Power Quality Problems Research Articles

Harmonics and Flicker in an Iron and Steel Industry with AC arc furnaces

An AC arc furnace is an unbalanced, non-linear and time-varying load, which can cause many power quality problems to the electric network inside the plant and in its electrical vicinity. Although different studies addressing harmonics and flicker analyses on arc furnaces can be found in the bibliography, it is very difficult obtain an exact model that considers all the parameters that influence the process, and therefore it is necessary to obtain actual measurements under different conditions. This paper presents measurement results for harmonic distortion, flicker and unbalance obtained over three different measurement campaigns on an iron and steel industry (SNL), as well as the pertinent conclusions. Measurement campaigns were performed on an AC arc furnace of 83 MW (170 TM) with a 120 MVA transformer connected by a ‘dirty’ 220 kV line (55 km) to the Substation of Carregado, where other feeders supply industrial and domestic consumers. Finally, the dynamic behaviour of an SVC will be analysed and compared to that of a STATCOM by means of simulation studies.

Dynamic load prediction of charging piles for energy storage electric vehicles based on Space-time constraints in the internet of things environment

Abstract This paper puts forward the dynamic load prediction of charging piles of energy storage electric vehicles based on time and space constraints in the Internet of Things environment, which can improve the load prediction effect of charging piles of electric vehicles and solve the problems of difficult power grid control and low power quality caused by the randomness of charging loads in time and space. After constructing a traffic road network model based on the Internet of Things, a travel chain model with different complexity and an electric vehicle charging model, the travel chain is randomly extracted. With the shortest travel time as a constraint, combined with the traffic road network model based on the Internet of Things, the travel route and travel time are determined. According to the State of Charge (SOC) and the travel destination, the location and charging time of the energy storage electric vehicle charging pile are determined. After obtaining the time-space distribution information of the energy storage electric vehicle charging pile at different times and in different regions, it is used as the input of the deep multi-step time-space dynamic neural network, and the network output is the dynamic electric vehicle charging pile. The experimental results show that this method can realize the dynamic load prediction of electric vehicle charging piles. When the number of stacking units is 11, the indexes of Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE) are the lowest and the index of R 2 is the largest. The load of charging piles in residential areas and work areas exists in the morning and evening peak hours, while the load fluctuation of charging piles in other areas presents a decentralized change law; The higher the complexity of regional traffic network, the greater the load of electric vehicle charging piles in the morning rush hour.

Field experiences in power quality problem solving in Spain.

This paper is a summary of the experiences gathered by PQC during 10 years of field work in Power Quality problem solving in final customers. Topics which have been found to be in the origin of power quality problems will be analysed: earthing, UPS and emergency standby generators, harmonic distortion, transient overvoltages and monitoring.

Power Quality as a Reliability Problem for Electronic Equipment.

Power quality standards introduce the definitions of several power quality disturbances and define limits for their amplitudes, repetition rates and, or maximum number of occurrences in a time period. The definitions of those parameters result from the observation of the disturbance phenomena in the networks and are not related with the consequences of power quality disturbances in the reliability of electronic equipments. In this paper, are described the main reliability effects caused by power quality problems, in electronic equipment. The authors explain the physical limitations of power supplies, concerning power quality problems and developed a simple, low cost power quality analyser, designed for the evaluation of the parameters that are critical to the failure rates of electronic equipment.

A comparative study of fuzzy logic based UPQC and D-STATCOM for mitigation of power quality problem

This paper begins by investigating a power quality problem in the case study area using monthly energy consumption data, the peak and minimum load of the substation, a fault summary, and the RMS voltage profile of the case study area. The content of the paper comprises three parts: the first involves MATLAB design and simulation of D-STATCOM with a fuzzy logic controller for the selected case study area. The second part entails MATLAB design and simulation of the DVR with a fuzzy logic controller. The final part presents a hybrid of the DVR and the D-STATCOM back-to-back using a DC link capacitor to implement a more recent and effective power quality improvement technique, namely UPQC. In the case of a three-phase fault, the voltage sag in the case study area is 0.6PU, with the remaining 0.4PU drop-down voltage requiring injection using the proposed FACT device for compensation. All proposed power quality problem mitigation techniques inject the required voltage and compensate for the voltage sag in the substation. For instance, D-STATCOM compensates the RMS voltage from 9KV to 14KV, DVR compensates the RMS voltage from 9KV to 14.7 KV, and UPQC compensates the value to 14.9KV. Due to the three-phase fault, the rise in reactive power of the existing outgoing feeder is 13MW. This unexpected rise in reactive power is reduced to 2.6 MW using D-STATCOM, DVR reduces it to 1.2 MW, and UPQC reduces the value below 1MW. The existing power factor of the case study area without any mitigation technique is 0.68. All proposed techniques improve the existing power factor to a more acceptable value. For instance, D-STATCOM improves the power factor from 0.68 to 0.83, DVR improves the value to 0.88, and UPQC, the more accurate power quality mitigation technique, improves the power factor to 0.93. Finally, the results are compared based on the simulation results.

