Introduction
In distributed photovoltaic power stations, residential solar systems, and commercial rooftop projects, the islanding effect poses a significant threat to grid safety. If the grid experiences a power outage due to a fault, and the photovoltaic system continues to supply power to local loads, it can lead to equipment damage and accidents involving maintenance personnel.
The CGS7001M anti-islanding protection device from Shanghai Changgao Electric Co., Ltd. quickly disconnects the grid connection within 0.2 seconds by monitoring grid voltage, frequency, and other parameters in real-time, thus preventing unintentional island operation.
Core Functions of Anti-Islanding Protection
- Ensuring Grid Operation Safety: Utilizing the Active Frequency Disturbance (AFD) method or passive voltage/frequency detection technologies, the device guarantees that the photovoltaic system automatically disconnects from the grid during a power outage.
- Enhancing Power Quality: It provides millisecond-level responses to abnormal conditions such as excessive harmonics or sudden voltage fluctuations, complying with the photovoltaic station connection standards set by GB/T 19964-2012.
- Extending Equipment Lifespan: The device prevents inverters from operating under overload conditions during islanding, reducing the failure rates of photovoltaic modules and energy storage systems.
Typical Application Scenarios and Case Studies
Case Study 1: In an industrial park, a 5MW rooftop photovoltaic project at an automobile manufacturing plant experienced a power outage due to lightning. The anti-islanding device successfully tripped the grid-connected circuit breaker within 0.15 seconds, preventing damage to a control cabinet worth millions associated with the painting production line.
Case Study 2: In a rural photovoltaic poverty alleviation project located in mountainous areas with delayed grid upgrades, the device utilized its adaptive impedance measurement capability to accurately identify islanding conditions under weak grid conditions, successfully preventing multiple reverse power transmission incidents caused by aging lines.
Key Technical Requirements for Grid Connection Acceptance
According to the NB/T 32015-2022 standard, the device must meet the following criteria:
- Frequency Protection Range: 49.5Hz – 50.5Hz (adjustable)
- Voltage Protection Threshold: ±10% Un (triggered within 0.2 seconds)
- Island Detection Time: ≤2 seconds (as per State Grid Q/GDW 617 requirements)
It is recommended to configure protection devices with GOOSE communication capabilities at the photovoltaic grid connection point to achieve coordinated control with the station’s relay protection system, ensuring selective tripping in complex multi-source scenarios.
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