This article proposes a novel distributed control approach for Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) method to determine Energy Storage Systems (ESSs) requirements for three-phase, inverter-based Microgrids (MGs). Here, local system references are obtained through a primary d-q droop control which is supported by a level-zero Hamiltonian controller. ESS devices are the actuators of the system to enforce reference points. The control approach as well as power flow and energy transfer model of the MG enables the ESS capacity and bandwidth to be obtained. As a result, a zero-output ESS element analysis is defined which can further be used to study storage requirements versus additional constraints. Communication network update-rate can affect ESSs and filtering requirements. The developed analysis is demonstrated in parallel and looped nine-bus WSCC reduced-order MG system examples to obtain ESS requirements versus communication network update-rate (bandwidth).

This paper presents a proof-of-concept for a novel dq droop control technique that applies DC droop control methods to fixed frequency inverter-based AC microgrids using the dq0 transformation. Microgrids are usually composed of distributed generation units (DGUs) that are electronically coupled to each other through power converters. An inherent property of inverter-based microgrids is that, unlike microgrids with spinning machines, the frequency of the parallel-connected DGUs is a global variable independent from the output power since the inverters can control the output waveform frequency with a high level of precision. Therefore, conventional droop control methods that distort the system frequency are not suitable for microgrids operating at a fixed frequency. It is shown that the proposed distributed droop control allows accurate sharing of the active and reactive power without altering the microgrid frequency. The simulation and hardware-in-the-loop (HIL) results are presented to demonstrate the efficacy of the proposed droop control. Indeed, following a load change, the dq droop controller was able to share both active and reactive power between the DGUs, whereas maintaining the microgrid frequency deviation at 0% and the bus voltage deviations below 6% of their respective nominal values.

The intermittent nature of renewable sources requires the integration of Energy Storage Systems (ESSs) with appropriate power and energy densities. One of the applications of Hamiltonian Surface Shaping and Power Flow Control (HSSPFC) is to size ESSs for power and energy densities by employing them as sole actuators of Microgrid (MG) systems. This Article provides a comprehensive yet simplified example of utilization of HSSPFC to size ESSs of inverter-based three-phase MG systems under hierarchical control. Here, the distributed Hamiltonian controller is expanded for control of parallel ESSs and power sharing metrics are defined to distribute power between hybrid storage systems according to their power and energy density capabilities. Simulated hybrid ESSs comprising battery and flywheel systems are used as examples to demonstrate the behaviour of the expanded control, verify the power sharing criteria and illustrate ESS design and specification by utilizing HSSPFC.