Modeling and Simulation of Superconducting Magnetic Energy Storage System as Distributed Generation Power Source

In recent years, energy storage systems such as superconducting magnetic energy storage (SMES), have received significant interest as an advanced solutions for distributed generation and high power applications, gradually. In this paper, a detailed model of the SMES system as a distributed generation source has been proposed. This model is composed of a bi-directional three-level chopper, a three-level Neutral pointclamped (NPC) voltage source converter (VSC), a LCL filter and a power network coupling transformer. This model has been studied through electrical circuits, switching and control strategies for each component. Also, a novel switching strategy and control approach for controlling bi-directional three-level chopper, as feeding a three-level VSC in the SMES system, is presented. Simultaneously and independently DC-link capacitors voltage control, and high-speed and limiting the switching frequency, are the most important features of proposed switching algorithm. TheSMES system can be employed in two connected and disconnected cases to the power grid, for supply the local load and active and reactive power exchange with grid, respectively. A control scheme to simultaneously and independently control active and reactive power flows in the connected case is proposed. Proposed model and control approaches have been verified through digital simulations carried out in MATLAB/Simulink. Studies on the simulation results show the validity and effectiveness of the proposed modeling and control approaches.

Keywords:

Superconducting magnetic energy storage (SMES) , Bi-directional threelevel chopper , Power controller