Transformer Station Research Articles

A cohort study on adult hematological malignancies and brain tumors in relation to magnetic fields from indoor transformer stations.

Extremely low frequency (ELF) magnetic fields (MF) have been classified as possibly carcinogenic. This classification was mainly based on studies indicating increased risk of leukemia in children living near power lines. Increased risks of adult hematological malignancies and brain tumors have also been reported, but the results are mixed. We assessed incidence of adult hematological malignancies and brain tumors associated with residential MF exposure. All cohort members had lived in buildings with indoor transformer stations (TS). MF exposure was assessed based on apartment location. Out of the 256,372 individuals, 9,636 (165,000 person-years of follow-up) living in apartments next to TSs were considered as exposed. Associations between MF exposure and neoplasms were examined using Cox proportional hazard models. The hazard ratio (HR) for MF exposure≥1 month was below one for most hematological neoplasms (HR for any hematological neoplasm: 0.75; 95% CI: 0.54-1.03), and decreased with increasing duration of exposure (HR for exposure≥10 years: 0.47; 95% CI: 0.22-0.99). However, the HR for acute lymphocytic leukemia (ALL) was 2.86 (95% CI: 1.00-8.15), based on 4 exposed cases; the risk increased with duration of exposure (HR for exposure ≥3 years: 3.61; 95% CI: 1.05-12.4) and was particularly associated with childhood exposure (2 exposed cases, HR for exposure during the first two years of life: 11.5; 95% CI: 1.92-68.9). The HR for meningioma was 0.46 (95% CI: 0.19-1.11), with no evidence of exposure-response gradient with increasing duration of exposure. The HR for glioma was 1.47 (95% CI: 0.84-2.57). The hypothesis of a positive association between ELF MFs and adult hematological malignancies was supported only for ALL. The results suggested decreased rather than increased risk of most hematological neoplasms.

Improving distribution system state estimation with synthetic measurements

Distribution state estimation is a desired feature of modern power systems. The availability of measurements from smart meters has opened the door to extend the application of state estimation techniques down to end customers, preferably at the secondary distribution transformer level. However, the light coupling between phases makes the estimation of certain state variables, such as voltage phase angles, a great challenge. This paper proposes the use of synthetic measurements as a means of including cross-coupled information in the available set of measurements. This possibility can be easily implemented in line supervisors located at secondary transformer stations without the need for new hardware, just by embracing a different connection of measurement devices. This work demonstrates that this costless action results in a strong reduction of the sensibility of phase angle estimation errors with respect to measurement noise, thus leading to an important improvement in the quality of the results.

Voltage Optimization in MV Network with Distributed Generation Using Power Consumption Control in Electrolysis Installations

Connecting a large number of distributed sources to the medium and low voltage grid poses many problems. The most important of these are the voltage changes inside the network, what can be observed when the power flow from these sources towards the HV/MV (High Voltage/Medium Voltage) transformer station. In particular, if the power consumption in nodes of the MV network is small and the distance between the place of installation of the source and the substation is large, increases and changes in voltage may be dangerous for the insulation of the network and burdensome for the consumers connected to it. The solution most frequently used to control voltage increases is the appropriate setting of the controller that affects the on-load tap changer of the MV/HV or even MV/LV (Medium Voltage/Low Voltage) transformer. It is also possible to regulate the reactive power of the sources and, of course, to limit their generated active power (curtailment of generation). The development of energy storage technology has made it possible to introduce consumers into the network, whose power can be controlled in a wide range. The article proposes the concept of an innovative voltage control system in the MV network, whose output values are three groups of parameters: HV/MV transformer ratio, reactive power of sources and active power of consumers connected in generation nodes. In the technological sense, it has been assumed that the loads are installations of electrolyzers used to produce “green hydrogen”, according to the P2G (Power to Gas) formula. The tests consisting in the execution of several hundred calculation cycles for the IEEE 37 test network, using the Monte Carlo simulation, have shown that the subordination of the hydrogen production process to the objectives of voltage control in the MV network clearly contributes to stabilizing its value, while meeting the technological requirements. The control variables of the proposed control system are the result of the optimization algorithm described in the article, the function of which is the quality of network voltage.

