The aim of this paper is to present the investigation of complex icing system for the transmission grid. The introduced investigation forms a two-level method, which in the first stage gives a warning for system operators when the environmental factors are appropriate for ice formation on conductors. Then a mathematical model forecasts the radius and mass of the expected ice-layer. The mathematical relationship between the conductor’s tensile force and sag is crucial for the calculation of the conductor’s expansion (tension) and final length over a constant span distance. The reliability of ice thickness calculations mainly depends on the accuracy of conductor temperature and angle/sag measurements. The OTLM-ICE application enables the operator of the transmission network to monitor sag and clearance changes on a conductor, subjected to ice overloads. The operator can optimize and determine the suitable ampacity of transmission lines in order to prevent the damage in the early phases of ice-rain. The second level of the system monitoring the ice-formation on the phase conductors with line-monitoring sensors, thus the system operators get real information about the line condition. The operation of the methodology is also investigated, which are also presented through case studies. FLEXITRANTORE as a HORIZON 2020 project aims to develop an integrated platform for the next generation flexible electricity transmission system.
Due to the increasing energy demand, new questions raise for engineers such as how to achieve high utilization of the existing transmission system. For this purpose, the investigation of network equipment and elements is indispensable. Dynamic line rating (DLR) is a cost-efficient way to raise the transmission power capacity of the existing high voltage overhead lines. DLR technology is based on the real-time thermal equilibrium of the conductors, which is the basis of the ampacity calculation of the given line. Therefore, the investigation of the thermal behavior of wires is essential to fine tune the existing calculation methodologies. The aim of this paper is to present the research regarding to the thermal behavior of high voltage conductors performed in the High Voltage Laboratory of Budapest University of Technology and Economics. In this research the time constant of a wire was determined both in case of different static and dynamic thermal processes, thus the heating and cooling mechanism of the conductor can be described in a more precise way in case of thermal monitoring of the wires.
The transmission and distribution network play a central role in the electricity system. According to this, their operational safety and reliability are highly important due to the continuous availability of electrical energy. Live Working (hereinafter referred to as LW) is a group of activities where line workers work on energized network elements, reducing the number of blackouts and interrupts on the network. However, in the last few years the electricity system has changed, so that new challenges have been appeared for system operators. One of the main goals is to increase the flexibility of the transmission and distribution network while maintaining the reliability level. As a result, new methods such as Dynamic Line Rating (hereinafter referred to as DLR) are being introduced to increase the capacity of transmission lines. In addition to the emergence of new methods, existing technologies also need to be reviewed. The main aim of this article is to present how live line maintenance (LLM) equipment test and technology education were revised, and how DLR method could improve the reliability of the distribution network.
Rail and road constructions, especially tunnels, will be examined and documented in 3 dimensional models during the complete life circle. The execution of such measurements is economical and highly precise feasible with kinematic laser scanners. Based on two international projects the activities will be described and the solutions shown. First, a tunnel as- built survey including a tunnel inspection, for German Railway DB, and second a dynamic clearance analysis in Glasgow, for Stadler Rail. Both are extraordinary projects and were executed with Amberg Technologies AG equipment. The IMS 5000 and the MISS are perfectly suitable for this kind of work. Common, but terrestrial technologies have been used in local environment and will be presented in combination with ground penetrating radar measurements as tunnel lining condition and voids detecting in railway tunnel as well. Based on those applied solutions the possibilities of such systems will be explained. A view in the digital world of Building Information Modeling and the new standards IFC 4 and IFC 5 will finalize this technical essay.
Modern electric transmission systems provide additional data about conductor conditions under different weather conditions as temperature and sag of conductor. Except direct measurement on high voltage conductor, nowadays the indirect measurement technique is possible to apply in pillar's legs of transmission line. Results of strain measurement in pillar's legs of transmission line shows correlation between weather conditions, temperature of air and temperature of conductor vs. length of conductor, sag and change of tensile force in conductor. The study is dealing with change of deformation in legs of pillars. The boundary conditions are obtained by experimental measurement of strain in legs and geometrical measurement of all three conductors between two pillars. The performed study shows that online monitoring of change strain can be connected with change of geometry of conductors and consequently the change of tensile force in conductor. The change of tensile force in conductor can be caused by additional weight or temperature change. The measurement of natural frequencies shows that natural frequencies depends on temperature of pillar and tensile forces in conductors.