Control strategy and capacity optimization of energy-storage-based railway power conditioner

Electrified railroad has the characteristics of high safety factors, high comfort, large transportation capacity, and less time-consuming, which is an effective means to solve traffic congestion. However, with the rapid development of China’s electrified railroad, harmonic, negative sequence and other power quality problems have also been widely concerned, while more and more regenerative braking energy in the traction power supply system can not be effectively utilized. The input of railroad power regulators makes the power quality problem be solved effectively, this paper studies the control strategy of traditional railroad power regulators. Combined with the actual working conditions of railroad vehicles, the simulation model of traction network, vehicles, and railroad power conditioner is established, and the load characteristics of traction substation are simulated by this model. Secondly, for a domestic substation field collection data processing to obtain the actual train operation load changes, to the battery energy storage device life within the maximum economic returns as the optimization goal, for the peak load reduction judgment threshold and the capacity of the battery energy storage device through the genetic algorithm to process the data of previous years to optimize the design.

A Novel Three-Phase Multiobjective Unified Power Quality Conditioner

The decarbonization of the economy and the increasing integration of renewable energy sources into the generation mix are bringing new challenges, requiring novel technological solutions in the topic of smart grids, which include smart transformers and energy storage systems. Additionally, power quality is a vital concern for the future smart grids; therefore, the continuous development of power electronics solutions to overcome power quality problems is of the utmost importance. In this context, this paper proposes a novel three-phase multi-objective unified power quality conditioner (MO-UPQC), considering interfaces for solar PV panels and for energy storage in batteries. The MO-UPQC is capable of compensating power quality problems in the voltages (at the load side) and in the currents (at the power grid side), while it enables injecting power into the grid (from the PV panels or batteries) or charging the batteries (from the PV panels or from the grid). Experimental results were obtained with a three-phase four-wire laboratory prototype, demonstrating the feasibility and the large range of applications of the proposed MO-UPQC.

Source Current Harmonic Cancellation in Distribution System by Using ANFIS Controller

Ensuring a reliable and stable power supply to consumers is of utmost importance in modern distribution systems. Many power quality issues, such as voltage fluctuations, harmonic distortions, transient events, load forecasting, and voltage sag/swell compensation, can lead to operational inefficiencies and compromise the performance of sensitive electronic equipment. The main causes of power quality problems are short circuits and overloads, reactive power imbalance, transients, equipment malfunctions, and ground issues. The ANFIS model leverages the strengths of both neural networks and fuzzy logic to effectively address power quality challenges. Thus, by using the ANFIS model for power quality improvement, we reduce the supply current harmonics by maintaining IEEE 519 standards. The stimulation results are implemented using MATLAB Simulink software. The simulation results are verified source current, load current and supply voltage, The THD value of source current.

Enhancement of power quality problems using DSTATCOM: An optimized control approach

The Distributed Static Compensator (DSTATCOM) is a compensator that regulates the flow of reactive power in distribution systems/networks by providing quick control of reactive as well as active powers. This work introduces the modeling and implementation of a 3-phase DSTATCOM using a Weighted Chimp (WdCH) optimization algorithm for Power Quality (PQ) improvement. The DSTATCOM is critical in improving the distribution network’s PQ with balanced and unbalanced loads. Also, there is a quick deviation in the DC link voltage coupled with the compensating device during the load disturbance in the systems. The proposed control algorithm optimizes the fundamental weight values of load currents for determining the reference grid currents’ magnitude and phase values, as a result, provides gating pulses for a 3-phase Voltage Source Converter via SPWM. The efficacy of the proposed control approach is analyzed concerning the convergence of the weighted values and the minimization of the Total Harmonic Distortion (THD) value.

