1. Introduction to Substation Lightning Protection

Lightning strikes pose one of the greatest risks to electrical substations, potentially causing:

• Damage to substation equipment (transformers, circuit breakers, insulators)

• Power outages and grid instability

• Fire hazards and safety risks

Effective lightning protection combines external shielding (against direct strikes) and internal protection (against surges).

2. Key Components of Substation Lightning Protection

A. External Protection (Direct Strike Mitigation)

B. Internal Protection (Surge Suppression)

3. Grounding System Design

A low-impedance ground network is critical for dissipating lightning current safely:

• Target ground resistance: ≤5Ω (≤0.5Ω for critical EHV substations)

• Materials: Copper-clad steel rods (≥3m deep) or chemical electrodes

• Grid configuration:

• Mesh size ≤10m×10m

• Equipotential bonding for all metallic structures

• Lightning mast grounding: Separate electrode (≥3m from main grid) to prevent "backflash"

4. Lightning Risk Assessment & Standards

A. Risk Calculation (IEC 62305)

• Risk (R) = (Probability of strike) × (Consequences)

• Factors: Local keraunic level (thunderstorm days/year), soil resistivity, equipment BIL (Basic Insulation Level)

B. International Standards

5. Maintenance & Testing

• Annual inspections:

• Check arrester leakage current (should be <1mA)

• Measure ground resistance (spring/fall)

• Inspect SPD status indicators

• After severe storms:

• Thermographic scan of connections

• Insulation resistance tests

6. Case Study: 220kV Substation Protection

Problem: Frequent lightning-caused outages in mountainous region.
Solution:

1. Installed 4×45m lightning masts (rolling sphere radius=45m)

2. Upgraded to ZnO surge arresters (Uc=192kV, residual <400kV)

3. Improved grounding with 2,000m copper grid + 20 deep electrodes (R=0.8Ω)
   Result: Zero lightning-related failures in 3 years.

7. Emerging Technologies

• Early Streamer Emission (ESE) air terminals - 30% larger protection radius

• Real-time monitoring:

• Arrester leakage current sensors

• Lightning current measurement (Rogowski coils)

• GIS-based risk mapping for optimal mast placement

8. Cost-Benefit Analysis

Conclusion

An effective substation lightning protection system requires:

1. Physical interception of strikes (masts/wires)

2. Proper grounding to dissipate energy

3. Surge suppression at all voltage levels

4. Regular maintenance to ensure integrity

For a customized design, provide:

• Substation voltage level (e.g., 110kV, 500kV)

• Local lightning density (thunderstorm days/year)

• Single-line diagram of existing equipment

The above content is published by demiks, please specify, demiks is a substation equipment manufacturer, specializing in the production of high-voltage tester, transformer test equipment, circuit breaker test equipment, relay tester, SF6 gas analyser, cable fault tester and other products, if you have power test testing needs, please feel free to contact demiks power science and technology limited company or send an email! Give us: contact@demikspower.com