Description of PD IEC TR 61400-21-3:2019 2019

This part of IEC 61400 provides guidance on principles which can be used as the basis for determining the application, structure and recommendations for the WT harmonic model. For the purpose of this Technical Report, a harmonic model means a model that represents harmonic emissions of different WT types interacting with the connected network.

This document is focused on providing technical guidance concerning the WT harmonic model. It describes the harmonic model in detail, covering such aspects as application, structure, as well as validation. By introducing a common understanding of the WT representation from a harmonic performance perspective, this document aims to bring the overall concept of the harmonic model closer to the industry (e.g. suppliers, developers, system operators, academia, etc.).

A standardized approach of WT harmonic model representation is presented in this document. The harmonic model will find a broad application in many areas of electrical engineering related to design, analysis, and optimisation of electrical infrastructure of onshore as well as offshore WPPs.

The structure of the harmonic model presented in this document will find an application in the following potential areas:

• evaluation of the WT harmonic performance during the design of electrical infrastructure and grid-connection studies;

• harmonic studies/analysis of modern power systems incorporating a number of WTs with line side converters;

• active or passive harmonic filter design to optimize electrical infrastructure (e.g. resonance characteristic shaping) as well as meet requirements in various grid codes;

• sizing of electrical components (e.g. harmonic losses, static reactive power compensation, noise emission, harmonic compatibility levels, etc.) within WPP electrical infrastructure;

• evaluation of external network background distortion impact on WT harmonic assessment;

• standardised communication interfaces in relation to WT harmonic data exchange between different stakeholders (e.g. system operators, generators, developers, etc.);

• universal interface for harmonic studies for engineering software developers;

• possible benchmark of WT introduced to the academia and the industry.

The advantage of having standardized WT harmonic performance assessment by means of the harmonic model is getting more and more crucial in case of large systems with different types of WTs connected to them, e.g. multi-cluster wind power plants incorporating different types of WTs connected to the same offshore or onshore substation.

The WT harmonic model can cover the integer harmonic range up to the 40^th, 50^th, or 100^th. And can be expanded, depending on requirements and application, to higher harmonic range as well as can also cover interharmonic components.

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