Pole Transformer Research Articles

A study on the water content in distribution pole transformer using random forest model

This study proposes and validates an artificial intelligence (AI)-based method for estimating the water content in the insulating oil of distribution-level transformers. The methodology includes data augmentation using noise addition, outlier removal via Isolation Forest, and data normalization through square root transformation. A Random Forest (RF) model is developed to estimate water content based on the usage period of the transformer. Correlation analyses identified the usage period as the key variable affecting water content. The model demonstrated high estimation accuracy with an R-squared value of 0.83, closely aligning estimated values with measured data. This approach provides a practical solution for real-world applications, expanding the focus to distribution-level transformers and ensuring reliable estimations through validation with actual field data. Despite limitations due to a dataset comprising 100 samples of transformer usage and oil analysis data, the method shows promise for accurate transformer lifespan assessment and efficient asset management. Future research will enhance model performance by incorporating diverse environmental conditions and comparative analyses with other machine learning (ML) algorithms, aiming to optimize estimation reliability and safety for distribution-level transformers. Consistency in the methodology description and actual models used will be maintained to avoid discrepancies.

Testing of The Insulation Resistance and Turns Test Ratio (TTR) of The Distribution Transformers at PT PLN (Pesero) UP3 Sidoarjo

Electricity plays a vital role in human life and the economic growth of Indonesia. Therefore, a reliable electrical transmission and distribution system is essential. Transformers, especially in an industrial context, play a key role in power supply. Transformer maintenance is a critical step in maintaining a stable flow of electricity. This study adopts the Research and Development (R&D) method and focuses on measuring insulation resistance and voltage ratios in the context of transformer maintenance. The research was conducted at the Pole Transformer Substation (GTT) in P. Melati, Sidoarjo Regency, East Java, starting in August 2023. The research variables involve measuring the insulation resistance referring to IEC standards and measuring the voltage ratio to ensure proper transformer performance. The test results indicate that the insulation resistance in the transformer, both on the primary and secondary sides, meets the standards, demonstrating that the transformer functions well and safely. Voltage ratio measurements closely approximate theoretical calculations and fall within a tolerance of ± 0.5%. This study underscores the importance of transformer maintenance in maintaining a stable flow of electricity. Proper maintenance will prevent disruptions that can be detrimental, such as current leakage or short circuits. With good maintenance, the continuity of a reliable and safe electricity distribution service for consumers can be ensured.

Optimal Voltage Control Method for a Step Voltage Regulator Considering the Under-Load Tap Changer in a Distribution System Interconnected with a Renewable Energy Source

The voltage in distribution systems is controlled by the under-load tap changer of the substation and the pole transformer of the primary feeders. Recently, as one of the main countermeasures, a step voltage regulator is being introduced to solve voltage problems such as overvoltage phenomena in a distribution feeder interconnected with a renewable energy source and under voltage in a long-distance feeder. However, the tap of the step voltage regulator may be frequently operated due to its interdependent relationship with the under-load tap changer in the distribution system. Furthermore, given the existing operating characteristics of the step voltage regulator, it is difficult to perfectly maintain the customer voltage within an allowable limit using existing methods such as the line drop compensation method for a step voltage regulator. In addition, the existing line drop compensation method, considering the distributed generators, may be not able to control the proper voltage within an allowable limit. Therefore, in order to solve such voltage problems, this paper proposes a voltage control method for a step voltage regulator by considering the output voltage of an under-load tap changer that is operated via the line drop compensation method. In other words, to overcome the limitations of existing voltage control methods for step voltage regulators, this paper proposes an optimal control method to determine the optimal compensation rate for a step voltage regulator by considering the reverse power flow from a renewable energy source and the output voltage of the under-load tap changer of the main transformer.

Analisis Perencanaan Sistem Jaringan Distribusi Listrik dan Perkembangan Beban Pada Perumahan The Grand Kenjeran Surabaya