Spatial analysis of distribution grid capacity and costs to enable massive deployment of PV, electric mobility and electric heating

Rapid deployment of solar photovoltaics (PV), electric heat pumps (HP) and electric vehicles (EV) is needed to decarbonize the economy. However, the integration of these technologies into the power system creates challenges for the distribution grid infrastructure. It is therefore vital to analyse to which extent grid reinforcement is needed to enable decarbonization strategies while also studying alternative flexibility measures. In this GIS-based study, we model the impact of the deployment of PV, HP and EV on a low-voltage distribution grid network serving 170’000 households in Switzerland, and analyse scenarios for their penetration in the years 2035 and 2050. Using a detailed grid model in collaboration with a distribution system operator, we find that PV leads to 18.5% and 13.7% more voltage violation issues compared to HP and EV respectively, which on the other hand, cause slightly more line overloading, 0.5% and 2.5%, respectively. We also find that grid reinforcement costs markedly depend on the type of urban setting ranging between 51–213 CHF/kWp, 46–1’385 CHF/kW and 34–143 CHF/kW for PV, HP and EV, respectively, with the higher limit corresponding to rural areas. The total distribution grid reinforcement costs can amount up to 11 billion CHF until 2050 i.e. 2’900 CHF per household in Switzerland. Interestingly, we find that batteries, even with current costs, have the potential to defer grid reinforcement for up to 15% of the transformer stations with the highest specific grid reinforcement costs. Our study aims to inform various stakeholders about the required grid investments to enable the massive deployment of low carbon technologies.

Cost of energy infrastructure in Europe and Austria: electricity, gas, oil, and heat

The present research analysis of over 250 pieces of literature identifies the cost of energy networks. a) The basic question is: what does the energy infrastructure cost now?; b) The further perspective is: how much will energy networks cost in the future when achieving the climate protection goals by an energy transition? For the target of cost finding estimates, the current Austrian projects to construct new energy lines are used because cost data can be retrieved for them. Network costs are (as a mean with a wide spread within the energy sources): electricity: 1.5 M€/km to 3 M€/km, with an average of 2.3 M€/km; gas: 0.5 M€/km to 2.5 M€/km (mainly depending on the pipe diameter), oil: 1.6 M€/km; and heat: 0.2 to 1.8 M€/km. Overall, a very rough estimate for all four energy carriers is: around 2 M€/km (i.e., ~1+1 M€/km each for line-oriented + point-oriented costs, such as transformer stations).

The analyses of definite profitable power of the city web trаnsformer

It gives the analyse of offered metodics of detinite profitable power оf the transformer stations (TS) and the colculation formuls received in building standarts and rules (B.S.K 2.04.17-98). Тhe offered new metodics.

Rekonstrukcija transformatorske stanice 35/10kV u spoljašnje razvodno postrojenje 20kV 20211, XXIII

In the distribution area of Novi Sad, owned by ODS EPS Distribucija, there are 35 substations 35/10kV that are on average over 50 years old. Considering the tendency to gradually eliminate the voltage levels of 35kV and 10kV in this distribution area and the transition to the voltage level of 20kV, some of these substations are planned for reconstruction into 20kV distribution plants. Reconstruction of these substations requires large financial resources, because their construction part is in a very bad condition, electric power equipment is unreliable and difficult to maintain, and operational readiness is an increasingly important factor in presenting successful business. During the reconstruction of these transformer stations, the possibility of a backup power supply route for electricity customers, the speed of intervention and the smooth performance of preventive maintenance must be taken into account. The appearance of reclosers opened a new chapter in the world of electricity. Namely, now the above problems and requirements can be solved in a simpler and cheaper way with the use of reclosers. The paper will present a proposal for the reconstruction of the substaion 35/10 kV "Kuzmin" in the area of the Branch Distribution Sremska Mitrovica, which has been operating for more than 60 years, in an external 20 kV distribution plant formed with the help of reclosers built on steel lattice poles. The proposed solution can be used to solve the same or similar problems, primarily in the distribution area of Novi Sad.

Idejno rešenje regionalnog Data Centra kod Beograda napajanog iz obnovljivih izvora energije

