On August 26-31, 2018, the 47th Session of CIGRE was held in Paris, France.
International Council for Large Electric Systems CIGRE is a non-governmental and non-profit international organization that unites scientists and specialists in the field of electric power systems (established in France in 1921).
The main goal of CIGRE as a scientific and technical association in the energy sector is the organization of the exchange of scientific and technical knowledge, coordination of research in the field of operation of large electric power systems. The focus is on the development, creation and operation of high-voltage equipment; tasks of planning and operation of power systems; the development and implementation of new systems of the collection and processing of information and control systems.
Delegates from JSC “NPO VEI Elektroizolyatsiya” were representatives of the company management having the status of individual members of CIGRE and members of subcommittees of the Russian National Committee of CIGRE –
A1 “Rotating electrical machines”: Nikolai V. Krupenin – General Director;
A3 “High Voltage Equipment”: Vladimir N. Varivodov – Deputy General Director.
The professional interests of JSC “NPO VEI Elektroizolyatsiya” were the issues of operation of large electric machines, upgrading, in particular the interaction of turbine-generators with the grid, the development of grid codes. Particular attention is drawn to the results of research set out in the Technical Brochure, developed by the working group A1.29 under the leadership of Luis Rouco (Spain) “GUIDE ON NEW GENERATOR-GRID INTERACTION REQUIREMENTS”. The elaboration of grid codes, their evolution, feasibility analysis of their parameters are very important challenges for Transmission System Operators, generators and manufacturers due to the constant development of the grid and the incorporation of new technologies. The authors of the Technical Brochure offered the following conclusions:
- IEC and IEEE standards define frequency and voltage limits for continuous operation and operation outside these limits should be limited in extent, duration and frequency of occurrence. Grid codes define time limited ranges for the frequency and voltage that are often beyond the IEC or IEEE defined limits as well as lacking statements on the frequency of occurrence. Occurrence statements (historic and expectations / planning values) will typically be found in operational codes (as in Europe) rather than in connection codes (which were examined here).
- Translation of reactive power requirement at the high voltage bus to the low voltage bus might either result in overloaded machine or require an under load tap changing transformer. Care should be taken to draw conclusions too early (Europe 2018) from ranges of non-exhaustive requirements made available for national choices.
- Fault ride through capability requirement could not be met in some cases especially in the extreme leading power factor operating range although the leading conditions may not be part of the final national choices for evaluation of required performance in combination with the longer fault duration option considered here.
- Machine short circuit ratio has little impact on fault ride through capability.
The 47th Session reports of a direct professional interest for the specialists of JSC “NPO VEI Elektroizolyatsiya” are:
1) “Operation experience of asynchronized turbine-generator sets in the Moscow power system” Yu. G. Shakarian, P.V. Sokur “R&D Center @ FGC UES” JSC Yu.K. Petrenia, N.D. Pinchuk, M.B. Roitharts “Power Machines” PJSC S.N. Lenev, A.D. Gritsenko “Mosenergo” PJSC F.A. Poliakov, D.V. Kuznetsov “Electroservis-NTSG” LLC
In the report, the authors carry out a technical and economic analysis of the use of asynchronized turbine- generators, state an increase in reliability in comparison with the synchronized turbine-generators. The example of the Moscow power system shows a positive experience of their use with the analysis of operational parameters over the past five years, as well as the technical condition based on the results of complex diagnostic tests during repairs with the withdrawal of the rotor.
2) “Research and development of the switching performance of gas insulated disconnecting switch of switchgear” Rotblut A.R. , Chernoskutov D.V. , Bunkov A.S. , Labut A.P. , Karmazin M.I. , Ryzhkov K.А. JSC «ELMASH (UETM)» Joint-stock company “Research and Development Center of Federal Grid Company of Unified Energy System”.
The authors consider the development of an outdoor switchgear with a combined gas-insulated module of a disconnector-earthing switch to a voltage class of 126 kV with an increased breaking capacity in the part of commutation of the equalizing current 1600 A in accordance with the requirements of IEC 62271-102. The stages of designing and investigating of the main functions of the disconnector are described using methods of numerical simulation of the characteristics of a high-voltage switching device.