Simplified control strategy based three-phase reduced switch UPQC for mitigation of power quality problems

Simplified control strategy based three-phase reduced switch UPQC for mitigation of power quality problems

Simplified control strategy-based three-phase reduced switch UPQC for mitigation of power quality problems

Simplified control strategy-based three-phase reduced switch UPQC for mitigation of power quality problems

PEV’s Smart Charging Strategy Based on Individual State of Charge

Themain contribution of this work is a smart-charging strategy based on the state of charge analyses to avoid the undervoltages caused by plug-in electric vehicles into the distribution system. The work uses power hardware-in-the-loop simulations, where a modified IEEE 34 bus system, with five groups of electric vehicle stations, is modeled in a real-time digital simulator. The number of electric vehicles charging and the initial state of charge (SoC) are generated randomly. The first analyses identify the undervoltage problems due to the increased number of electric vehicles connected during peak hours load. After, a smart-charging solution is necessary to solve this power quality problem. So, if the voltage profile decreases under certain limits, defined by a hysteresis band, the control occurs, and the smart-charging is applied. The proposed strategy based on individual state of charge priority reduces the electric vehicle recharge power at virtual stations, by comparing its value with the mean of state of charge values from each station group. The experimental results presented show that, by varying the recharge current, the voltage profiles do not reach the limit for sags determined by the Brazilian standard, proving the performance and solving the problem even if not reducing the recharge current of all electric vehicles equally.

Power Quality Problems and New Solutions

In this paper, the main Power Quality (PQ) problems are presented with their associated causes and consequences. The economic impacts associated with PQ are characterized. Finally, some solutions to mitigate the PQ problems are presented

ANFIS Controlled MMC-UPQC to Mitigate Power Quality Problems in Solar PV Integrated Power System

This paper focuses on the implementation of a Modular Multilevel Converter (MMC) based Unified Power Quality Conditioner (UPQC) in a grid-integrated Photovoltaic (PV) system. The integration of photovoltaic (PV) systems into the grid brings numerous benefits in terms of renewable energy utilization like sustainable energy generation, energy security, grid resilience, and economic growth. However, the voltage source converters (VSCs) employed in PV systems can introduce power quality (PQ) issues, including voltage fluctuations, harmonics, and reactive power imbalances and grid instability. The objective of this work is to enhance power quality by mitigating voltage and current fluctuations and harmonics generated due to VSC, compensating reactive power requirements by the load and PV system, and regulating the DC link voltage. For DC voltage regulation, an Adaptive Neuro-Fuzzy Inference System (ANFIS) controller is employed to control for MMC-UPQC. The proposed control strategy is simulated using MATLAB/SIMULINK software and the results are compared with conventional Proportional Integral (PI) and fuzzy controllers. Various dynamic conditions such as voltage sag and swell at the point of common coupling (PCC), changes in irradiance for the PV system, and load variations are considered. The simulation results demonstrate that the ANFIS-controlled MMC-based UPQC outperforms the PI and fuzzy controllers in terms of power quality improvement. It effectively suppresses harmonics, maintains a stable DC link voltage, and compensates for reactive power fluctuations. The proposed control strategy provides superior performance and achieves better power quality compared to conventional controllers. The findings of this work highlight the potential of using an ANFIS controller in MMC-based UPQC systems for grid-integrated PV systems.

Novel Asymmetric/ Symmetric Half-Cascaded Multilevel Inverter for photovoltaic based shunt active power filter to mitigate power quality issues

Photovoltaic (PV) technology has been recently developing and upgrading with regard to the rapid and high request from various agricultural, domestic and industrial electric power systems. Due to feasibility and reliability of Multi-Level Inverter (MLI), it can be effectively implemented in the photovoltaic systems. The large number of switches used in the MLIs is their main drawback which leads to lack of cost-effectiveness and high Total Harmonic Distortion (THD). In this paper, a novel Asymmetric/Symmetric Half-Cascaded MLI (ASHC-MLI) which contains low number of switches is proposed to attain a cost-effective structure. After that, PV panels have been used as power sources of this structure to construct the overall Shunt Hybrid Active Power Filter (SHAPF) for mitigating the power quality problems. To evaluate the cost-effectiveness of the proposed ASHC-MLI, it has been compared with the prominent and inventive MLI structures in both asymmetric and symmetric statuses. Meanwhile, the understudy power system has been affected by different current distortions so that the harmonic elimination capability of the proposed SHAPF can be well revealed. The evaluation analysis has been simultaneously performed for the conventional active power filter to appropriately validate its harmonic elimination capability.

