The paper summarizes development of coordinated reactive power-voltage controller and PLC based laboratory test rig for multi generator thermal power plant. Theoretical background and basic practical requirements are clearly stated. Following this, several examples are presented to illustrate some of identified advantages and drawbacks of developed test rig during the laboratory testing of CQVC controller which led to improvement both test rig and CQVC controller design. The paper presents full cycle of development of advanced controller, from laboratory test model of steam power plant to practical device. It demonstrates the necessity for and benefits of developing adequate test platform and opens the possibility of its use in further applications.