Main Generator Stator Replacement

In association with company Siemens we prepared project documentation for the ''Replacement of Main Generator Stator'' which was replaced during the outage 2010. The main Generator of NPP Krško is 4-pole cylindrical-Rotor synchronous Generator, which was originally manufactured by Westinghouse Electric Corporation in 1977 and has been in continuous operation in base load regime from 1982.

Due to the wear of Thermalastic® insulation of Stator winding, design life of Generator and life extension anticipated NEK has decided to replace the old Stator. The new Generator Stator has been designed and manufactured per the NEK requirements by Siemens AG (Picture 1).

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Picture 1: New Stator of the Main Generator (outage 2010) 

Scope of the project has also included modifications on existing Generator and other supporting systems. Design analyses, calculations and procedures have been performed to ensure that new installed Stator of the Generator will be equivalent replacement for the old one. Few of the analysis and calculations that were performed:

  • Power Supply Cables Sizing 
  • Transport Route Analysis 
  • Turbine Building Foundation and Load Capacity Analysis 
  • Cable Tray and Conduit Supports Calculation 
  • Analysis of Explosion Protection 
  • GN Piping Supports Calculation 
  • Analysis of Additional Load on TC System 
  • Measurement and Control List 

Sipro responsibility was also examination of the analysis and calculations which were provided by the costumer:

  • Final procedure for the exchange of the Generator 
  • Calculation of Generator Parameters, Characteristics, Design 
  • Study for Isolated Phase Bus Duct 
  • Generator Mechanical Stress Evaluation 
  • Design Approach Report to Fulfill 40 Years Service Life 
  • Torsion Study 
  • Transformer Study 
  • Study of the Protection Setting for the Generator and Other Systems 
  • Protection Terminals Settings Calculation 

Based on results and conclusions of the analysis, studies and calculations Sipro has produced complete project documentation per NEK procedures.

Project Manager: Andrej Avšič, B.Sc.E.E.  

 

Main Generator Rotor Replacement

As an upgrade to the modernization of the main Generator NEK has decided to replace the old Rotor. In association with company Siemens, Sipro prepared project documentation for the ''Supply And Replacement of New Generator Rotor'' which was replaced during the outage 2012.

The new Generator Rotor has been designed and manufactured per the NEK requirements by Siemens AG (Picture 1).

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Picture 1: New Rotor of the Main Generator (outage 2012) 

We have examined analyses, calculations that have been performed or revised to ensure that new installed Rotor of the Generator will be equivalent replacement for the old one:

  •  Generator Parameters, Characteristics, Design
  •  Torsion Analysis  Study of the Protection Setting
  •  Compatibility, Mechanical Stress Evaluation and Elongation Considerations
  •  Replacement Rotor Design Approach to fulfill 40 year service life
  •  Study of the WTA Settings for the 850 MVA Generator
  •  Protection Terminals Settings Calculation

Based on results and conclusions of the analysis, studies and calculations Sipro has developed complete project documentation per NEK procedures.

Project Manager: Božidar Linke, B.Sc.E.E.  

TEŠ 6 – Design Documentation for Construction Permission for Water Pumping Plant, Water Treatment Facility, Bypass Filtration Station and Ammonia Water Plant

Sipro Engineering was involved in the design for construction permission for 600 MWe block 6 of Thermal Power Plant Šoštanj (Slovenia). Sipro developed the design of mechanical installations, technology and equipment and the design of electrical installation and equipment, for the following technological parts:

  • Water pumping plant
  • Water treatment facility
  • Bypass filtration Station
  • Ammonia Water Plant

Water pumping plant is located by the Paka river. Designed capacity of the new Pumping plant is 1.500 m3/h. The water is pumped from the Paka river, but in case of low stream flow from the lake of Družmir.

