Reduce Voltage Fluctuations Research Articles

The Impact of Post-Furnace Steel Processing Equipment on Reducing Voltage Fluctuations Caused by Arc Furnaces

Arc devices are among the receivers with the highest power connected to power systems. Due to dynamic load changes, these receivers generate a number of disturbances that affect the quality of electric power. The most important disturbances include voltage fluctuations. It is also worth mentioning the asymmetry and deformation of the supply voltage curve. This article discusses the mutual interaction of receivers operating in parallel, operating stably, and devices with dynamic current consumption. Calculations based on model tests and the results of parameters characterizing the quality of energy, which were recorded in the line supplying the steelworks, are presented. The power supply conditions (power of the short-circuit network) were assessed to influence the degree of suppression of voltage fluctuations by loads with stable current consumption.

An adaptive power control method for soft open points based on virtual impedance

The fluctuations in power output from distributed power sources are rapid and dramatic, causing voltage fluctuations in the distribution network that threaten the safety of electricity consumption. Soft open points (SOPs) can replace traditional contact switches and are expected to suppress voltage fluctuations. However, traditional power regulation methods based on the reference values are unable to address rapid and large voltage fluctuations. Therefore, this paper proposes an adaptive power control method for SOPs based on virtual impedance. The SOP is modeled as a series link of adjustable impedance and a voltage source. Then, the voltage difference component is used to calculate the reference for the DQ domain to regulate the power flow in real time automatically. By doing so, the proposed method can smooth the voltage fluctuations in the distribution network. Additionally, the virtual impedance is also optimized to minimize the power loss. Finally, the method is validated through simulation and experiments, demonstrating that this method can automatically regulate power and significantly reduce voltage fluctuations.

Exploration of proton exchange membrane fuel cell performance under dynamic humidification conditions

Controlling the relative humidity is crucial for improving fuel cell performance in self-humidifying fuel cells. In light of this, this study investigates the influence of humidity variation on Proton Exchange Membrane Fuel Cells (PEMFC) performance through single-cell testing and a two-dimensional two-phase model. In the experiment, different humidity conditions are achieved by adjusting the inlet air temperature, and the effect of relative humidity on cell performance is observed. The research findings indicate that as the relative humidity increases, the performance of the fuel cell gradually improves. Increasing humidity reduces voltage fluctuations, particularly at low flow rates, demonstrating more stable performance. Under different humidity conditions, when the inlet air flow rate exceeds a certain value, the voltage non-uniformity of the cell remains within 1, indicating insignificant voltage fluctuations, attributed to the effects of inlet air flow rate on performance improvement and alleviation of flooding phenomena. Analysis of the two-dimensional two-phase model reveals that liquid water impedes gas mass transfer, with gas transport under the rib particularly affected. Increasing the flow rate helps remove liquid water under the rib, promoting cell performance stability.

Influence of microbial inoculation site on trichloroethylene degradation in electrokinetic-enhanced bioremediation of low-permeability soils

The integration of electrokinetic and bioremediation (EK-BIO) represents an innovative approach for addressing trichloroethylene (TCE) contamination in low-permeability soil. However, there remains a knowledge gap in the impact of the inoculation approach on TCE dechlorination and the microbial response with the presence of co-existing substances. In this study, four 1-dimensional columns were constructed with different inoculation treatments. Monitoring the operation conditions revealed that a stabilization period (∼40 days) was required to reduce voltage fluctuation. The group with inoculation into the soil middle (Group B) exhibited the highest TCE dechlorination efficiency, achieving a TCE removal rate of 84%, which was 1.1–3.2 fold higher compared to the others. Among degraded products in Group B, 39% was ethylene. The physicochemical properties of the post-soil at different regions illustrated that dechlorination coincided with the Fe(III) and SO42− reduction, meaning that the EK-BIO system promoted the formation of a reducing environment. Microbial community analysis demonstrated that Dehalococcoides was only detected in the treatment of injection at soil middle or near the cathode, with abundance enriched by 2.1%–7.2%. The principal components analysis indicated that the inoculation approach significantly affected the evolution of functional bacteria. Quantitative polymerase chain reaction (qPCR) analysis demonstrated that Group B exhibited at least 2.8 and 4.2-fold higher copies of functional genes (tceA, vcrA) than those of other groups. In conclusion, this study contributes to the development of effective strategies for enhancing TCE biodechlorination in the EK-BIO system, which is particularly beneficial for the remediation of low-permeability soils.

