| 1. |
- Arifianto, I., et al.
(författare)
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Investigation of transformer top-oil temperature considering external factors
- 2012
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Ingår i: Condition Monitoring and Diagnosis (CMD), 2012 International Conference on. - : IEEE. - 9781467310208 ; , s. 198-201
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Konferensbidrag (refereegranskat)abstract
- Standard estimation of top-oil temperature uses a thermal model related to load changes and variation of ambient temperature. Attempts have been done to improve the accuracy of top-oil temperature calculations by introducing internal properties into the model i.e. oil viscosity and winding resistance. The interest of this paper is to investigate the effect of external factors on top-oil temperature by looking into the weather, i.e. wind velocity. The results are compared with measurements on a 63MVA-ONAF 55/140 kV transformer unit, which is operated in ONAN cooling mode. The unit is located in subarctic climate, and it is equipped with a monitoring system and a weather station.
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| 2. |
- Ariza Rocha, Oscar David, et al.
(författare)
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Dynamic rating assists cost-effective expansion of wind farms by utilizing the hidden capacity of transformers
- 2020
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Ingår i: International Journal of Electrical Power & Energy Systems. - : Elsevier. - 0142-0615 .- 1879-3517. ; 123
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic rating of power transmission devices is a technology that allows better equipment utilization through real-time monitoring of the weather conditions and the load. Dynamic rating of transformers is a fairly new technology if compared to the dynamic rating of power lines, and has a high potential for significantly improving component utilization while lowering investment costs on installing new transformers.The following work investigates how to utilize already operational transformers, which are used for wind farm connection, for expanding wind generation capacity. Also, this paper shows improvements that dynamic transformer rating can bring to both power grid operators and wind farm owners by exploring the economic benefits of expanding wind parks without investing in new power transformers. Connecting additional wind turbines at sites with high wind potential after the wind park is already in exploitation can assist in lowering electricity price and provide a possibility of less risky investment in the wind energy sector. This paper uses transformer thermal modelling and wind farm expansion techniques such as convolution method and product method to investigate to which extent existing wind farms can be expanded using already installed transformer units.Five transformer locations and nine units are studied for finding the potential of dynamic transformer rating for network expansion applications. The analysis shows that the optimal expansion of wind power from a generator perspective is around 30%" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">% to 50%" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">%, although, it can be limited further by network restrictions. A possibility to use a large component, such as power transformer, closer to its full potential can provide material and cost savings for building new devices and decrease investment costs on manufacturing, transportation and installation of new units. Dynamic rating of power transformers can also increase the socio-economic benefits of renewable energy by lowering electricity price from renewables and incentivize an increased share of green power in electricity markets.
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| 3. |
- Ariza Rocha, Oscar David, et al.
(författare)
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Dynamic rating assists cost-effective expansion of wind farms byutilizing hidden capacity of transformers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Dynamic rating of power transmission devices is a technology that allows better equipment utilization through real-time information about the system state. Dynamic rating of transformers is a fairly new technology if compared to dynamic rating of power lines, and has high potential for significantly improving component utilization while lowering investment costs on installing new transformers.Dynamic transformer rating increases the rating of the transformer considering load and temperature variations without affecting safe operation. Dynamic rating is highly suitable for being used in conjunction with renewable energy generation, specifically wind power. The following work investigates how to utilize existing transformers, which are under exploitation at wind farms, for expanding wind generation capacity. Also, this paper shows improvements that dynamic rating can bring to both power grid operators and wind farm owners by exploring the economic benefits of expanding wind parks while using dynamic rating. Connecting additional wind turbines with the same transformer at sites with high wind capacity after the wind park is already in exploitation can assist in lowering electricity price and provide a possibility of less risky investment in wind power.Five transformer locations and nine units are studied for finding the potential of dynamic transformer rating for network expansion applications. The analysis shows that the optimal expansion of wind power from a generator perspective is around 30 % to 50 %, although, it can be limited further by network restrictions. A possibility to use a large device, suchas power transformer, closer to its full potential can provide material and cost savings for building new devices and decrease investment costs on manufacturing, transportation and installation of new units. Dynamic rating of power transformers can also increase the socio-economic benefits of renewable energy by lowering electricity price from renewables and incentivize an increased share of green power in electricity markets.
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| 4. |
- Babu, Sajeesh, 1987-, et al.
(författare)
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Analyses of Smart Grid Technologies and Solutions from a System Perspective
- 2015
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Ingår i: Smart Grid Technologies - Asia (ISGT ASIA), 2015 IEEE Innovative. - : IEEE conference proceedings. - 9781509012374 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This paper consolidates the data, analysis andobservations from a case study conducted in cooperation withthe Smart Grid Gotland project. The analysis identifies howelectrical power consumption interacts with distributedelectricity generation such as wind and solar power andpresents how it correlates to weather data and smart gridsolutions. The analysis model developed based on the Gotlandnetwork is generic and hence can be functional in investigatingother power networks of different size, voltage level andstructures. The key observations from the study of smart gridsolutions such as dynamic load capacity and energy storagesolutions are specified. Based on the project, an overview offuture risks and opportunities of smart grid systems is presented.
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| 5. |
- Babu, Sajeesh, et al.
