5.7 Determine two ways of removing the constraint violations that you identified in Problem 5.6 by redispatching generating units. Which redispatch is preferable? .7 Method 1: key answer of problem 5.7 and 5.8 PA = 0 MW; PB 48 MW; Pc = 72 MW; Pb 400 MW F21 = 102 MW; F31 = 250 MW; F32 = 182 MW Increase in cost: $240 Method 2: Pa = 80 MW; PB = 0 MW; Pc = 40 MW; PD = 400 MW F21 = 150 MW; F31 = 250 MW; F32 = 150 MW Increase in cost: $160 Method 2 is preferable because it is cheaper. N1 = 13.33 $/MWh; 12 = 12.00 $/MWh; 13 = 10.00 $/MWh .8 5.12 Using the linearized mathematical formulation (DC power flow approximation), calculate the nodal prices and the marginal cost of the inequality constraint for the optimal redispatch that you obtained in Problem 5.7. Check that your results are identical to those that you obtained in Problem 5.8. Use bus 3 as the slack bus. 5.13 Show that the choice of slack bus does not influence the nodal prices for the DC power flow approximation by repeating Problem 5.12 using bus 1 and then bus 2 as the slack bus. 5.7 Determine two ways of removing the constraint violations that you identified in Problem 5.6 by redispatching generating units. Which redispatch is preferable? .7 Method 1: key answer of problem 5.7 and 5.8 PA = 0 MW; PB 48 MW; Pc = 72 MW; Pb 400 MW F21 = 102 MW; F31 = 250 MW; F32 = 182 MW Increase in cost: $240 Method 2: Pa = 80 MW; PB = 0 MW; Pc = 40 MW; PD = 400 MW F21 = 150 MW; F31 = 250 MW; F32 = 150 MW Increase in cost: $160 Method 2 is preferable because it is cheaper. N1 = 13.33 $/MWh; 12 = 12.00 $/MWh; 13 = 10.00 $/MWh .8 5.12 Using the linearized mathematical formulation (DC power flow approximation), calculate the nodal prices and the marginal cost of the inequality constraint for the optimal redispatch that you obtained in Problem 5.7. Check that your results are identical to those that you obtained in Problem 5.8. Use bus 3 as the slack bus. 5.13 Show that the choice of slack bus does not influence the nodal prices for the DC power flow approximation by repeating Problem 5.12 using bus 1 and then bus 2 as the slack bus