A minimal-order observer based coordinated control method for isolated power utility connected multiple PV systems to reduce frequency deviations

In this paper, a simple coordinated control method based on minimal-order observer for multiple PV systems is proposed. Here, output power command is generated in two steps: central and local. Estimated load power is used to generate the central output power command considering load variation index and PV base power. Load power is estimated by a minimal-order observer. Then, load variation index is calculated. PV base power is produced from available maximum PV power using a low-pass filter and is added with load variation index to generate central PV output power command. In local step, a simple coordination is maintained between central power command and local power commands by producing a common tuning factor. The proposed method is compared with the method where maximum power point tracking (MPPT) control is used for each of the PV systems without coordination. Simulation results show that the proposed method is feasible to reduce the frequency deviations of the power utility and also delivers power near maximum PV power.