New Water pumping plant consists from following systems and equipment:

  • Mechanical water gates
  • Valves in river water intake
  • Rotating sieve with the capacity 1.400 m3/h
  • Pumps for water supply to the new decarbonizing plant
  • Pumps for water supply to technological consumers
  • Pumps for backup washing of the rotating sieve
  • I&C and electrical equipment
  • Electrical power supply for the consumers

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Picture 1: Reactor

The water treatment plant with the capacity of 1.200 m3/h is based on decarbonizing with dosing of:

  • Lime milk – 8 % concentrated suspension of lime (dosing into reactor)
  • Iron tetrachloride (4 % FeCl3, dosing into reactor)
  • Polyelectrolyte (dosing into reactor)
  • Hardness stabilizer (dosing into cooling water pipe)
  • Bio dispersant (dosing into cooling water pipe)

Main technological parameters of the decarbonizing plant are:

  • Reactor
  • Settler (sludge basin)
  • Decarbonized water basin
  • FeCl3 dosing station
  • Polyelectrolyte dosing station Nr. 1
  • Polyelectrolyte dosing station Nr. 2
  • Water hardness stabilizer station
  • Lime milk dozing station (dosing tanks and dosing pumps)
  • Centrifuge Nr. 1 and Nr. 2
  • Decarbonized water pumps
  • Washing pumps
  • Sludge pumps
  • Cleaned water pumps
  • I&C and electrical equipment
  • Power supply and distribution

Bypass filtration facility with sand filters assures filtration of approximately 5 % of condenser cooling water. The facility consists of:

  • Sand filters
  • Circulating pumps of cooling water through filters
  • Filters washing pumps
  • Fans for sand filters
  • Back up washing water pump
  • Auxiliary systems
  • I&C and electrical equipment
  • Power supply and distribution

For the purpose of NOx reduction in the exhaust gases of the boiler the catalytic cleaning system (DeNOx reactor) for unit 6 as well as unit 5 has been used. For the purpose of catalytic reaction the ammonia water is supplied into the system. Ammonia water with the concentration of 25 % is used, 1.500 to 2.000 l/h, about 45 % for unit 5 and about 55 % for unit 6.

The components of ammonia plant are:

  • Wagon decanting facility (decanting platform with railway track, drainage reservoir, cover, four discharge units, valves)
  • Truck decanting facility (decanting platform with the drain to collecting drainage tank, cover, connections for truck cisterns discharge, connection for underground drainage tank discharge, flexible hoses…)
  • Ammonia water pumping station (lime for wagon cisterns or truck cisterna discharge, pumping line for the consumers, drainage reservoir 50 m3)
  • Double wall overhead reservoir of the capacity 1.000 m3 for the ammonia water storage with the connections and auxiliary equipment
  • Underground drainage reservoir for discharging of the facility or its sectors
  • I&C and electrical equipment
  • Power supply and distribution

Project Manager for technology and mechanical design: Matjaž Pleteršek

Project Manager for electrical and I&C design: Franc Katič

Substations 110/10 kV - Dolginovskaya, Vesnyanka, Petrovschina, Grushevskaya - Minsk - Belarus

Company Riko, Ljubljana from Slovenia has constructed two new substations 110/10 kV (Dolginovskaya and Grushevskaya) and reconstructed another two (Petrovschina and Vesnyanka) in Minsk, Belarus on turnkey basis. Sipro Inzeniring has performed for Riko engineering activities for electrical portion of the total scope.

Sipro involvement in the project was:

  • Technical concept development
  • Equipment specifications
  • Technical support in the equipment purchasing process
  • Support during testing of equipment and systems including Factory acceptance tests
  • Documentation preparation support
  • Supervision during production, installation and startup

Substations 110/10 kV Dolginovskaya in Vesnyanka together comprise one LOT and substations 110/10 kV Grushevskaya in Petrovschina another LOT.

The substations of one LOT are located several kilometers apart from each other and are connected with 110 kV high voltage underground cables. All the interconnection cable connections, including excavation and civil construction work were in the scope of the project.