Suitability of capacitor allocation methods in different kinds of distribution networks

In the context of power systems with “a high percentage of renewable energy” and “a high percentage of power electronic equipment”, reactive power capacitors are demanded to support the voltage and keep the economic operation of the distribution network. Reasonable configuration of reactive power compensation including capacitor location and compensation capacity can keep the system voltage at a reasonable level, improve the system voltage stability, and reduce the network loss. In this paper, a reactive power optimization model based on three capacitor allocation methods, namely the reactive power sensitivity method, the active power loss method, and the voltage stability method, was established. Considering the stability and economy of distribution network operation, the suitability of the different methods in different kinds of distribution networks was evaluated in terms of the indicators of minimizing the network loss, minimizing the voltage offset, and minimizing the system operation cost. The simulation results show that the active power loss method is the most suitable for reducing voltage fluctuations and network losses.

Transfer operation ride though control strategy of the aircraft power supply system with lithium battery energy storage

The aircraft power supply system turns towards multi-source, and transfer operation will likely happen during flight missions and fault conditions. The transfer may lead to voltage interruptions and current surges, adversely affecting power quality. This paper proposes incorporating a lithium battery energy storage system (ESS) into the aircraft high-voltage direct current (HVDC) power system. The ESS employs a voltage control model with a lower voltage reference base, facilitating a smooth transfer operation during power interruptions. This approach reduces voltage fluctuations in the power supply system, enhances power quality, and enables seamless power transfer during the transfer operation.

Design and Optimization of Voltage Mode PWM Control of DC-DC Buck Converter with a PI-Lead Compensator Using the Simulated Annealing Algorithm

This paper presents a method for improving the performance of DC-DC Buck Converter Systems using voltage mode Pulse Width Modulation (PWM) control. We explore the effectiveness of Proportional-Integral (PI) and Lead Compensator controllers in enhancing system stability, minimizing voltage fluctuations, and improving load response. The system is modeled through transfer functions, and the controllers' impacts are analyzed both individually and in tandem. A key contribution of this work is the optimization of the PI-Lead Compensator parameters utilizing the Simulated Annealing Algorithm, which is fine-tuned to improve phase margin, gain crossover frequency, and steady state error. These parameters are critical for optimizing the system’s output performance. Through MATLAB simulations, we demonstrate the iterative process of parameter optimization and validate the algorithm's efficacy in managing the DC-DC Buck Converter. The results highlight the enhanced performance achieved with the optimized parameters, providing a viable solution for effective control of DC-DC Buck Converter Systems.

The optimization and operation of multi-energy-coupled microgrids by the improved fireworks algorithm-shuffled frog-leaping algorithm.

This study aims to address optimization and operational challenges in multi-energy coupled microgrids to enhance system stability and reliability. After analyzing the requirements of such systems within comprehensive energy systems, an improved fireworks algorithm (IFWA) is proposed. This algorithm combines an adaptive resource allocation strategy with a community genetic strategy, automatically adjusting explosion range and spark quantity based on individual optimization status to meet actual needs. Additionally, a multi-objective optimization model considering active power network losses and static voltage is constructed, utilizing the shuffled frog-leaping algorithm (SFLA) to solve constrained multi-objective optimization problems. Through simulation experiments on a typical northern comprehensive energy system, conducted with a scheduling period of T = 24, the feasibility and superiority of IFWA-SFLA are validated. Results indicate that IFWA-SFLA performs well in optimizing microgrid stability, managing electrical energy flow effectively within the microgrid, and reducing voltage fluctuations. Furthermore, the circuit structure and control strategy of microgrid energy storage bidirectional inverters based on IFWA are discussed, along with relevant simulation results.

