electric power quality improvement are analyzed. Power Quality (PQ) variables that considered in this analysis include power factor, unbalance current load and harmonics distortion. Analysis of correlation between PQ variables is required to determine the power loss on the distribution line of buildings. Using data of PQ variables recorded by Fluke Power Analyzer 435 series II, the energy losses of the distribution line without/with PQ improvement for each building is calculated. Analysis results have shown that the reduction potential is proportional to the value of PQ variables. Administrative faculty building with poor power quality has the potential to reduce its energy losses on the distribution line by 52.62% through power quality improvement. Civil engineering building group with quite good power quality only has the potential to reduce energy losses by 32.81%. Overall, the buildings in this faculty have the potential to reduce energy losses on distribution lines by 34.42% through its power quality improvement.

Fuel Saving And Electric Power Quality Improvement In Autonomous Power Supply Systems By Using Energy Storages

In autonomous power supply systems for diesel power stations located in remote areas, the main component of costs is the cost of imported fuel. The use of energy storage systems reduces fuel consumption for an autonomous power station. Reducing the northern import of liquid fuel is a relevant task for Russia. The organization of the charge-discharge process of an energy system storage according to the criterion of the minimum daily fuel consumption depends on both the load schedule and the type of flow rate characteristic of the primary engine. When making design and investment decisions on the feasibility of using alternative technical solutions for the modernization of sources in isolated energy supply systems, a comparative assessment of their economic efficiency is necessary. The paper studies the choice of energy storage system power in terms of fuel economy, reducing the installed capacity of a power station for electric power supply systems.

Improvements in Bidirectional Power-Flow Balancing and Electric Power Quality of a Microgrid with Unbalanced Distributed Generators and Loads by Using Shunt Compensators

Improper connections of unbalanced distributed generators (DGs) and loads in a three-phase microgrid cause unbalanced and bidirectional power flow problems. The unbalanced DGs and loads may also aggravate the electric power quality (EPQ), such as voltage regulation, power factor, and unbalanced current and voltage. This increases the difficulty of operation in a microgrid. In this study, a three-phase, delta-connected, shunt-type universal compensator was employed for achieving the bidirectional power-flow balancing and improving the EPQ of a three-phase, distribution-level microgrid with unbalanced DGs and loads. A feedforward compensation scheme was derived for the compensator by using the symmetrical components method. In practical applications, the universal compensator can be implemented as static var compensators (SVCs), static synchronous compensators (STATCOMs), or an additional function of active filters. With the on-line compensation of the proposed compensator, the bidirectional power-flow balancing and EPQ improvement in the microgrid were achieved. A demonstration system was proposed to present the effectiveness of the compensator.

Development of a Model and Research of Active Voltage Rectifier Prototype as a Part of Frequency Converters of Submersible Electric Motor Power Supply Systems

Рассмотрен вопрос о необходимости повышения качества потребляемой электроэнергии на нефтяных месторождениях. Отмечен один из наиболее эффективных методов повышения качества электроэнергии - активный выпрямитель напряжения. Представлена модель активного выпрямителя, и описан принцип ее работы. Исследована работа макета активного выпрямителя, нагруженного на частотный преобразователь. Приведены осциллограммы токов и напряжений при нагрузке выпрямителя на преобразователь частоты, а также приведены характеристики макета. Показано влияние искаженной и несимметричной питающей сети на параметры потребляемого тока выпрямителя. Предложены методы компенсации влияния искажений сети на качество работы активного выпрямителя. Представлены сравнительные характеристики выпрямителя при работе с компенсатором искажений.

Optimization of Electric Power Leveling Systems by Taper‐Off‐Reflectance Particle Swarm Optimization

SUMMARYIt has become desirable to develop energy control technologies for environmental issues such as global warming and exhaustion of fossil fuel. Power fluctuations in large power consumer facilities may cause instability of electric power systems and increase the cost of the electric power facilities and electricity charges. Developing electric power leveling systems (EPLS) to compensate power fluctuations is necessary for future electric power systems. EPLS with an SMES has been proposed as one countermeasure for use in electric power quality improvement. SMES is superior to other energy storage devices in response and storage efficiency. The authors have proposed EPLS based on fuzzy control with SMES. For this practical implementation, optimizing the control gain and SMES capacity is an important issue. This paper proposes a new method for optimization of the EPLS. The proposed algorithm is a novel particle swarm optimization based on taper‐off reflectance (TRPSO). The proposed TRPSO optimizes the design variables of the EPLS efficiently and effectively. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 10–18, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22472

The Study of the Deforming Regime of AC/AC Converter using Fourier and Multiresolution Analysis

For electric power quality improvement should be identified and followed the deforming consumers. This is necessary, because the number of equipments producing harmonic distortion is increasing, primarily by expanding the use of static power converters. This paper presents the study of the deforming state generated by the AC/AC converter with full-wave AC control using two SCRs (silicon – controlled rectifier) connected in inverse parallel. The harmonic spectrums of distorted current and voltage signals are determined by the load and the thyristors delay angle. For this study, we use Fourier and Wavelet transform. A multiresolution signal decomposition technique is presented in the analysis of the deforming signals from the AC/AC converter. Ill. 10, bibl. 8 (in English; abstracts in English and Lithuanian). DOI: http://dx.doi.org/10.5755/j01.eee.121.5.1643

Optimization of Electric Power Leveling Systems by a Novel Cluster-Structured GA with Masking

Power fluctuations of the rolling mill may cause the instability of electric power systems, and increase the cost of the electric power facility and electricity charges. Therefore, in order to compensate the power fluctuations, the development of the electric power-leveling systems (EPLS) is very important in the future electric power system. The EPLS with a SMES has been proposed as one of the countermeasures for the electric power quality improvement. However, the SMES is very expensive and it is difficult to decide the gains of the controller. It is essential in the practical use that the reduction of SMES capacity is realized.This paper proposes a new optimization method of the EPLS. The proposed algorithm is Cluster-Structured GA with Masking (CSGA). The optimization of the EPLS can be achieved by the proposed CSGA compared to the GA.

ＳｉｍＥとＧＡのハイブリッドアルゴリズムによる電力平準化システムの最適化

Electric power demand has an increasing tendency year by year. The fluctuation of the electric power causes further increase in the cost of the electric power facility and electricity charges. The development of the electric power-leveling systems (EPLS) using energy storage technology is desired to improve the electric power quality. The EPLS with a SMES is proposed as one of the countermeasures for the electric power quality improvement. However, the SMES is very expensive and it is difficult to decide the gains of the controller. It is essential in the practical use that the reduction of SMES capacity is realized.This paper proposes a new optimization method of the EPLS. The proposed algorithm is hybrid architecture with a combination of SimE (Simulated Evolution) and GA (Genetic Algorithms). The optimization of the EPLS can be achieved by the proposed hybrid algorithm compared to the SimE and the GA.

HT-SMES operating at liquid nitrogen temperatures for electric power quality improvement demonstrating

We have developed and tested a laboratory scale High-T/sub C/ Superconducting Magnetic Energy Storage (HT-SMES) system with storage capacity of up to 1.2 kJ. It was designed to improve the power quality for a consumer supplied by 3-phase standard commercial electric power grid at a consumer power of up to 20 kW. This SMES is based on a high-T/sub C/ superconducting coil with a ferromagnetic core, immersed in liquid nitrogen at 65 K to provide efficient thermal contact with the coolant. We also developed a cryogenic DC-DC converter based on low resistance power MOSFET transistors, providing low losses in the stored energy and high operational efficiency. The power conditioning capability of our HT-SMES was proved, and compensation of voltage drops in the electric grid was successfully demonstrated.