Minutes of Meeting
VGB-Technical Committee: Generation and Technology VGB-Technical Group: PGMON Power Generation Maintenance Optimisation Netzwork 61st Meeting on 14 October 2020; Onlinemeeting
Participants:
Andrejkowic Milan CEZ Basus Martin CEZ Hoffmann Martin CEZ Krempasky Jakub CEZ Krickis Otto Latvenergo Le Bris Yves EDF Martin Conor ESB Meinke Sebastian Vattenfall Tereso Bruno EDP Wels Henk DNV GL Wolbers Patrick DNV GL
VGB Secretariat: Göhring Sven VGB
Agenda
Welcome (Henk Wels)
TOP 1: Use of parts from decommissioned coal-fired power plants Milan Andrejkovic, CEZ
TOP 2: CCGT eHGPI Martin Hoffman, CEZ
TOP 3: Siemens SGT-800 gas turbine’s upgrade process, related technical issues and preliminary results Otto Krickis, Latvenergo
TOP 4: Diag Engine, a new monitoring solution for reciprocating engines Yves Le Bris, EDF
TOP 5: RAM prediction for a district heating station consisting of aux boilers and a buffer Henk Wels, Dekra
TOP 6: Ancillary Services Market: ESB CCGT Plant Flexibility Improvements Conor Martin, ESB
TOP 7: Statistical analysis of VGB Forced Unavailability data on cycling CCGTs Henk Wels, Dekra
TOP 8: The new VGB-Workspace Sven Göhring, VGB
TOP 9: Place and date of next venue
TOP 1: Use of parts from decommissioned coal-fired power plants Milan Andrejkovič & Martin Bašus, CEZ
The introductory part of the presentation summarizes current information on CEZ Group's strategy and economic development in the Czech Republic in relation to the energy market, significantly affected by the Covid-19 pandemic.
The history pf the power plant Prunerov 1 was presented. It was commissioned in 1967- 1968. The first reconstruction was taken in 1985-1988. This reconstruction solved recovery of important components. For example, the new rotors of steam turbines or replacement boiler’s parts. flue gas cleaner (absorber) were installed in 1996 (efficiency 95 %). Current state, when we shutdown power plant Prunerov 1 in June this year (4 units x 110 MWe). Next section shows part’s, which can be reused. The presentation shows examples of used components and spare parts in portfolio CEZ GROUP. The greatest interest is in control components and electric engines 6 kV. A stator of generator will be removed in November and taken to a service centre. There will be checked and repaired, then will be taken to power plant Ledvice. The same subject is with the transformer.
The process of selling parts was shown - firstly, we do marketing research and if there is interest, then run the usual sales process.
TOP 2: CCGT eHGPI Martin Hoffman & Jakub Krempaský, CEZ
In first part of the presentation, CEZ presented actual operated CCGT units. CEZ is currently operates 1 CCGT power plant, which was started in 2014 at the perimeter of the coal-fired power plant. The operations are independent of each other; power plants have a common raw water supply. Total power output of CCGT is over 800 MW, multishaft arrangement of 2 gas turbines, HRSG boiler and steam turbine. Since commissioning, the market demand for operation of the power plant has been steadily rising. Subsequently, CEZ presented the possibilities of adjustments to the employees´ time fund, these possibilities are approached very sensitively and very rarely.
Second part of the presentation was about power outage conducted at that time at CCGT Pocerady power plant. Main content of this power outage includes hot gas path inspection and power upgrade. Gas turbine, compressor, generator and auxiliary equipment are inspected and reconditioned during this outage. CEZ presented some organizational and technical insights regarding this power outage together with a brief overview of the works currently done there. CEZ also presented several improvements which are implemented during the power outage. Improvements concern replacement of several stages of compressor and gas turbines blades and vanes, optimized combustion and installing new designed equipment with increased durability. Results of these improvement are increased electrical power output of both gas turbines, lower start up times and higher operation flexibility.
TOP 3: Siemens SGT-800 gas turbine’s upgrade process, related technical issues and preliminary results Otto Krickis, Latvenergo
State company AS “Latvenergo” operates two thermal plants with installed capacity 144 MW (TEC-1) and 832 MW (TEC-2). At the thermal power plant TEC-1 with electrical capacity 144 MW are installed SIEMENS SGT-800A two gas turbines in combination with one steam turbine. In order to improve efficiency of the gas turbines of TEC-1 was decided to extend planned D level inspection with turbines' upgrade package, which allows achieving the latest modification of the turbine currently available now on the market. Upgrade of the gas turbine allows increasing power by 7 MW per GT unit, as well as allows to extend time between overhauls by 10 k EOH (overall time between overhauls 30 k EOH). In the framework of the upgrade compressor's blading was exchanged to the latest modification, as well as HGP was impacted too. During inspection of the first gas turbine were found several technical issues: defective pinion of the gearbox and alignment problems of the compressor. After opening gearbox casing was identified one damaged tooth of the turbine's pinion as well as bearing pads had signs of the deposits and melting. Results of the blue contact test were outside acceptance criteria. In order to put unit in operation as fast as possible damaged gearbox was replaced with completely new gearset.
