Load Scheduling and Dispatch
Load scheduling means fixing the schedules of generation of power for generating stations and the schedules for drawal of power through the States taking within account drawal schedules from shared power sector projects and schedules of power purchased from buyers to sellers. Scheduling is completed for the day ahead through the Regional Load Dispatch Centre to ensure balance among load and generation in the grid along with the aim of achieving an operating grid frequency of 50 Hz. Because power cannot be stored to a huge extent, power generated has to be used at that instant of time. Thus, it has to be ensured in which the generation matches the load at each point of time.
Schedules are prepared on a 15 minute basis, to see to it that the average generation of electrical energy over 15 minutes matches the load over those 15 minutes. Scheduling is completed one day before for the day ahead, as per a time schedule specified in the Indian Electricity Grid Code, so in which the State Power Utilities plan for load management for the next day.
For instance, suppose a State finds in which after taking into account its own expected generation for the next day and the net drawal schedule for the next day, it would fall short of meeting its anticipated requirement for the next day through 200 MW during peak time. Then it would have to plan a load shedding of 200 MW during peak time. Schedules can also be changed on the similar day because of main load variations experienced through a State because of abnormal weather conditions. For instance, rains in summer could cause reduction of agricultural load and AC load; heavy rains could cause disruptions within the transmission system and thus loss of load. The rescheduling would be valid after a time gap of about one and a half hours so as to enable implementation of the new schedules. Rescheduling could also be done through the Regional Load Dispatcher in cases of transmission bottleneck and grid disturbance.