he electric power system is a system consisting of several parts, namely generating units, transmission units, distributionunits, and load units that are interconnected and work together to serve the electricity needs of customers according to their needs. In theprocess itself, electrical energy is distributed from the generator through the transmission network until it is received by consumers orcustomers so that in this case a related plan is needed. Planning here aims to get an optimal service flexibility so that it is able to quicklyanticipate the growth of electrical energy and how dense the load that must be served. So that the planning of the electricity distributionnetwork system must pay attention to the load conditions in the field, this is intended so that the planned distribution network system can stillwork well for the next few years. The data collection method used is in the form of field observations which aim to determine field conditionsand obtain load data that will be planned. The results of research conducted at The Grand Kenjeran Surabaya housing show that there are76 housing units to be built in this housing. The 76 housing units will be divided into 4 blocks D, E, F, G and are planned with an initial powerof 5500 VA for each housing unit along with Public Road Planning in residential areas. Taking into account field conditions, ground cablesare used as a distribution network system which includes SKTM and SKTR. The total power obtained is 435,107.5 VA and is served by 3units of distribution transformer using Pole Transformer Substation, 3 PHB-TR, 12 Main PHB, and 3 Branch PHB. The magnitude of thepossible voltage drop is around 0.97% for medium voltage, 0.3% - 0.92% for Main PHB group, 0.7% - 1.54% for Branch PHB group.

전기설비 절연진단용 원추형센서

Existing power facilities are being maintained through preventive maintenance in various ways. Among them, ultrasonic, thermal imaging, and wireless load monitoring have been mainly used for insulation diagnosis methods of pole transformers, which can be easily accessed in the vicinity. In this paper, in order to compensate for the disadvantages of the existing diagnosis method of pole-type transformers in power facilities, a conical diagnostic sensor was designed that can analyze electromagnetic waves radiated from partial discharge by modeling pole-type transformers and measure electromagnetic waves radiated to the outside. The characteristics of the sensor were confirmed through simulation. The proposed sensor was confirmed to have a return loss characteristic of less than -10dB in the 0.8~2.0GHz band, confirming that it can be used as a sensor for insulation diagnosis.

Proportional‐integral‐derivative controller‐based self‐healing of distribution system using wireless sensor networks in smart grid

SummaryThe grid is a platform of distributing the power to the consumers; if an automatic controlling and monitoring are connected with the grid, it referred to as smart grid (SG). Self‐healing is the approach of restoring the unaffected areas without affecting the system performance. The term restoration is if a fault occurs on a distribution system, it must be isolated; after that, it can be reconfigured to restore the unaffected areas. The distribution system cannot work as efficient without the self‐healing approach because it will affect the unaffected areas without any proper reason. This paper proposed a multiagent system with controlled voltage (MAS‐CV) along with self‐healing of wireless sensor network (WSN) with proportional integral derivative (PID) controller in smart grid. At initial, the magnetic flux sensors are placed in the pole transformer for detection of flux leakage. The sensed data are transferred to the distribution grid, where the multiagent system (MAS) is established to carrying out the load restoration process (i.e., self‐healing). Connection agents (CA), monitor agent (MA), main feeder agent (MFA), backup feeder agent (BFA), supporting feeder agent (SFA), and local agent (LA) are the agents presented in the paper. Each agent is communicating via agent communication language (ACL) for the restoration process; after all the loads are restored, the voltage drop of the system is controlled by the proportional integral derivative controller. The simulation results of the proposed method show that the restoration of loads is improved and number of switching is reduced with improved data transmission. Thus, the cost of the proposed method is reduced by the reduced switches. At last, the controlled power from the distribution grid is send to the consumer.

Advanced voltage control method for improving the voltage quality of low-voltage distribution networks with photovoltaic penetrations

As the number of photovoltaic (PV) power generators connected to the distribution grid increases, applications of on-load tap changers (OLTCs), power conditioning systems, and static reactive power compensators are being considered to mitigate the problem of voltage violation in low voltage distribution systems. The reactive power control by power conditioning systems and static reactive power compensators can mitigate steep voltage fluctuations. However, it creates losses in generation opportunities. On the other hand, OLTCs are installed at the bases of distribution lines and can collectively manage the entire system. However, the conventional voltage control method, i.e., the line drop compensation (LDC) method, is not designed for the case in which a large number of PV systems are installed in the distribution network, which results in voltage violations above the limit of the acceptable range. This study proposes a method to determine the optimal LDC control parameters of the voltage regulator, considering the power factor of PV systems to minimize the magnitude of voltage violations based on the voltage profile analysis of low-voltage (LV) distribution networks. Specifically, during a measurement period of several days, the voltages at some LV consumers and pole transformers were measured, and the optimal parameters were determined by analyzing the collected data. The effectiveness of the proposed method was verified through a numerical simulation study using the actual distribution system model under several scenarios of PV penetration rates. Additionally, the difference in the effectiveness of voltage violation reduction was verified in the case where all the LV consumer’s consumer voltage data measured per minute were used as well as in the case where only the maximum and minimum values of the data within the measurement period were used. The results reveal that the proposed method, which operates within the parameters determined by the voltage analysis of the LV distribution network, is superior to the conventional method. Furthermore, it was found that even if only the maximum and minimum values of the measurement data were used, an effective voltage violation reduction could be expected.