Power Quality Enhancement Using Renewable Energy Sources and Electric Mobility

In the present day, there is a growing emergence of obstacles pertaining to the remuneration of power quality (PQ) issues. In this context, the implementation of renewable energy sources (RES) solutions has a critical significance. The transition from traditional electrical power grids to smart grids necessitates the utilization of a significant quantity of power electronics converters and RES. These converters are essential for the incorporation of crucial technologies like renewable energies, electric mobility, and energy storage systems. Consequently, PQ concerns gain heightened significance in this context. The article focuses on elucidating the primary phenomena related to PQ issues in smart grids, their origins, and consequences across various sectors. Additionally, the paper provides a comprehensive examination and categorization of the primary PQ issues, along with their corresponding alignment with established standards. It also offers an assessment of PQ problems associated with RES and their integration with electric mobility.

Solar PV-Fed Multilevel Inverter with Series Compensator for Power Quality Improvement in Grid Connected Systems

Power quality problems arise as a result of RES integration into the grid. Voltage fluctuations, harmonic distortion, and spikes all impact customers as power quality issues on the grid. A cheap series compensator, such as the Dynamic Voltage Restorer (DVR), is the best approach to fix these problems. In order to enhance the grid's power quality, this research introduces a novel multilayer inverter that uses solar PV as a distributed voltage rectifier. The main objective of the proposed work is to enhance power quality through the development of a DVR that simultaneously functions as an integrated 23-level multilevel inverter. Beyond that, the boost converter has an improved INC-MPPT implementation. Despite their numerous benefits, multilayer inverters encounter reliability concerns such as reduced total harmonic distortion (THD) and fewer components. The suggested design has the potential to produce 23 distinct output voltage levels by use of asymmetrical DC sources. An inverter that is both smaller and cheaper with fewer parts is one of the advantages of the MLI. On top of that, the dq reference frame rotation adjustment is well studied mathematically. To test the DVR's flexibility with an equal load, simulation approaches are used. The simulation results of the suggested structure are generated using MATLAB/Simulink. Results from the Fuzzy Logic System show that the proposed technique improves power quality and compensates better for voltage sag.

Grid Connected Wind Energy System Power Quality Improvement Using STATCOM

The wind energy generation, utilization and its grid penetration in electrical grid are increasing worldwide. Injection of the wind power into an electric grid affects the power quality. The wind generated power is always fluctuating due to its time varying nature and causing stability problems. This weak interconnection of wind generating source in the electrical network affects the power quality and reliability. This paper demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme Static Compensator (STATCOM) is connected at a point of common coupling with a battery energy storage system to mitigate the power quality issues. The STATCOM gives reactive power support to wind generator and also load. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme is simulated using MATLAB/SIMULINK in power system block set.

Performance Analysis of Meta-Heuristic Algorithms for Optimal PI Tuning of PFC

The popularity of the average current mode (ACM) controlled boost type power factor correction (PFC) topologies is increasing due to their suitability for power quality problems. Proportional-Integral (PI) controller method is generally used in ACM controlled boost PFC circuits which include two controllers. However, the most important complexity of ACM controlled PFC circuits is tuning the coefficients of the PI controllers optimally. Therefore, this paper proposes the optimal tuning of PI coefficients used in ACM controlled boost PFC circuits using different meta-heuristics algorithms. First, the proposed ACM controller-based boost PFC topology is analyzed in MATLAB/Simulink software by using variable loads. Then the simulation results of the Cuckoo Optimization Algorithm (COA) based ACM controlled boost PFC converter are compared with the results determined via Ziegler-Nichols (ZN), Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Imperialistic Competitive Algorithm (ICA), and Invasive Weed Optimization (IWO). Finally, the experimental verification of the topology has been done using a 600 W prototype and eZdsp F28335. As COA showed better results among other evolutionary algorithms used in this paper, we used COA parameters to observe the performance of the proposed tuning method. The experimental studies have been done under different load variations similar to the simulation studies.

Optimal Configuration of Voltage Sag Monitoring Points Considering Branch Current based on War Strategy Optimization Algorithm

In recent years, a large number of distributed power sources have been connected to the power grid, and the power quality problem has been deteriorating. In order to comprehensively evaluate the voltage information and current information and realize the guidance of power quality monitoring, this paper considers the global monitoring of fault points and obtains branch current information as much as possible. The concept of average redundancy is added to establish the optimal configuration model of voltage sag monitor. The model is solved by the war strategy optimization algorithm, and the optimal configuration simulation of IEEE39 nodes is carried out by MATLAB. The optimal configuration scheme of the monitor is obtained, and the feasibility and effectiveness of the scheme are verified.