Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind 2004 Integration of Offshore Wind Farms into the Local Distribution Network Charles A. Lynch

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind DTI Project K/EL/0272 Final Report publications/pdfs/kel00272.pdf

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Partners IPSA Power Ltd. EEPS Group, UMIST Innogy/National Wind Power Powergen

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Objectives Establish viability of 100MW+ of wind generation connected to 132kV Establish validity of analysis tools for systems with doubly fed generators Compare the behaviour of the different types of wind generator Investigate using converter controls to assist is local area voltage control

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Project Phases DFIG Model Development Steady State and Dynamic Connections Studies Optimal Power Flow Development DFIG model Voltage Control Studies

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Generation Alternatives ‘Fixed Speed’ Induction Generator Variable Speed Synchronous or Induction Generation via Static Converters Doubly Fed Induction Generator (DFIG)

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Double Fed Induction Generator What is a DFIG? Wound rotor Induction Machine Variable frequency voltage applied to the rotor windings Why is it needed? Variable speed, from about 0.7 to 1.3 per unit Optimise performance over a range of wind speeds

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Typical configuration of DFIG wind turbine As

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Modelling Requirements Load Flow Studies Voltage Stability and Control Variation of real and reactive power over operating regimes Fault Analysis Studies Dynamic Analysis Studies Transient and Dynamic stability

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Modelling Detail Control Modes Speed Control plus Power Factor control Associated AC/DC Converters Two Points of Power Injection May not be explicitly modelled Rotor reactive power is not provided by the network

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind DFIG Performance Characteristic

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Connection Studies Collaborators Scottish Power, Manweb United Utilities

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Variable speed synchronous generation

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Steady State Studies Fixed Speed Induction Machines Higher reactive power flows Increased voltage regulation Higher make duty fault levels DFIG Lower increase in make duty fault levels Variable Speed Synchronous Machines Least impact

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Dynamic Analysis All three generation types modelled Fault clearance studies for faults at the wind farm and on the 132kV network Further development of controller modelling by User Defined Modelling DTI Project: K/EL/0321 Facilitating the modelling of embedded generation

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Fault at 132kV, example 1

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Fault at 132kV, example 2

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind User Defined Modelling

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Voltage Control Studies Load Flow and Optimal Power Flow (OPF) studies Compare fixed speed and variable speed machines Determine optimal control strategy over a range of network conditions Coordinated area based voltage control Maximise generation penetration

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Voltage Control Results Significant improvement operating wind farm under voltage control compared with constant power factor control (DFIG) Increased generation penetration possible Fixed speed machine power factor correction is an additional constraint OPF very helpful in addressing a wide range of issues

Power Systems Consulting and Software 4 March 2004 BWEA Conference: UK Offshore Wind Conclusions Alternative generation types successfully modelled in system wide studies Connection of 100+ MW of offshore generation is possible at 132kV More generation can be connected if it participates in voltage control Full report: publications/pdfs/kel00272.pdf