Telecommunications and computer equipment centralisation trends for the purpose of achieving economic benefits, usage of technological innovations and new technical solutions implementation leads to the requirements for building bigger Data Centres (DCs). An increase in the size of the DC facility i.e. the number of racks inside occupied with equipment and the number of devices that enables the proper functioning of that equipment leads to necessarily power energy requirements increasing for power supply. For the DCs that require a large amount of energy, the building of their own, usually renewable energy sources (RES) is cost-effective. In such a caser, RES are primary and Power System (PS) is secondary and redundant power source. A concept of a DC primary powered from RES is presented in this paper. Generated electrical energy in RES is transmitted in PS through high voltage switch-gears (SGs) while DC is power supplied from PS through low voltage, medium voltage and high voltage SG-s. For the purpose of realisation of such facility, it is necessary to enable adequate conditions related to geographical location, physical access to the facility, possibility of connecting to the PS and possibility of connecting to the telecommunications centres. Based on carried out researches related to RESs potential, available roads, power supply infrastructure and telecommunication infrastructure, development conditions for DC on location near to Belgrade, close to power transformer station „Belgrade 20“ are analysed in this paper. From the aspect of DC power supply, proposed solution includes wind farm, solar plant and landfill gas power plant, as well as related SGs. Telecommunication connections from DC to the PS and other important telecommunication centres are provided. These connections are realised through optical cables placed next to the electrical lines and cables, and, when that is not possible, placed independently in the ground. The design of the DC interior is given and calculations of the required electrical energy for the power supply of the equipment and devices in the facility are performed. Based on calculation results, capacity calculation of the RES and calculation of SGs are performed. Design of the interior optical connections inside DC is also given. A General assessment of the investment and economics of building such DC are given at the end of the paper.

Analysis of the Technico-Economic Viability of an Electric Micro-Grid with Renewable Electricity Production Sources in Elokato-Bingerville, Cote d’Ivoire

In this study, the technico-economic viability is studied, on the basis of different scenarios of electric micro-grids with renewable energy production sources, autonomous and supplied by the interconnected grid. HOMER Pro 3.13.3 Pro simulation and optimization software, Xlstat and Energy sentinel software are used for the evaluation of different technical and economic scenarios of system components, in order to obtain the most cost-effective configuration. To do this, the case study of the village of ELOKATO identifies the optimal options for the use of renewable energies for rural electrification in order to increase the electricity coverage rate. In our case study, after the various simulations, HOMER identified 13 scenarios and configurations deemed to be the most profitable, from the parameters and configurations without photovoltaic components have high COEs and very high initial investment costs in the order of several million US $. Renewable energy power generators require high initial investments and relatively low operating costs. The most important costs are generated by the battery park and then come the photovoltaic panels. The hybrid PV/wind/diesel/hydropower system is profitable if the distance from the village to the transformer station is greater than 1.90 km. The results show great potential for using these hybridized production sources with or without a generator to meet the electricity needs of a village.

Optimization of Electric Vehicle Charging Points Based on Efficient Use of Chargers and Providing Private Charging Spaces

Electric vehicles are a mobility innovation that can help significantly reduce greenhouse gas emissions and mitigate climate change. However, increasing numbers of electric vehicles require the construction of a dense charging infrastructure with a sufficient number of chargers. Based on the identified requirements for existing electric vehicle users and potential new customers, the paper proposes a charging point model for an urban area equipped with a local transformer station and a sufficient number of low-power chargers. In particular, the model focuses on efficient use of chargers throughout the day, considering private rental of chargers paid by residents in the evening. The model uses an optimization method that compares the non-covered fixed costs due to unsold electricity to nonresidents and the annualized costs of building an additional transformer. The proposed optimal charging point solution was tested in a case study using real data capturing users’ habits and their arrivals in and departures from the car park. As our model results show, the great benefit of a park-and-ride car park equipped with chargers consists of a simple increase in car park efficiency, ensuring sufficient numbers of private charging lots, optimizing operating costs, and supporting the development of electromobility.

Influence of FACTS Device Implementation on Performance of Distribution Network with Integrated Renewable Energy Sources

In the modern power system, Flexible Alternating Current Transmission System (FACTS) devices are widely used. An increased share of the distributed generation (DG) and the development of microgrids change the power flows in the existing distribution networks as well as a conventional power flow direction from the transmission to the distribution network level which may affect the overall stability aspects. The paper shows the FACTS devices’ implementation influence on the performance of the distribution network with integrated renewable energy sources (RES) observing the aspects of the oscillatory stability and the low-voltage motor starting. The FACTS devices, in particular the static var compensators (SVC), have been allocated according to a novel algorithm proposed in the paper. The algorithm uses an iterative process to determine an optimal location for implementation and rating power of SVC considering active power losses minimization, improvement of the voltage profile and maximizing return of investment (ROI) of FACTS devices. Novel constraints—transformer station construction constraint, SVC industrial nominal power value constraint and the constraint of distribution system operator (DSO) economic willingness to investment in the distribution network development are considered in the proposed algorithm. The analysis has been performed on 20 kV rural distribution network model in DIgSILENT PowerFactory software.

