scholarly journals Loss Analysis Due to Influence of Harmonics in a Distribution System

2021 ◽  
Vol 19 ◽  
pp. 402-406
Author(s):  
R.M. Soares ◽  
◽  
M. E. Oliveira ◽  
M. A. A. Freitas ◽  
G.P. Viajante ◽  
...  
Keyword(s):  
Distribution System ◽  
Test System ◽  
Electrical Network ◽  
Joule Effect ◽  
Loss Analysis ◽  
Non Linear ◽  
Network Simulations ◽  
Harmonic Components ◽  
Load Shape ◽  
Made In

The electrical system is subject to rules to guarantee a standard, where several factors can reduce its quality. This can lead to undesirable consequences, such as increased electrical losses in the distribution. As the technology advances and the constant presence of non-linear loads, the electrical network is subject to harmonic distortions that increase the effective value of the current, resulting in inconvenient effects, such as increased losses. In another words, a bigger fraction of the energy is lost by Joule effect and a smaller fraction came to the final consumers. In Brazil, the regulatory agency, in its recommendations, does not consider the effect of harmonic components, obtaining lower results for losses. So, to analyze the influence of these distortions on the operation of a distribution network, simulations were done with the test system LVTestCaseNorthAmerican, with 390 buses. Three distinct climatic cases were analysed, each with a load shape generated from fuzzy logic, all considering the presence of non-linear loads. The simulations were made in OpenDSS, and the losses demonstrated for the three situations. Finally, the importance of considering these distortions in the calculation of losses is discussed.

scholarly journals STUDY OF THE NATURE OF OVERVOLTAGES IN THE ELECTRICAL NETWORK ARISING FROM VOLTAGE TRANSFORMERS

2021 ◽  
pp. 28-36
Author(s):  
Oleksii Hanus ◽  
Kostiantyn Starkov
Keyword(s):  
Transient Process ◽  
Distribution System ◽  
Forced Oscillations ◽  
Electrical Network ◽  
Secondary Circuit ◽  
Electric Networks ◽  
Voltage Transformer ◽  
Secondary Resistance ◽  
Non Linear ◽  
Secondary Winding

A non-linear dynamic mathematical model of voltage transformer has been considered and overvoltages arising on the elements of voltage transformer equivalent circuit during transient processes have been investigated. The influence of voltage transformer secondary circuit capacitance on overvoltage multiplicity in the primary circuits and the duration of transients has been determined. The advantages of approximation of nonlinearity of voltage transformers by hyperbolic sine are used. Mathematical expressions determining the nature of changes in the forced and free components of the transient process in an electrical network with a voltage transformer have been obtained. It is shown that with the increase of the electric network capacitance the duration of the transition process damping increases and the frequency of the forced oscillations and the level of overvoltage decrease. It is proved that even small, in comparison with the primary nominal sinusoidal voltage, aperiodic components of the voltage transient process can lead to significant overvoltages during voltage transformer outages. It has been substantiated that both the secondary resistance and the switching torque influence the overvoltage multiplicity arising in the primary winding of voltage transformers. It is shown that the closed secondary winding worsens the disconnection process of non-linear inductance of voltage transformers. The values to which overvoltages increase in this case are determined. According to the results of calculations it is determined that with open secondary winding of voltage transformers the duration of transient process significantly increases. It has been found that the decrease of frequency of forced oscillations, which occurs in this case, is accompanied by an increase of currents in the primary winding of the voltage transformer, which is dangerous in terms of thermal stability of the winding insulation. It is shown, that closing the secondary winding of voltage transformers leads to significant reduction of transient damping time. It is suggested that this algorithm can be used to provide a rapid breakdown (suppression) of ferroresonant processes. The effectiveness of such a measure of stopping of ferroresonance processes as short-term shunting of secondary winding of voltage transformers has been investigated. The correlation of parameters of electric networks (capacity of busbar sections, nonlinearity of characteristics of voltage transformers, disconnection torque, etc.) at which ferroresonance process may occur and consideration of which may allow, in terms of prevention of ferroresonance processes, to identify substations (electric networks) that require more detailed research has been determined. The results of analytical studies were tested in the electric networks of JSC "Kharkivoblenergo" and used in the electricity distribution system for the selection of specific voltage transformers for certain configurations of electrical networks.

