Specific Requirements for Prefabricated Substations in Wind Power Generation Systems

As a core component of wind power generation systems, prefabricated substations bear the critical functions of power boosting, transmission, protection, and monitoring from wind turbines. Their performance parameters directly determine the safe and stable operation, power generation efficiency, and operation and maintenance costs of the wind power system. To adapt to the unique characteristics of wind power generation—such as large turbine power fluctuations, outdoor/harsh environment deployment, and high remote operation and maintenance requirements—strict specifications must be applied to various data related to the electrical, insulation, load, environmental, and protection aspects of the prefabricated substation. The following are detailed data requirements:

1. Basic Electrical Parameters

• Rated Capacity: Substation capacity ≥ turbine rated power / (power factor × efficiency); 5MW turbines typically require 5500～6000kVA, with a 10%～20% margin.
• Voltage Level: Low-voltage side (turbine side) 690V/1140V (690V is commonly used), high-voltage side (grid side) 35kV.
• Connection Group: Dyn11 (Suppresses third harmonics, withstands unbalanced loads).
• Short-circuit impedance: 6%～8% (Limits fault current).
• Voltage regulation range: ±2×2.5% (Accommodates voltage fluctuations).

Rated frequency: 50Hz.

2. Insulation and Withstand Voltage Levels (35kV Side)

• High-voltage side power frequency withstand voltage: 85kV/1min.
• Lightning impulse withstand voltage (peak): 200kV.
• Low-voltage side power frequency withstand voltage: 3.5kV/1min.
• Partial discharge: ≤5pC (Suppresses high-frequency harmonic interference).

3. Load and Overload Capacity

• Short-time overload: 1.5 times rated current, lasting 2 hours.
• Harmonic tolerance: Total harmonic distortion of load current ≤5%.
• Starting impulse: Withstands 3～5 times rated current impulse (fan start-up).

4. Environmental and Mechanical Parameters

• Altitude: ≤1000m (derating/reinforced insulation required above altitude).
• Temperature: -40^oC～+40^oC (outdoor).
• Protection Rating: IP54 (outdoor), IP65 for marine/dust environments.
• Wind Resistance: ≥12 (34m/s).
• Noise: ≤68dB(A) (5000kVA and below).

5. Protection and Monitoring Data

• Protection Configuration: Instantaneous overcurrent, zero-sequence, overvoltage, undervoltage, gas, and oil temperature protection.
• Monitoring Data: Three-phase voltage/current, active/reactive power/power factor, frequency, winding/oil temperature, oil level, partial discharge, switch status, and fault information.
• Communication Interface: RS485/Ethernet, supports IEC 61850 or Modbus, data refresh ≤1s.

6. Loss Limits (35kV oil-immersed, 5000kVA)

• No-load loss: ≤2.8kW.
• Load loss (75^oC): ≤28.2kW.

7. Typical Configuration (5MW wind turbine)

• Capacity: 5500kVA.
• Voltage ratio: 35±2×2.5%/0.69kV.
• Short-circuit impedance: 7%.
• Connection group: Dyn11.
• Protection level: IP54.
• Cooling method: ONAN (oil-immersed self-cooling).

The data requirements for prefabricated substations in wind power generation systems are all based on the special characteristics of wind power scenarios, equipment safety and stability, power generation efficiency, and ease of operation and maintenance. The core is to achieve efficient and safe transmission and grid connection of wind turbine power. The above data requirements can serve as the core basis for the selection, design, and acceptance of wind power transformer substations. At the same time, it is necessary to flexibly adjust the parameter details in combination with the wind turbine power, deployment environment, grid access standards, etc. of specific wind power projects to ensure efficient adaptation between the transformer substation and the wind power system and provide a guarantee for the long-term stable operation of wind power projects.

Written by

Huihai Electric Co., Ltd.

Editor Xu

www.huihai-electric.com

WhatsApp:+86 139 1136 0187

Email:13705388456@163.com