Electric Power Distribution Systems Research Articles

Three-phase model of SCIG-based variable speed wind turbine for unbalanced DSLF analysis

Steady state performances of the electric power distribution system are normally assessed or evaluated based on load flow analysis. To properly carry out the analysis, a valid steady state load flow model of each distribution system component, including the wind power plant (WPP), needs to be developed. The present paper proposes a method for modeling and integrating squirrel cage induction generator (SCIG)-based variable speed WPP into a three-phase unbalanced distribution system load flow (DSLF) analysis. The proposed method is based on a single-phase T-circuit model of fixed speed WPP, which has successfully been applied to balanced electric power systems. In the present work, the single-phase T-circuit model is extended and modified to be used in steady state load flow analysis of three-phase unbalanced distribution systems embedded with SCIG-based variable speed WPP. Results of the case studies confirm the validity of the proposed method.

SISTEM KETIDAK SEIMBANGAN BEBAN PADA JARINGAN TEGANGAN RENDAH MENGGUNAKAN ALAT PHB – SR ( PERALATAN HUBUNG BAGI SAMBUNGAN RUMAH) DI PT. PLN PERSERO ULP BINJAI TIMUR

Load imbalance in an electric power distribution system often occurs in the field. This is a single-phase load on Low Voltage Network customers that is not the same due to the large number of additional electrical loads that do not pay attention to system load imbalances. As a result of this imbalance, a current appears in the transformer neutral. The current flowing in the neutral of the transformer causes losses, namely losses due to neutral current in the neutral conductor of the transformer and losses due to neutral current flowing to the ground. By realizing PHB SR (Home Connection Equipment) is able to balance the load on the Low Voltage Network. balance the load on the Low Voltage Network periodically and continuously so as to reduce technical shrinkage (losses), simplify the Connection Field in the technical connection of the Low Voltage Network. Connection in the technical connection of the House Connection (SR) on the pole, improve the aesthetics and neatness of the Network System.

Development of portable deterioration diagnosis device for oil filled transformers based on near‐infrared spectroscopic information

AbstractA transformer plays a key role in electric power distribution system; therefore, when the transformer fails, several electrical components may get affected. As a result, diagnosing the deterioration of transformers is important for the management of electric power distribution system. The furfural content in the insulating oil of a transformer is widely used as an indicator of deterioration because furfural is generated by the decomposition of insulating paper. However, analyzing the furfural content is time consuming because of the requirement of a professional and the complexity of the diagnosis process. In this study, we propose a novel method for analyzing the amount of furfural in the insulating oil based on near‐infrared spectroscopic data obtained using the developed portable spectrometer, which can be used for the on‐site analysis at transformer installation sites. We selected wavenumbers with high correlation coefficients between the furfural content of oil and the spectroscopic data and estimated the furfural content by partial least squares regression. The results suggest that the furfural content can be analyzed in a few minutes using a small amount of oil through a portable diagnostic device.

Analysis of Load Imbalance in Tarakan Distribution Transformer of PT PLN (Persero) Sukarami Customer Service Unit

Load imbalance in an electric power distribution system always occurs and the cause of this imbalance is unbalanced single-phase loads on low voltage network customers. As a result of this load imbalance, a current arises in the neutral of the transformer, which can cause power losses. The aim of the research is to analyse the load imbalance of the Distribution Transformer PC0044, PC0074, PC0088, PC0129, PC1319 on the Tarakan Feeder of PT PLN (Persero) Sukarami Customer Service Unit. The results of the research show that the highest peak load percentage occurs on the PC1319 Distribution Transformer, namely 93.0874%, and based on PLN ED Decree No. 0017.E/DIR/2014, transformer loading. The largest percentage of load imbalance occurs in the PC0044 Distribution Transformer, namely 38.0952%, and based on PLN ED Decree No. 0017.E/DIR/2014, the current imbalance between phases is included in the bad category because the load imbalance is ≥ 25%. The largest percentage of power losses due to neutral current in the transformer neutral conductor occurs in the PC0044 Distribution Transformer, namely 2.6737%, and based on PLN ED Decree No. 0017.E/DIR/2014, the neutral current TR is included in the good category because the power losses due to the neutral current in the transformer neutral conductor are <10%. The largest percentage of power losses due to neutral current flowing to the ground occurs in the PC0044 Distribution Transformer, namely 5.0784%.