A Novel Oil-Immersed Medium Frequency Transformer for Offshore HVDC Wind Farms

Offshore wind farms pose the challenge of transmission of produced energy in an economic and effective way over long distances, justifying investments in High Voltage Direct Current (HVDC) systems. A solution to surmount the need for an expensive and large power transformer station is to connect each wind turbine to a DC/DC converter in which a Medium Frequency Transformer (MFT) is utilized to reduce the size of the station. Further, the DC outputs of the converters of the wind turbines can be connected in series to create a high DC voltage. In this solution, the MFTs are required to be insulated against a high DC voltage to ground in a limited compartment. This contribution presents a prototype of a 50 kW oil-paper insulated MFT operating at biased 422/4500 V/V AC 5 kHz and 125 kV DC test voltage, which has been manufactured and subjected to verification HV tests. The dielectric design of the prototype MFT based on finite element solution of non-linear Maxwell-Wagner equations is introduced and the acceptance criteria and practical design considerations are discussed.

Statistical correction scheme for the wind power allocation to transformer stations in the transmission grid

The expansion of photovoltaics and wind energy shifts the feed-in from the transmission grids down to the lower voltage levels of the distribution grids. It is a challenging task to determine at which transformer station of the extra-high voltage grid photovoltaic and wind energy is fed via the cascade of the different grid levels. In principle, this allocation problem of generation to transformer stations can be solved with a power flow calculation if the topology and parameters of all grids are known. In reality, however, this knowledge is spread over several grid operators and alternative solutions could be promising. We propose a method for inversely correcting an initially estimated allocation of wind power generators to transformer stations between the transmission and the distribution grid based on correlating the wind power feed-in with the vertical power flows measured at the considered transformer stations.Our experimental setup involves the allocation optimization of about 29 GW of installed wind power to 136 transformer stations within the two largest German control zones. By shifting a total amount of 12.6 GW of allocated wind power between these transformer stations, our scheme is able to detect and correct erroneous allocations and to improve the reliability of the estimated wind power feed-in per transformer station.

Enhancing Performance of Load Scheduling Using Grid Learning

The hourly flitting desire for electricity loads at suburban level or true to form of an espresso voltage transformer station probably won't be depicted as a troublesome brain diminished proportion of information. As a matter of fact, the proportion of data available for this model is colossal enough to utilize any other gauging procedure yet looking to the pile graph for example hourly weight regard twists, we adequately recognize that past estimations of the utilization aren't incredibly obliging when conjecture is expected of. That remains regardless, for data from the sooner day and for data from that day inside the prior week. As a portrayal of the case in this work we give three weight diagrams visiting with eventually usage of 1 load on a) Friday January 31, 2009, b) Thursday January 30, 2009, and c) Friday January 24, 2009. The numerical values are showed up in this work. The power is normalized by a component of 200 being the turn extent of the correct current transformer inside the transformer station. One may even observe the similarity of the general shape and in this manner the qualification in principle nuances confirming the crucial noteworthiness of the most up to date data for desire. As requirements are, we propose the trouble of evaluating of the pile a motivating force inside the next hour to be continued as a deterministic desire snared in to short – eventually – time game plan. To help the desire, regardless, in an appropriate way, we present past characteristics for example stacks for that day yet in prior weeks. That is in accordance with existing experience attesting that reliably inside the week has its own general usage profile.

IMPROVIMG THE DLC (DISTRIBUTION LINE CARRIER) SYSTEM BEHAVIOR THROUGH MEIUM VOLTAGE NETWORKS (MVNs)

With the great available technological advances, MVNs are still difficult to control, because of their dense meshing and their automation is very cost-intensive. There are generally no communication cables in the MVNs' equipment such as the MV transformer and distribution stations. One of the costless technologies used to communicate between the MVNs' equipment and the control center of a SCADA system is the DLC communication technology, where, data transfer occurs directly on the medium voltage cables, i.e. on the conductors of the underground and/or the overhead cables or on the shields of the underground cables. However, the DLC system suffers from many problems concerned in MVNs. In addition, the design of the DLC system itself has some defects, which affect its performance and stability. Here, we explain with simulation the exits instability margins of the operation of the DLC system to help us how we can improve the stability margins of the system to achieve a good performance

Dispatching and scheduling at load peak with the optimal location of the compensation under constraints in real-time

The development of the electricity grid and the use of intelligent control in real-time has today become one of the most important pillars that control the quality and continuity of the electricity supply for industrial consumers and even ordinary consumers. The increase in the load led to an increase in the demand for electrical energy, so this increase was accompanied by multiple problems such as a decrease in the voltage, an increase in the reactive energy in the lines of transport, a decrease in active transited energy, also an increase in active losses and other problems related to electrical synchronization and ultimately overall instability of the electrical network. Through this study, we offer some solutions related to electrical control, using specially developed algorithms to determine the optimal reactive energy compensation locations, taking into account the technical limitations in transformer stations related to high lines 220 kV electric transmission voltage. Thanks to the good results obtained, we were able to apply the algorithms to the real network by taking the southwest region of Algeria as a study sample in order to improve the electrical quality of this region. The modelling, analysis, control and confirmation techniques were studied using an advanced numerical simulation.