(författare)
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Analysing Correlated Events in Power System Using Fault Statistics
- 2016
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Ingår i: Probabilistic Methods Applied to Power Systems (PMAPS), 2016 International Conference on. - : IEEE. - 9781509019700
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Power system automation requires logical presumptions made on practical grids to correctly comprehend and manage complex and correlated faults occurring in real world systems. Traditional grid fault analysis methods lack in-depth understanding of these complex events and demand development of approaches that make use of available data to address this problem. Here, the traditional classification approach and challenges relating control equipment in power system are reviewed and a method observing the affected customers during faults along with grid design is discussed based on Swedish case study data. Various contrasting observations are made on the data recorded over two time periods to understand the trend developing over years. Moreover, it will be shown that the classification method also has potential in identifying weak spots in the grid when it comes to the reliability of control equipment.
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| 6. |
- Babu, Sajeesh, et al.
(författare)
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On the status of reliability studies involving primary and secondary equipment applied to power system
- 2014
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Ingår i: 2014 International Conference on Probabilistic Methods Applied to Power Systems, PMAPS 2014 - Conference Proceedings. - : IEEE. - 9781479935611 ; , s. 6960653-
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Konferensbidrag (refereegranskat)abstract
- Growth in infrastructure and energy utilization consistently put forward the demand for added quality and quantity of electric power. Reliability concerns over power systems are widespread within its different associated divisions like 'primary' power system structure, protection system, control equipment, ICT (Information and Communication Technologies) etc. This paper is a review of the present status of practices regarding reliability analysis in these divisions and works towards collectively assessing some of the studies in the respective areas. The idea of integrating reliability analysis from the above areas is introduced along with pointing out the major challenges associated. A set of tools for operators to make use in these reliability evaluations and modelling are mentioned. The earlier attempts towards combined overall system reliability analysis are discussed and the approach in this regard with the help of 'control functions' is emphasised. The paper includes works dealing with theory, different methodologies and data associated with power system reliability.
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| 7. |
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| 8. |
- Babu, Sajeesh, 1987-
(författare)
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Reliability Evaluation of Distribution ArchitecturesConsidering Failure Modes and Correlated Events
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Power systems are in a phase of automation where intelligent components and sub-systems are employed to monitor, control and manage the grid. Quantifying the complex consequences on system reliability, from the integration of such automated and semi-automated equipment into the existing grid is important for maintenance optimisation and fault mitigation. This thesis identifies the advanced approaches in power system reliability analysis with the potential to capture the complications and correlations in modern power grid after reviewing the traditional reliability evaluation methods.A method for modelling the different modes of failures, possible in a substation and feeder architecture along with the probable false tripping scenarios was developed. An improved Reliability Block Diagram based approach was designed to count in the traditionally unaccounted failure cases affecting both the primary grid and the protectionand control equipment. The effect and corresponding trend of additional feeder lines in a radial distribution system on the net interruption rate experienced at load ends of feeders are derived and modelled. Such real-world substation architectures are analysed and the aforementioned trends are compared with those from the practical grid. Thus, the analysis was able to identify and measure the complex hidden failure probabilities due to both unwanted operation of breakers and functional failure of protection systems.The measured probabilities were used to calculate the impact of protection and control equipment on system reliability. The obtained results were verified by comparing it with the observations by energy researchers on ten years of protection system failure statistics. The application of the model and results, in optimal maintenance planning and power network optimisation are identified as the next step.
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| 9. |
- Babu, Sajeesh, et al.
(författare)
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Reliability Evaluation of Distribution Structures Considering the Presence of False Trips
- 2018
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Ingår i: IEEE Transactions on Smart Grid. - : IEEE. - 1949-3053 .- 1949-3061.
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method for modelling the different modes of failures in a substation and feeder architecture along with updating the possible false tripping scenarios in it. A traditional approach to collectively assess the failure modes using reliability block diagram is reviewed, and the method is updated to count in the unaccounted false tripping scenarios. A generalizable radial feeder branching structure is adopted and the effect of total feeder length and number of feeders from each busbar is examined and modelled with the help of the updated reliability block diagram. The modelled trends are also studied from real-world substation architectures. Thus, the analysis attains an improved estimation of the complex hidden failure probabilities combining theoretical and practical models.
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| 10. |
- Babu, Sajeesh, 1987-
(författare)
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Reliability Evaluation of Distribution Systems Considering Failure Modes and Network Configuration
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Power distribution networks are recognized as the constituent part of power systems with the highest concentration of failure events. Even though the faults in distribution networks have a local effect when compared to the generation and transmission sides, major contingency escalation events are being more frequently reported from this section. The various aspects regarding the reliability and performance of distribution networks are identified as an important topic. Integration of new technologies, automation and increased penetration of distributed generation is expected to make improving and even sustaining high reliability standards a complex task. This thesis presents developed approaches to quantify and analyze the complex correlated failure probabilities of different failure modes in distribution networks. A theoretical simulation model that relates to real world data to measure false tripping probabilities is developed and tested. More simplified approaches that utilities can exercise with readily available data in fault registers are also established. Optimal configurations that could improve system performance and respective investment costs are analyzed and savings in system reliability at the cost of grid investments are modelled. The optimization helps in prioritizing the most critical investments by considering the system impact of reconfigurations focusing on meeting customer demands and respecting transfer capacities of weak links. The value of existing networks and willingness of the grid owner in investing can be integrated into suggestive alterations to assist decision making in planning and maintenance allocation. The thesis makes both system specific and generalizable observations from detailed data collection from power utilities. The observations and results have potential in aiding future research by giving important understanding of the reliability impacts of network structures and of control and protection equipment.
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