Multilevel Aircraft-Inverter Design Based on Wavelet PWM for More Electric Aircraft

This paper proposes a comprehensive power system designed for the use of a more electric aircraft power distribution system. Instead of traditional Nicad battery solutions as the energy source of the aircraft power system, lithium battery structures, which are a recent and promising solution in the field of aviation power systems, are modeled and analyzed. In this study, a WPWM-based, single-phase, multi-level pure sine wave static aircraft-inverter system is designed and integrated to improve the performance of conventional aircraft power systems. In the designed power system, a boost converter structure is proposed that boosts 28 VDC-to-270 VDC voltage coming from the lithium–ion battery pack and can reach a steady state in 0.032 s. The performance of the modeled WPWM-based aircraft-inverter system, compared to SPWM Bipolar and Unipolar switching techniques commonly used in single-phase inverter designs, reveals a THD reduction of approximately 27% with WPWM, resulting in a THD value below 2% for both load current and load voltage. As a result of the study, a power system that will enable the aircraft avionics, ventilation, and navigation systems to perform better than conventional power systems and comply with aircraft electric-power characteristic standards has been designed and detailed.

Semi-autonomous mobile robot coupled to a drone for debris removal from high-voltage power lines

The importance of electrical energy in human life has grown considerably, resulting in a great surge in demand for this energy form. As a consequence, numerous power transmission lines are continuously under construction. Periodic inspections and maintenance of equipment and accessories associated with these lines are crucial to ensuring their proper functioning. Thus, this paper introduces a novel mobile robot designed to remove debris from high-voltage power lines up to 138 kV. This robot offers several advantages, including reduced costs related to maintenance operations that require specialized human labor, increased task efficiency, and reduced risks to human physical integrity by eliminating the need for manual tasks in direct contact with high-voltage lines. This paper outlines the development and validation of a novel robot that can be integrated with a drone for transportation, bringing an innovation to the format for carrying out maintenance in the electric power distribution system. After reviewing robots applied to debris removal, our study presents the novel robot's design and control system. The robot was developed and tested in both simulated and real environments, proving to be efficient and cost-effective in improving debris removal from high-voltage lines while ensuring linemen's safety.

Operational Analysis of an Axial and Solid Double-Pole Configuration in a Permanent Magnet Flux-Switching Generator

There are two main beneficial characteristics that doubly salient permanent magnet (PM) electrical machines present for aircraft applications: armature windings and PMs excitation sources placed on the stator side (maintenance and thermal management), and having a clear-cut rotor without PMs or excitation windings (vulnerable at high speeds due to associated centripetal mechanical stresses). Within this framework, a doubly salient permanent magnet (DSPM) generator was conceived by optimizing the stator size and rotor structure to minimize the torque ripple and maximize the root-mean-square (RMS) voltage value per turn of each generator phase. Firstly, a comparison between the 2D and 3D finite element method (FEM) models is made considering the results of 3D finite element analysis (FEA) as our benchmark in order to understand the accuracy of the 2D results against our benchmark model, the 3D one. A multi-objective design strategy based on a 2D FEA is made, it is set to have characteristics closest to optimal for a Boeing 767 turbine, that is, the necessary electromotive force for a required power of 90 kW at 3000 rpm, feeding a simplified Boeing 767 electrical power distribution system. The results show that the machine could not deliver the required power at 3000 rpm since the 2D FEA demonstrates that the 2D model gives optimistic results when compared with the 3D FEM model. However, with a 3D FEA of the machine feeding the aircraft load, it was seen that the machine’s efficiency is 92%, suggesting that this machine can be a plausible solution.