A model for calculating losses in transformer related to orders and harmonic amplitude under analysis of joule effect, eddy current and hysteresis

2020 ◽  
Vol 21 (4) ◽  
Author(s):  
Gabriel Santos ◽  
Bruno M. Laurindo ◽  
Marcio Z. Fortes ◽  
Bruno W. França ◽  
Flavio G.R. Martins
Keyword(s):  
Power Systems ◽  
Eddy Current ◽  
Distribution System ◽  
Electrical Power ◽  
Real Life ◽  
Harmonic Amplitude ◽  
Electrical Power System ◽  
Joule Effect ◽  
Non Linear ◽  
Electrical Transformers

AbstractThe electrical transformer is one of the most used equipment in electrical power systems. The non-linear electrical loads are increasing, mainly in the electrical distribution system, and the electrical power transformer is inserted in this scenario, supplying these loads. Consequently, the increasing non-linear loads affect the electrical transformers and their factors directly, like in the dependency between temperature and harmonic increase. Therefore, to study the influence of harmonics in the transformer’s temperature, one should understand how it will behave with these changes in the electrical power system. For this reason, in this article, numeric simulations and tests were performed to predict the transformer temperature behavior. The proposal is a numeric technique for coupling two equations, thermal and electromagnetic, of an electrical transformer, considering heat sources regarding joule, eddy current, and hysteresis effect. To evaluate the numeric simulation and understanding the electrical transformer behavior in real-life, tests with specific harmonic orders (3rd, 5th, and 7th) and their combinations and a test with less than 10% total harmonic distortion, according to IEEE 519 standard were performed. It is verified that the electrical transformer temperature rises with the increase in harmonic amplitude and its orders. Results show that the industry must be aware of the effects of the increasing non-linear loads when designing the next generation of transformers concerning their durability and lifetime.

Imprecision of Laboratory Determinations and Diagnostic Accuracy: Theoretical Considerations

1974 ◽  
Vol 13 (03) ◽  
pp. 151-158 ◽  
Author(s):  
D. A. B. Lindbebo ◽  
Fr. R. Watson
Keyword(s):  
Mathematical Model ◽  
Diagnostic Accuracy ◽  
Diagnostic Process ◽  
Clinical Laboratories ◽  
Non Linear ◽  
Theoretical Considerations ◽  
Made In

Recent studies suggest the determinations of clinical laboratories must be made more precise than at present. This paper presents a means of examining benefits of improvement in precision. To do this we use a mathematical model of the effect upon the diagnostic process of imprecision in measurements and the influence upon these two of Importance of Diagnosis and Prevalence of Disease. The interaction of these effects is grossly non-linear. There is therefore no proper intuitive answer to questions involving these matters. The effects can always, however, be calculated.Including a great many assumptions the modeling suggests that improvements in precision of any determination ought probably to be made in hospital rather than screening laboratories, unless Importance of Diagnosis is extremely high.

Evaluation of the disinfection potential of low chlorine concentrations in tap water using immobilised enterococcus faecium in a continuous flow device

1997 ◽  
Vol 35 (11-12) ◽  
pp. 77-80 ◽  
Author(s):  
A. Wiedenmann ◽  
M. Braun ◽  
K. Botzenhart
Keyword(s):  
Distribution System ◽  
Enterococcus Faecium ◽  
Continuous Flow ◽  
Tap Water ◽  
Test System ◽  
Batch Experiments ◽  
Membrane Filters ◽  
Upper Limit ◽  
Flow Device ◽  
Faecal Streptococci

A simple continuous flow device in which bacteria were immobilised on membrane filters and flushed with tap water with free chlorine residuals of 0.05, 0.1, 0.2 and 0.4mg/L at pH 7.7 and 10°C, has been used for disinfection experiments with faecal streptococci. A 99.99% reduction of Enterococcus faecium was observed between 3.4–5.2min (0.05mg/L), between 2.8–4.1min (0.1mg/L), between 1.7–3.1min (0.2mg/L) and between 0.8–2.1min (0.4mg/L). CT-products covered a range of 0.17 (0.05mg/L, lower limit) up to 0.85mg/L/min (0.4mg/L, upper limit). The test system is suggested as a more reliable alternative to batch experiments when the disinfection potential of low chlorine concentrations acting for several minutes has to be evaluated. The system cannot be used to demonstrate exact reduction kinetics but it allows the calculation of CT values and the evaluation of the disinfection potential of chlorinated water at any point of a distribution system where initial chlorine concentrations may have already remarkably declined.