Atmospheric Corrosion Behavior of Arc Thermal Spray Zn-Al Coatings Using Accelerated atmospheric Field Test for Ten-Years

Thermal spray such as Al, Zn-Al and Al-Mg is one of the surface treatments technologies that long-term high corrosion resistance can expect. Therefore, in recent years, these coatings technologies is widely used for infrastructures such as a large-scale bridges, wind-power generating tower and a intricately shaped pole transformer. However, there are few reports about the corrosion life investigations while a sprayed coating is applied in various environment.In this study, as a basic study on corrosion life of thermal spray coatings, accelerated field test with artificial sea water for 10 years were carried out for thermal spray Zn-Al coatings. By using artificial sea water, accelerated field test accelerates corrosion due to chloride in comparison with a general atmosphere field test. Thermal sprayed specimens were prepared using an arc thermal spraying method with compressed air on carbon steel subjected surface treatment. The dimensions of specimens for corrosion field tests are 70×150×2.3mm. The edges of each specimens were protected by a coating of epoxy resin. The chemical composition (mass%) of arc spraying Zn-Al layer is 70% Zn, 30% Al. The average thickness of arc spraying layer were 150, 120 and 90µm, respectively, which was obtained by measuring the thickness of arc spraying layer from confocal laser scanning microscope. After arc spraying, sealing was not performed to penetrate the inherent pores and void of arc spraying layer. Furthermore, the average thickness 90µm of hot dip galvanized was prepared as comparison specimens of arc spraying Al-Zn coating. The scratched were made straight on a lower part center of each specimen surface. The accelerated field test were performed with artificial sea water in conformity with ASTM D1141. The artificial sea water was applied to the surface of each specimens uniformly by a brush as 24 hour is set one cycle. In additions, a general atmospheric field test was carried out for the same periods. Atmospheric corrosion behavior of arc thermal spray coating were evaluated by surface observation, X-ray diffraction (XRD), coating thickness measurement, element analyses using electro probe micro-analyser (EPMA) and electrochemical measurement.In arc spray Zn-Al coating for 10 years under accelerated field test, the granular white corrosion product were observed uniformly on the whole surface of each coating thicknesses. In hot dip galvanized coating, the powdery white corrosion product of Zn were observed uniformly on the whole surface. Furthermore, red rust was slightly observed at the edge of specimen. As a results of XRD, the corrosion product of the arc sprayed coating formed by an accelerated field test using the artificial sea water formed the product which is the same as a general atmosphere field test. In the coating thickness of Zn-Al 150µm, there is no significant difference in the coating thickness in atmospheric field tests for 10 years. On the other hand, the coating thickness of Zn-Al coating 90µm decreased. In addition, the effects of artificial sea water cannot be recognized in each thickness of arc spray Zn-Al. In EPMA analysis, corrosion products of Zn6Al2(OH)16CO3・4H2O were preferentially formed in the scratched regions of the arc spray Zn-Al surface.Consequently, arc spray Zn-Al coating maintained the high corrosion resistance in an accelerated field test for 10 years.

Decentralized BESS Charging and Discharging Control Method for Avoiding Pole Transformer Overcapacity

Decentralized BESS Charging and Discharging Control Method for Avoiding Pole Transformer Overcapacity

An Innovative Operation Strategy of ESS for Capacity Expansion of Renewable Energy and Customer Load with Electric Vehicle Chargers in Low Voltage Distribution Systems

This paper proposes an innovative operation strategy to extend the acceptance of EVC (Electric Vehicle Charger) and RES (Renewable Energy Resource) in LVDS (Low Voltage Distribution System) by introducing an ESS (Energy Storage System). In conventional LVDS, the load and RES capacity are designed not to exceed the pole transformer capacity. However, when the ESS is connected to the end of LVDS and the bidirectional power flow becomes possible, the linkable capacity of the load and renewable energy can be improved up to twice the capacity of the pole transformer. In addition, even though the power consumption of the load and the power generation of RES exceed the pole transformer capacity, it is possible to maintain the feeder capacity and grid voltage within the allowable limit by the appropriate operation of the ESS. The simulations are performed in the environment of PSCAD/EMTDC, and the ability of the proposed strategy is assessed and discussed.

