IEC 61400-21-2 - Wind energy generation systems - Measurement and assessment of electrical characteristics - Wind power plants - has the following scope: IEC 61400-21-2 defines and specifies the quantities that shall be determined to characterize the electrical characteristics of grid-connected power plants (PP).
IEC 61400-21-2 defines the measurement and test procedures for quantifying the electrical characteristics as basis for the verification of compliance of PP, including:
- Power quality aspects
- Steady state operation
- Dynamic response (undervoltage and overvoltage fault ride-through)
- Disconnection from grid (Grid protection)
- Control performance
IEC 61400-21-2 defines a uniform functionality test and measurement procedure for the power plant controller (PPC), as a basis for the unit test of the power plant controller.
IEC 61400-21-2 defines the procedures for assessing compliance with electrical connection requirements, including the aggregation methods for power quality aspects such as voltage variations, flicker, harmonics and interharmonics.
IEC 61400-21-2 defines the procedures for measurement and fault recording for the verification of power plant electrical simulation models in relation to undervoltage and overvoltage ride through events.
These measurement procedures are valid for power plants, including the power plant controller and other connected equipment, necessary for the operation of the Power Plant. The measurement procedures are valid for any size of power plant connected to the point of connection (POC) at one connection point.
The procedures for assessing and verifying the compliance with grid connection requirements are valid for power plants in power systems with fixed frequency and a sufficient short-circuit power.
Out of the scope of this standard are:
- Multi park control, i.e. cluster management of several power plants (PP) or several connection points
- Compliance test and performance requirements, including pass or fail criteria
- Specific component test and validation of the PP equipment (switchgear, cables, transformers, etc.), which are covered by other IEC standards
- Wind power plant model validation, as defined in the IEC 61400-27-2
- Load flow calculation methods and load flow study guidelines
- Test and measurement of the communication interface and system of the PP as defined in the IEC 61400-25 series
For the purposes of this document, the following terms for system voltage apply, based on IEC 60038
Low voltage (LV) refers to 100 V < Un ≤ 1 kV;
Medium voltage (MV) refers 106 to 1 kV < Un ≤ 35 kV;
High voltage (HV) refers to 35 kV < Un ≤ 230 kV;
Extra high voltage (EHV) refers to Un > 230 kV