Load-current demand forecasting in substations of urban railway lines

Load-current forecasting is important in the operation and energy management of urban railway lines. It helps control strategies to manage and distribute energy optimally, thereby saving energy and reducing voltage fluctuations. This paper presents a method to predict the traction current at the busbar of a substation using the supervised machine learning algorithm. Because the traction power load is supplied from both adjacent traction power stations, and the energy exchange process between trains also takes place during work, the input data are selected to combine the value history of busbar currents and feeder currents. Besides, the neural network configuration and the number of training cycles in the estimated model can be adjusted to achieve the desired accuracy. The proposed method was tested and adjusted based on the actual operation data at the Lang traction station on 24 June, 2022. The estimated results compared with measurement data from the supervisory control and data acquisition (SCADA) have proven that the largest absolute error is no more than 5 (A). The maximum relative error is not more than 0.005, and the mean squared error does not exceed 0.01 over the whole operating time of a day from 4h45 to 22h45.

Reduction of Voltage Fluctuations in Electrical Networks Supplying Motors with a Rapidly Changing Load by Installing Longitudinal Compensation Batteries

The article deals with the reduction of voltage fluctuations in electrical networks of industrial enterprises with the help of longitudinal compensation batteries. The purpose of the article is to develop a method for calculating the optimal parameters of the longitudinal compensation installation, which makes it possible to perform calculations using numerical characteristics of the range of changes in the voltage and flicker dose. To achieve this goal, it is necessary to solve the following tasks: to develop a method for selecting the parameters of reducing voltage fluctuations, taking into account the random nature of the change in the parameters of network modes; using the proposed method, to develop a calculation method that allows choosing optimal parameters of capacitor units. The most significant result is the experimental and theoretical confirmation that the proposed method for selecting the parameters of longitudinal compensation batteries, taking into account the random nature of the change in the flicker dose, makes it possible to effectively apply longitudinal compensation to reduce voltage fluctuations in electrical networks of industrial enterprises with a rapidly changing load. The significance of the results is proved by the fact that the proposed method makes it possible to select a longitudinal compensation installation to limit voltage fluctuations at the design stage, thereby ensuring the quality of electric energy in networks with consumers having a rapidly changing load. The resulting calculation method is planned to be used in distribution electrical networks when performing technical measures to ensure the quality of electrical energy.

An Optimal Fuzzy Logic Sliding Mode Voltage Regulation DC-grid System for Hybrid Electric Ships with FC-Battery Energy Storage System

This work proposes a fuzzy logic sliding mode control based on MOPSO optimization to increase voltage stability, particularly during load variations, while also combining FC-battery storage systems. The controller makes advantage of the converters' existing capabilities to reduce voltage fluctuations and improve system efficiency in a number of ship operating modes, including transient loads, without the need for additional equipment like as DC choppers or passive/active filters. By minimising voltage variation under load fluctuations and other influencing variables, the MOPSO develops control orders to manage load distribution among the FC and DG battery storage systems. The suggested control approach is compared to traditional sliding mode and PI controllers in terms of performance. According to the findings, the novel approach can improve battery power smoothing, steady state voltage management, and stable and speedy control performance.

Effect of gradient anode flow field designs on polymer electrolyte membrane fuel cells

This study investigates non-uniform anode flow fields in polymer electrolyte membrane fuel cells, exploring ascending and descending gradient configurations in channels and metal foams. Implementing ascending gradient enhances maximum power density by up to 3.8% for channels and 5.7% for metal foams compared to descending gradients, reducing voltage fluctuations. Further analysis of gradient metal foams using water-cooling cells reveals that both designs achieve a peak power density of 1.13 W/cm2 at RH100%, with a marginal 0.2% difference. As RH decreases to 60% and 30%, performance disparities of 4.3% and 5.7% are observed, favoring ascending design. HFR values of 3.27 mΩ for ascending and 3.78 mΩ for descending metal foams at RH30% indicate superior membrane hydration properties of the ascending design, but accelerated stress tests evidence its susceptibility to degradation. This study highlights the potential for optimizing fuel cell design by manipulating anode flow field gradients, offering insight for enhancing performance.

