This technical guidance document specifies the technical requirements for connecting wind farm to power network.
This technical guidance document is applicable to connecting new or extended wind farms through transmission lines and transmission networks whose voltage grade is 66kV and above.
This technical guidance document may also be referred to for connecting wind farm to distribution network through distribution wires.
2 Normative References
The following normative documents contain provisions which, through reference in this technical guidance document, constitute provisions of this technical guidance document. For dated reference, subsequent amendments, or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this technical guidance document are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document referred to applies.
GB/T2900.53-2001 Electrotechnical terminology-Wind turbine generator systems (idt IEC 60050-415: 1999)
GB/T12325-2003 Power quality-Admissible deviation of supply voltage
GB12326-2000 Power quality-Voltage fluctuation and flicker
GB/T14549-1993 Quality of electric energy supply-Harmonics in public supply network
GB/T15945-1995 Quality of electric energy supply. Permissible deviation of frequency for power system
DL755-2001 Guide on security and stability for power system
SD325-1989 Voltage and reactive technical guide for power system
IEC61400-21 Wind Turbine Generator Systems Part 21: Measurement and assessment of power quality characteristics of grid connected wind turbines (Measurement and assessment of power quality characteristics of wind turbine generator system)
3 Terms and Definition
The following terms and Definitions apply to this technical guidance document.
3.1 wind turbine generator system; WTGS (abbreviation)
System changes kinetic energy of the wind into electric power.
3.2 Wind power station; wind farm
Power stations are composed by the same lot of wind turbine generator systems or wind turbine generator groups.
3.3 Active power of wind farm
Active power is connecting the wind farm to the connection points.
3.4 Reactive power of wind farm
Reactive power is connecting the wind farm to the connection points.
3.5 Power ramp rate
Variation is measured on the output power of the wind farm in unit time.
3.6 Connection point
It refers to the connection point of wind farm and electric network.
3.7 Point of common coupling
It is the connection of more than one user in the power network.
3.8 Relative voltage change characteristic
It refers to the time function of the voltage root mean square value change, which is indicated by the percentage of the nominal system voltage.
3.9 Relative voltage change
It refers to the difference between two adjacent extreme values in the relative voltage change characteristic.
3.10 Short term severity
One statistic value is used to measure the flicker strong or weak within a short term (several minutes). =1is the general limit for flicker causing visual stimulation.
3.11 Long term severity
It is calculated by the short term severity . It is used to reflect the flicker strong or weak within a long time (several hours).
4 Active Power of Wind Farm
4.1 Basic Requirements
In the following particular cases, the output active power of the wind farm shall be controlled according to instructions of the electric network dispatching department:
a) System fault or special operating mode requires declining the active power of wind farm to prevent the transmission lines from overload and guarantee the power system stability;
b) Power ramp rate (MW/min) of wind farm shall be limited when the frequency modulation capacity of the power network is insufficient;
c) When the network frequency is too high, if the conventional frequency modulation capacity is insufficient, then the active power of wind farm shall be declined.
