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

Vziman

06/03/2025

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.