Different DC-Link Control Methods with Multilevel Inverter for Low Harmonic and Efficient Power Transfer in Grid-Tied Hydrogen Fuel Cell Systems

In grid-connected power generation systems, dc-link voltage control is needed to prevent energy losses, reduce voltage fluctuations and provide a stable energy flow. In addition, control of the power factor via the voltage source inverter is a process that supports the efficient use of the energy produced. Moreover, keeping the total harmonic distortion (THD) of the current injected into the grid in accordance with IEEE-519 harmonic standards (

Optimal Design and Performance Investigation of Artificial Neural Network Controller for Solar- and Battery-Connected Unified Power Quality Conditioner

Nowadays, integration of renewable sources into the local distribution system and the nonlinear behavior of advanced power electronic equipment have made a large impact on the power quality (PQ). The unified power quality conditioner (UPQC) is a multifunctional FACTS device, which is a combination of both shunt active filter and series active filters via a common DC link. Presently, the artificial intelligence is playing a vital role in the development of the intelligent control methods. Traditional training methods of artificial neural network (ANN) like back propagation and Levenberg-Marquardt may get stuck in local optimal solution which leads to the invention of ANN trained optimally by metaheuristic algorithms. This paper develops a firefly algorithm-trained ANN (FF-ANNC) controller for the shunt active filter and proportional integral controller (PI-C) for the series active filter of the UPQC integrated with the solar energy system and battery energy storage via boost converter (B-C) and buck boost converters (B-B-C). The main aim of the proposed FF-ANNC is to reduce the mean square error (MSE) thereby achieving the constant DC link capacitor voltage (DLCV) during load and irradiation variations, reduction of imperfections in current waveforms, improvement in power factor (PF), and mitigation of sag, swell, disturbances, and unbalances in the grid voltage. The working of developed FF-ANNC was tested on five test studies with different types of loads and source voltage balancing/unbalancing conditions. However, to demonstrate supremacy of the suggested FF-ANNC, a comparative study with the training methods like genetic algorithm (GA) and ant colony optimization (AC-O) and also with other methods that exist in literature like PI-C, fuzzy logic controller (FL-C), and artificial neuro fuzzy interface system (ANFI-S) was conducted. The proposed method reduces the total harmonic distortion to 2.39%, 2.32%, 2.27%, 2.45%, and 2.66% which are lower than the existing methods that are available in literature. The FF-ANNC shows an excellent performance in reducing voltage fluctuations and total harmonic distortion (THD) successfully and thereby improving PF.

НАКОПИЧУВАЧІ ЕЛЕКТРИЧНОЇ ЕНЕРГІЇ

The article provides an analytical review of reverse-acting electric energy storage devices that can be used to solve systemic problems of the United Energy System of Ukraine. The need for the use of electric energy storage is due to the existing shortage of maneuverable capacities of the United Energy System and the construction of solar and wind power plants, which, due to the stochastic mode of operation, are a significant destabilizing factor. Due to the lack of market pricing mechanisms, the possibility of adjusting the rates of the "green" tariff, and the decrease in the cost of solar and wind power plant technologies, a rapid increase in their number and capacity has been observed in recent years. At the beginning of 2021, the installed capacity of solar power plants was 6.87 GW, and wind power plants – was 1.31 GW, and by 2030, their growth is planned to be 10.5 GW and 5.0 GW, respectively. Without adequate regulatory capacity, this can lead to catastrophic consequences, as happened in South Australia. The conducted review and analysis showed that the dominant technology of electric energy storage in the world is hydro-storage power plants, the implementation costs of which are about 260 USD/kWh. Compressed air energy storage is the cheapest technology but needs to be located near the energy systems of natural caves. Accumulator systems of energy storage are developing at a fast pace, the costs of their implementation are 311-520 USD/kWh with a tendency to decrease by 2030 by about 25%. They are the most promising for work in energy systems. These storage devices can be used to regulate frequency and power, reduce electricity flows, reduce voltage fluctuations in electrical networks, consolidate daily schedules of electrical loads, prevent overloads of electrical networks and transformers, increase the reliability of electricity supply, increase the stability of the operation of solar and wind power plants, as well as for commercial purposes in various segments of the electricity market of Ukraine. Keywords: energy system, electricity storage, power, capacity.