Astrophysics-based transit search optimization heuristics for parameter estimation of multi-frequency sinusoidal signals

This study investigates an astrophysics-based Transit search optimization algorithm (TSOA) for solving a challenging engineering problem. This innovative strategy uses the fundamentals of physics to improve the accuracy and efficacy of problem solving techniques. Harmonic distortions in power systems have become a massive challenge because of the nonlinear loads associated with the electrical power distribution system. Overheating of the equipment, motor failure, capacitor failure, and improper power metering are all issues caused by harmonic distortion. A new examination of the causes and consequences of these issues, as well as the status of hardware and software available for harmonic evaluation, is necessary in light of the unprecedented advancements in power electronic devices and their integration at all levels in the power and energy system. In order to estimate phase and amplitude simultaneously with a specified frequency, an objective function of power system harmonics is created. Keeping in mind the adverse effects of harmonics, parameter estimation is carried out under various conditions by taking different particle sizes and signal-to-noise ratios. TSOA proved its efficacy for both phase and amplitude parameters under different situations and precisely estimated the harmonics signal up to an accuracy of 1.1648E–15. Two harmonic signals were taken in this research work, and the best MSE values achieved are 9.748E–4, 8.287E–07, 6.157E–10, and 1.165E–15 for 30, 60, 90, and 150 dB noise, respectively, under case study 1 while varying the particle size from 50 to 450. The results for case study 2 proved to be best up to 7.373E–16, and no significant change occurred by increasing the generations above 500. The proposed study would be a step further in developing a more accurate and robust computing platform for robust estimation of harmonics arising in power and energy systems.

Hotspot temperature analysis of distribution transformer under unbalanced harmonic loads using finite element method

In an electrical power distribution system, harmonic distortion is the most prominent power quality problem that causes long-term adverse effects such as failure of distribution transformers. Considering that most transformer problems are caused by heat losses due to the presence of harmonics, it was decided to use a numerical method with the highest accuracy, finite element method (FEM) to analyze the hot spot temperature (HST) of the thermal distribution transformer model. Through the use of COMSOL Multiphysics software, three phases of unbalanced harmonic loads are considered, which contribute to three different total harmonic distortion current (THDI) levels and five different insulation temperature classes. Using the IEEE C57.110-2018 guidance, the simulation outputs are then verified with HST results from the HST mathematical model. The findings indicated that with the increased loadings, the unbalanced harmonic currents have impacted the HST increment and distinguished the HST values between the phases.

Protection System of the Electric Power Distribution System of Notre Dame of Marbel University, Koronadal City, South Cotabato

A vital instrument for evaluating the effectiveness and safety of electrical systems is the power system analysis. Protecting people and equipment from errors is part of this. These assessments examine the load, the equipment, and the foreseeable needs. A lack of short-circuit current protection can harm equipment and endanger workers. The main goal of this study is to assess if the various protection devices utilized in the Notre Dame of Marbel University’s Main Campus electrical system comply with the established standards. Through a real survey (opening panel boxes and reviewing the original Electrical Plan), the researcher will ascertain the various protection devices in operation. Two approaches are used to test for short circuits: the MVA method and the per-unit method. When determining fault current, only the three-phase fault is considered in the calculation since it is the one having the largest fault value. Aside from the mentioned, the transformer rating calculations were also done. The resulting data will then be compared to the actual protective devices installed in the building. Short circuit currents must be less than the Kilo Ampere Interrupting Capacity rating of the installed protective devices. In conclusion, after conducting a thorough analysis of the current loading schedule and comparing the results obtained through the MVA and per-unit methods, it is evident that the various installed Overcurrent Protective Devices are operating safely. The calculations revealed a substantial disparity of 35.57% between the two methods. Furthermore, the t-test conducted on paired data confirmed the statistical significance of the differences between these two approaches. With this, the researcher recommends conducting a separate study to verify branch circuit calculations, implementing primary metering, and prioritizing the rehabilitation of the Pantua and Alunan lines to enhance the safety and reliability of the electrical system, particularly in tracing complex branch circuits. Keywords: power system analysis, MVA method, per unit method, comparative analysis, Notre Dame of Marbel University

