Compensation of Oscillating Instantaneous Power in Modern Microgrids Based on the Conservative Power Theory

Abstract

Considering the application of multi-functional grid-tied inverters in modern microgrids, this paper proposes a novel control strategy derived from the Conservative Power Theory (CPT), which makes possible the compensation of instantaneous power oscillations. Such approach is based on the instantaneous power and instantaneous reactive energy terms defined by the CPT, allowing the extraction of oscillating power components directly in the abc frame. Simulation results are presented to demonstrate the applicability of the control strategy considering the scenario of a weak microgrid with linear, non-linear, and unbalanced loads, as well as comprising a three-phase multi-functional grid-tied inverter with LCL filter. The results show that active power dispatchability can be offered by the inverter, while concomitantly supporting the microgrid to operate at constant instantaneous power. Experimental results comprising a 3.6 kVA inverter prototype also validate the proposed decomposition of oscillating power terms, showing that they can be satisfactorily employed on compensation purposes.

Keywords

• Conservative Power Theory
• Instantaneous Power Oscillations
• Microgrid
• Multifunctional Grid-Tied Inverters
• Power Quality