A Real Distribution Network Voltage Regulation Incorporating Auto-Tap-Changer Pole Transformer Multiobjective Optimization

A number of studies realized operation of power systems are unstable in developing countries due to misconfiguration of distribution systems, limited power transfer capability, inconsistency of renewable resources integration, paucity of control and protection measures, timeworn technologies, and disproportionately topology. This study underlines an Afghanistan case study with 40% power losses that is mainly pertinent from old distribution systems. The long length of distribution systems, low-power transfer capability, insufficient control and protection strategy, peak-demand elimination, and unstable operation (low energy quality and excessive voltage deviations) are perceived pre-eminent challenges of Afghanistan distribution systems. Some attainable solutions that fit challenges are remodeling (network reduction), networks reinforcement, optimum compensation strategy, reconfiguration options, improving, and transfer capability. This paper attempts to propose a viable solution using multiobjective optimization method of auto-tap-changer pole transformer (ATCTr). The proposed methodology in terms of optimal numbers and placement of ATCTr can be known as a novel two-dimensional solution. For this purpose, a real case of Kabul City distribution system is evaluated. Simulation results indicate the effectiveness of the proposed method in reducing system losses and improving system overall performance. This approach tends to regulate the voltage deviation in a proper and statutory range with minimum number and optimum placement of ATCTrs. The proposed method is simulated using MATLAB® environment to compare and evaluate performance of the proposed network under different situations and scenarios.

A study on operating lifetime estimation for electrical components in power grids on the basis of analysis of maintenance records

This paper presents an estimation method of operating lifetime for electric power components, such as electric poles and pole transformers, utilizing massive records on their inspection and mainten...

柱上変圧器絶縁紙の高温負荷時における劣化特性

柱上変圧器絶縁紙の高温負荷時における劣化特性

Integrated planning of low-voltage power grids and subsidies toward a distributed generation system – Case study of the diffusion of photovoltaics in a Japanese dormitory town

This study proposes a novel approach for a local society to design effective diffusion scenarios for distributed energy systems, namely, the integrated planning of two design problems: the design of low-voltage power grid systems and the design of subsidy systems for the introduction of photovoltaic systems. In particular, a household photovoltaic system is considered to be a distributed generation system. Integrated planning comprises (1) upgrading of power grids and the installation of the photovoltaic system supported, at least in part, by a local government, (2) controlling the timing of photovoltaics installation and the upgrading of the power grid section by section, and (3) increasing the distributed generation capacity in low-voltage grids by upgrading a pole transformer to an auto-adjusting transformer. This study focuses on a case study of rooftop photovoltaics in a Japanese town. The proposed concept is verified through a multi-agent simulation, which supports quantitative evaluation of the proposed plans. The input data of the simulation for the behaviors and interactions of stakeholders are obtained through a questionnaire survey. A voltage analysis of a power grid is included in the multi-agent simulation. The analyses reveal that integrating the two planning problems provides synergic effects toward advancing the diffusion of photovoltaic systems.

A simplified control algorithm for utilities to utilize plug-in electric vehicles to reduce distribution transformer overloading

The introduction of electric vehicles on the power grid translates to operational challenges and opportunities of using these vehicles as distributed energy resources. This paper presents an algorithm for utilities to identify optimal scenarios for controlling electric load of plug-in electric vehicles on a neighborhood transformer, and their potential contribution to reducing overloading through controlled charging and feeding power back to the grid. A dataset of real-world driving data of 2800 vehicles in Canada is used to emulate realistic driving patterns for the simulations. The electric load of vehicles charging is estimated for different charging scenarios, battery capacities, and numbers of electric vehicle. Operational energy consumption data of single-family homes are used to predict realistic power profiles of a residential neighborhood. Different scenarios of controlling the electric load on a pole transformer are investigated for two seasons to account for ambient temperatures. By simulating the charging impacts of electric vehicles on a neighborhood transformer, the research presents a simplified control algorithm of optimal strategies to control and reduce transformer overloading. Results show that vehicle-to-grid is an effective measure to reduce peak loads, while climate condition, vehicle penetration rate, and driving profile are the key factors to the control strategies.

