Enhancing the provision of ancillary services from storage systems using smart transformer and smart meters

The Smart Transformer, a solid-state transformer with control and communication functionalities, can be the ideal solution for integrating storage into the grid. By leveraging the knowledge of the grid state of distribution grids thanks to smart meters and/or dedicated remote terminal units, in the paper, it is proposed a control strategy for a MV/LV smart transformer (ST) with integrated storage to achieve: i) dispatched-by-design operation of the LV network by controlling the ST active power set-point on the MV power converter, and ii) voltage regulation of both MV and LV networks by controlling the reactive power injections of both LV and MV converter. The former is achieved by dispatching the active power flow of the LV network according to a profile established the day before the operation, called \emph{dispatch plan}, with the objective of reducing the amount of regulating power required to operate the grid. It is based on the use of forecast to compute a dispatch plan, and a tracking problem to compensate in real-time the mismatch between realization and dispatch plan by taking advantage of the storage capacity. The latter is achieved by using sensitivity coefficients, which are calculated from the state of the grid and integrating the information on the network topology. The problem formulation is given in the paper, and the proof-of-concept is shown by simulation using the IEEE 34 nodes test feeder and the CIGRE Low Voltage reference network

Strategic allocation and energy management of BESS for the provision of ancillary services in active distribution networks

The increased penetration of renewables has prompted the integration of battery energy storage systems (BESSs) in active distribution networks. The BESS not only act as backup power supply but also provides various ancillary services with extra degree of flexibility to distribution networks by changing its' role as generation and load. In this study, a new optimization framework is developed to optimally allocate the intense wind power generation units and BESSs considering its ancillary services in distribution systems. The BESSs are strategically allocated at two sites in coordination with the renewable generating source. One is installed at grid substation to participate in central ancillary services whereas; second will be used to participate in distributed ancillary services. The objective is to minimize the cost of annual energy loss while performing various ancillary services in distribution network. The proposed optimization framework is implemented on a real-life 108-bus Indian distribution system for different cases and solved using genetic algorithm. The comparison of simulation results show that the proposed optimization framework provides more energy loss reduction, improved system voltage and power factor at higher penetration of wind power generation units as compared to the cases in which ancillary services are not considered in planning