This paper presents an arc flash risk assessment procedure using different computer tools from different countries. Different computation methods according new requirements in NFPA 70E (2018), IEEE 1584 and DGUV I 203-077 standard. Three different software are used and compared incident energy (EI) or full energy (WE), arc flash boundary and the level of Personnel Protection Equipment (PPE). Arc flash risk assessment is today a mandatory part of each risk assessment for electrical workplaces and several recommendations exist in different countries. National OSHA rules in USA, EN 50110-1 in Europe and PPE Directive in Europe. A short circuit analysis is performed to calculate the values of arching currents and compute arc flash energy dissipated at busbars at HV and LV voltage busbars. Worst case scenario approach is used to examine what is highest level of Arc Thermal Performance Value (ATPV). There different software tools where used in computation: “EasyPower Arc Flash” (USA), BSD Arc Calculator (Germany) and RENblad 1710 (Norway). A practical sample case is presented and arc flash energy is computed and PPE recommended for high and low voltage busbars in one stone pit facility in Slovenia and biomass power plant in Croatia.
Historical meteorological data indicates, that our weather is becoming more and more extreme. For the electrical utility operators (Distribution System Operators - DSOs and Transmission System Operators - TSOs), these changes arise in new operation challenges that need to be addressed. For example, frequent icing phenomenon affects all the components of the power line by a significant mechanical overload: it endangers the conductors, the insulators and the towers, as well. The result is often fatal and beside serious failures, it effects on operators’ decisions. These not only endanger the reliability of electrical grids by the loss of a power line for weeks or even months, but in general, the safety in the surroundings of the power line. As technology advances, we will be able to collected, analyses and predict very large databases in the field of meteorology and electrical engineering. The ability of processing mentioned data, combined with know-how results in the capacity to operate power lines at their thermal limits during different ambient parameters. This technology called Dynamic Line Rating (DLR) – is not only a great way to increase the transmission capacity of a given line, but can also be effectively used to prevent, or even solve icing-related issues. Higher currents result in higher Joule-heats, that consequently heat the conductors. If limits can be reached or approached, icing can be prevented. If prevention is not possible, detection and removal of ice layer is necessary. The proper handling of this icing issues, requires advanced algorithms (expert systems) and reliable measuring equipment. The combination and synchronization between algorithms, weather service and measuring equipment is the key of the successful operation. An EU H2020 financed project called FLEXITRANSTORE has just been launched to develop a cross-country co-operation, with objective to improve anti-icing and de-icing solutions. To establish and analyse different solutions, the project includes several universities, TSOs and DSOs. To solve mentioned icing issues Budapest University of Technology and Economics’ (BME) developed an advanced neural-network based algorithm which use OTLM system. It is planned to install and demonstrate the capabilities of this new technology on the DSOs grid (Electro Ljubljana - ELJ). Besides the introduction of DLR and icing, this paper also focuses on the preparation/organisation of co-operation between different companies and universities.
The purpose of this paper is to compare the quality management and safety aspects within the Live working (LW) framework. The study draws upon study carried out among the Slovenian electrical distribution and international study which was carried out among Slovenian and foreign LW experts. The results of the first study suggested that health and safety aspects of LW are vital for achieving efficiency and effectiveness of LW. Furthermore, it can be argued that there are no substantial differences among workers and coordinators. Similarly, the results of the international survey showed that health and safety aspects of LW are considered as very important in achieving desired outcomes of LW as expressed by the foreign LW experts. However, the results indicated that Slovenian experts perceived the elements of LW in a similar way as foreign experts.
An interesting parallel has been discovered when studying the sources of quality and safety management in healthcare and carrying out of live working in the maintenance of electrical installations. The awareness and efforts of healthcare professionals focused on the increase in patient safety as well as the electrical profession in carrying out live working have a hundred year tradition. In both fields, the first success was observed in Slovenia in the last decade. Patient safety is the first priority of all the persons involved in the healthcare system. The Slovene health policy started the systematic preparation of supporting documents in 2006 in order to assist the implementation of continuous improvement in quality and safety management in hospitals. In recent years, several medical institutions have started and successfully completed the certification under the quality management standards and many of them efficiently concluded the process of accreditation in accordance with the international standards. Live working was introduced into the Slovene electric power system in 2006 when the discussions about the benefits of preventive maintenance of electrical installations started. In 2009, live working officially began in the Krško Nuclear Power Plant. In 2011, it was started in the Slovene electricity distribution and in the University Medical Centre (UKCL) when a very complex re-connection on the main low voltage panel was required. When reviewing the scientific and professional literature a large gap was discovered in patient safety when the reliable supply of healthcare institutions with electricity is to be provided and high requirements of standards in electrical installation maintenance in healthcare facilities are to be met. The paper presents the connections between live working, patient safety and the valuable Slovene experience in carrying out live working in healthcare. It has to be pointed out that the contribution of live working to the safety management in healthcare is indispensable.
