The problem that is often faced by a power generating unit, especially thermal generators, is the high
operating costs. In relation to operating costs, in this study, the calculation of operation optimization of thermal
power plants aims to determine the optimal operating model, compare operating costs with various methods, and
determine the lowest basic tariff cost for each generating unit. In this study, the method used for the optimal
calculation of operating costs is the Lagrange multiplier method and dynamic programming. The main criteria
that must be met is to know the input-output characteristics of the generating units. From the results of
optimization calculations, it is known that the Lagrange multiplier method is more optimal than using the
dynamic programming method even though the calculation results are almost the same. In general, the
calculation results are more optimal than the real conditions of the PLTU Barru. Especially in May 2016, the
optimal calculation results throughout the day (for 24 hours) with an average total power of 71.58 MW (71.58%)
namely on the 7th, 20th, 21st, 26th, 27th, 28th, 29th, 30, and 31. The real condition of the PLTU Barru is more
optimal than the calculation results with an average total power of 50.36 MW (50.36%) which is on the 4th at
17:00 – 24:00, the 5th at 01:00 – 16:00, the 6th at 01:00 – 17:00, the 8th at 17:00 – 24:00, the 10th at 01:00 –
08:00, the 11th at 01:00 – 12:00, date 18 hours 01:00 – 12:00, the 19th 01:00 – 02:00, the 22nd at 06:00, and the
25th at 21:00 – 22:00, and outside of that time the calculation results show the optimal value.