After upgrade of the turbine to the version SGT-800A4 as well as replacement of the gearset, output of the gas turbine increased more than by 7 MW and efficiency improved in average by 1.5 %.
TOP 4: Diag Engine, a new monitoring solution for reciprocating engines Yves Le Bris, EDF
In order to avoid too much maintenance EDF R&D center developed in the mid-2005, some dedicated algorithmic to monitor reciprocating engine of the nuclear fleet. 11 defects have been mathematically processed. Though, to those different degradation processes had been associated mathematical signatures in terms of impact on the acyclism signal. Several indicators have been created on the basis of those signatures
This Adaptable solution can be used for diesel or gas engines, from 100 kW to 20 MW, with 2 and 4 strokes, for L and V technology and whatever base load or back-up engines.
DIAG ENGINE is easy to use with an outside implementation and a minimum instrumentation, only 2 sensors are required;
This service offers an engine spot complete health check and expertise, and cylinder by cylinder the defects are analyzed. Remote continuous health monitoring and early fault detection can be proposed.
EDF is independent from manufacturers and O&M companies and with more than 2 GW of diesel engines, has a strong expertise and return of experience as a diesel generator set operator.
TOP 5: RAM prediction for a district heating station consisting of aux boilers and a buffer Henk Wels, Dekra
Background
Vattenfall realizes a remotely operated Heat Transfer Station with auxiliary boilers and a heat buffer connecting the heat distribution networks for the NW and SE side of Amsterdam. The connection is beneficial as production for NW by a Waste-to-Energy plant has a surplus while production for SE by a CCGT can be further optimized. The Heat Transfer Station is being built by a contractor under a fixed price contract including
a RAM analysis to check if RAM demands are being met (so called RAM specification). The contractor has realized a RAM model in a documented Excel spreadsheet.
The contractor RAM analysis was reviewed by DNV GL. This analysis was by no means simple as many operating conditions are possible with regard to number of boilers in operation, delivery to NW and/or SE, operation with/without buffer, etc. As not all components are in use at each operating situation, boiler and pump redundancy had to be handled carefully. Similarly, there are 2 essentially products. What if a boiler producing for NW fails? Will NW have priority over SE?
Review method
DNV GL was involved as third party assessor and reviewed by separate memos each product of the contractor, such as the RAM analysis proposal, a preliminary RAM spreadsheet with input data and the RAM report. Some preferred ways of handling RAM specification are given in the UNIPEDE guideline.
Working in parallel to the contractor, DNV GL produced a documented data analysis using practice data for auxiliary boilers, a Fault Tree analysis for the electrical systems, a Reliability Block Diagram containing system states (full out, 50 % production due to failures, etc.), a heat production duration curve resulting in estimated operating hours of auxiliary boilers and a full report of these activities. That made comparison with contractor results easy with the additional advantage that errors from both sides could be removed by comparison.
TOP 6: Ancillary Services Market: ESB CCGT Plant Flexibility Improvements Conor Martin, ESB
Conor Martin from Generation Asset Performance represented ESB Generation & Trading at PGMON 61 in October. Before the presentation details commenced a high level introduction to the ESB Group was presented for the benefit of new members of PGMON. ESB Generation & Trading then presented an update on CCGT plant flexibilities which have been implemented in the ESB portfolio in recent years. Some background detail on the creation of a system services (DS3) market in the Irish energy sector was provided to
give some context around the commercial drivers for flexibility improvements and upgrades. The influence of wind penetration on demand and price was highlighted to show what the TSO requires to maintain system stability and the services it requires for different generator technologies. An overview of the changes implemented at Poolbeg CCGT plant was given to highlight how and low merit lower efficiency plant can be sustained commercially by providing fast start capabilities. Details of updates to the start-up sequence were presented to give a view of the changes implemented to change the unit from a slow starting conventional plant to a fast start peaking plant. The CCGT plant can now synchronize and export in less than 5 minutes from receipt of a dispatch instruction from the TSO. Upgrades and changes at higher merit base load plants was also given to show how minimum load changes and turn down improvements have been implemented at Dublin Bay, Aghada and Coolkeeragh CCGT plants. An overview of the future market direction for system services in Ireland was provided, with some details of how zero MW technologies such as batteries and synchronous compensators will influence system services provision in future. An update to ESB’s predictive maintenance e-monitoring roll-out was then presented, including details of some of the findings and benefits which have been identified since the system has been live in Carrington Power Station.
