Recently, CYG SUNRI Co., Ltd. (CYG SUNRI), a subsidiary of Changyuan Technology Group Ltd.(CYG), successfully completed the grid-connected trial operation of China’s first high-sensitivity dry-type air-core reactor interturn protection device at the Bazhou substation in North Hebei. Jointly developed with the China Electric Power Research Institute (CEPRI), this achievement marks another key technological breakthrough in relay protection for power equipment, providing a reusable technical reference for the development of a high-reliability, next-generation power system.

Dry-type air-core reactors play a critical role in limiting short-circuit currents, filtering grid harmonics, and compensating reactive power. Their operational safety is essential to grid stability. However, early interturn short-circuit faults in such reactors result in minimal changes in electrical parameters, making them difficult to detect. Existing protection solutions often have long response delays, risking delayed fault isolation.

To address this pain point, CEPRI initiated a dedicated research effort in June 2024 under the guidance of the National Dispatching Center and the State Grid Equipment Department. The team proposed a new high-sensitivity protection principle for detecting interturn faults in dry-type air-core reactors. Working closely with CEPRI, CYG SUNRI developed a protection prototype that embeds advanced algorithms and passed a rigorous three-tier validation framework, including: RTDS (Real-Time Digital Simulation) testing, Physical dynamic model testing, On-site waveform playback and fault scenario simulations.

On November 22, 2024, the protection principle and its test results passed expert evaluation organized by the State Grid Corporation of China’s Equipment Department and National Dispatching Control Center.

Key outcomes from the expert review:

? Significantly enhanced protection sensitivity compared to traditional schemes

? Capable of interturn short-circuit alarming and tripping functions

? 10x faster response time, effectively reducing the risk of equipment fires

? No misoperations under various out-of-zone faults and system disturbances

Expert Review of New Protection Principle and Test Results for Dry-Type Air-Core Reactors

In its trial operation, the new protection device has already demonstrated strong practical value, offering a robust technological enhancement for smart grid development. Moving forward, CYG SUNRI will continue to focus on core technology innovation, accelerating the iterative upgrade of critical equipment and the adaptation of solutions to diverse application scenarios, injecting new momentum into the high-quality development of the energy and power industry.

CYG SUNRI Co., Ltd.(CYG SUNRI), a subsidiary of Changyuan Technology Group Ltd.(CYG), is a core company within CYG Digital Energy and Power Business Group(CYG EPBG). With the mission of "For a safer and easier use of energy." CYG SUNRI is dedicated to grid safety, promoting independent and controllable research, development, and application of core components for critical grid equipment. Its products and services reach 80 countries and regions, focusing on equipment, solutions, and system integration services in the power industry, contributing to the development of China's power grid sector.