Intelligent High Voltage Outdoor Disconnector Solution for Vietnam's Distributed PV and Storage Projects

1. Project Background​

Distributed photovoltaic (PV) and energy storage projects are developing rapidly in Vietnam and Southeast Asia, but face severe challenges:

1.1 ​Grid Vulnerability:​​

• Vietnam's grid experiences frequent fluctuations (especially in northern industrial zones). In 2023, coal power shortages caused large-scale blackouts, resulting in daily losses exceeding USD 5 million.
• Traditional PV systems lack rapid isolation capability, making them prone to equipment damage and safety incidents during grid faults. ​This underscores the critical need for a reliable High voltage Disconnect Switch.​​

​1.2 Policy and Safety Compliance Pressure:​​

• Vietnam's new 2024 regulations require energy storage systems to pass EVN (Vietnam Electricity Group)'s 72-hour islanding operation test and possess high-voltage ride-through (HVRT) capability.
• High-voltage risks on the DC side are prominent; arc faults (with instantaneous temperatures reaching 1000°C) can trigger fires. ​A robust High voltage Disconnect Switch is essential for mitigating these DC-side risks.​​

1.3 ​Environmental Adaptability Requirements:​​

• High temperature and humidity climates (average annual humidity >80%) accelerate equipment aging, demanding disconnecting switches with strong anti-corrosion and moisture-proof performance. ​The High voltage Disconnect Switch must meet these stringent environmental demands.​​

​2. Solution: Intelligent High-Voltage Disconnecting Switch System​

2.1 ​Core Technology Design​

• ​Three-Position High voltage Disconnect Switch (Open-Closed-Grounded):​​

Utilizes a double-break rotary structure, rated voltage ≥15kV, rated current 6300A (forced air-cooling design), meeting the needs of large-scale distributed power plants.

​Arc Extinguishing Optimization:​​Equipped with built-in magnetic blowout arc extinguishing devices, DC arc breaking time ≤20ms, preventing arc faults from causing fires. ​This rapid arc extinction is a key safety feature of the High voltage Disconnect Switch.​​ 

• ​Environmental Adaptability Enhancement:​​

Enclosure features IP65 protection rating; core components are silver-plated to withstand salt spray corrosion (compliant with IEC 60068-2-52 standard). ​These protections ensure the long-term reliability of the High voltage Disconnect Switch.​​

​Thermal Design:​​Added aluminum alloy heat sinks, temperature rise controlled at ≤40K (in 40°C ambient). ​Effective thermal management is vital for the High voltage Disconnect Switch in tropical climates.​​ 

2.2 ​Intelligent Monitoring and Protection System​

• ​Integrated Sensor Module:​​

Real-time monitoring of contact temperature, arc signals, and insulation status; data synchronized to local SCADA and cloud platforms (e.g., Hoymiles S-miles Cloud) within milliseconds. ​Continuous monitoring enhances the safety profile of the High voltage Disconnect Switch.​​

• ​Protection Logic Coordination:​​

​Collaboration with Circuit Breakers:​​Automatically opens within 10 seconds upon detecting grid voltage drop to 20% UN (meeting Vietnam's low-voltage lockout requirement).

​Cooperation with AFCI (Arc Fault Circuit Interrupter) System:​​Cuts off the fault circuit within 0.5 seconds. ​This fast protection logic integrates seamlessly with the High voltage Disconnect Switch.​​ 

2.3 ​Localized Adaptation Improvements​

• ​Grid Compliance:​​

Supports EVN-required islanding test mode, simulating seamless switch to energy storage supply after grid interruption. ​The High voltage Disconnect Switch is integral to passing this critical test.​​

Pre-installed sealing wire interfaces to meet Vietnam's mandatory metering room sealing requirements.

• ​Maintenance Convenience:​​

Contact lifespan ≥10,000 operations; maintenance cycle extended to 5 years, reducing O&M costs in tropical regions. ​The durability of the High voltage Disconnect Switch significantly lowers lifetime costs.​​

3. Achieved Results​

3.1 ​Enhanced Safety and Reliability​

• Achieves off-grid switching within 10ms during grid faults (exceeding Vietnam's 50ms standard), ensuring continuous operation of critical loads (e.g., factory production lines). ​This rapid isolation is enabled by the High voltage Disconnect Switch.​​
• After deployment in a 2024 Hanoi villa project, DC-side fire risk decreased by 90%, and electric shock incidents were eliminated.

3.2 ​Economic Benefits and Compliance​

• ​Reduced Penalty Risk:​​Meets carbon emission requirements of the "Green Industry Act," avoiding annual revenue fines of 3%.
• ​Shortened Payback Period:​​Due to reduced maintenance costs (down 30%) and decreased downtime losses, IRR increased by 2-3 percentage points.

3.3 ​Strengthened Grid Support Capability​

Passed dynamic curtailment clause testing: Supports power regulation of up to 30% installed capacity under EVN's flexible dispatch (when grid load <75%), enabling power plants to participate in the Frequency Regulation Market (FRP). ​The High voltage Disconnect Switch contributes to this grid support functionality.​