3) “Evaluation of the paper insulation condition of power transformers based on the content of methanol dissolved in transformer oil” L.A. Darian, R.M. Obraztsov, A.V. Maksimchenko, L.K. Le Electric Power University Socialist Republic of Vietnam and JSC «Technical Inspection UES» .
The report presents the results of improving the methodology for conducting research and expanding the range of materials studied, in particular paper insulation and transformer oil of the Russian production, work was carried out to collect data on the methanol content in transformer equipment of various designs and age, as well as operating conditions.
4) “Using optical spectroscopy for quality control of mineral transformer oils” V.K. Kozlov, M.Sh. Garifullin (Kazan State Power Engineering University Russia)
The authors substantiate the efficiency of using optical spectroscopy for quality control of mineral transformer oils. Various spectral ranges and research options are described.
5) “Extending metering technology limits with new approach to combined instrument transformers using IEC61850-9-2LE protocol” M. Yanin JSC “PROFOTECH” Russia, Dr.Thomas Heid Maxwell – CONDIS® metering products & solutions Switzerland.
A new line of instrument transformers JSC “Profotech” is presented. They are designed in order to solve problems on the typification of design solutions and equipment due to the increase in usage of electronic current and voltage transformers because of the urgency of creating digital substations.
The foreign colleagues’ reports of particular interest for JSC “NPO VEI Elektroizolyatsiya” are:
Rotating electrical machines:
- “Hybridizing gas turbine with battery energy storage: Performance and economics” N.W.MILLER, W. KAUSHIK, J. HEINZMANN, J. FRAZIER (USA) А1-101
Analyzing California energy market, the authors consider one of the major issues facing generation utilities faced with the very high, and increasing, levels of renewable energy sources that are penetrating the market. It led to the closure of large-scale oil and flammable gas deposits, in traditional sources of energy, for example, gas turbine generators, for the stable functioning of the power system. The use of a gas turbine plant hybridized with a battery storage system is proposed as a solution. The details of the first installation and the technical and economic parameters of the system are provided.
- Impact of grid code evolution on the design of the generators for nuclear plants (Half speed, power above 800 MVA) B. WAHDAME (FR) A1-104
The report provides a clear assessment of the operating problems and impacts associated with the ENTSO-E grid code requirements on large synchronous generators (> 800 MVA). These include general requirements for type D power-generating modules (voltage and frequency ranges), Fault Ride Through (FRT) capability, faster excitation system response, frequency variation withstand capability according to the specified Rate of Change of Frequency (ROCOF), and Low Voltage Ride Through (LVRT). If the operating point deviates from the nominal voltage and frequency values, the temperature of the generator core, the armature and field winding temperatures may increase significantly, which leads to damage to the stator core of the generator and insulation of the windings, which in turn affects the lifetime of the generator. For this reason, it is usually recommended to limit the amount, duration and frequency of occurrence of such operating conditions. However, it might be a challenge for generating units to stay within the defined operating limits, and the solution then is to over-dimension the machine, or to use on-load tap changers. For a final solution of the problem, some compromise may be required between the grid operator, plant owner and the manufacturer.
- Calculation of Rotor Eddy Current Losses in High-Speed PM Synchronous Generators using Transfer Matrices J.R. ANGLADA – GB, S.M. SHARKH – GB, M.A. YURATICH (GB) A1-106
The authors submitted to consideration an analytical method of calculating the loss of eddy currents in the rotors of high-speed synchronous generators with permanent magnets by means of transfer matrices as a faster and more practical approach in the iteration of machine design, as opposed to a slower but more accurate finite element method. Using the example of a generator with permanent magnets of 50 kW, 65,000 rpm, a correlation between the transfer matrix method and the FE method is shown to determine the rotational eddy current losses for both the load and no load.
- Variability of PD readings and failure location in high voltage bars T. HILDINGER (BR) A1-201
The report presents the results of a study of the variability of partial discharge results performed in a number of laboratories when testing the same test objects using the same equipment. Three independent laboratories conducted PD testing on a group of six Roebel bars that underwent accelerated aging. In addition, the results of testing conducted by the authors of the report showed significant variability in PD values, thereby raising questions about the prospects for determining the criteria for failure based on this parameter.