Sympathetic Trip Analysis in Distribution System of PLTU and PLTA Nagan Raya

At the PT unit, PLN (Persero), there is an issue with the 20 kV electric power distribution system, such as feeder disruption. As a result, many felt sorry for the feeders of PLTA Krueng Isep and PLTU Nagan Raya, whose consumers were without power for extended periods of time. Of course, it can impact how well a business performs, particularly in terms of service and electrical revenue. In order to examine the causes of Sympathetic, study is required. In order to conduct the research, data on disturbances are gathered, tests are run, simulation results are analyzed using the ETAP application, non-directional relays are swapped out for directional relays, protection coordination is reset, and evaluation is done. The findings of this study have the potential to improve performance at PT. PLN (Persero) and decrease or even completely eradicate the incidence of sympathy in the 20 kV distribution network.

Metaheuristic‐based graded objective function strategy for optimal thyristor‐controlled series capacitors estimation in weak distribution systems with uncertain distributed generation

AbstractThis study proposes an optimal approach for enhancing the quality of a weak electrical power distribution system by utilizing thyristor‐controlled series capacitors (TCSC). The proposed approach considers various system components, including shunt capacitors and distributed generators that rely on renewable energy sources, which are characterized by uncertainty due to changing weather conditions. The proposed system maximizes the benefits of these components by updating its parameters to improve the distribution power system's quality under all operating conditions, which change due to the varying energy generated by the distributed generators and load changes. The optimal TCSC values are calculated for all operating conditions using the Hyper‐Spherical Search with graded objective functions management strategy (HSSA‐GOFMS) algorithm. The GOFMS converts all restrictions into objective functions with limits and prioritizes the search for objectives according to a sequential system of priorities. This strategy prevents the possibility of non‐convergence. The results demonstrate the effectiveness of the proposed approach in improving the performance quality of a weak electrical distribution system. The proposed strategy achieves the target voltage level limits within nominal values, even with the interference of the system with generators distributed at variable power levels. Furthermore, the proposed approach enhances the performance quality of the system under a wide range of load changes.

Design of 3-Phase Load Dividing Automatic System with Naive Bayes Method

The electric power distribution system is a process for distributing electricity from a 150 kV electric power transmission system to consumers, both 20 kV consumers and 380/220 V consumers. The problem that often occurs in the electric power distribution system at PT.X is load imbalance due to the different consumption power on each phase, so a neutral current appears. The current flowing in the neutral phase will cause power losses. Based on these problems, a load balancing device was made for a three-phase network with the standard SPLN No. 17 of 2014, namely the magnitude of the value of the current imbalance between the phases may not exceed 25%. This tool is also equipped with an overcurrent protection system and a tapping phase limitation system to support the performance of the load-balancing device on a three-phase network. The method used is the Naive Bayes method. The naïve Bayes method calculates the current parameters in the R, S, T, and N phases. The classification results will be used as a reference for activating the tapping phase system and the protection system. This system uses Internet of Things technology to monitor neutral current, current and voltage values in phases R, S and T, and power loss values. Based on the test results, when there is an imbalance of 30.20%, a neutral current of 1.20A appears, causing a power loss of 0.17W. After the tapping phase is carried out, the percentage of unbalance is reduced to 12.20%, the neutral current is 0.45A, and the power losses are 0.02W.

Analysis of fault current contributions from small‐scale single‐phase photovoltaic inverters and their impacts on the protection of electric power distribution systems

AbstractThis paper presents an analysis of the fault current contributions of small‐scale single‐phase photovoltaic inverters under grid‐connected operation and their potential impact on the protection of distribution systems. To conduct this analysis, an autotransformer‐based voltage dip generator is proposed as a means to test the photovoltaic inverters' contribution to short‐circuit currents. Laboratory tests are then performed to obtain the short‐circuit current contribution of eight single‐phase photovoltaic inverters. Using the short‐circuit current data obtained, a behaviour model is developed and simulated on Matlab‐Simulink. The model is then applied to a real distribution system and case studies are conducted to simulate the potential impacts on the protection system. Results indicate that while the massive penetration of small‐scale single‐phase photovoltaic inverters can alter the protection system's operating time, the impacts are not significant. Only in very specific scenarios, such as events related to high impedance faults, some impact can be observed. In these situations, the presence of photovoltaic inverters further complicates the already difficult task of identifying high impedance faults through conventional overcurrent protections. This study provides valuable insights into the integration of photovoltaic inverters into distribution systems, and can aid in the development of effective protection measures for future grid designs.

