Reactive Power Optimization problem has significant influence on secure and economic operation of power system. In this Book Bio - inspired Algorithms (AGA, SEPSO, ARPSO, and ACSA) has been applied to solve Reactive power optimization problem. And the proposed algorithms has been evaluated in standard IEEE, 30-bus system, 57-bus system & practical 191 utility (Indian) system. Secondly ACSA has been applied for unit commitment problem & tested in 10 unit's model power system. Thirdly ACSA has been applied to short-term generation scheduling problem & evaluated in 6 unit's model power system. Finally ACSA has applied to solve optimal power flow algorithm to evaluate load curtailment incorporating voltage stability margin criterion. And the proposed approach has been evaluated on WSCC 9-bus test system.