Design of UPQC with Solar PV and Battery Storage Systems for Power Quality Improvement

In this paper, the unified PQ conditioner (UPQC) is associated with photovoltaic (PV) and battery-storage systems (BSSs) to address the PQ issues. The hybrid fuzzy-sliding mode control (HFSMC) based maximum-power-point tracking system (MPPTs) is adopted for solar PV system to extract maximum output. To minimize the complexity of the conventional system, levenberg-marquardt trained artificial neural network (ANN) controller is proposed to the UPQC in order to generate the effective reference signals for shunt, series converters which eliminates the necessity of conventional abc, dq0, αβ transformations. The main aim of the proposed ANN based UPQC is to achieve the constant direct current (DC) link capacitor voltage during load changes with low settling time, elimination of imperfections in current waveforms, thereby reducing total harmonic distortions (THD) and to improve power factor, mitigation of sag, swell, disturbances and unbalances in source voltage. The performance of developed method is tested on five case studies with different combination of loads, variable irradiation and source voltages conditions. To demonstrate the supremacy of the developed method the comparative study with the proportional integral controller (PIC) was carried out. The proposed method shows an excellent performance in reducing voltage fluctuations and THD successfully and thereby improving power factor.

Data-driven model predictive control of community batteries for voltage regulation in power grids subject to EV charging

In this paper, a Model Predictive Control (MPC) for community Battery Energy Storage Systems (BESS) is proposed to mitigate the Electric Vehicle (EV) charging demand while maintaining voltage regulation in residential power grids. With the increased penetration of renewable-based Distributed Energy Resources (DERs) and the EV uptake, distribution grids are highly subject to voltage fluctuations due to back power feed from DERs or significant EV charging demand. Conventionally, Distribution Network Operators (DNOs) have addressed this issue by adjusting the taps of transformers. However, managing the naturally unpredictable renewable generation and the power consumption behaviour of technology owners requires advanced real-time algorithms. In this paper, we apply a real-time control algorithm, based on Model Predictive Control (MPC), to a community BESS in order to reduce voltage fluctuations. The MPC algorithm performs in real-time based on readings from smart meters of households. It predicts the future values of voltages at households based on the current and past readings of smart meters, and calculates the BESS charging or discharging rate such that future voltage deviations are minimised. Simulations on the real-world power consumption data from Victorian residential consumers, in Australia, show that the proposed controller performs significantly better than the fixed charging/discharging BESS schedule in both voltage regulation and BESS degradation.

Дослідження ефективності схеми керування напругою конденсатора уніфікованого регулятора якості електроенергії для зменшення коливань напруги

