Energy Savings Estimation of a Distribution System in Presence of Intelligent Volt-VAr Control Based on IEEE Std. 1547-2018

In the present scenario, many solar photovoltaic (SPV) systems have been installed in the distribution network, most of them are operating at the unity power factor, which does not provide any reactive power support. In future distribution grids, there will be significant advances in operating strategies of SPV systems with the introduction of smart inverter functions. The new IEEE Std. 1547-2018 incorporates dynamic Volt/VAr control (VVC) for smart inverters. These smart inverters can inject or absorb reactive power and maintain voltages at points of common coupling (PCCs) based on local voltage measurements. With multiple inverter-interfaced SPV systems connected to the grid, it becomes a necessary task to develop local, distributed or hybrid VVC algorithms for maximization of energy savings. This paper aims to estimate substation energy savings through centralized and decentralized control of inverters of SPV system alongside various VVC devices. Control strategies of each SPV inverter have been accomplished in compliance with IEEE Std. 1547-2018. Time-series simulations are carried out on the modified IEEE-123 node test system. By utilizing smart inverters in traditional SPV systems, considerable energy savings can be obtained. These savings can be further increased by incorporating optimal intelligent VVC characteristics (IVVCC). Results show that just by allowing smart inverters on a predefined IVVCC (as per IEEE Std. 1547-2018), a reduction of 11.69% in reactive demand and 5.63% in active demand have been acquired when compared with a conventional SPV system. Reactive energy demand is additionally reduced to 48.42% by considering centralized control of VVC devices alongside optimal IVVCC.