TOP 7: Statistical analysis of VGB Forced Unavailability data on cycling CCGTs Henk Wels, Dekra
Background A VGB KELI presentation on the subject, postponed due to COVID-19, is to be held November 2020 in Bremen. This work was initiated by the VGB committee TC Materials & Quality Assurance and a paper in VGB Power Tech will follow. Several German utilities are present in the Working Group. One can see from the KISSY data using yearly averages that f.i. in the category of plant > 600 MW the forced unavailability FOR is clearly rising with # starts. However yearly averaging may be insufficient as many factors are varied at the same time, as not all plants supply starts, plants age in time, there is an effect of both starts and operating hrs, etc.
Therefore more advanced statistical methods were applied, taking account of outliers systematically (so-called Robust Statistics) and using variance analysis, regression analysis, factor analysis, clustering, pattern assessments, separate analysis of HILPs and assessing the failure descriptions in the KISSY records along the line of Tukey’s Exploratory Data analysis. For this analysis VGB supplied CCGT & Combi plants of in total 4135 failure event records for 33 plants over 393 plant years as well as a very large data set for coal & lignite fired plants of in total 11430 failure event records for 129 plants over 1212 plant years.
Conclusions Based on engineering reasoning and damage investigations one may expect for instance for LB = steam system that the forced unavailability of this system increases with more starts per year. The data show that reality is more complex as for instance some end-of-life issues for (thick walled) steam chests (KKS = LB) are solved by repair during overhauls, which is only visible in the KISSY system as free text added to overhaul records. Yet, scatter X-Y plots show in general that the more starts, the larger the forced unavailability in total. More operating hours however may result in fewer failures (“base load operation is favorable”). Yet, the effect of more starts appears to be dominant. Gas turbines show little ageing (given proper maintenance), boilers in general show ageing as an increased FOR with age is present. The picture for steam turbines and generators is different for GUD & Combi plants compared to coal & lignite plants as GUD & Combis do not show ageing effects on forced unavailability of STs and generators yet while coal & lignite plants do. The effect of outliers is large, the plants having caused these outliers were marked & analyzed and average coefficients were derived without these outliers. Time and often limited detail in the data did not permit analyzing the technical reason for outliers in detail. Variance analysis shows that effects of age, plant size, starts per year and operating hours on forced unavailability cannot be attributed to chance, yet they explain in general less than 10 % of the total variance (spread) in the data.
The effect of individual plants is larger, explaining 23 % of the variance in the group of CCGT and Combi (single shaft, multi shaft, GUD as well as Combis). The effect of individual plants explains 69 % of the variance in the group of coal & lignite plants. This means that in order to find a plant fit for cycling, one should carry out a (detailed) investigation taking plant and component characteristics into account. To improve cycling in practice one also needs to analyze feedwater conditioning and to train plant operators to improve on the failure probability per start. On average, a simple causal model with regression coefficients shows that when cycling GUD & Combi plants on average the forced unavailability rises from about 1.2 % in baseload to 3.6 % with substantial cycling, not taking HILP events into account. For coal & lignite the effect is even larger, from 1.9 % to 7.9 %. For the VGB coal & lignite data this is an extrapolation as these plants generally do not cycle daily yet. For ageing plants the rise is still higher, yet it may be within bounds if the construction details allow and the plant is given proper maintenance.
TOP 8: The new VGB-Workspace Sven Göhring, VGB
VGB has set up a new platform for communication. This platform will simplify and intensify the cooperation within the members of the technical group and with VGB in the future. The so called “eNet” is a modern digital workspace and will replace the old known closed user groups. Beside the already known document folders it offers further possibilities for a digital communication. The access data to the new tool are identical to the previous access data to myVGB and therefore remain unchanged. The URL of the new system is https://connect.vgbe.net. The well-known committee structures and contents are transferred one by one from myVGB to eNet. With the new tool, not only session documents can be made available, the system offers, among other things, also the possibility to schedule appointments and to exchange views through a chat area. Further options such as shared documents or integrated video conferences will be developed in collaboration with you in the future.
Step by step we will also facilitate an exchange overarching the committee structure. All TG members were asked to register within the new system and use the possibilities of the new workspace.
TOP 9: Place and date of next venue The next meeting will be held on 29th of April 2021 as an online meeting.