- A Study of the Propagation Behaviour of Partial Discharge Pulses in the High-Voltage Winding of Hydro Generators F. OETTL (AT) A1-202
The author considers the study of the propagation of a partial discharge on two stator windings with different voltages and nominal powers that must be subjected to rewinding. The stated aim of the research is to provide a reliable identification of the partial discharge in different parts of the stator winding. The key point of which is the introduction of an “attenuation matrix” obtained from a set of frequency-selective measurements. The purpose of this method is to try to eliminate the attenuation and dispersion of high-frequency partial discharges as they pass through the stator winding. By changing the frequency response of the detector, the authors show that this method can be used to identify defective features in the winding.
- Partial Discharge Activity in Isolated Phase Bus (IPB) – Case Studies from UK Power Stations A. SINGH – GB, M. HUGHES-NARBOROUGH (GB) A1-203
Studies based on partial discharge tests to assess the state and, consequently, the prospects for reliable operation of phase-insulated conductors, show that there are a number of options for performing online measurements of partial discharges. Although the IPB is not an integral part of the rotating machine, the failure of this system has serious consequences, given that it functions to connect the generator to the main output transformer or the generator circuit breaker.
- Analysis of Insulation Diagnosis for Generator-Motor Stator Winding and Core in Pumped Storage Power Plants S. H. LEE – KR, T. S. KONG – KR, H. D. KIM – KR, D. M. KIM (KR) A1-204
The report attempts to establish the reasons for the failure of insulation of the stator winding of two pumped storage generators, and apply a program for monitoring the grid condition, including in real time, is proposed to prevent future failures. The analysis of failures showed that, in one case, the cause of insulation failure was a large number of starts / stops for 25 years; the second failure was caused by the weakening of the stator core. Based on these findings, online measurements of partial discharges and additional off-line tests (PD, insulation resistance, polarization index, diffusion coefficient, low energy stator core flux, 8 UV camera, etc.) were carried out.
- Novel fiber optics technology monitors in-slot vibration and hot spots in an air cooled gas generator P. KUNG (CA) A1-205
The report presents the results of an air-cooled generator test obtained using fiber-optic sensors mounted on gas-turbine air-cooled generators, including slit temperature and winding temperature data, as well as vibration data obtained in the slot cell, the end wires of the frontal part winding and neutral endwinding bus. A good correlation of measured temperatures was observed between the new fiber optic temperature sensor and traditional remote temperature sensors. It is planned to apply the described monitoring technology for testing on hydrogen-cooled equipment.
- Importance of operating parameters when assessing the condition of machines on-line J. LETAL (CA) A1-207
The report presents three studies that show the sensitivity of the monitored parameters (vibration of the end winding parts, air gap and vibration) to changes in operating conditions (stator winding temperature, speed and load, respectively). Depending on the technology, various operating parameters affect the controlled data in different ways, some of which have a significant impact.
- Torsional Oscillations Mitigation for Interconnected Power System via Novel Fuzzy Control Based Braking Resistor Model M. FAYEZ AHMED – EG, M.A. EBRAHIM – EG, M.A. EL-HADIDY – EG, W.M. MANSOUR (EG) A1-208
The authors propose to consider a new model of a braking resistor, namely a rectifier controlled braking resistor (RCBR) model, controlled by FLC (fuzzy logic controller) to reduce torsion oscillations after re-inclusion. The braking resistor with a controlled rectifier is basically the only brake resistor unit connected to the generator terminals via a six-pulse full-wave bridge rectifier, which has no analogues to reduce torsional oscillations in multicomponent interconnected power systems. The proposed scheme makes it possible to safely use high-speed re-inclusion near power plants without compromising the mechanical integrity of the machine, which in the future allows resolving disputes between electric power enterprises and manufacturers of turbine generators in terms of the use of rapid re-inclusion near power plants. In addition, the use of one braking resistor block for each generator can lead to a reduction in the size and cost of the system. The advantages of the scheme can stimulate electric power enterprises to use it to reduce the torsion vibrations of the turbogenerator shaft, arising from unlimited rapid re-inclusion.
- Using an air gap monitoring system during initial commissioning stages of a hydro generator A. TÉTREAULT (CA) A1-209
The author demonstrates the development of air gap monitoring over the last 30 years, from the point of view of protection, namely avoidance of contact between the rotor and the stator, through proper diagnosis of problems during operation, especially when the operating conditions change. The document presents a web platform that allows end users to use not only data, but also analytical tools necessary for the full use of such systems.
