BS EN IEC 61400-21-1:2019+A11:2020 - Page 2

Wind energy generation systems. Measurement and assessment of electrical characteristics. Wind turbines | Status: Current

1 Scope This part of IEC 61400 includes:

• • definition and specification of the quantities to be determined for characterizing the electrical characteristics of a grid-connected wind turbine;
• • measurement procedures for quantifying the electrical characteristics;
• • procedures for assessing compliance with electrical connection requirements, including estimation of the power quality expected from the wind turbine type when deployed at a specific site.

The measurement procedures are valid for single wind turbines with a three-phase grid connection. The measurement procedures are valid for any size of wind turbine, though this part of IEC 61400 only requires wind turbine types intended for connection to an electricity supply network to be tested and characterized as specified in this part of IEC 61400. The measured characteristics are valid for the specific configuration and operational mode of the assessed wind turbine product platform. If a measured property is based on control parameters and the behavior of the wind turbine can be changed for this property, it is stated in the test report. Example: Grid protection, where the disconnect level is based on a parameter and the test only verifies the proper functioning of the protection, not the specific level. The measurement procedures are designed to be as non-site-specific as possible, so that electrical characteristics measured at for example a test site can be considered representative for other sites. This document is for the testing of wind turbines; all procedures, measurements and tests related to wind power plants are covered by IEC 61400‑21‑2. The procedures for assessing electrical characteristics are valid for wind turbines with the connection to the PCC in power systems with stable grid frequency.

NOTE For the purposes of this document, the following terms for system voltage apply:

• – Low voltage (LV) refers to Un ≤ 1 kV;
• – Medium voltage (MV) refers to 1 kV < Un ≤ 35 kV;
• – High voltage (HV) refers to 35 kV < Un ≤ 220 kV;
• – Extra high voltage (EHV) refers to Un > 220 kV.