scholarly journals Distribution system power quality compensation using a HSeAPF based on SRF and SMC features

2021 ◽  
Author(s):  
Akram Qashou ◽  
Sufian Yousef ◽  
Abdallah A. Smadi ◽  
Amani A. AlOmari
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Reactive Power ◽  
Sliding Mode ◽  
Distribution Network ◽  
Harmonic Distortion ◽  
Phase Locked Loop ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Non Linear

AbstractThe purpose of this paper is to describe the design of a Hybrid Series Active Power Filter (HSeAPF) system to improve the quality of power on three-phase power distribution grids. The system controls are comprise of Pulse Width Modulation (PWM) based on the Synchronous Reference Frame (SRF) theory, and supported by Phase Locked Loop (PLL) for generating the switching pulses to control a Voltage Source Converter (VSC). The DC link voltage is controlled by Non-Linear Sliding Mode Control (SMC) for faster response and to ensure that it is maintained at a constant value. When this voltage is compared with Proportional Integral (PI), then the improvements made can be shown. The function of HSeAPF control is to eliminate voltage fluctuations, voltage swell/sag, and prevent voltage/current harmonics are produced by both non-linear loads and small inverters connected to the distribution network. A digital Phase Locked Loop that generates frequencies and an oscillating phase-locked output signal controls the voltage. The results from the simulation indicate that the HSeAPF can effectively suppress the dynamic and harmonic reactive power compensation system. Also, the distribution network has a low Total Harmonic Distortion (< 5%), demonstrating that the designed system is efficient, which is an essential requirement when it comes to the IEEE-519 and IEC 61,000–3-6 standards.

scholarly journals Leveraging a Genetic Algorithm for the Optimal Placement of Distributed Generation and the Need for Energy Management Strategies Using a Fuzzy Inference System

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 172
Author(s):  
Sunny Katyara ◽  
Muhammad Fawad Shaikh ◽  
Shoaib Shaikh ◽  
Zahid Hussain Khand ◽  
Lukasz Staszewski ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Energy Management ◽  
Fuzzy Inference System ◽  
Distribution System ◽  
Fuzzy Inference ◽  
Management Strategies ◽  
Test System ◽  
Optimal Placement ◽  
Inference System ◽  
Simulated Environment

With the rising load demand and power losses, the equipment in the utility network often operates close to its marginal limits, creating a dire need for the installation of new Distributed Generators (DGs). Their proper placement is one of the prerequisites for fully achieving the benefits; otherwise, this may result in the worsening of their performance. This could even lead to further deterioration if an effective Energy Management System (EMS) is not installed. Firstly, addressing these issues, this research exploits a Genetic Algorithm (GA) for the proper placement of new DGs in a distribution system. This approach is based on the system losses, voltage profiles, and phase angle jump variations. Secondly, the energy management models are designed using a fuzzy inference system. The models are then analyzed under heavy loading and fault conditions. This research is conducted on a six bus radial test system in a simulated environment together with a real-time Power Hardware-In-the-Loop (PHIL) setup. It is concluded that the optimal placement of a 3.33 MVA synchronous DG is near the load center, and the robustness of the proposed EMS is proven by mitigating the distinct contingencies within the approximately 2.5 cycles of the operating period.

scholarly journals Laboratory Test Bed for Analyzing Fault-Detection Reaction Times of Protection Relays in Different Substation Topologies

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2482 ◽  
Author(s):  
Goran Jurišić ◽  
Juraj Havelka ◽  
Tomislav Capuder ◽  
Stjepan Sučić
Keyword(s):  
Distribution System ◽  
Information Exchange ◽  
Transition Period ◽  
Reaction Times ◽  
Energy Transition ◽  
Test System ◽  
Protection System ◽  
International Electrotechnical Commission ◽  
Test Bed ◽  
Iec 61850