- Application of Differential Magnetic Field Measurement (DMFM method) in winding fault detection of AC rotating machines as part of expert monitoring systems A. ELEZ (HR) A1-210
The report describes the method of differential measurement of the magnetic field, as a method for detecting faults in windings on induction and synchronous machines using two detection coils installed on the stator teeth, which makes it easier to interpret the signal, unlike existing ones with one coil, and is considered more sensitive. Validation of the method includes both FE-simulation and laboratory testing. The data are presented only for induction machines, but also applicable to synchronous salient pole aggregates and turbine generators.
- Generators as Synchronous Condensers to meet Dynamic System Requirement by Renewable Mix. – Indian Scenario D.K. CHATURVEDI – IN, A.K. GUPTA (IN) A1-211
The authors consider the use of existing retired generating sets or strategic spare generators as synchronous capacitors to facilitate compensation of reactive energy in the Indian grid as a result of rapid capacity expansion using wind and solar installations. A concrete example of three generators with hydrogen cooling with a capacity of 95 MW is described. Also, the advantages of using rotating machines in front of static compensators to compensate for reactive energy are discussed.
- A Study of the failure and repair rate indicators of the Itaipu generator units R. SILVA (BR) A1-301
The report presents a six-state model for assessing the unavailability and failure of generators at the Itaipu power plant in Brazil. The model considers the states “Operation”, “Failure”, “Reserve”, “Shutdown failure”, “Start-up failure”, “Maintenance”, and also the transitions between these states for 29 years of operation.
- Analyses of possible refurbishment of generators in HPP Perucica R. BATAKOVIC , B. ÐORDAN (ME) A1-303
The authors provide an overview of the problems of maintenance and operation of the generators of the hydro power plant of Perucica HPP in Montenegro for more than 50 years of operation due to the oiling and the presence of graphite dust on the surfaces of the rotor and stator windings. The combination of graphite dust, oil and moisture led to the fat deposits necessary for disposal. The crack of the old insulation on some devices exacerbated the problem that the fat deposits entered the cracks and could not be easily cleaned. The source of graphite dust appears to have been the motor-generator sets of excitation systems that were originally installed, but these problems were subsequently leveled, since the motor-generator sets of excitation systems were gradually replaced by static excitation systems. To eliminate this problem, it is proposed in the future to return to modern brushless excitation systems. The results of diagnostic tests performed in 2014 are also presented, with a general conclusion on the state of insulation systems and recommendations for the further operation of generators. The paper also discusses future options for upgrading the facility through redesign, in order to increase output power and efficiency.
- Analysis on the effect of screen ventilation width on end flux distribution and eddy current losses of Turbo-generator L. WANG (CN) A1-305
The report presents the results of an investigation of the eddy current losses in the stator core clamping flux shield arrangement of a 330 MW generator. The study considers a two-layer copper-film screening device in which the spacing between layers is used as a vent channel and varies to study the overall effect on screening efficiency and the resulting losses. The loss of clamping plates by 7% is achieved due to the greater distance between the screens due to a small increase in the screen losses.
- Loss Reduction by Large-Scale Electromagnetic Analysis H KOMETANI (JP) A1-307
This article reports on the model of electromagnetic finite elements, which has been used to analyze losses in different parts of the generator with indirect hydrogen cooling 900 MVA. The analysis demonstrates the design features of reducing losses, which can be used to increase the overall efficiency of the generator. These components and design features include cutting the end plates of the stator core and the laminated electromagnetic shield, using a non-magnetic material in the casing design near the endwindings and phase joints, the Roebel end connection applied to the stator bars, and improving the contact resistance between the wedges of the rotor and the retaining ring.
High voltage equipment:
- Simulation and Measurement of Pressure Rise in GIS 145 kV due to Internal Arcing D. GORENC (HR) A3-110
The author of the report conducted one- and three-phase tests on test models of switchgears with gas insulation at 145 kV. The values of the test results are compared as the pressure is increased, calculated by modeling on the basis of the technical brochure CIGRE 602 (WG A3-24, 2014). During testing the author examines the volume of the outer compartment for exhaust gases, the evaporation of the conductor material and the exothermic reaction of the conductive materials. He perfected the gas model described in TB 602. As in TB 602, the author states that the pressure and temperature due to the evaporation of aluminum and the exothermic reaction increase more than with copper conductors. In addition, a higher gas temperature results in a higher specific thermal capacity.
