Role of STATCOM or SVC in Wind Farm:

The installation of STATCOM (Static Synchronous Compensator) or SVC (Static Var Compensator) in wind farms is essential to meet grid compliance due to the unique characteristics of wind power generation and the specific requirements set by grid operators for voltage stability, reactive power support, and fault ride-through capabilities. These devices provide fast, dynamic control of reactive power, which is crucial for integrating variable renewable energy sources like wind into the grid while maintaining stability and reliability.

Key Reasons for STATCOM/SVC Installation in Wind Farms

1. Voltage Control and Stability

- Wind farms generate fluctuating power depending on wind speed variations, which can cause voltage fluctuations at the point of grid connection (Point of Common Coupling, PCC).

- Grid operators require stable voltage levels within certain limits (e.g., ±5% of the nominal voltage). Without proper voltage regulation, fluctuating wind power could lead to over-voltage or under-voltage conditions, which can compromise grid stability.

- STATCOM or SVC provides dynamic voltage support by rapidly injecting or absorbing reactive power, which helps stabilize voltage at the PCC and ensures compliance with grid codes.

2. Reactive Power Compensation

- Wind turbines (especially Type 3 DFIG and Type 4 full converter turbines) can operate with varying power factors and may not always provide sufficient reactive power to support grid voltage.

- Grid codes often require wind farms to maintain a specific power factor (usually close to unity) or provide reactive power support under various operating conditions (low or high wind speeds).

- STATCOMs and SVCs are used to compensate for reactive power deficiencies, ensuring that the wind farm can either absorb or inject reactive power as needed to maintain grid voltage and meet the required power factor. They also allow wind farms to operate in different modes (e.g., fixed power factor or voltage control).

3. Dynamic Response to Grid Disturbances (Fault Ride-Through)

- Modern grid codes require that wind farms remain connected during short-term disturbances, such as voltage dips caused by faults, and provide fault ride-through (FRT) capability.

- During faults, the voltage at the PCC can drop significantly, causing a large demand for reactive power to support the grid voltage. Without proper reactive power support, the wind farm may be disconnected, leading to further instability.

- STATCOM and SVC can provide fast, dynamic reactive power during these voltage dips, helping to maintain voltage levels at the PCC and allowing the wind farm to remain connected during and after the fault, which is crucial for fault ride-through compliance.

4. Power Quality Improvement

- Wind turbines with power electronics (inverters) can introduce harmonics into the grid, impacting power quality.

- Grid operators have stringent requirements on harmonic distortion and voltage flicker limits.

- STATCOMs and SVCs help mitigate harmonics and flicker by providing smooth, dynamic reactive power support, reducing voltage fluctuations, and improving the overall power quality of the wind farm’s output.

5. Support During Low Wind Speeds

- At low wind speeds, wind turbines may generate insufficient reactive power to support the grid, potentially leading to under-voltage issues at the PCC.

- In such scenarios, STATCOM or SVC can compensate by injecting the necessary reactive power, ensuring that the wind farm still meets voltage requirements even when the wind generation is low.

6. Compliance with Grid Codes for Renewable Integration

- Grid codes in many countries (e.g., Europe, North America, etc.) have become stricter as the penetration of renewable energy sources increases. These grid codes specify that large-scale wind farms must provide:

- Voltage regulation at the PCC.

- Reactive power control and capability to generate or absorb reactive power.

- Fault ride-through capability, ensuring that the wind farm remains connected during grid faults.

- Fast dynamic response to voltage or frequency fluctuations.

- STATCOMs and SVCs provide the required dynamic reactive power support and control flexibility, making them essential for ensuring that wind farms comply with these grid codes.

7. Grid Stability Under High Wind Penetration

- In areas with high penetration of wind energy, maintaining grid stability becomes more challenging, particularly in terms of voltage and reactive power management.

- Wind farms can have a significant impact on the local and regional grid voltage due to their large-scale integration, especially if located far from load centers.

- STATCOMs or SVCs provide centralized reactive power compensation for the wind farm, ensuring that large-scale wind integration does not negatively affect grid voltage stability.

STATCOM vs. SVC: Comparison in Wind Farms

Both STATCOM and SVC are widely used for similar purposes, but they differ in terms of performance and application:

While STATCOM offers faster dynamic response and better performance under deep voltage sags, SVC is still a viable option for many wind farms, especially when cost and space are constraints. STATCOM is often preferred for wind farms subject to stringent grid codes that require high dynamic performance.

Conclusion

The installation of STATCOM or SVC is essential in wind farms to:

- Stabilize voltage at the point of connection,

- Compensate for reactive power deficiencies,

- Enhance fault ride-through capability,

- Ensure compliance with modern grid codes for reactive power and voltage control,

- Improve overall power quality and dynamic stability in the grid.

These devices help wind farms operate efficiently and meet the technical standards required for reliable grid integration, especially as the penetration of wind power increases globally.