ABSTRACT
The transmission system grew from local and regional grids to a large interconnected network that was managed by coordinated operating and planning procedures. Peak demand and energy consumption grew at predictable rates, and technology evolved in a relatively well-defined operational and regulatory environment. With the growing demand the need for generation flexibility comes from the need to control the system frequency, so it is helpful to briefly review frequency control in the power system. In normal operation, the control area follows a predetermined schedule of power exchange with its neighboring areas. Schedules are prepared based on the forecasted load and are negotiated well in advance; they are an input to system operation in real time. The residual generation/load imbalance is handled by the automatic generation control (AGC). This chapter gives the details of the same.