Multi-objective optimization of planning single-tuned harmonic filter utilizing interactive forest algorithm

This paper proposes an interactive forest algorithm for planning single-tuned harmonic filters for electric power distribution systems. The planning of harmonic filters is a complex problem that must consider multiple objectives, including minimizing the total cost of installed filters and the individual and total harmonic distortion while adhering to operational constraints, such as the voltage drop, the current loading and the harmonic limits. Moreover, system perturbations must be considered, such as frequency variations. This paper proposes a new method for multi-objective optimization of planning single-tuned harmonic filters utilizing the proposed interactive forest algorithm with a non-differentiable multi-objective function involving continuous and discrete variables. A multi-objective optimization technique based on the proposed interactive forest algorithm is proposed. In the interactive approach, planners set expectations for each objective and use the forest algorithm to figure out the optimization problems. The results of the Pareto Front are analyzed and the answers are searched through the interactive process to identify a solution that meets the planner’s expectations, allowing for practical compromise or satisfactory solutions. A case study is reported to show the superiority of the proposed method.

Pengaruh Pembebanan Terhadap Efisiensi Transformator Distribusi Di PT. PLN (Persero) UP3 Garut

Transformer efficiency is defined as the ratio of the incoming power to the outgoing electric power. Even so the ideal transformer has 100% efficiency, this ideal transformer does not exist, because the energy that goes out is always less than the energy that goes in, meaning that there is energy loss. Load imbalance in an electric power distribution system always occurs and the imbalance is in single-phase loads in low-voltage network subscribers. Due to the load imbalance, a current appears in the neutral of the transformer. Perform analysis and compare efficiency. Analysis of used load capacity is not efficient. Analysis of the results of current and voltage measurements at the substation to obtain efficiency, and transformer losses in day and night conditions using LWBP and WBP methods. In this study, observations were made regarding the transformer efficiency analysis using the Outside Peak Load Time (LWBP) and Peak Load Time (WBP) methods. The LWBP method is carried out during the day for 20 hours, while the WBP method is carried out at night for 4 hours, from 18.00 to 22.00. Then measurements were made at PT. PLN (Persero) UP3 Garut. For the highest percentage of loading which is close to the standard of 80%, namely the afternoon loading at the PDDK substation, which is 50.93%, the load used is 50.93 kVA. The night load at the CITL substation is 77.49%, the load used is 77.49 kVA. For the lowest percentage of loading that deviates from the standard 80%, namely the daytime loading at the SJRK substation, which is 16.32%, the load used is 16.32 kVA. The night load at the SJRK substation is 21.52%, the load used is 21.52 kVA. Based on observations, it is not efficient because the unused load is very large, it is recommended to use a smaller transformer capacity. The highest efficiency in the LWBP method is at the CITK substation 97.87%, the lowest at the PDDK substation 94.55%. The highest efficiency in the WBP method is at SJRK substations 95.5%, the lowest at PDDK substations is 92.1%.

Constant Voltage Model of SCIG-Based Variable Speed Wind Power Plant for Load Flow Analysis

In recent years, the application of variable-speed wind power plants (WPPs) has become more and more popular and surpassed fixed-speed WPPs. This popularity is mainly because variable-speed WPPs are much more efficient in capturing or extracting wind energy than fixed-speed WPPs. Due to its relatively cheaper cost, the use of SCIG (Squirrel Cage Induction Generator)-based variable-speed WPP is currently increasing. This type of WPP is usually equipped with a power electronics converter to obtain a broader range of variable-speed operations. Modeling the power system components is undoubtedly necessary for performing the system analysis (including load flow analysis). This paper discusses the steady-state model of SCIG-based variable-speed WPP for load flow analysis of electric power distribution systems. The proposed model can be used for SCIG-based variable-speed WPP with voltage control operating mode. The model was developed based on formulas that calculate the turbine mechanical power input and the WPP electrical power output. This paper also presents a case study in which the proposed model is applied to a representative electric power distribution system.

