A New Approach for Solving the Unit Commitment Problem by Cuckoo Search Algorithm Alireza Gharegozi * and Rozbeh Jahani Shahindezh Branch, Islamic Azad University, Shahindezh, Iran; gharegozi@yahoo.com Abstract In this paper, a new approach to solving the issue of optimal production planning (Unit Commitment or UC) has been presented by using Cuckoo Search Algorithm. Results of testing this paper indicate that not only this algorithm includes all limits of issue well, but it has also the benefits all such as the most appropriate convergence in the response, high compu- tational speed and high accuracy. A sample power system with 10 power plant units has been used in this study in order to test this new algorithm. Optimal planning in generation of power units of this system is also obtained from the results of experiment and they will be inferable given the establishment and observation of the constraints in the target function of issue. Numerical results of this paper indicate that the performance of Cuckoo Search Algorithm has had significant improvement than other algorithms and it results in the minimum production cost. 1. Signs and Abbreviations i: Specifies the unit. t: Timeframes. G: Number of generator units. U it : Status of on or off i unit in the timeframe t. P it : Generation power of unit i in the timeframe t. F i (P it ): Current cost function of power plant unit i in the timeframe t. a i ‒b i ‒c i : Coefficients of cost function i. S i : cost of starting up the unit i. τ i ‒S 1i ‒S 0i : Coefficients of startup cost for unit i. P Dt : System load demand in the timeframe t. λ: Rate of increased loss cost. P imax : Maximum production capacity of unit i. P imin : Minimum production capacity of unit i. M i : Time constraints in turning on or off the unit i. TO i : Minimum startup time for unit i. * Corresponding author: Alireza Gharegozi (gharegozi@yahoo.com) Indian Journal of Science and Technology Keywords: Cuckoo Search Algorithm, Power Systems, Optimal Production Planning, System Constraints, System Limitations. TS i : Minimum time of turning off for unit i. TO i : e length of time during which the unit is on. TS i : e length of time during which the unit is off. 2. Introduction e purpose of economic planning of power units is to achieve an optimal combination of producing units connected to the network in order to supply the load of network. e issue of economic load distribution is classi- fied into two sub-problems: 1) UC problem, 2) Online load economic distribution (optimal load distribution). e UC problem selects the units which supply the predicted load of system at the lowest cost in a specified timeframe and also includes spinning reserve requirements. Sub-issue of load economic distribution distributes the predicted load in the selected power plant units so that the network load is distributed among the generating units in a way that