Completely new is the substation Dolginovskaya (Picture 1). It is comprised from 110 kV Switchyard, Transformation 110/10 kV, 10 kV Switchgear, Protection, Control and Measuring Systems and the Auxiliary Power Supply Systems. 110 kV Switchyard is performed in H connection, with two outgoing feeders, two transformer feeders and interconnecting feeder.                                                                                                                        

 

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Picture 1: Substation Dolginovskaya - outlook

Transformation 110/10 kV is assured by two Power Transformers with on load tap changers, 40 MVA each. Each of two Power transformers has two secondary windings, 20 MVA rated power each (Picture 2). 

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Picture 2: Power Transformer in transformer room  

Middle voltage switchgear is comprised of four sections, with 56 single busbars 10 kV cubicles in all sections. Middle voltage system is grounded through grounding transformers and grounding resistors. All of the equipment is installed indoor. Similar, as the configuration of substation Dolginovskaya is also configuration of the substation Grushevskaya. These substations have differences only in technical parameters of equipment, differences in configuration of 110 kV H connection, different numbers of 10 kV cubicles, etc. Both substations are completely located in buildings, with approximately squared ground plan, with the length and width of approximately 40 to 45 (Picture 3). The buildings and all correlated construction works were in the project's scope.

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Picture 3: Dolginovskaya – indoor 110 kV Switchyard

Substation Vesnyanka was reconstructed. The construction works comprised the upgrade of existing 110 kV GIS with two additional outgoing feeders with upgrade of Protection, Control and Metering Systems with the purpose to assure a new supply for substation Dolginovskaya, from 110 kV busbar of Vesnyanka.

The scope for substation TP Petrovschina was the complete reconstruction of 110/10 kV substation. All the old 110 kV open air switchyard was demolished and was replaced with new modern 110 kV GIS switchgear with 20 feeders. Four transformers 110/10 kV were installed, 40 MVA each. There were installed also 8 sections of 10 kV switchgear and all Protection, Control, Metering and Communication systems were replaced. A new building in which have been installed all the equipment was also in the scope of the project, with all engineering and civil activities. The portals and the HV line towers next to them for outgoing HV lines were replaced. The Protective and Communication devices on the other side of the HV lines were also replaced. Instead of grounding wires on the top of incoming HV lines, there were installed OPGW wires, and some towers on incoming HV lines were replaced. The reconstruction of the substation Petrovschina was performed so that the substation was all the time partly in the operation, as can be seen from Picture 4. Before the beginning of the construction work, it was necessary to implement all temporary modifications to assure constantly operation and supply in the part of the station. That was done through temporary installed HV equipment and temporary 110 kV bypass cables connections. 

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Picture 4: Reconstruction of substation Petrovschina

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Picture 5: Substation Petrovschina

Reconstructed substations Vesnyanka and new substation Dolginovskaya have been successfully operating from July 2012, and substations Petrovschina and Grushevskaya from the summer 2013.

 

Project Manager: Franc Katič, M.Sc.E.E.

 

Replacement of synchro verifier relays and relocation of LV fuses

Purpose of modification 709-EE-L was replacement of worn synchronization verification relays. These relays serve purpose during ''Fast Transfer'' procedure, when power supply is switched from regular T1 and T2 transformers to auxiliary transformer T3. T1 and T2 are supplied from plants generator, while T3 gets power from network, hence the possibility that there is phase shift between two voltages, which could cause damage to running equipment during supply switch.

Such relays with one contact in control scheme of transformer’s circuit breakers prevent closing of breaker in case of non-synchronization. Existing relays did operate, but they experienced strong contact chatter, that caused problem when performing ''Fast Transfer'' procedure. With this modification, eight existing relays were replaced with new versions; these required power supply that was not originally needed.

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Picture 1: "Synchro Verifier" relays

In scope of this modification, LV fuses from voltage indication circuits were relocated from HV compartment to LV compartment. This was done to ensure greater safety for maintenance personnel, who were exposed to possibility of arc flash due to close proximity of high voltage. Therefore fuses were relocated to low voltage compartment, where there is no high voltage danger. This modification required new cabling in voltage indication circuits.  

Project manager: Matjaž Stanko, B.Sc.E.E.