A novel cost-based optimization model for electric power distribution systems resilience improvement under dust storms

In the recent years, dust storms (DSs) pose a serious threat to critical infrastructure such as power distribution networks (PDNs). During DSs, the contamination of insulators, increases the possibility of damage to the PDNs insulation system and flashover induced power outage may occur. Power outages disrupt the performance of other urban infrastructures and, in addition to heavy financial losses, cause public dissatisfaction. Although this issue is of particular importance in areas with humid climate, a few studies have been reported on PDNs resilience improvement against DSs. This paper proposes a novel cost-based optimization model to make PDNs more resilient to DSs considering uncertainties. The proposed model is based on the two-stage stochastic mixed-integer programming (SMIP). In the first stage, decisions are made to equip repair crews (RCs) with insulator washing machines, hardening distribution lines with silicone-rubber insulators (SIs), and deploy backup distributed generators (DGs). Decisions in the second stage include network reconfiguration, RCs routing, DGs power dispatch, and load shedding as the critical options for PDN outage management during/after DSs. Case studies are evaluated in the IEEE 69-bus test system and a real 209-bus PDN in Khuzestan province, a coastal province in southwestern Iran. The simulation results at different budget levels have confirmed the efficiency of the proposed model for cost-optimal resilience enhancement planning of PDNs against DSs.

Towards an interpretable data-driven switch placement model in electric power distribution systems: An explainable artificial intelligence-based approach

The fault management process is facilitated by equipping power distribution systems with automated devices, especially remote-controlled switches (RCSs). Although RCS plays a key role in improving the system's reliability, it imposes significant investment, installation, and maintenance costs. Hence, RCSs should be optimally located in distribution feeders for the highest profit. In previous works, reliability-oriented mathematical optimization models have been formulated to reach this goal. However, the number of test solutions exponentially grows with the problem size to find the globally optimal solution. This paper uses machine learning to propose a scalable and easy-to-implement model for optimal switch placement in real power distribution systems. At first, the features of candidate points for installing RCSs are introduced. Then, a learning model is applied to deeply explore the relationship between these features and optimal locations for installing RCSs. After training, the learning-based surrogate model directly determines the optimal RCS placement strategy in real power distribution systems by leveraging knowledge gained from past experiences. Simulation results demonstrate that the proposed surrogate model is approximately 29 times faster than the integer programming-based mathematical model, without a significant loss of accuracy, when implemented on a modified 11 kV network connected to Bus 4 of the Roy Billiton test system. This paper also employs explainable artificial intelligence (XAI) tools to select the most important features, where the Hamming loss is decreased by approximately 5%.

AVALIAÇÃO DA INFLUÊNCIA DA INSERÇÃO DA GERAÇÃO DISTRIBUÍDA EM SISTEMAS DE DISTRIBUIÇÃO DE ENERGIA ELÉTRICA

This paper seeks to evaluate the impacts arising from the insertion of distributed generation (DG) in electrical power distribution systems. In this circumstance, using the OpenDSS computational tool, simulations of four different scenarios were carried out, varying the DG penetration levels as a function of the total feeder load, considering a specific point of operation. Finally, the same feeder was simulated with photovoltaic generating sources distributed in bars next to the loads, in order to analyze the temporal characteristic of solar generation as a function of demand. Through the simulations, it was possible to analyze, interpret and highlight the impacts that the insertion of DG produces in the electrical power distribution systems. It was evident that the increase in DG penetration led to an improvement in the feeder voltage profile, power flow inversion and reduction of electrical losses in the feeder. It should be noted that the insertion of DG from renewable sources is a Brazilian reality and a path to be followed, since the diversification of the energy matrix in line with the use of new technologies, such as smart grids, will provide electrical power systems with greater safety, operational efficiency and quality in the product delivered to consumers.