Study of Power Converter Topologies with Energy Recovery and grid power flow control Part B: boost converter with energy storage

In the framework of a Transfer line (TT2) Consolidation Programme, a number of studies on Energy cycling have been commissioned. Part of this work involves the study of dierent power electronic system topologies for magnet energy recovery. In this report, the use of a boost front-end converter supplying DC link of a 4-quadrant magnet supply is analysed. The key objective of the study is to find control strategies that result in the control of the peak power required from the power network as well as to recover the magnet energy into capacitor banks with controlled voltage fluctuation. The study comprises the modelling of the system by means of the method of state averaging and the development of regulation strategies to energy management. The proposed control strategies can be divided in two groups: in the first group, the magnet current is used to define the reference for the control system, while in the second group this current is unknown and some strategies are devised to limit the power drawn from the electrical network. The control strategies of the first group (named energy balance) result in an indirect control of the grid peak power by means of achieving an energy flow balance between the magnet and the energy storing elements. In the second group, the reference of the control system is defined to bound the grid current during either generation of a magnet cycle or between cycles. The development of the required design equations is presented and the main features of each strategy are highlighted. In addition, a comparative study about the energy that must handle the boost converter, which allows to properly size the reactive elements, together with the current drawn from the electrical network is presented for each strategy.