Protection Relays

Products > Energy

VISION offers unique and complete solutions for the protection and control of large power systems, in an effective way to ensure the stability of the regional and / or national electrical system, in order to avoid large areas of black-out in case Of accidents or faults in the electrical network.

The system consists of several control devices in several substations (protection relays). All control devices are connected to each other via communication channels.

VISION has established a unique three-line defense system to protect the electrical system against blackout. This system significantly improves the stability of the electrical network.

Three Defense Line

The first line of defense consists of fast and accurate protection relays to ensure that the fault is quickly eliminated to maintain system stability.

The second line of defense is emergency control for serious failures. If the imbalance between generation and load arises, the protection will take some measures, such as the generator shutdown or the discharge of loads, to guarantee the stability of the system.

While the stability of the power system is affected after the failure, VISION’s stability control system (SPCS) will calculate the energy flow and generate corresponding control strategies. Control commands are then sent to the execution device to generate actions that maintain system stability.

The third line of defense is local corrective control, such as out-of-step and waste disposal for extremely serious contingencies. If the second line of defense does not rescue stability, the third line will operate to prevent collapse and minimize the loss of load.

Three Defense Line


Total operating time less than 90ms;
Slow steady state process & fast transient process;
Stability Control in real time;
Detection of the operating state of output lines, transformers and generators;
According to the load flow and the type of fault, it calculates the optimized control strategy;
Determine which measures should be taken: shutdown of generators, discharge of loads, etc.