Compensating-symmetrizing process control using virtual instrumentation

The single phase high power receivers, mains connected according to Steinmetz schemes, can produce important asymmetries of the network currents and voltages. Therefore, a compensation and symmetrization control strategy is required in order to minimize the mentioned asymmetries. The negative asymmetry (dissymmetry) coefficient has been chosen as aim function of the entire process. Consequently, after each data acquisition, the method goal is to find the adequate combination of the circuit components steps from the realised laboratory work-bench, in order to provide the optimal run of the system. For an accurate symmetrizing estimation, a data acquisition and computing system, based on a PC and a data acquisition (DAQ) card, connected to the single phase receiver electrical installation, is required. The virtual instrumentation, based on the Lab VIEW software, has been chosen in order to solve the software problems of this application. The implemented program includes the following main steps: the real frequency calculus, the amplitude and phase determination for each variable; the optimum value for the compensating capacitor; the minimization of the dissymmetry coefficient, the automatic control of the process.