Objectives of Power System and Operation and Control

The main objective of power system operation is providing  power to consumers meeting strict tolerances on voltage magnitude and frequency. consequently,
the operation control problems logically segregate into the control of voltage magnitudes or the voltage control issues and the system frequency control or the problems related to frequency control. As a power system is an interconnected system, large system spread over a galobally wide network, operation of the large system is complex. The controls are built to exploit the inherent timescale and structural properties of the system.

For your information, the automatic frequency control installed in the North American electric power grid was the first instance of a successful performance of a large-scale network-based control scheme. The frequency control systems face two subproblems. First, cost- benefit balance; there is need to determine optimal values of generations that results into minimization of the total generation costs while meeting the load demands. This problem is referred to as the economic dispatch problem.

The gap between total active power generation and the total active power consumption lead to frequency drifting. Because the load fluctuations themselves are random, it is almost impossible to 100 percent match the total supply with the power consumption demands at all times. Therefore, the system frequency will have a propensity to drift around on its own.

 In North American grids, there locates a central closed-loop controller that maintains system-wide power flows and regulate frequency to maintain the system within tight tolerance levels. It is also responsible for maintaining economically dispatched generations.