Should a fault occur in an electrical power system, there can exist the possibility of significant risk of damage to property and injury to personnel. In addition, there can be indirect monetary losses in the form of unserved energy and production stoppages.
In general, the severity of the fault increases in proportion to the energy level of the electrical power system.
In order to limit the risks associated with a fault, electrical protection systems are used. The role of the protection is to interrupt the electrical circuit and extinguish the fault.
Protection systems are critical to the safety and function of a modern electrical power network.
Networks which may be more exposed to extended losses are islanded power systems, electrical equipment in hazardous areas, mission critical systems, networks with legacy equipment and remote area power systems. Off-grid networks don’t have the availability of alternate sources of supply, which are often available in grid networks.
The economic value of the protection system can be justified by calculating the cost of a fault and the likelihood of a fault using the mean time between failures and the mean time for repair. There are published standard values available for all typical network components.
Modern protection systems can range in scale from simple feeder protection to sophisticated network-wide systems. The wide area scale of modern protection systems has been made possible by advances in communication technology and protection protocols, such as IEC 61850.
An integral part of developing the design of a protection system is the construction of a network model. From the model, electrical power system studies can be run of different case studies and configuration scenarios.
A protection system can be bench-marked by how the protection system limits the loss of supply to the faulty circuit. A fault which occurs in a downstream circuit should only result in the trip the circuit which has faulted. This requires co-ordination between the protection devices and grouping the protection system into zones.
Conversely, a poorly designed protection system can cause three problems for the electrical network. The first problem is that there may be faults for which the protection system does not operate. The second problem is that the protection system may not be optimised, in that the number of circuits tripped is more than what is necessary to isolate the fault. The third problem is that spurious, nuisance tripping may occur, without a real fault event.
BESST Engineering can provide the design of standards compliant, optimised protection systems for islanded power systems, electrical equipment in hazardous areas, mission critical systems, networks with legacy equipment and remote area power systems. The designs are developed from electrical power system studies.