Chapter 5: Economic Operation of Power Systems

Coordination Between LFC And Economic Dispatch

Both the load frequency control and the economic dispatch issue commands to change the power setting of each turbine-governor unit. At a first glance it may seem that these two commands can be conflicting. This however is not true. A typical automatic generation control strategy is shown in Fig. 5.5 in which both the objective are coordinated. First we compute the area control error. A share of this ACE, proportional to αi , is allocated to each of the turbine-generator unit of an area. Also the share of unit- i , γi X Σ( PDK - Pk ), for the deviation of total generation from actual generation is computed. Also the error between the economic power setting and actual power setting of unit- i is computed. All these signals are then combined and passed through a proportional gain Ki to obtain the turbine-governor control signal.

Fig. 5.5 Automatic generation control of unit-i.