Power transmission line protection systems is one of the most important system under electrical power system. Transmission system is a system which between the generation and the distribution centers. . There are two main power transmission system which use in electrical industry . Distance relays are use to protect transmission line and this are simple to apply . Advantage of the distance relays are they are high-speed operation. In here we are plan to discuss on several factors which affect on protecting high voltage transmission lines.
Transmission Line systems
Electrical power transmission line systems can classified according to the type of current . Direct current and Alternative current are the two main types of current which utilized . Following are the transmission line classification according to the type of current supply.
High Voltage Direct Current (HVDC) System – HVDC Power transmission system are much used for the power transmission between very long distances.
High Voltage Alternating Current (HVAC) System– HVAC power transmission system are much economical for shorter distance power transmission.
Factors to Get Protected From
There are several factors which we need to consider while protection transmission lines. Following are those factors which got effect on the protection.
- Wind and Ice
- Contamination
- Vandalism
- External forces
- Equipment Failures
- System Disturbances
- Overloading of system
- Lightning
These factors play vital role on protect against of Transmission towers and lines of the electrical system.
Transmission Line Protection Systems
If we consider about the protection of transmission line there are three protection types are used to protect these lines .
- Differential Protection
- Phase Comparison
- Over Current Protection
- Earth fault overcurrent protection (Use for protect from large residual current)
- Distance Protection
- Thermal overload protection (Use for underground power system)
We are plan to discuss more about this transmission line protection systems in our future articles separately.
Transmission Line Protection Relays
Main purpose of the transmission protection relay are to identify the fault of the location . This relays are also use to identify the type of the fault in transmission lines too. Transmission line protections are much based on relays. There are several relay system are use to protect transmission lines. Following are some of the protective relay types which use in transmission lines.
- Protective Relays – Protective relays are function as to detect the fault and also to initiate the appropriate control signal such as the tripping signal.
- Regulating Relays – Regulating relay is a device which manages the operation of the load of tap changer on the transformer.
- Reclosing and Synchronizing Relays this is a programmable relay whose the function is to initiate a sequence of actions leading to the automatic reclosing of the circuit breaker.
- Auxiliary Relays- This relay which assist other relays by applying supplementary actions.
Normally protective relays are very important in transmission line protection. Hope that you have some basic understanding on the protections of the electrical power transmission lines . In future articles we are plan to discuss more about the other protections schemes of power transmission lines in future.
