Clarification of possible network interaction between turbine-generator train and converters in the power network at VISUND – Accomplished project for Norsk Hydro

• Technical report: TR F5451
• ”Investigation of Possible Network Interaction between Turbine-Generator Trains and Converters in the Power Grid at the Oil Platform Visund”
  - Paper presented on PCC-Osaka 2002:
  - Presentation at the seminar: “Elkraft offshore forsyning og anvendelse” September 2003
• "Clarification of possible interactions between generator train and converter at GRANE” – Accomplished project for Kvaerner Oil and Gas
  - Technical report TR F5477
• Simulation of possible VSD and Gas Turbine-Generator interaction at the HAMMERFEST LNG-plant – Ongoing project for Linde AG
  - A project in cooperation with: Ødegaard & Danneskiold-Samsøe A/S (ØDS)
  - 5 generators with detailed modelling of electrical and mechanical dynamics
  - 4 large compressor drives with detailed modelling of electrical and mechanical dynamics
  - Underlying grid with i.a. several direct coupled asynchronous motors
  - Cables and lines to external grid (Hammerfest, Skaidi)

Analysis of inter-harmonic in the Hammerfest LNG-plant

• Determination of generator and compressor shaft torque oscillations due to inter-harmonic currents from grid connected converters
• Detailed models of mechanical system was interfaced to the electrical system model
• Challenges:
  - Modelling variable speed drive controllers
  - Getting the necessary input data
  - Modelling the mechanical systems (generator trains and compressors)
  - Interfacing the mechanical system model

Project for Linde AG on analysing risk for vibration problems, in electric machinery at the Hammerfest LNG plant

• Linde AG is the major contractor for the process equipment, including the electric power system
• Large power electronic converters are applied for controlling compressor motors for the gas liquefaction process
• Experience from similar installations gives reason to fear that vibration problems in rotating machineries, caused by power electronic converters, may cause operating problems
• Linde and Statoil have decided that possible problems, and alternative  countermeasures need to be clarified
• SINTEF Energy Research and ØDS was chosen for this job. Both companies have experience from analysing similar installations
• SINTEF Energy Research contributes with its power electronic expertise, while ØDS contributes with its mechanical expertise

Execution of the Hammerfest LNG plant project

• The project has been executed by running numerical simulations of the electric power system, including detailed models of the most important power component like gas turbines, generators, converters, motors and compressors
• In order to establish true models of the components, cooperation with several subcontractors has been necessary, e.g.  Siemens and  Nouvo Pignone
• Status:
  - The project is accomplished, and important results have been presented
  - As a direct consequence from the project SINTEF was in a position to assist with adjustments of the VSD control during the test phase in Massa in Italy, thereby  overcoming serious operating problems
  - Several smaller follow-up projects have also been accomplished
  - One more follow-up project is in the start up phase with the objective to sort out worst case operating conditions, including verification of alternative  countermeasures