Question

Resolve Example 6.20, except with the generation at bus 2 set to a fixed value (i.e., modeled as off of AGC). Plot the variation in the total hourly cost as the generation at bus 2 is varied between 0 to 200 MW in 5-MW steps, resolving the economic dispatch at each step. What is the relationship between bus 2 generation at the minimum point on this plot and the value from economic dispatch in Example 6.20? Assume a load scalar of 1.0

Example 6.20: PowerWorld Simulator case Example 6_20 uses a five-bus, three-generator lossless case to show the interaction between economic dispatch and the transmission system (see Figure 6.19). The variable operating costs for each of the units are given by C1 = 10P1 + 0.016P 1 Square $yhr C2 =8P2 + 0.018P2 Square $yhr C4 = 12P4 + 0.018P 4 Square $yhr where P1, P2, and P4 are the generator outputs in megawatts. Each generator has minimum/maximum limits of 100 <=P1 <=400 MW 150 <=P2 <= 500 MW 50 <= P4 <=300 MW In addition to solving the power flow equations, PowerWorld Simulator can simultaneously solve the economic dispatch problem to optimally allocate the generation in an area. To turn on this option, select Case Information, Aggregation,
Areas… to view a list of each of the control areas in a case (just one in this example). Then toggle the AGC Status field to ED. Now anytime the power flow equations are solved, the generator outputs are also changed using the economic dispatchInitially, the case has a total load of 392 MW with an economic dispatch of P1 =141 MW, P2 = 181, and P4 = 70, and an incremental operating cost, l, of 14.52 $?MWh. To view a graph showing the incremental cost curves for all of the area generators, right-click on any generator to display the generator’s local menu, and then select All Area Gen IC Curves (right-click on the graph’s axes to change their scaling). To see how changing the load impacts the economic dispatch and power flow solutions, first select Tools, Play to begin the simulation. Then, on the oneline, click on the up/down arrows next to the Load Scalar field. This field is used to scale the load at each bus in the system. Notice that the change in the Total Hourly Cost field is well approximated by the change in the load multiplied by the incremental operating cost. Determine the maximum amount of load this system can supply without overloading any transmission line with the generators dispatched using economic dispatch.

Answer 1