- Digital Disconnector: return on experience on digital substation E. STELLA , J.L. RAYON, G. HENRY (IT-FR) A3- 201
The industry enters a new intellectual era, and modern digital tools must necessarily be integrated into substations in order to increase the safety, reliability and quality of monitoring. The disconnectors play a fundamental role. The report analyzes the results of the application of the digital disconnector in the real conditions of the substation (a pilot project, implemented in 2016 in France, the Blocaux 245kV substation). The installed disconnectors are equipped with real-time monitoring functions and a digital drive. The introduction of a digital disconnector with digital on-line monitoring has a significant positive impact on the safety of the substation, allows the intelligent control programs to implement, leads to a reduction in the cost of substation maintenance, increased reliability and extended equipment service life.
- Performance Evaluation of CO2/Fluoronitrile Mixture at High Short Circuit Current Level in GIS and Dead-Tank High-Voltage Circuit Breakers V. HERMOSILLO, C. GREGOIRE , D. VANCELL, J. OZIL, Y. KEIFFEL, E. PIERRES (USA-FR) A3-301
Vacuum Generator Circuit Breaker as a Reliable SF6 Alternative with Reduced Life Cycle Costs for Power Plants up to 400 MW P. LEUFKENS , R. NAYER , K.R. VENNA (USA-DE) A3-302
Physical Aspects of Arc Interruption in CO2/O2/Fluoroketones Gas Mixtures J.D. MANTILLA , M. CLAESSENS (CH) A3-305
Application of a Heptafluoroisobutyronitrile gas (C4F7N) mixed with the Background gas of CO2 in GIS as SF6 Alternative H. E. JUNG, H. S. AHN, J. CHOI, Y.G. KIM, P. HUGEUENOT, R. LÜSCHER – SZ, K. BOUSOLTANE – FR, J. OZIL (KR-CH-SZ-FR) A3-307
Performance evaluation of CO2 and Fluoronitrile mixture in comparison with SF6 K. BOUSOLTANE (FR) A3-309
As alternative technologies to SF6, various gas mixtures are considered in four reports A3-301, A3-305, A3-307 and A3-309; the latest technologies used in a vacuum arc interrupter are considered in A3-302. The main component in gas mixtures is CO2, the second and third gases differ in the four listed reports. The A3-305 report discusses the arc extinguishing process with a gas mixture of CO2, O2 and fluoroketone, while a gas mixture of CO2, O2 and fluoronitrile is used in report A3-301, and a gas mixture of CO2 and fluoronitrile (ie, without O2) is used in A3-307 and A3-309. The authors discuss the questions of the methodologies for choosing the optimal content of gas mixtures and their switching performances. The use of additional O2 is of particular interest. The reports indicate that the use of alternative gases should be studied in the most thorough way. Similar trends are observed in the studies: the design of the arcing chamber should be changed due to the use of gas mixture technology as an alternative to SF6 gas, the static gas pressure should be higher than with SF6 gas, and the gas pressure in the transient mode differs from SF6 gas, mechanical and electrical endurance must be confirmed. In addition, critical switching parameters are important for each gas mixture. In the reports A3-301 and A3-309, the L75 is subjected to a test for the breaking capacity when the thermal parameters change, as one of the most complex tests of a fluoronitrile mixture on the breaking capacity. The report A3-309 also indicates a higher arc voltage in the fluoronitrile mixture than in SF6 gas during the L75 test. On the other hand, the authors of A3-305 demonstrate a good switching ability for thermal changes of L90, partially attributed to the formation of CF4 and confirmed by the current values at the arc terminals and the shorter peak reaching time. However, the dielectric trip indicators tend to decrease with a lower content of fluoroketone. When the molecular percentage is reduced to 3% from the initial 5% (corresponding to SF6), an increase in gas pressure of 50% is required. As an alternative to SF6 vacuum interrupters are discussed in report A3-302 for generator circuit breakers.
