Equi-Potential Concept
This concept is an important tool for the air break switch (Isolator) inside the sub-station. The terminals in the system to be connected by the isolator are charged to the same potential. Then the air break switch/isolator is operated smoothly without developing a spark in the system.
Dead Line Charging
Charging or electrification of any bus/line from zero potential is called deadline charging. Generally, this line charging does not involve any flow of load current, but due to the capacitive and inductive effect of the system, the charging current only flows.
Synchronization Charging
In literal meaning, synchronization means a successful combination of two systems. When two different systems are planned to be combined, the electrical parameters of both systems should be alike or in phase.
These parameters are 1.Voltage(Its magnitude, phase angle, sequence) 2.Frequency (Its magnitude). So to monitor the parameters the synchroscope is used, which indicates the condition of synchronization, the systems are allowed to be closed either manually or automatically. This facility of Synchronization is available generating station.
Interlock Scheme
During the motorized operation of isolators/breakers, conditional locking is provided between them to avoid the wrong operation. This condition of locking is called interlock.
Under-Frequency Load Shedding Concept
Under frequency load shedding is a technique used in power systems to automatically shed or disconnect a portion of the load when the frequency of the electrical grid falls below a certain threshold. It is typically employed as a protective measure to prevent a widespread blackout or collapse of the power system due to a severe shortage of generation capacity.
When the frequency of the power system drops below the normal operating range, it indicates that the supply of electricity is not sufficient to meet the demand. Under frequency load shedding is activated to shed a portion of the load in a controlled manner, typically based on pre-set priority levels or shedding sequences, in order to bring the supply and demand balance back to a stable state and avoid further frequency decline.
The load shedding process involves selectively disconnecting certain loads, such as industrial processes, commercial buildings, or residential areas, in a controlled and coordinated manner. This is usually done through automatic relays or control systems that are configured to respond to changes in frequency and initiate load shedding as needed.
Under frequency load shedding is an important tool for maintaining the stability and reliability of power systems during abnormal operating conditions, such as generation shortages, equipment failures, or unforeseen events. It helps prevent the risk of widespread blackouts or system collapses by shedding non-essential loads, prioritizing critical loads, and restoring the frequency to a safe and stable level.
However, under frequency load shedding can also have economic and social impacts, as it involves intentionally interrupting power supply to certain areas or customers. Therefore, careful planning, coordination, and monitoring are necessary to ensure that load shedding is done in a controlled and effective manner, minimizing the impact on customers while safeguarding the stability of the power system.
