Contributions to the size reduction of a battery used for PV power ramp rate control

Resumen

In order to mitigate PV power fluctuations, ramp rate control is performed coupling battery energy storage systems to PV plants. In previous works, we developed a method to minimise the power and energy capacity of a battery by considering the probability of occurrence of fluctuations and a penalty imposed in the event of not complying with a certain prescribed ramp-rate limitation. In this work, two new techniques are proposed for enhancing that method, by including in the analysis the smoothing capabilities provided by PV inverters power limitation and the oversizing of the PV array. In the first technique, a control strategy is implemented to mitigate upwards fluctuations by balancing the use of a highly reduced battery with the control of inverters power. In the second technique, the PV array is oversized to smooth high frequency fluctuations by means of the low pass filter effect provided by a larger array and by clipping the low amplitude fluctuations. With the proposed techniques, a battery can be reduced by up to 70% without penalising the energy production injected following the requirements of a grid-code.