Experimental study on power output suppression control of photovoltaic power generation during electricity surplus in electric power system

In a future electric power system with high penetration photovoltaic power generation system (PVS), the surplus power may occur during the daytime in the middle season of low electricity demand. Suppressing the PVS power output as well as absorbing the surplus power by using electric storage facilities is one of the measures. By considering the fairness among a number of PVS dispersed in a large area with different insolation level, this study proposes a method to keep the PVS power output at the utility's requested ratio to the available power, and demonstrated the usability of the proposed method by using a simplified experimental setup of PVS. In the proposed method, the operation point on the I-V curve is kept at lower value than the maximum power point (P PV-X), so that the mean value of PV power during a certain period meets the requested value. P PV-X is detected without any additional sensor devices by changing the operation point with a certain interval. An experimental test using a test inverter unit demonstrated that the proposed suppression control works well to keep the requested suppression level when the insolation is stable. Two types of control modes, i.e. proposed suppression mode and upper bounded MPPT mode, were applied, so that the proposed suppression control works well for various insolation patterns, which was revealed by using a simulation model of the inverter test unit and the insolation data for a year. © 2012 The Institute of Electrical Engineers of Japan.