Energy Space Modeling of Power Electronics in Local Area Power Networks

Power electronics are a core enabling technology for local area power networks and microgrids for renewable energy, telecom, data centers, and many other applications. Unfortunately, the modeling, simulation, and control of power electronics in these systems are complicated when using traditional converter models in conjunction with the network nodal equations. This work proposes a change of variables for the power electronic converter models from traditional voltage and currents to input conductance and stored energy. From this change of state, a universal point of load converter model can be utilized in the network nodal equations irrespective of the topology of the converter. The only impact the original converter topology has on the new model is the bounds on the control and state variables, and the mapping back to the switching or duty cycle controls. The proposed approach greatly simplifies the modeling of local area power networks and microgrids. This simpler model can be used to study stability and energy utilization and develop high-level control strategies that were not previously feasible. 1. Introduction Power electronics are increasingly being used as the interface between a local area power network, or microgrid, and the final load (FL). The wide ranges of applications include the terrestrial grid, hybrid and electric vehicles, consumer electronics, telecom systems, and many others. Interfacing point of load converters (POLCs) are used to provide controllability and act as an energy gate to an FL application. In ac power networks, the dc/dc POLC typically also implements a power factor correction function [1] that is difficult to model as a networked systems. Even in dc power networks and microgrids, such as telecom [2], future naval electric ships [3], electric aircraft [4], computer data centers [5], and other highly sensitive and robust systems [6–8], the modeling of the power distribution network and the power electronics is not integrated. This paper proposes a modeling approach for power electronic converters that enables direct and simple model integration into the nodal equations of a power distribution network. The POLCs are typically viewed, modeled, and controlled as a voltage translator, converting voltage levels from those provided by the source to a suitable level needed by the FL. An alternative approach is to view a POLC as an admittance translator that takes the FL impedance and reflects it to the power network. In this way, the analysis, modeling, and control synthesis of the POLCs in the local area power network becomes