Visions of energy transition focus on activating end users, meaning that numerous flexible-distribution network-level devices become active participants in power-system operations. This implies a fast, reliable, and secure exchange of data, enabling the distribution-system operators to maintain, or even improve, the quality and delivery of service. With the introduction of the International Electrotechnical Commission (IEC) 61850 standard, the path is set for a single communication topology covering all substation levels. The standard has the potential to change the way substations are designed, built, tested, and maintained. This means that the key segment of the substation, its protection system, will go through a transition period with the end goal of having a digitized substation where all information exchange is performed over an Ethernet communication bus. This paper analyzes the performance impact of the IEC 61850-9-2LE on the protection system. To do this, a laboratory hardware-in-the-loop test setup was developed representing traditional-, hybrid-, and digital-substation topology. The setup serves to simulate faults and create transient waveforms in an extended IEEE 123-node test system, which is then used to detect the reaction times of protection relay devices. To verify the results, a significant number of tests was performed clearly showing the benefits of digitalizing the distribution system.

scholarly journals Fractional order proportional-integral controller applied to a back-to-back converters

2018 ◽  
Vol 210 ◽  
pp. 02013
Author(s):  
Manuel A. Duarte-Mermoud ◽  
Juan-Carlos Travieso-Torres ◽  
Tedy A. Crespo-Herrera
Keyword(s):  
Fractional Order ◽  
Synchronous Generator ◽  
Power Converter ◽  
Electrical Network ◽  
Proportional Integral ◽  
Constant Torque ◽  
Pi Controllers ◽  
Network Simulations ◽  
Integral Controller ◽  
Proportional Integral Controller

The use of fractional order proportional-integral (FOPI) controllers, applied to back-to-back (BTB) power converters is proposed and studied in this paper. A comparative study with the integer order proportional-integral (PI) controllers, traditionally used for this purposes, is performed and the result are discussed. The BTB power converter is connected between a permanent magnet synchronous generator (PMSG) -which is moved by a turbine placed in line with a mineral pipeline for energy recovery purposesand the electrical network, to inject the recovered energy through a voltage control into the electrical network. Simulations under normal conditions (constant torque) as well as under variable torque variations are studied, representing different possible operating scenarios for the generator.

scholarly journals Influence of field-dependent critical current on harmonic AC loss analysis in HTS coils for superconducting transformers supplying non-linear loads

Cryogenics ◽  
2021 ◽  
Vol 113 ◽  
pp. 103234
Author(s):  
Mohammad Yazdani-Asrami ◽  
S. Asghar Gholamian ◽  
Seyyed Mehdi Mirimani ◽  
Jafar Adabi
Keyword(s):  
Critical Current ◽  
Ac Loss ◽  
Loss Analysis ◽  
Field Dependent ◽  
Non Linear

scholarly journals A day-ahead hybrid optimization algorithm for finding the dispatch schedule of VPP in a distribution system

2020 ◽  
Author(s):  
Seyed Iman Taheri ◽  
Lucas Lima Rodrigues ◽  
Mauricio B. C. Salles ◽  
Alfeu Joãozinho Sguarezi Filho
Keyword(s):  
Open Source Software ◽  
Optimization Algorithm ◽  
Distribution System ◽  
Hybrid Optimization ◽  
Genetic Optimization ◽  
Hybrid Optimization Algorithm ◽  
System Operator ◽  
Voltage Deviation ◽  
Ieee Standard ◽  
Load Shape

Distributed renewable generations such as photovoltaic units are electricity generators for installing close to the loads on the distribution system. In this paper, the dispatch function of a non-centralized Virtual Power Plant (VPP) with having a photovoltaic unit in each bus is considered to optimize. This dispatch function is assigned based on the predicted load shape of the next day. A new day-ahead hybrid optimization algorithm is presented to optimize the dispatch function. The proposed algorithm implements a new hybrid combination of Particle Swarm Optimization (PSO) and Genetic Optimization (GA) algorithms simultaneously to benefit both algorithms’ advantages. The objective function is the optimization of the voltage deviation of the VPP. The suggested algorithm is executed on a 13-bus-radial IEEE standard VPP system using MATLAB software coupled with open-source software called Open-DSS. The results show the importance of the proposed algorithm to optimize the voltage deviation of the VPP. The superiority of the proposed algorithm is related to the accuracy and calculation velocity in comparison with the other tested evolutionary algorithms. The Distribution System Operator could map and move towards its full benefits of the increasing integration of DGs with a strategic placement that could keen prosumers on integrating these actions.

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