- Evolution of functional requirements for MV switchgear A. JANSSEN (NL) A3-303
The author of the report analyzes the radical changes taking place in the field of distribution electric grids, caused by different trends in their development. To meet new requirements for power systems, modern standards for switching equipment should be developed, dealing with the dielectric strength at open contacts to facilitate the separation of two parts of the power system (or generator) operating in an asynchronous manner. Taking into account the spatial, visual aspects and environmental impact of the complete power distribution unit, the author emphasizes the need to create compact and / or underground equipment. Reducing the size and areas leads to problems in the field of security, including during repair and modernization due to bidirectional power flows. The issue of using more complex protection, monitoring and control systems in real time, instead of fuses and switches, is also of current interest, including for life cycle testing and maintainability. There is a challenge in the field of shortage of qualified personnel to ensure the safety of the life of the energy system due to the development of distribution electrical networks.
- The future evolution of medium voltage circuit-breakers: new developments and possible applications M. RIVA , P. BERTOLOTTO, M. BONACONSA, L. CHENET, F. VIARO (IT) A3-304
The report provides an overview of the latest advanced medium voltage circuit breakers and their advantages provided by a deliberate single-phase reverse action for discussion in an open dialogue between users and manufacturers. In addition to the new switching technologies used, other advantages of the development are highlighted, such as: increased mechanical resource, additional diagnostic and prognostic functions, minimization of influence on the grid, improved monitoring and synchronization of certain operations.
- A new microtunneling technology for extra-high-voltage power cable installations C. TAPPEL, T. FREHN, R. PUFFER, M. ANDRES, M. PETERS, T. ENGEL , J. BRÜGGMANN, T. WINKEL (DE) B1-108
The tunneling technology using a developed boring machine, tested in the framework of a real cable project, allows the expansion of tunnels longer than 1000 m (work in the direction of increasing to the maximum possible) by drilling at shallow depths. The development described by the authors is aimed at reducing the impact on the environment and saving the cost of building a cable system in comparison with the open trench method.
- Distributed Temperature Sensing on the NorNed HVDC Cable System Ø. GARVIK (NO) B1-126
This report presents an analysis of the two-year temperature measurements on the NorNed HVDC channel. The temperature of the cable system along the first 5-6 km from the terminal to the underwater part was measured by a DTS monitoring system with optical fibers embedded in the lead sheath of the cables. The measured temperatures were compared with the calculations given in the reports of IEC 60287, made using parameters and approximate values at the design stage. The analysis was carried out taking into account the different conditions of the gasket. The differences between the calculated and measured temperatures were significant in micro-tunnels filled with air and water.
- Optical system for broadband data transmission concomitant to monitoring the physical integrity of conductors in overhead transmission lines J. ROSOLEM (BR) B2-101
The author describes a method for using an optical phase conductor to determine the integrity of a phase conductor of an overhead power transmission line. In places where public safety is threatened due to the failure of the conductor, the system is integrated with the substation protection system, for example, by blocking automatic re-activation in the event of such a failure of the conductor.
- The composite pylon M.H. MIKKELSEN (DK) B2- 308
The report describes a pylon constructed using only a composite material, taking into account lightning protection characteristics, gaps, electromagnetic fields, corona, electrical and mechanical tests. The pylon design was tested according to a number of technical criteria.
- Study on application of SF6/N2 mixture insulated GIL L. GAO (CN) B3-111
The author describes the use of the SF6 / N2 gas mixture in China. The main driver of the reduction of SF6 gas in China is a large number of installations of gas-insulated switchgears and their increase by more than 15% per year. Eight substations with compartments filled with a gas mixture were put into operation.
Protection and automation
- Development of Sampled Values Generation Device for Testing Process Bus-Based Busbar Protection IEDs S. Y. MOON , K. H. NHO (KR) B5- 210
The report describes the design, development and application of a portable generation device of digitized values IEC61850-9 with more than 20 channels, transmitting 80 SV frames / cycles per channel using the example of a KEPCO 154kV substation. It is capable of testing basic operations without the need for equipment to generate voltage / current or Merging Units. The device can provide an inexpensive and effective means for testing the protection of a busbar trunking system, which would otherwise be more complex, expensive and time-consuming due to more digital and analog signals. Since the device is also capable of generating currents and voltages at the level of errors, it can be used for testing, FAT, SAT, as well as for commissioning of process bus applications.
The full program of the 47 th Session of CIGRE is available on the website of the Russian National Committee of CIGRE http://www.cigre.ru