Abstract: Aiming at the problems of limited voltage adjustment margin, high penetration rate of variable frequency air conditioners and their low sensitivity to voltage changes for conservation voltage reduction(CVR) technology, a multi-time scale control technology for flexible resources in distribution networks within the framework of voltage-load regulation is proposed. Firstly, CVR is modeled and its energy-saving benefits in the distribution network are analyzed. Secondly, a load model for variable frequency air conditioners is established to assess its regulation and control potential. On this basis, a multi-time scale optimization control strategy for the distribution network is proposed and formulated. In the day-ahead scheduling phase, the regulation and control schemes for onload tap changers(OLTC), air conditioning loads, and distributed resources are planned in advance to reduce the peak regulation pressure of the distribution network on the upper grid. In the intra-day optimization phase, in response to potential voltage limit violations, the OLTC gear is adjusted in real time, and flexible and adjustable resources in the distribution network are controlled in real time based on electrical distance to realize rapid recovery of grid voltage, thereby enhancing the stability and robustness of the system. Finally, a case study based on the IEEE 33-node system is conducted to verify the effectiveness of the proposed strategy.

Key words: distribution network, meeting the peak in summer, conservation voltage reduction(CVR), air conditioning load, multi-time scale optimization, electrical distance