This thesis was previously held under moratorium from 27th November 2019 until 27th November 2024.

Creator

• Amico, Gabriele

Rights statement

• Strathclyde Thesis Copyright

Awarding institution

• University of Strathclyde

Date of award

• 2019

Thesis identifier

• T15385

Person Identifier (Local)

• 201550649

Qualification Level

• Doctoral (Postgraduate)

Qualification Name

• Doctor of Philosophy (PhD)

Department, School or Faculty

• Department of Electronic and Electrical Engineering

Abstract

• The installation of larger wind farms has introduced new grid integration challenges. Among these, high frequency electrical resonances caused by the cables and lines connecting the wind farm to the grid have been described in literature. These resonances may cause instability as they typically occur at frequencies close to the current controller bandwidth of the wind turbine inverter. Different mitigation techniques have been proposed in the literature to counteract these resonances. However, these techniques lack of generality as they rely on parameter tuning, which varies on a case-by-case scenario. In order to analyse the problem, an impedance-based stability approach has been applied. A systematic technique to derived the sequence-frame converter admittance has been dened, and a stability study methodology including the coupling between the positive and negative sequence converter admittances has been formulated. Compared to the existing impedance-based stability criterion, where such coupling is ignored, the proposed technique is more accurate in the system stability assessment. The study has shown that the delay introduced by the controller implementation is the main cause of the investigated wind farm stability issues. An innovative hardware implementation of the controller is proposed to compensate for this delay, without altering the converter switching frequency but making a more efficient use of the available hardware processing power. Hence, a more general and portable solution to the problem is proposed, which does not require parameter tuning. An experimental validation of the applied stability analysis methodology and of the proposed mitigation techniques has been carried out, making use of a purposed built prototype of a converter-grid system.

Advisor / supervisor

• Egea-Àlvarez, Agusti
• Xu, Lie

Resource Type

• Doctoral thesis

DOI

• 10.48730/9y5y-k667

Date Created

• 2019

Former identifier

• 9912773392602996