Electromagnetic-Thermal-Flow Field Coupling Simulation of 12-kV Medium-Voltage Switchgear

Long-term heating and excessive temperature rise will significantly affect the electrical and insulation performance of electric power equipment, causing the potential security risk. In this paper, the temperature rise situation under normal operation of a 12-kV medium voltage switchgear is studied through modeling and simulation method. First, in the simulation analysis of the whole switchgear, based on the theory of eddy-current field, gas flow field, and temperature field, the temperature rise distribution of the switchgear under the condition of natural convection and forced convection is simulated and analyzed. Then, several improvement methods are taken to reduce the temperature rise that emerges in the switchgear, including using spring contact finger structure to replace flexible connection structure, and also the optimization scheme of vacuum circuit breaker (VCB) pole and current transformer (CT). Then, simulation and research of different improvement schemes are conducted based on the electromagnetic-thermal-flow field coupling method. The simulation results of whole switchgear show that the above coupling method is very useful for the calculation of temperature rise. The simulation results also show that the spring contact structure is beneficial to reduce the temperature rise of vacuum interrupter and mechanical connection part. After the modification of design, the temperature rise conditions of the VCB pole and CT are significantly improved.

Effect of Grounding Resistance Connected to Surge Arresters in Power Distribution Lines on Lightning Surge Behavior Observed in Customer's Equipment

SUMMARYIn Japan, electric power companies have been spending large amounts of money on the construction costs and maintenance costs of low grounding resistances connected to surge arresters (Arrs) that are basically maintained below 30 Ω. In a recent study, it has been clarified that the rate of protection against direct lightning hits on distribution lines with an overhead ground wire (GW) hardly decreases, even if the grounding resistance of Arrs is high. However the installation of Arrs on a pole where a pole transformer (Tr) is mounted has not been considered, and in the case of a high grounding resistance, the lightning surge behavior observed in the customer's equipment has not yet been clarified. To examine the grounding resistance of Arrs, it is necessary to understand such behavior in the case in which the grounding resistance of Arrs is varied. In this paper, we clarified the relationship between the grounding resistance connected to Arrs and lightning surge behavior in customer's equipment. The result shows that the grounding resistance of Arrs installed on a pole with a Tr can be increased to some extent without decreasing the lightning protection level of the customer's equipment by the installation of a GW and the shortening of the interval between concrete poles with Arrs. A reduction in the cost of grounding construction can be expected.

Lightning-Induced Voltages in the Presence of Nearby Buildings: FDTD Simulation Versus Small-Scale Experiment

In this paper, we have computed lightning-induced voltages on overhead distribution lines in the presence of nearby buildings using the 3-D finite-difference time-domain method. In the simulations, four-conductor lines with surge arresters and pole transformers are considered. It appears that the presence of nearby buildings causes reduction of lightning induced voltages, as expected. The observed trend is in general agreement with that reported from the small-scale experiment by Piantini et al.

Basic Study on Islanding Detection Method for PV Systems by Harmonic Impedance Detection in Case of Including Induction Motor in Load System

SUMMARYIt is important that photovoltaic (PV) systems detect islanding caused by power system faults to ensure electrical safety. Thus we propose a novel islanding detection method which detects the harmonic impedance by injecting harmonic currents synchronized with the exciting current harmonics of the pole transformer. For the case in which an induction motor load is included in the load system, basic experiments on islanding detection and simulation analysis are conducted to verify the effectiveness of the proposed method.

벡터 회로망 분석기 측정을 기반으로 한 3상 변압기의 시간영역 펄스 신호에 대한 응답 분석

Abstract Transformer is widely used element on power system and industrial area. Especially the transformers installed at power system are exposed to an environment of arbitrary changed. Thus the prediction of degradation and the analysis of response to impulse are important. To conduct those works, the electrical characteristics of system should be analyzed, effectively. But the analysis of electrical characteristic in electric machine level such as pole and pad-mounted transformer is almost no, thus commercial VNA (Vector Network Analyzer) is used to getting the response in wide frequency range. However, the output power of VNA is usually under 10mW, so verification for effectiveness of measuring electrically large component should be conducted, firstly. Next, after getting total S-parameter of transformer, predicting impulse response can be performed in time-domain with circuit simulator. In this paper, it is introduced that verification effectiveness of VNA using transfer function from SFRA (Sweep Frequency Response Analyzer), firstly. Next, total S-parameter, six by six matix form, was built using measured 2 port S-parameter from vector network analyzer. To get the response to impulse which is defined by IEC 60060-1, time-domain simulation is conducted to ADS (Advenced Design System) circuit simulator.