An NIHOC-GI-FLL Control With Seasonal ToU Tariff Based Economic Power Regulation for a Weak Grid Tied Optimally Sized SPV-BES System

A seasonal, time-incentivized tariff structure is followed to remunerate the consumers to draw power during low demand conditions from the grid and sell surplus power during peak demand conditions. The incentivized tariff also depends on seasonal generation and demand profiles. The economic operation of the microgrid largely depends on the coherency between the power utilization profile with the seasonal time of use (ToU) tariff. Moreover, the microgrid operators may also be penalized for drawing nonlinear and highly reactive currents from the grids. Therefore, in this work, a complete power regulation strategy is developed to enable the overall energy consumption profile analogous to the seasonal ToU tariff profile keeping battery constraints and overloading protection into consideration. The system under consideration comprises of a grid-tied, two-stage solar photovoltaic (PV) array and a battery to ensure the required degree of freedom for power levelling. To prevent the reflection of the harmonics of the load currents, a non-identical higher order cascaded generalized integrator (NIHOC-GI) type filter is used to linearize the grid currents, even during weak grid and distorted load conditions. A frequency locked loop (FLL) is used to make the NIHOC-GI adaptive to the varying grid frequency. An optimization technique is also presented to select the optimal battery energy storage (BES) size for a given/ selected PV array size. The model of the above system is developed in Simulink and its performance with the NIHOC-GI-FLL control and the proposed seasonal ToU tariff-based power regulation strategy is analyzed in various conditions using simulation results.