1st Biannual report

WP 1: Inventory

This work package was started with a literature study of available technologies for a modular North Sea Transnational Grid based on HVDC technology. The literature study has not been completed yet. The 8th International Workshop on Large-Scale Integration of Wind Power into Power Systems and Transmission Networks for Offshore Wind Farms on 14 and 15 October in Bremen was visited.

WP2: Techno-Economic Evaluation

In this work package steady state wind farm and offshore grid models will be used to compare different scenarios (individual connection, national interconnection and transnational grid). The work has been started by gathering data on possible future locations of wind farms in the North Sea. Based on this data, a preliminary layout for each of the scenario’s will be made. A discussion has been started with I. Doornbos (Min. Econ. Affairs) on synchronization of this investigation with the European 10 Countries Initiative (future North Sea grid).

WP3: Multi-Terminal Converter

This work package started in december 2009 with the arrival of the TUD-Electrical Power Processing PhD student  R. Teixeira Pinto. TUD-EPP produced two interim reports during the first six month of the project. Interim report “VSC-HVDC Inner Current Controller” initializes the work package and discusses the basics of modelling and control of a VSC-HVDC system. Two simulations are presented, the first simulation uses an averaged VSC-HVDC model and the second is based on a VSC-HVDC model with PWM modulator. The second interim report “Investigation of Multi-terminal HVDC networks for the NSTG project” includes:

Ø     a description of current HVDC technology: CSC-HVDC, also called HVDC Classic and VSC-HVDC, i.e. HVDC Light or HVDC Plus;

Ø     a discussion on modularity and options for multi-terminal operation of a HVDC system;

Ø     a simulation example for a CSC-HVDC and a VSC-HVDC system;

Ø     a HVDC grid stability exercise.

Furthermore, wind power dispatching methods for  multi-terminal HVDC networks are investigated (TUD-HCPS).

WP6: Grid

This work package is devoted to simulating and studying the influence of severe voltage and current fluctuations on system stability and proposes methods to improve the overall system stability. Appropriate simplifications must be realized in order to model and numerically simulate a large-scale network. These include: complex phasor representation of voltages and currents instead of sinusoidal waveforms, simplified generator modeling, implementation of quasi steady-state schemes of wind power plants, and appropriate implementation of converter behavior. The focus up till now has been on how to properly represent the converter interface within transient stability simulations. A paper (“Combined Stability and Electro-Magnetic Transients Simulation of Offshore Wind Power Connected through Multi-Terminal VSC-HVDC”) has been accepted for presentation at the IEEE Power Engineering Society General Meeting, July 2010 in Minneapolis (USA). Future research will initially continue to focus on the simulation aspects of this interface.

WP6 also includes the long term effects of a transnational grid  on the operation and control of the onshore AC systems. This work is intended to be carried out by a post doctoral researcher and has not been started yet.

WP8: Contribution to IEA Annex 25

The fall 2009 IEA Annex 25 workshop was organized at ECN on 12 and 13 october 2009.

The IEA Annex 25 workshop on 16-17 march 2010 in Toledo was visited (TUD- HCPS).

WP10: Coordination

The first Advisory Group meeting was organised at Schiphol on 21 April 2010. Due to an airtrafic problem (vulcanic ash), a number of participants could not attend and the meeting was cancelled. The new date is 16 June 2010.