OTLM (Overhead Transmission Line Monitoring) is a system solution for monitoring and rating of existing and new overhead lines (OHL) based on real-time monitoring of conductor temperature, sag, load, and weather conditions in order to ensure save maximum utilization of transmission line ampacity. Successful development and more than 10 years' of experience in using the OTLM system on transmission networks in several countries all over the world has initiated some system upgrades to ensure even more crucial information on OHL behaviour. The existing functionality of conductor temperature measurements (used for static rating–STR) was initially combined with a weather station measurement that enables the determination of dynamic rating (DTR). With additional inclination (sag/tension) measurements, we developed the OTLM-SAG application. With this additional feature we are able to determine the sag on critical spans. This additional information is especially useful in case of OHL crossings over roads, railroads, other overhead lines, etc. Additionally, measured data like angle (sag) is implemented to the software application to detect ice overloads or fallen trees. The mathematical relationship between the conductor’s tensile force and sag is crucial for the calculation of the conductor’s expansion (tension) and final length over a constant span distance. The reliability of ice thickness calculations mainly depends on the accuracy of conductor temperature and angle/sag measurements. The OTLM-ICE application enables the operator of the transmission network to monitor sag and clearance changes on a conductor, subjected to ice overloads. The operator can optimize and determine the suitable ampacity of transmission lines in order to prevent the damage in early phases of ice-rain.
The developed system for Overhead Transmission Line Monitoring (OTLM) monitors the temperature and the conductor angle of inclination in order to maximise the utilization of the transmission line. Additionally, the measured temperature and the angle can be used by software application to detect conductor elongation by ice overload or a fallen tree. The mathematical relationship between the tensile force in the conductor and the sag is crucial for the calculation of the conductor elongation and the final length of the conductor over the constant span distance. The conductor elongation increases the deflection and the angle of inclination at the position of OTLM device. The reliability of ice thickness calculation depends on the reliability of temperature and angle measurements. The ice thickness on the conductor depends also on weather conditions and the temperature of the conductor. The difference between environment temperature and temperature of the conductor depends mainly on transmission current. In the framework of the OTLM-ICE application the operator of the transmission network can monitor the change in the sag and clearance of the conductor subjected to ice overloading. The operator can optimize and determine the suitable current of the transmission line in order to prevent damage in the early phase of freezing rain.
Putting the transmission network in the service of the electricity market causes a large energy flow in certain transmission directions. The key technical question is how much time will transmission network tolerate this situation without damage. In this case, for the system operator, very helpful information is the actual thermal loading of the conductor in normal and emergency state for re-dispatching energy. This can be achieved through thermal monitoring system installed on overhead power lines (OHLs). In this paper 110 kV OHL Crikvenica – Vrataruša in the Croatian power system was analyzed. The line was created after interpolation of a wind farm (WF) Vrataruša of 42 MW in the existing OHL Crikvenica – Senj at the beginning of 2010. The operation of WF Vrataruša at full power, in some cases, may require a change in network topology. This is done by sectioning of busbars in substations or by redispatching production of hydro power plants (HPPs) in neighboring area. Given that this situation is not present throughout the year but occurs only in certain periods, the problem of safe energy evacuation was attempted to be solved by using the Overhead Transmission Line Monitoring (OTLM) system. This paper describes the experience with OTLM devices within the pilot project on the 110 kV OHL Crikvenica - Vrataruša, along with viewpoints from grid dispatcher and relay protection specialist.
The electric utility industry is restructuring itself to operate in a competitive wholesale market. However, the transmission system remains a regulated entity that connects deregulated generation with the end consumer. In many countries, the pace of investment in OHLs has lagged behind the rate of load growth and generated additional capacities, due to public, regulatory, environmental and financial obstacles to the construction of new transmission facilities. Consequently, many OHLs reached critical values of ampacity and sag. Many renewable energy sources, especially hydro plants, solar or wind farms also require dynamic operation of the power grid. OTLM – Overhead Transmission Line Monitoring system is adding new dimensions to the operation of OHLs enables more efficient performance while at the same time enhances the safety of system operation. A maximum utilization of the OHL ampacity is only possible, if the operators have accurate data about the actual ground clearance, crossed lines, vegetation, instantaneous conductor temperature and current. With the measurements captured and processed by OTLM, the operator of the transmission network can optimize and determine the operation mode of OHLs. Software solutions also provide the means for a short-term prediction of conductor temperature. Temperature data along with data gained by laser scanning or similar measurements and diagnostics of the OHLs is necessary to up-rate OHL projects. This paper is supported with case studies, which prove that temperature and sag monitoring is an essential part of the transmission smart-grid.
