Conservative power theory and its applications in modern smart grid: Review and prospect

As the worldwide trend of “carbon neutrality” action spreads, renewable energy substitution for fossil fuels in the electricity sector is inevitable. The traditional power system is updating to a new paradigm of smart grid to promote the consumption of renewable energy and phasing out of fossil fuels. However, this transition would bring about new tremendous challenges on power quality and operation & control of the power system. As the traditional power theories may not be able to handle the non-sinusoidal voltages, unbalanced and/or non-linear loads that are prevalent in evolving smart grid, a novel time-domain Conservative Power Theory (CPT) was proposed in the early 2000 s. So far, more than 190 papers have been published focusing on this attractive theory. This paper gives a summative and comparative overview of CPT and its innovative applications in modern smart grids. Horizontal comparisons among CPT and other common non-sinusoidal power theories are briefly performed and then the mile-stones in CPT’s development are highlighted. Basic power and current definitions under the CPT framework for both single-phase and three-phase systems are described in detail, and four main applications of CPT are discussed, which are load characteristic identification, accountability and revenue, filter and compensation, and power converters. Based on the review, the motivations, definitions, developments, and applications of CPT are comprehensively presented, some possible research aspects of CPT are itemized, and a future vision of CPT-based smart grid scenario is then conclusively predicted.