This article investigated the effectiveness of using a unified power quality regulator (UPQR) to reduce voltage fluctuations in electrical networks with a rapidly changing nonlinear load. It is proposed to use a voltage control scheme on the URYAE storage capacitor based on an FIR filter in order to minimize rapid voltage changes and the flicker indicator, as well as the total coefficient of harmonic distortions in the distribution system. The final simulation of the study is carried out using MATLAB/Simulink. To demonstrate the effectiveness of the proposed control scheme, a comparison of simulation results with a PI controller is made from the point of view of improving the specified power quality indicators. The initial data for performing calculations of voltage fluctuations are information on the parameters of the electrical network and the graph of a random, rapidly changing electrical load. Rapidly changing loads cause rapid changes in the network voltage, the amplitudes of which can reach unacceptable values, for example, in the case of frequent start-ups of an asynchronous motor with a large starting current. Voltage fluctuations can also be caused by technological installations, the operation of which is accompanied by active and reactive power surges , such as the drive of reversible rolling mills, arc steel melting furnaces, contact electric welding installations, etc. The main task of the research is to improve the quality of electricity, and, as a result, to increase the service life of electrical equipment and to ensure the conditions for the normal technological process of electricity consumers. Indicators characterizing voltage fluctuations were quantified: voltage change range (δUt) and flicker indicator (Pt). The effectiveness of the new capacitor voltage control scheme for reducing higher current harmonics compared to the classical one based on the PI-regulator is verified.

Experimental investigation of energy storage and reuse of recovered waste heat based on thermoelectric generation

Heat energy may be converted into electric energy via a thermoelectric generator (TEG). It is an effective method of recovering and utilizing low-grade energy. However, the output voltage of a TEG is typically too low for direct applications. A waste heat recovery system based on thermoelectric generation was developed to convert waste heat energy into electric energy for energy storage and to operate an LED car light. The variability of thermal-electrical conversion and energy distribution in different stages of the system, as well as the response characteristics of the LED car light under heating temperature fluctuations, are investigated experimentally. The performance of different energy storage components on the time-dependent output characteristics of the light is also analyzed. The results indicate that the energy storage elements can store the energy derived from waste heat, power an LED car light independently, and buffer the power fluctuations caused by the heat source's temperature variation. The energy distribution ratio differs for different energy storage components. Lithium batteries have a high energy density and can store more electricity. The cold start of the LED car light is quick, and the illumination time is longer, but it requires more time to obtain a full charge. The supercapacitor has a sluggish cold start but a high charge and discharge speed, reducing voltage fluctuations when the waste heat recovery system is turned on for a short period. In addition, the system may be utilized to power additional low-power devices.

Harmonic Performance Analysis of Static Var Compensator Connected to the Power Transmission Network

The static var compensator (SVC) is a device which is designed to compensate reactive power, increase voltage stability and to reduce voltage fluctuations. Thyristor controlled reactors (TCRs) are composed of reactors in series with bidirectional pair of thyristors. Current through reactors can be continuously controlled by changing the firing angle of thyristor valves, thus
 the inductive power can be easily controlled. Typical applications of TCRs in AC systems are voltage stabilization and temporary overvoltage reduction, stability improvement, damping of power oscillations and load balancing. In this paper, harmonic performance analysis of SVC equipped with TCRs is presented. SVCs utilizing TCRs generate harmonic currents and therefore it is necessary to determine the effect of harmonics generated by the SVC on the power system and its elements. This includes interaction of the SVC with the system, the SVC performance under balanced and unbalanced operating conditions and finally, evaluation of countermeasures such as installation of harmonic filters. In order to carry out these analysis, it is necessary to determine harmonic characteristics of the network at the point of SVC connection, existing levels of harmonics, and to know appropriate standards regarding acceptable harmonic levels in the power system. Since harmonic distortions in the system are caused by the interaction between SVC and the system, all system contingencies which may affect system’s frequency response should be evaluated. Detailed power system model should be considered to make sure that parallel resonance points of system do not directly coincide with characteristic harmonics from the SVC. Harmonics generated by SVCs are largely dependent on the operating point within the SVC characteristic. A conservative approach is to use the maximum values of harmonics generated within the spectrum irrespective of the operating point. The results of harmonic performance analysis are important for appropriate design of SVC. Harmonic performance analysis related to SVC application which are presented in this paper include the determination of: frequency response of the transmission network impedance required for the specification and design of filters; the effects of SVC generated harmonics on the power system; the overall filter requirements and countermeasures to reduce harmonics to acceptable levels.