The Slovenian TSO – Eles started to prepare the concept and first mobile maintenance solution almost ten years ago. Before implementing the mobile maintenance system into Eles’ business environment, the following key requirements were set: reliability, compatibility, extendibility and minimal organizational influence. The first application was less extensive due to the technology limitation and less accessible devices at that time. Technology development in the field of mobile devices (higher battery capacity, bigger memory, tablet computers, better processors) and their expansion to the private sector resulted in better conditions for more economic and user-friendly applications. The trend of using “smart” mobile devices in private and business sector has encouraged Eles to expand the mobile part of maintenance from the current Windows to Android operating system for tablet computers and mobile phones. With the implementation of mobile maintenance for the substation and overhead lines, Eles achieved an important step forward from paper-based maintenance to an information supported maintenance system for its entire infrastructure.
Legal foundations for training electricians for live work (LW) differ amongst individual countries. In some places, it is included in education and in others, it is part of the health and safety at work. Some countries regulate it on the level of national agencies and others on the company level. Basic training includes theoretical and practical training in specialised educational centres and polygons with the technical equipment for carrying out the practical programme of LW. Professional literature and manuals talk about the recommended extent of individual initial LW programmes for different voltage levels (HV, MV, LV) and periodical training for the competency sustenance. This paper describes the concepts of training for LW on LV in Slovenia and Croatia, where the legal foundations differ but the training programmes are similar because the training manuals for LW on LV are practically identical and both countries carry out the basic training on the polygon HEP NOC.
Live working can be considered a contribution to safety at work, as it is an example of electrical installation maintenance with the zero accidents philosophy. The purpose of this paper is to promote the concepts of maintenance work without accidents or with “zero accidents”. Live working can be identified as an unquestionable foundation of business excellence. This paper introduces the legitimacy of implementing and carrying out live working from the perspective of safety and health at work, critically analyses accidents that happen at work in a de-energized state and arguments the goals of implementing live work as work with “zero injuries”. Organisations with an integrated management system have excellent organisational conditions for safe implementation of live work and can therefore achieve the goal “zero defects” or the idea “zero accidents” or “zero injuries” at work due to electrical shock.
Broken semi-insulated conductors (often called downed covered conductors - CC) present increased risks for humans and animals that might come in contact with conductors under voltage. The solution is in the protection of broken conductors LiSa®, which detects faults on the medium-voltage power network and substations. Protection of broken conductors LiSa® helps to ensure the safety of both producers as well as distributors of electricity. Described LiSa® solution is an integral part of the remote control systems of transformer stations MV/LV (Medium-Voltages/Low Voltages).
Maintenance information of over head lines (OHL) or substations is usually based on the use of ERP, GIS and other technical systems with partial use of paper documents. Documentation in paper is quite inefficient, which results in less detailed and less transparent work monitoring (hours, equipment, etc) and planning. Based on this information, we can say that paper based maintenance lowers the quality of business decision-making. PSA (a software named: Power Service Assistant) is a solution to the maintenance process, that supports and complements existing systems. For the purposes of planning, management and supervision of maintenance are required different documents (work order, an inventory, etc.). PSA software enables aggregation, integration and complementarily of the necessary documents in electronic form. PSA exploit new technological opportunities and offers maintainers system to support the maintenance process. The software can provide high mobility and efficiency to field teams, because it allows adequate operational even without personal knowledge of the situation on the ground. The ability of PSA software is in the connectivity to different ERP systems (Maximo, SAP), flexibility and integration with purely internal company solutions. PSA system cooperates and complements existing management information.
Due to the growth of consumption and difficulties with the erection of new overhead transmission lines, loading of majority of the power lines is gradually increasing and pushing some lines into violation of the current margin at which the line is designed to operate. This in turn means that the probability of high line loading, high temperature and low wind speeds which tailor the phase conductor temperature. As a result, power utilities and system operators are looking for solutions to increase ampacity of the existing OHL without increasing the risk of equipment or system failure due to higher loading. One approach to manage the reliable operation of these systems is to utilize modern monitoring techniques, which help to safely drive overhead line over the static thermal limit. The results obtained from a pilot project 110 kV OHL (Idrija – Ajdovščina) where several monitoring devices and systems were used are presented and discussed. The measurements were obtained from the following measuring devices and systems: OTLM – overhead transmission monitoring system for conductor temperature, DAMOS station – for outside temperature, wind speed and direction, and sun radiation, and ODIN – VIS –dynamic thermal rating module and Line load module). Measurements and events where transferred to the control centre (SCADA) via standard IEC protocols and presented in 3D (4D). The results show that with the utilization of conductor temperature measurements, ambient measurements and with the help of thermal rating algorithms increase in power loading is possible.