Application of BIM in design conflict detection: a case study of Vietnam

Design conflict detection in construction projects is a very important task for ensuring the quality, time and cost. This job now has become more convenient due to the use of BIM. This paper proposes a process for BIM-based clash detection for introducing to the BIM practitioners in Vietnam. This process was then adopted in a complicated control house, which is a part of transformer station project in Vietnam, where the design was developed with 2D-CAD. The process discovered 36 design conflicts, including inconsistencies and geometric interferences. The results contribute as a proof-of-concept of BIM-based design conflict detection in Vietnam, where BIM is not very widely adopted.

Gaps in Knowledge Relevant to the "Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz-100 kHz)".

Sources of low-frequency fields are widely found in modern society. All wires or devices carrying or using electricity generate extremely low frequency (ELF) electric fields (EFs) and magnetic fields (MFs), but they decline rapidly with distance to the source. High magnetic flux densities are usually found in the vicinity of power lines and close to equipment using strong electrical currents, but can also be found in buildings with unbalanced return currents, or indoor transformer stations. For decades, epidemiological as well as experimental studies have addressed possible health effects of exposure to ELF-MFs. The main goal of ICNIRP is to protect people and the environment from detrimental exposure to all forms of non-ionizing radiation (NIR). To this end, ICNIRP provides advice and guidance by developing and disseminating exposure guidelines based on the available scientific research. Research in the low-frequency range began more than 40 years ago, and there is now a large body of literature available on which ICNIRP set its protection guidelines. A review of the literature has been carried out to identify possible relevant knowledge gaps, and the aim of this statement is to describe data gaps in research that would, if addressed, assist ICNIRP in further developing guidelines and setting revised recommendations on limiting exposure to electric and magnetic fields. It is articulated in two parts: the main document, which reviews the science related to LF data gaps, and the annex, which explains the methodology used to identify the data gaps.

Technical Possibilities for Implementing Measures to Reduce the Emitted Electromagnetic Field of a High-voltage Distribution Transformer

This paper deals with the measurement of electromagnetic field parameters near high voltage systems, characteristics of electric field, magnetic field and electromagnetic field, as well as the possibilities of implementing measures to reduce the emitted electromagnetic field. The paper describes the measurement of electromagnetic field parameters in the vicinity of high voltage systems, the analysis and synthesis of the measurement results in the external and internal environment of particular transformer stations is evaluated. The objects of interest in these measurements were brick transformer stations for transforming AC voltage from 22 kV to 400 V and 230 V at the operating frequency of 50 Hz. With regard to the influence of electromagnetic fields in the environment, individual measurements were assessed in accordance with selected criteria.

Optimal scheduling of power transformers preventive maintenance with Bayesian statistical learning and influence diagrams

Transformer preventive maintenance scheduling—as an integral part of the power utility company’s asset–management process—if optimized properly affords considerable savings in maintenance costs and results in the increased reliability of transformer stations. However, situation is exacerbated by the considerable uncertainty involved in the assessment of the transformer health status, not necessarily associated with its age, as well as in the projected asset replacement and maintenance costs. There is also uncertainty inherent in the transformer tests as such. This paper proposes a novel transformer optimal preventive maintenance scheduling approach, with the use of the Bayesian statistical learning and a generalization of the Bayesian networks, for decision-making based on the expected utility hypothesis. Proposed approach, in essence, manages risk associated with taking different preventive actions by leveraging uncertain information regarding the transformer health and the expected costs of these actions. In this way, each prospective decision has a monetary value attached to it, which depends on the particular circumstances defined by the power utility company. Time-related effects are introduced into the decision-making process by the Bayesian updating of the prior belief concerning the transformer health with new information. Solving a decision problem amounts to determining an (optimal) strategy that maximizes the expected utility for the decision maker. On top of that, Bayesian approach, uniquely, offers explicit account for the full uncertainty associated with every step of the decision-making process. The proposed approach, and its advantages, will be demonstrated on a fleet of power transformers. It will be shown that model can predict with a 90% accuracy and a high confidence the transformer health index class from a small dataset. It will also be shown that it can predict with high expected profits which transformers in the dataset would benefit the most from the early intervention (recuperating around 25% of the projected costs and retaining over 90% of the projected savings).