Cascade-Controller System of Hydroponic Nutrient Solution

Generally, the process of making hydroponic nutrients with AB mix basic ingredients is done manually. Starting from defining the ratio of solutions "A" and "B", water supply, and the stirring process until the solution is evenly mixed. Nowadays, our technology is allowing the process to be done automatically. The multilevel control system applied to this process has 2 control variables and 1 support system, namely stirrer. The first variable; water volume; is controlled by the PID method, with servo output as the setting of the water tap opening. The second variable; nutrient concentration; is also controlled by the PID method, where the output is a DC pump that injects solutions "A" and "B". In maximizing the yield of an even solution, stirrer is also applied which is controlled by the multilevel control method. This means that the stirrer is regulated by PID control of water volume and PID of nutrient concentration. The test results of the variable water volume system with Kp = 1.2, Ki = 0.0001, and Kd = 0.0008 obtained a rise time of 76 seconds and a settling time of 74 seconds for a volume input value of 2.5 liters. The variation of nutrient concentration with Kp = 2, Ki = 0.0001, and Kd = 0.001 obtained a rise time of 30 seconds and a settling time of 55 seconds for the difference in concentration between the initial and final values of 50 ppm.