This paper describes newly designed coordinated Q-V controller (CQVC), for a multi machine steam power plant (SPP). After giving design specification and theoretical background for designed CQVC, the paper focuses on practical implementation and performance of commissioned CQVC. Following several innovations are introduced in design of controller: sensitivity matrix concept is applied at plant level to decouple generators connected to the same busbars, steady state detection is used for the decoupling between synchronous generator dynamics and network dynamics, the response is shaped by the use of predictor corrector method. Issues related to practical implementation of CQVC in SPP such as online estimation of network reactance and generators' reactive power capability are also addressed and discussed in the paper. Finally the paper shows examples of recorded plant responses after commissioning of the proposed controller. © 2013 IEEE.